Attitudinal and Relational Factors Predicting the Use of Solar Water Disinfection: A Field Study in Nicaragua

ERIC Educational Resources Information Center

Altherr, Anne-Marie; Mosler, Hans-Joachim; Tobias, Robert; Butera, Fabrizio

2008-01-01

Solar water disinfection (SODIS) is an uncomplicated and cheap technology providing individuals with safe drinking water by exposing water-filled plastic bottles to sunlight for 6 hours to kill waterborne pathogens. Two communities were visited, and 81 families (40 SODIS users and 41 nonusers) were interviewed. The relationship between several…

Combining sun-based technologies (microalgae and solar disinfection) for urban wastewater regeneration.

PubMed

Gutiérrez-Alfaro, Sergio; Rueda-Márquez, Juan J; Perales, José A; Manzano, Manuel A

2018-04-01

Solar disinfection (SODIS) of urban wastewater can be a suitable technology for improving the microbiological quality of reclaimed water as a complement to other extensive and environmentally friendly technologies such as microalgae biotreatment. The objective of this work is to evaluate the feasibility of incorporating the SODIS technology at the end of a pilot scale urban wastewater treatment plant (WWTP) where the processes are based on microalgae biotechnology and comprising three Upflow Anaerobic Sludge Blanket (UASB, 20m 3 each one) reactor, six High Rate Algal Ponds (HRAP, 32m 2 each one), and a Dissolved Air Flotation (DAF, 1m 3 ) unit. E. coli concentration was monitored at the effluent of the different units (UASB, HRAP, DAF) of the pilot WWTP. The efficiency of the SODIS process was studied for the inactivation of three of the commonly employed indicator microorganisms (Escherichia coli, Enterococcus spp. and Clostridium perfringens) using a compound parabolic collector (CPC) for five months under various conditions of irradiance and temperature. E. coli and Enterococcus spp. were more effectively disinfected by the SODIS unit (2.9 and 2.5 logarithms of reduction on average, respectively) than by the HRAP (2 and 1.1) or the DAF (0.9 and 0.1). On the contrary, the DAF technology achieved better reduction rates of C. perfringens (1.7) than the SODIS (0.9) and the HRAP (0.1). No regrowth of any microorganisms was detected during dark storage after the SODIS treatment. Incorporating a SODIS unit after the non-conventional WWTP processes substantially increases the possibilities for reuse of the treated water after receiving a cumulative UV radiation dose of 25W·h/m 2 (50min of normalized time of solar illumination). The surface requirement of the SODIS equipment would be 3.5 times smaller than the HRAP's surface. Copyright © 2017 Elsevier B.V. All rights reserved.

Achieving long-term use of solar water disinfection in Zimbabwe.

PubMed

Mosler, H-J; Kraemer, S M; Johnston, R B

2013-01-01

To use a psychological theory of behavioural change to measure and interpret the effectiveness of different promotional strategies for achieving long-term usage of a household water treatment and safe storage (HWTS) system in peri-urban Zimbabwe. Solar disinfection (SODIS) was introduced into five peri-urban communities near Harare, Zimbabwe. Six different interventions were developed and were applied in four communities in different combinations, with the fifth remaining as a control area where no interventions were implemented. Throughout the 26 months of the study nine longitudinal panel surveys were conducted in which SODIS usage was estimated using three separate metrics: reported, calculated, and observed. A total of 1551 people were interviewed. The three indicators of SODIS usage broadly agreed with one another. By any measure, the most effective intervention was household visits by trained promoters in combination with persuasion. Households which received household visits maintained SODIS usage rates of 65% or more, even six months after the cessation of all promotional activities. Households receiving other interventions were significantly less effective. Interventions like prompts or public commitment after the application of household visits were effective at maintaining good practices once these were established. Household promotion in combination with persuasion appears more effective than other approaches, especially when followed with interventions targeting the maintenance of the new behaviour. With this intervention it is possible that around 65% of the households continue to use solar water disinfection (SODIS) more than two years after the initial promotion, and six months after the end of all interventions. Copyright © 2012 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Safety and durability of low-density polyethylene bags in solar water disinfection applications.

PubMed

Danwittayakul, Supamas; Songngam, Supachai; Fhulua, Tipawan; Muangkasem, Panida; Sukkasi, Sittha

2017-08-01

Solar water disinfection (SODIS) is a simple point-of-use process that uses sunlight to disinfect water for drinking. Polyethylene terephthalate (PET) bottles are typically used as water containers for SODIS, but a new SODIS container design has recently been developed with low-density polyethylene (LDPE) bags and can overcome the drawbacks of PET bottles. Two nesting layers of LDPE bags are used in the new design: the inner layer containing the water to be disinfected and the outer one creating air insulation to minimize heat loss from the water to the surroundings. This work investigated the degradation of LDPE bags used in the new design in actual SODIS conditions over a period of 12 weeks. The degradation of the LDPE bags was investigated weekly using a scanning electron microscope, Fourier transform infrared spectroscopy, ultraviolet-visible spectrophotometer, and tensile strength tester. It was found that the LDPE bags gradually degraded under the sunlight due to photo-oxidation reactions, especially in the outer bags, which were directly exposed to the sun and surroundings, leading to the reduction of light transmittance (by 11% at 300 nm) and tensile strength (by 33%). In addition, possible leaching of organic compounds into the water contained in the inner bags was examined using gas chromatography-mass spectrometer. 2,4-Di-tert-butylphenol was found in some SODIS water samples as well as the as-received water samples, in the concentration range of 1-4 μg/L, which passes the Environmental Protection Agency Drinking Water Guidance on Disinfection By-Products.

Application of solar disinfection for treatment of contaminated public water supply in a developing country: field observations.

PubMed

Mustafa, Atif; Scholz, Miklas; Khan, Sadia; Ghaffar, Abdul

2013-03-01

A sustainable and low-cost point-of-use household drinking water solar disinfection (SODIS) technology was successfully applied to treat microbiologically contaminated water. Field experiments were conducted to determine the efficiency of SODIS and evaluate the potential benefits and limitations of SODIS under local climatic conditions in Karachi, Pakistan. In order to enhance the efficiency of SODIS, the application of physical interventions were also investigated. Twenty per cent of the total samples met drinking water guidelines under strong sunlight weather conditions, showing that SODIS is effective for complete disinfection under specific conditions. Physical interventions, including black-backed and reflecting rear surfaces in the batch reactors, enhanced SODIS performance. Microbial regrowth was also investigated and found to be more controlled in reactors with reflective and black-backed surfaces. The transfer of plasticizer di(2-ethylhexyl)phthalate (DEHP) released from the bottle material polyethylene terephthalate (PET) under SODIS conditions was also investigated. The maximum DEHP concentration in SODIS-treated water was 0.38 μg/L less than the value of 0.71 μg/L reported in a previous study and well below the WHO drinking-quality guideline value. Thus SODIS-treated water can successfully be used by the people living in squatter settlements of mega-cities, such as Karachi, with some limitations.

Carbon nanoparticles for solar disinfection of water.

PubMed

Maddigpu, Pratap Reddy; Sawant, Bhairavi; Wanjari, Snehal; Goel, M D; Vione, Davide; Dhodapkar, Rita S; Rayalu, S

2018-02-05

The present manuscript deals with the application of carbon nano particles (CNP) and chitosan (CHIT) in the form of CHIT-CNP composite for the disinfection of water. The CHIT-CNP composite was prepared by the solution casting method and characterized by TEM, XRD and elemental analysis. In the present investigation we study the disinfection efficiency towards E. coli bacteria of both CNP and CHIT-CNP, under sunlight (SODIS) in identical experimental conditions. Both CNP and CHIT-CNP enhanced disinfection as compared to SODIS alone, and comparable performance was achieved when the same dose of CNP in the two materials was applied. However, the CHIT-CNP composite is in the form of a fabric and it is easier to use and handle as compared to the CNP powder, especially in rural and resource-constrained areas. Moreover the SODIS-CHIT-CNP setup, when used in a compound parabolic collector (CPC) reactor showed high bactericidal efficiency compared to SODIS alone, which is promising for practical applications. The disinfection potential of the CNP powder was compared with that of the well-known material TiO 2 Degussa P25 (DP 25 ): DP 25 gave 6-log kill of bacteria in 180min, whereas CNP produced 6-log kill in 150min. Copyright © 2017. Published by Elsevier B.V.

The potential of solar water disinfection as a household water treatment method in peri-urban Zimbabwe

NASA Astrophysics Data System (ADS)

Murinda, Sharon; Kraemer, Silvie

The potential for reducing diarrhoea morbidity and improving the health status of children in developing countries using solar water disinfection (SODIS) has been demonstrated in past research. A baseline survey was conducted to explore the feasibility and necessity of introducing SODIS in peri-urban communities of Zimbabwe. The survey sought to establish drinking water quality in these areas and to determine the health and hygiene beliefs as well as practices related to water handling in the household. Microbiological water quality tests and personal interviews were carried out in Epworth township and Hopley farm, two peri-urban areas near the capital of Zimbabwe, Harare. These two areas are among the poorest settlements around Harare with 80% of inhabitants being informal settlers. Community meetings were held to introduce solar water disinfection prior to the survey. This was followed by administration of questionnaires, which aimed to investigate whether the community had ever heard about SODIS, whether they were practicing it, other means that were being used to treat drinking water as well as health and hygiene beliefs and practices. It was found out that most households cannot afford basic water treatment like boiling as firewood is expensive. People generally reported that the water was not palatable due to objectionable odour and taste. Microbiological water quality tests proved that drinking water was contaminated in both areas, which makes the water unsafe for drinking and shows the necessity of treatment. Although the majority of people interviewed had not heard of SODIS prior to the interview, attitudes towards its introduction were very positive and the intention to do SODIS in the future was high. Amongst the ones who had heard about SODIS before the study, usage was high. Plastic PET bottles, which were used for the SODIS experiments are currently unavailable and this has been identified as a potential hindrance to the successful implementation of

Effect of Batch-Process Solar Disinfection on Survival of Cryptosporidium parvum Oocysts in Drinking Water

PubMed Central

Méndez-Hermida, F.; Castro-Hermida, J. A.; Ares-Mazás, E.; Kehoe, S. C.; McGuigan, K. G.

2005-01-01

The results of batch-process solar disinfection (SODIS) of Cryptosporidium parvum oocysts in water are reported. Oocyst suspensions were exposed to simulated sunlight (830 W m−2) at 40°C. Viability assays (4′,6′-diamidino-2-phenylindole [DAPI]/propidium iodide and excystation) and infectivity tests (Swiss CD-1 suckling mice) were performed. SODIS exposures of 6 and 12 h reduced oocyst infectivity from 100% to 7.5% (standard deviation = 2.3) and 0% (standard deviation = 0.0), respectively. PMID:15746372

Comparative analysis of solar pasteurization versus solar disinfection for the treatment of harvested rainwater.

PubMed

Strauss, André; Dobrowsky, Penelope Heather; Ndlovu, Thando; Reyneke, Brandon; Khan, Wesaal

2016-12-09

Numerous pathogens and opportunistic pathogens have been detected in harvested rainwater. Developing countries, in particular, require time- and cost-effective treatment strategies to improve the quality of this water source. The primary aim of the current study was thus to compare solar pasteurization (SOPAS; 70 to 79 °C; 80 to 89 °C; and ≥90 °C) to solar disinfection (SODIS; 6 and 8 hrs) for their efficiency in reducing the level of microbial contamination in harvested rainwater. The chemical quality (anions and cations) of the SOPAS and SODIS treated and untreated rainwater samples were also monitored. While the anion concentrations in all the samples were within drinking water guidelines, the concentrations of lead (Pb) and nickel (Ni) exceeded the guidelines in all the SOPAS samples. Additionally, the iron (Fe) concentrations in both the SODIS 6 and 8 hr samples were above the drinking water guidelines. A >99% reduction in Escherichia coli and heterotrophic bacteria counts was then obtained in the SOPAS and SODIS samples. Ethidium monoazide bromide quantitative polymerase chain reaction (EMA-qPCR) analysis revealed a 94.70% reduction in viable Legionella copy numbers in the SOPAS samples, while SODIS after 6 and 8 hrs yielded a 50.60% and 75.22% decrease, respectively. Similarly, a 99.61% reduction in viable Pseudomonas copy numbers was observed after SOPAS treatment, while SODIS after 6 and 8 hrs yielded a 47.27% and 58.31% decrease, respectively. While both the SOPAS and SODIS systems reduced the indicator counts to below the detection limit, EMA-qPCR analysis indicated that SOPAS treatment yielded a 2- and 3-log reduction in viable Legionella and Pseudomonas copy numbers, respectively. Additionally, SODIS after 8 hrs yielded a 2-log and 1-log reduction in Legionella and Pseudomonas copy numbers, respectively and could be considered as an alternative, cost-effective treatment method for harvested rainwater.

Solar Disinfection of Viruses in Polyethylene Terephthalate Bottles

PubMed Central

Carratalà, Anna; Dionisio Calado, Alex; Mattle, Michael J.; Meierhofer, Regula; Luzi, Samuel

2015-01-01

Solar disinfection (SODIS) of drinking water in polyethylene terephthalate (PET) bottles is a simple, efficient point-of-use technique for the inactivation of many bacterial pathogens. In contrast, the efficiency of SODIS against viruses is not well known. In this work, we studied the inactivation of bacteriophages (MS2 and ϕX174) and human viruses (echovirus 11 and adenovirus type 2) by SODIS. We conducted experiments in PET bottles exposed to (simulated) sunlight at different temperatures (15, 22, 26, and 40°C) and in water sources of diverse compositions and origins (India and Switzerland). Good inactivation of MS2 (>6-log inactivation after exposure to a total fluence of 1.34 kJ/cm2) was achieved in Swiss tap water at 22°C, while less-efficient inactivation was observed in Indian waters and for echovirus (1.5-log inactivation at the same fluence). The DNA viruses studied, ϕX174 and adenovirus, were resistant to SODIS, and the inactivation observed was equivalent to that occurring in the dark. High temperatures enhanced MS2 inactivation substantially; at 40°C, 3-log inactivation was achieved in Swiss tap water after exposure to a fluence of only 0.18 kJ/cm2. Overall, our findings demonstrate that SODIS may reduce the load of single-stranded RNA (ssRNA) viruses, such as echoviruses, particularly at high temperatures and in photoreactive matrices. In contrast, complementary measures may be needed to ensure efficient inactivation during SODIS of DNA viruses resistant to oxidation. PMID:26497451

Solar Disinfection of Viruses in Polyethylene Terephthalate Bottles.

PubMed

Carratalà, Anna; Dionisio Calado, Alex; Mattle, Michael J; Meierhofer, Regula; Luzi, Samuel; Kohn, Tamar

2016-01-01

Solar disinfection (SODIS) of drinking water in polyethylene terephthalate (PET) bottles is a simple, efficient point-of-use technique for the inactivation of many bacterial pathogens. In contrast, the efficiency of SODIS against viruses is not well known. In this work, we studied the inactivation of bacteriophages (MS2 and ϕX174) and human viruses (echovirus 11 and adenovirus type 2) by SODIS. We conducted experiments in PET bottles exposed to (simulated) sunlight at different temperatures (15, 22, 26, and 40°C) and in water sources of diverse compositions and origins (India and Switzerland). Good inactivation of MS2 (>6-log inactivation after exposure to a total fluence of 1.34 kJ/cm(2)) was achieved in Swiss tap water at 22°C, while less-efficient inactivation was observed in Indian waters and for echovirus (1.5-log inactivation at the same fluence). The DNA viruses studied, ϕX174 and adenovirus, were resistant to SODIS, and the inactivation observed was equivalent to that occurring in the dark. High temperatures enhanced MS2 inactivation substantially; at 40°C, 3-log inactivation was achieved in Swiss tap water after exposure to a fluence of only 0.18 kJ/cm(2). Overall, our findings demonstrate that SODIS may reduce the load of single-stranded RNA (ssRNA) viruses, such as echoviruses, particularly at high temperatures and in photoreactive matrices. In contrast, complementary measures may be needed to ensure efficient inactivation during SODIS of DNA viruses resistant to oxidation. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Thermal Contribution to the Inactivation of Cryptosporidium in Plastic Bottles during Solar Water Disinfection Procedures

PubMed Central

Gómez-Couso, Hipólito; Fontán-Sainz, María; Ares-Mazás, Elvira

2010-01-01

To determine the thermal contribution, independent of ultraviolet radiation, on the inactivation of Cryptosporidium parvum during solar water disinfection procedures (SODIS), oocysts were exposed for 4, 8, and 12 hours to temperatures recorded in polyethylene terephthalate bottles in previous SODIS studies carried out under field conditions. Inclusion/exclusion of the fluorogenic vital dye propidium iodide, spontaneous excystation, and infectivity studies were used to determine the inactivation of oocysts. There was a significant increase in the percentage of oocysts that took up propidium iodide and in the number of oocysts that excysted spontaneously. There was also a significant decrease in the intensity of infection elicited in suckling mice at the end of all exposure times. The results of the study demonstrate the importance of temperature in the inactivation of C. parvum oocysts during application of SODIS under natural conditions. PMID:20064992

Factors associated with compliance among users of solar water disinfection in rural Bolivia

PubMed Central

2011-01-01

Background Diarrhoea is the second leading cause of childhood mortality, with an estimated 1.3 million deaths per year. Promotion of Solar Water Disinfection (SODIS) has been suggested as a strategy for reducing the global burden of diarrhoea by improving the microbiological quality of drinking water. Despite increasing support for the large-scale dissemination of SODIS, there are few reports describing the effectiveness of its implementation. It is, therefore, important to identify and understand the mechanisms that lead to adoption and regular use of SODIS. Methods We investigated the behaviours associated with SODIS adoption among households assigned to receive SODIS promotion during a cluster-randomized trial in rural Bolivia. Distinct groups of SODIS-users were identified on the basis of six compliance indicators using principal components and cluster analysis. The probability of adopting SODIS as a function of campaign exposure and household characteristics was evaluated using ordinal logistic regression models. Results Standardised, community-level SODIS-implementation in a rural Bolivian setting was associated with a median SODIS use of 32% (IQR: 17-50). Households that were more likely to use SODIS were those that participated more frequently in SODIS promotional events (OR = 1.07, 95%CI: 1.01-1.13), included women (OR = 1.18, 95%CI: 1.07-1.30), owned latrines (OR = 3.38, 95%CI: 1.07-10.70), and had severely wasted children living in the home (OR = 2.17, 95%CI: 1.34-3.49). Conclusions Most of the observed household characteristics showed limited potential to predict compliance with a comprehensive, year-long SODIS-promotion campaign; this finding reflects the complexity of behaviour change in the context of household water treatment. However, our findings also suggest that the motivation to adopt new water treatment habits and to acquire new knowledge about drinking water treatment is associated with prior engagements in sanitary hygiene and with the

Comparison of different solar reactors for household disinfection of drinking water in developing countries: evaluation of their efficacy in relation to the waterborne enteropathogen Cryptosporidium parvum.

PubMed

Gómez-Couso, H; Fontán-Sainz, M; Navntoft, C; Fernández-Ibáñez, P; Ares-Mazás, E

2012-11-01

Solar water disinfection (SODIS) is a type of treatment that can significantly improve the microbiological quality of drinking water at household level and therefore prevent waterborne diseases in developing countries. Cryptosporidium parvum is an obligate protozoan parasite responsible for the diarrhoeal disease cryptosporidiosis in humans and animals. Recently, this parasite has been selected by the WHO as a reference pathogen for protozoan parasites in the evaluation of household water treatment options. In this study, the field efficacy of different static solar reactors [1.5 l transparent plastic polyethylene terephthalate (PET) bottles as well as 2.5 l borosilicate glass and 25 l methacrylate reactors fitted with compound parabolic concentrators (CPC)] for solar disinfection of turbid waters experimentally contaminated with C. parvum oocysts was compared. Potential oocyst viability was determined by inclusion/exclusion of the fluorogenic vital dye propidium iodide. The results demonstrate that static solar reactors fitted with CPCs are an excellent alternative to the conventional SODIS method with PET bottles. These reactors improved the efficacy of the SODIS method by enabling larger volumes of water to be treated and, in some cases, the C. parvum oocysts were rendered totally unviable, minimising the negative effects of turbidity. Copyright © 2012 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

Solar Disinfection Improves Drinking Water Quality to Prevent Diarrhea in Under-Five Children in Sikkim, India

PubMed Central

Rai, BB; Pal, Ranabir; Kar, Sumit; Tsering, Dechen C

2010-01-01

Background: Solar radiations improve the microbiological quality of water and offer a method for disinfection of drinking water that requires few resources and no expertise and may reduce the prevalence of diarrhea among under-five children. Aims and Objectives: To find out the reduction in the prevalence of diarrhea in the under-five children after consumption of potable water treated with solar disinfection method. Materials and Methods: This was a population-based interventional prospective study in the urban slum area of Mazegoan, Jorethang, south Sikkim, during the period 1st May 2007 to 30th November 2007 on 136 children in the under-five age group in 102 households selected by random sampling. Main outcome measure was the assessment of the reduction of the prevalence of diarrhea among under-five children after consumption of potable water treated with solar disinfection method practiced by the caregivers in the intervention group keeping water in polyethylene terephthalate (PET) bottles as directed by the investigators. The data were collected by the interview method using a pre-tested questionnaire prepared on the basis of socio-demographics and prevalence of diarrhea. The data were subjected to percentages and chi-square tests, which were used to find the significance. Results: After four weeks of intervention among the study group, the diarrhea prevalence was 7.69% among solar disinfection (SODIS) users, while 31.82% prevalence was observed among non-users in that period; the reduction in prevalence of diarrhea was 75.83%. After eight weeks of intervention, the prevalence of diarrhea was 7.58% among SODIS users and 31.43% among non-users; the reduction in diarrhea was 75.88% in the study group. The findings were found to be statistically significant. Conclusions: In our study, we observed that the prevalence of diarrhea decreased significantly after solar disinfection of water was practiced by the caregivers keeping potable water in PET bottles in the

Evaluation of the Solar Water Disinfection Method Using an Ultraviolet Measurement Device

NASA Astrophysics Data System (ADS)

Leung, H.

2015-12-01

Drinking water security is a growing problem for the population of planet Earth. According to WHO, more than 750 million people on our planet lack access to safe drinking water, resulting in approximately 502,000 diarrhoea deaths in 2012. In order to solve this problem, the Swiss water research institute, Eawag, has developed a method of solar water disinfection, called, "SODIS" The theory of SODIS is simple to understand: a clear plastic bottle filled with water is placed under full sunlight for at least 6 hours. The ultraviolet radiation kills the pathogens in the water, making the originally contaminated water safe for drinking. In order to improve this method, Helioz, an Austrian social enterprise, has created the WADI, a UV measurement device which determines when water is safe for drinking using the SODIS method. When using the WADI, the device should be placed under the sun and surrounded with bottles of water that need to be decontaminated. There is a UV sensor on the WADI, and since the bottles of water and the WADI will have equal exposure to sunlight, the WADI will be able to measure the impact of the sunlight on the contaminated water. This experiment tests the accuracy of the WADI device regarding the time interval needed for contaminated water to be disinfected. The experiment involves using the SODIS method to purify bottles of water contaminated with controlled samples of E. coli. Samples of the water are taken at different time intervals, and the E. coli levels are determined by growing the bacteria from the water samples on agar plates. Ultimately, this helps determine when the water is safe for drinking, and are compared against the WADI's measurements to test the reliability of the device.

Solar disinfection of drinking water in the prevention of dysentery in South African children aged under 5 years: the role of participant motivation.

PubMed

Du Preez, Martella; Mcguigan, Kevin G; Conroy, Ronan M

2010-11-15

Solar disinfection (SODIS) effectively improves the microbial quality of drinking water for preventing diarrhea; however, the effect of participant motivation has not been studied. This 1-year randomized controlled trial investigated the effect of SODIS of drinking water and motivation on the incidence of dysentery and nondysentery diarrhea among children of age 6 months to 5 years living in periurban communities in South Africa.We compared 383 children in 297 households using SODIS with 335 children in 267 households with no intervention. At baseline 62.4% of the study households had stored water which met World Health Organization guidelines for zero thermotolerant coliforms per 100 mL. Dysentery was recorded using a pictorial diary. Incidence of dysentery was significantly associated with higher motivation, defined as 75% or better completion of diarrhea data. Incidence rates were lower in those drinking solar disinfected water (incidence rate ratio 0.64, 95% CI 0.39 - 1.0, P = 0.071) but not statistically significant. Compared with the control, participants with higher motivation achieved a significant reduction in dysentery (incidence rate ratio 0.36, 95% CI 0.16 - 0.81, P = 0.014). However, there was no significant reduction in risk at lower levels of motivation. Solar disinfection was not significantly associated with nondysentery diarrhea risk overall (P = 0.419). A statistically significant reduction in dysentery was achieved only in households with higher motivation, showing that motivation is a significant determinant for measurable health gains. Failure of three-quarters of participants to achieve a significant reduction in dysentery suggests that research into effective implementation is required.

Randomized intervention study of solar disinfection of drinking water in the prevention of dysentery in Kenyan children aged under 5 years.

PubMed

du Preez, Martella; Conroy, Ronan M; Ligondo, Sophie; Hennessy, James; Elmore-Meegan, Michael; Soita, Allan; McGuigan, Kevin G

2011-11-01

We report the results of a randomized controlled intervention study (September 2007 to March 2009) investigating the effect of solar disinfection (SODIS) of drinking water on the incidence of dysentery, nondysentery diarrhea, and anthropometric measurements of height and weight among children of age 6 months to 5 years living in peri-urban and rural communities in Nakuru, Kenya. We compared 555 children in 404 households using SODIS with 534 children in 361 households with no intervention. Dysentery was recorded using a pictorial diary. Incidence rate ratios (IRR) for both number of days and episodes of dysentery and nondysentery diarrhea were significantly (P < 0.001) reduced by use of solar disinfection: dysentery days IRR = 0.56 (95% CI 0.40 to 0.79); dysentery episodes IRR = 0.55 (95% CI 0.42 to 0.73); nondysentery days IRR = 0.70 (95% CI 0.59 to 0.84); nondysentery episodes IRR = 0.73 (95% CI 0.63 to 0.84). Anthropometry measurements of weight and height showed median height-for-age was significantly increased in those on SODIS, corresponding to an average of 0.8 cm over a 1-year period over the group as a whole (95% CI 0.7 to 1.6 cm, P = 0.031). Median weight-for-age was higher in those on SODIS, corresponding to a 0.23 kg difference in weight over the same period; however, the confidence interval spanned zero and the effect fell short of statistical significance (95% CI -0.02 to 0.47 kg, P = 0.068). SODIS and control households did not differ in the microbial quality of their untreated household water over the follow-up period (P = 0.119), but E. coli concentrations in SODIS bottles were significantly lower than those in storage containers over all follow-up visits (P < 0.001). This is the first trial to show evidence of the effect of SODIS on childhood anthropometry, compared with children in the control group and should alleviate concerns expressed by some commentators that the lower rates of dysentery associated with SODIS are the product of biased

Demonstration of the Enhanced Disinfection of E. coli Water Contamination by Associated Solar Irradiation with Potassium Persulfate

PubMed Central

GHANIZADEH, Ghader; NASERI ARA, Ali; ESMAILI, Davoud; MASOUMBEIGI, Hossein

2015-01-01

Background: Tremendous amount of researches have investigated the issue of water photodisnfection. The aim of this research is to illustrate the influences of bacterial density, turbidity, exposure time and potassium persulfate (KPS) dosage on the efficacy of associated solar disinfection (SODIS) with KPS for E. coli (ATCC: 25922) eradication as an efficient and inexpensive process. Methods: Desired bacterial density and turbidity was achieved by spiking of 0.5 Mc Farland (1.5×108 cell/ml) and sterile soil slurry in 1 liter of the commercially bottled water. Results: The highest value of UVA solar irradiation measured at 13.30 p.m was 5510 μW/Cm2. Increase of bacterial density from 1000 to 1500 cell/ml led to an increase in disinfection lapse time, except in 2 mMol/l KPS. Spiking of 0.1 mMol/l of KPS was not effective; however, increase of KPS dosage from 0.1 mMol/l to 0.7, 1.5 and 2 mMol/l led to the enhancement of disinfection time from 4 h to 3 h and 1 h, respectively. For bacterial density of 1000 cell/ml, increasing KPS dosage up to 0.7 mMol/l had no improved effect; however, beyond this dosage the disinfection time decreased to 1 h. Without KPS and up to 150 NTU within 4 h exposure time, E. coli disinfection was completed. In 2 mMol/l KPS and 1000 and 1500 cell/ml, the 2 h contact time was sufficient up to 150 and 100 NTU, respectively; moreover, complete disinfection was not achieved at higher turbidity. Conclusion: Association of KPS with SODIS can lead to decreasing of water disinfection time. PMID:26576351

Bactericidal Effect of Solar Water Disinfection under Real Sunlight Conditions▿

PubMed Central

Boyle, M.; Sichel, C.; Fernández-Ibáñez, P.; Arias-Quiroz, G. B.; Iriarte-Puña, M.; Mercado, A.; Ubomba-Jaswa, E.; McGuigan, K. G.

2008-01-01

Batch solar disinfection (SODIS) inactivation kinetics are reported for suspensions in water of Campylobacter jejuni, Yersinia enterocolitica, enteropathogenic Escherichia coli, Staphylococcus epidermidis, and endospores of Bacillus subtilis, exposed to strong natural sunlight in Spain and Bolivia. The exposure time required for complete inactivation (at least 4-log-unit reduction and below the limit of detection, 17 CFU/ml) under conditions of strong natural sunlight (maximum global irradiance, ∼1,050 W m−2 ± 10 W m−2) was as follows: C. jejuni, 20 min; S. epidermidis, 45 min; enteropathogenic E. coli, 90 min; Y. enterocolitica, 150 min. Following incomplete inactivation of B. subtilis endospores after the first day, reexposure of these samples on the following day found that 4% (standard error, 3%) of the endospores remained viable after a cumulative exposure time of 16 h of strong natural sunlight. SODIS is shown to be effective against the vegetative cells of a number of emerging waterborne pathogens; however, bacterial species which are spore forming may survive this intervention process. PMID:18359829

Batch solar disinfection inactivates oocysts of Cryptosporidium parvum and cysts of Giardia muris in drinking water.

PubMed

McGuigan, K G; Méndez-Hermida, F; Castro-Hermida, J A; Ares-Mazás, E; Kehoe, S C; Boyle, M; Sichel, C; Fernández-Ibáñez, P; Meyer, B P; Ramalingham, S; Meyer, E A

2006-08-01

To determine whether batch solar disinfection (SODIS) can be used to inactivate oocysts of Cryptosporidium parvum and cysts of Giardia muris in experimentally contaminated water. Suspensions of oocysts and cysts were exposed to simulated global solar irradiation of 830 W m(-2) for different exposure times at a constant temperature of 40 degrees C. Infectivity tests were carried out using CD-1 suckling mice in the Cryptosporidium experiments and newly weaned CD-1 mice in the Giardia experiments. Exposure times of > or =10 h (total optical dose c. 30 kJ) rendered C. parvum oocysts noninfective. Giardia muris cysts were rendered completely noninfective within 4 h (total optical dose >12 kJ). Scanning electron microscopy and viability (4',6-diamidino-2-phenylindole/propidium iodide fluorogenic dyes and excystation) studies on oocysts of C. parvum suggest that inactivation is caused by damage to the oocyst wall. Results show that cysts of G. muris and oocysts of C. parvum are rendered completely noninfective after batch SODIS exposures of 4 and 10 h (respectively) and is also likely to be effective against waterborne cysts of Giardia lamblia. These results demonstrate that SODIS is an appropriate household water treatment technology for use as an emergency intervention in aftermath of natural or man-made disasters against not only bacterial but also protozoan pathogens.

Effectiveness of solar disinfection using batch reactors with non-imaging aluminium reflectors under real conditions: Natural well-water and solar light.

PubMed

Navntoft, C; Ubomba-Jaswa, E; McGuigan, K G; Fernández-Ibáñez, P

2008-12-11

Inactivation kinetics are reported for suspensions of Escherichia coli in well-water using compound parabolic collector (CPC) mirrors to enhance the efficiency of solar disinfection (SODIS) for batch reactors under real, solar radiation (cloudy and cloudless) conditions. On clear days, the system with CPC reflectors achieved complete inactivation (more than 5-log unit reduction in bacterial population to below the detection limit of 4CFU/mL) one hour sooner than the system fitted with no CPC. On cloudy days, only systems fitted with CPCs achieved complete inactivation. Degradation of the mirrors under field conditions was also evaluated. The reflectivity of CPC systems that had been in use outdoors for at least 3 years deteriorated in a non-homogeneous fashion. Reflectivity values for these older systems were found to vary between 27% and 72% compared to uniform values of 87% for new CPC systems. The use of CPC has been proven to be a good technological enhancement to inactivate bacteria under real conditions in clear and cloudy days. A comparison between enhancing optics and thermal effect is also discussed.

Elimination of water pathogens with solar radiation using an automated sequential batch CPC reactor.

PubMed

Polo-López, M I; Fernández-Ibáñez, P; Ubomba-Jaswa, E; Navntoft, C; García-Fernández, I; Dunlop, P S M; Schmid, M; Byrne, J A; McGuigan, K G

2011-11-30

Solar disinfection (SODIS) of water is a well-known, effective treatment process which is practiced at household level in many developing countries. However, this process is limited by the small volume treated and there is no indication of treatment efficacy for the user. Low cost glass tube reactors, together with compound parabolic collector (CPC) technology, have been shown to significantly increase the efficiency of solar disinfection. However, these reactors still require user input to control each batch SODIS process and there is no feedback that the process is complete. Automatic operation of the batch SODIS process, controlled by UVA-radiation sensors, can provide information on the status of the process, can ensure the required UVA dose to achieve complete disinfection is received and reduces user work-load through automatic sequential batch processing. In this work, an enhanced CPC photo-reactor with a concentration factor of 1.89 was developed. The apparatus was automated to achieve exposure to a pre-determined UVA dose. Treated water was automatically dispensed into a reservoir tank. The reactor was tested using Escherichia coli as a model pathogen in natural well water. A 6-log inactivation of E. coli was achieved following exposure to the minimum uninterrupted lethal UVA dose. The enhanced reactor decreased the exposure time required to achieve the lethal UVA dose, in comparison to a CPC system with a concentration factor of 1.0. Doubling the lethal UVA dose prevented the need for a period of post-exposure dark inactivation and reduced the overall treatment time. Using this reactor, SODIS can be automatically carried out at an affordable cost, with reduced exposure time and minimal user input. Copyright © 2011 Elsevier B.V. All rights reserved.

Development and evaluation of a reflective solar disinfection pouch for treatment of drinking water.

PubMed

Walker, D Carey; Len, Soo-Voon; Sheehan, Brita

2004-04-01

A second-generation solar disinfection (SODIS) system (pouch) was constructed from food-grade, commercially available packaging materials selected to fully transmit and amplify the antimicrobial properties of sunlight. Depending upon the season, water source, and challenge organism, culturable bacteria were reduced between 3.5 and 5.5 log cycles. The system was also capable of reducing the background presumptive coliform population in nonsterile river water below the level of detection. Similar experiments conducted with a model virus, the F-specific RNA bacteriophage MS2, indicated that the pouch was slightly less efficient, reducing viable plaques by 3.5 log units in comparison to a 5.0 log reduction of enterotoxigenic Escherichia coli O18:H11 within the same time period. These results suggest that water of poor microbiological quality can be improved by using a freely available resource (sunlight) and a specifically designed plastic pouch constructed of food-grade packaging materials.

Development and Evaluation of a Reflective Solar Disinfection Pouch for Treatment of Drinking Water

PubMed Central

Walker, D. Carey; Len, Soo-Voon; Sheehan, Brita

2004-01-01

A second-generation solar disinfection (SODIS) system (pouch) was constructed from food-grade, commercially available packaging materials selected to fully transmit and amplify the antimicrobial properties of sunlight. Depending upon the season, water source, and challenge organism, culturable bacteria were reduced between 3.5 and 5.5 log cycles. The system was also capable of reducing the background presumptive coliform population in nonsterile river water below the level of detection. Similar experiments conducted with a model virus, the F-specific RNA bacteriophage MS2, indicated that the pouch was slightly less efficient, reducing viable plaques by 3.5 log units in comparison to a 5.0 log reduction of enterotoxigenic Escherichia coli O18:H11 within the same time period. These results suggest that water of poor microbiological quality can be improved by using a freely available resource (sunlight) and a specifically designed plastic pouch constructed of food-grade packaging materials. PMID:15066858

The Effect of Solar Irradiated Vibrio cholerae on the Secretion of Pro-Inflammatory Cytokines and Chemokines by the JAWS II Dendritic Cell Line In Vitro

PubMed Central

Ssemakalu, Cornelius Cano; Ubomba-Jaswa, Eunice; Motaung, Keolebogile Shirley; Pillay, Michael

2015-01-01

The use of solar irradiation to sterilize water prior to its consumption has resulted in the reduction of water related illnesses in waterborne disease endemic communities worldwide. Currently, research on solar water disinfection (SODIS) has been directed towards understanding the underlying mechanisms through which solar irradiation inactivates the culturability of microorganisms in water, enhancement of the disinfection process, and the health impact of SODIS water consumption. However, the immunological consequences of SODIS water consumption have not been explored. In this study, we investigated the effect that solar irradiated V. cholerae may have had on the secretion of cytokines and chemokines by the JAWS II dendritic cell line in vitro. The JAWS II dendritic cell line was stimulated with the different strains of V. cholerae that had been: (i) prepared in PBS, (ii) inactivated through a combination of heat and chemical, (iii) solar irradiated, and (iv) non-solar irradiated, in bottled water. As controls, LPS (1 μg/ml) and CTB (1 μg/ml) were used as stimulants. After 48 hours of stimulation the tissue culture media from each treatment was qualitatively and quantitatively analysed for the presence of IL-1α, IL-1β, IL-6, IL-7, IL-10, IL-12p40, IL-12p70, IL-15, MIP-1α, MIP-1β, MIP-2, RANTES, TNF-α, IL-23 and IL-27. Results showed that solar irradiated cultures of V. cholerae induced dendritic cells to secrete significant (p<0.05) levels of pro-inflammatory cytokines in comparison to the unstimulated dendritic cells. Furthermore, the amount of pro-inflammatory cytokines secreted by the dendritic cells in response to solar irradiated cultures of V. cholerae was not as high as observed in treatments involving non-solar irradiated cultures of V. cholerae or LPS. Our results suggest that solar irradiated microorganisms are capable of inducing the secretion of pro-inflammatory cytokines and chemokines. This novel finding is key towards understanding the

Rapid water disinfection using vertically aligned MoS 2 nanofilms and visible light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Chong; Kong, Desheng; Hsu, Po -Chun

Here, solar energy is readily available in most climates and can be used for water purification. However, solar disinfection of drinking water (SODIS) mostly relies on ultraviolet light, which represents only 4% of total solar energy, and this leads to slow treatment speed. The development of new materials that can harvest visible light for water disinfection, and speed up solar water purification, is therefore highly desirable. Here, we show that few-layered vertically aligned MoS 2 (FLV-MoS 2) films can be used to harvest the whole spectrum of visible light (~ 50% of solar energy) and achieve highly efficient water disinfection.more » The bandgap of MoS 2 was increased from 1.3 eV to 1.55 eV by decreasing the domain size, which allowed the FLV-MoS 2 to generate reactive oxygen species (ROS) for bacterial inactivation in water. The FLV-MoS 2 showed ~15 times better log inactivation efficiency of indicator bacteria compared to bulk MoS 2, and much faster inactivation of bacteria under both visible light and sunlight illumination compared to widely used TiO 2. Moreover, by using a 5 nm copper film on top of the FLV-MoS 2 as a catalyst to facilitate electron-hole pair separation and promote the generation of ROS, the disinfection rate was further increased 6 fold. With our approach, we achieved water disinfection of >99.999% inactivation of bacteria in 20 minutes with a small amount of material (1.6 mg/L) under simulated visible light.« less

Rapid water disinfection using vertically aligned MoS 2 nanofilms and visible light

DOE PAGES

Liu, Chong; Kong, Desheng; Hsu, Po -Chun; ...

2016-08-15

Here, solar energy is readily available in most climates and can be used for water purification. However, solar disinfection of drinking water (SODIS) mostly relies on ultraviolet light, which represents only 4% of total solar energy, and this leads to slow treatment speed. The development of new materials that can harvest visible light for water disinfection, and speed up solar water purification, is therefore highly desirable. Here, we show that few-layered vertically aligned MoS 2 (FLV-MoS 2) films can be used to harvest the whole spectrum of visible light (~ 50% of solar energy) and achieve highly efficient water disinfection.more » The bandgap of MoS 2 was increased from 1.3 eV to 1.55 eV by decreasing the domain size, which allowed the FLV-MoS 2 to generate reactive oxygen species (ROS) for bacterial inactivation in water. The FLV-MoS 2 showed ~15 times better log inactivation efficiency of indicator bacteria compared to bulk MoS 2, and much faster inactivation of bacteria under both visible light and sunlight illumination compared to widely used TiO 2. Moreover, by using a 5 nm copper film on top of the FLV-MoS 2 as a catalyst to facilitate electron-hole pair separation and promote the generation of ROS, the disinfection rate was further increased 6 fold. With our approach, we achieved water disinfection of >99.999% inactivation of bacteria in 20 minutes with a small amount of material (1.6 mg/L) under simulated visible light.« less

Hopkins during SODI-DCMIX 2 Experiment

NASA Image and Video Library

2013-11-30

ISS038-E-009255 (26 Nov. 2013) --- In the International Space Station?s Destiny laboratory, NASA astronaut Michael Hopkins, Expedition 38 flight engineer, prepares to install and activate the Selectable Optics Diagnostic Instrument (SODI) cell array two in the Microgravity Science Glovebox (MSG) for the Selectable Optics Diagnostic Instrument-Diffusion Coefficient in Mixtures 2 (SODI-DCMIX 2) experiment. SODI-DCMIX 2 is supporting research to determine diffusion coefficients in different petroleum field samples and refine petroleum reservoir models to help lead to more efficient extraction of oil resources.

Hopkins during SODI-DCMIX 2 Experiment

NASA Image and Video Library

2013-11-30

ISS038-E-009253 (26 Nov. 2013) --- In the International Space Station’s Destiny laboratory, NASA astronaut Michael Hopkins, Expedition 38 flight engineer, prepares to install and activate the Selectable Optics Diagnostic Instrument (SODI) cell array two in the Microgravity Science Glovebox (MSG) for the Selectable Optics Diagnostic Instrument-Diffusion Coefficient in Mixtures 2 (SODI-DCMIX 2) experiment. SODI-DCMIX 2 is supporting research to determine diffusion coefficients in different petroleum field samples and refine petroleum reservoir models to help lead to more efficient extraction of oil resources.

Evaluation of the Solar Water Disinfection Process (SODIS) Against Cryptosporidium parvum Using a 25-L Static Solar Reactor Fitted with a Compound Parabolic Collector (CPC)

PubMed Central

Fontán-Sainz, María; Gómez-Couso, Hipólito; Fernández-Ibáñez, Pilar; Ares-Mazás, Elvira

2012-01-01

Water samples of 0, 5, and 30 nephelometric turbidity units (NTU) spiked with Cryptosporidium parvum oocysts were exposed to natural sunlight using a 25-L static solar reactor fitted with a compound parabolic collector (CPC). The global oocyst viability was calculated by the evaluation of the inclusion/exclusion of the fluorogenic vital dye propidium iodide and the spontaneous excystation. After an exposure time of 8 hours, the global oocyst viabilities were 21.8 ± 3.1%, 31.3 ± 12.9%, and 45.0 ± 10.0% for turbidity levels of 0, 5, and 30 NTU, respectively, and these values were significantly lower (P < 0.05) that the initial global viability of the isolate (92.1 ± 0.9%). The 25-L static solar reactor that was evaluated can be an alternative system to the conventional solar water disinfection process for improving the microbiological quality of drinking water on a household level, and moreover, it enables treatment of larger volumes of water (> 10 times). PMID:22302852

Evaluation of the solar water disinfection process (SODIS) against Cryptosporidium parvum using a 25-L static solar reactor fitted with a compound parabolic collector (CPC).

PubMed

Fontán-Sainz, María; Gómez-Couso, Hipólito; Fernández-Ibáñez, Pilar; Ares-Mazás, Elvira

2012-02-01

Water samples of 0, 5, and 30 nephelometric turbidity units (NTU) spiked with Cryptosporidium parvum oocysts were exposed to natural sunlight using a 25-L static solar reactor fitted with a compound parabolic collector (CPC). The global oocyst viability was calculated by the evaluation of the inclusion/exclusion of the fluorogenic vital dye propidium iodide and the spontaneous excystation. After an exposure time of 8 hours, the global oocyst viabilities were 21.8 ± 3.1%, 31.3 ± 12.9%, and 45.0 ± 10.0% for turbidity levels of 0, 5, and 30 NTU, respectively, and these values were significantly lower (P < 0.05) that the initial global viability of the isolate (92.1 ± 0.9%). The 25-L static solar reactor that was evaluated can be an alternative system to the conventional solar water disinfection process for improving the microbiological quality of drinking water on a household level, and moreover, it enables treatment of larger volumes of water (> 10 times).

Disinfection of Contaminated Water by Using Solar Irradiation

PubMed Central

Caslake, Laurie F.; Connolly, Daniel J.; Menon, Vilas; Duncanson, Catriona M.; Rojas, Ricardo; Tavakoli, Javad

2004-01-01

Contaminated water causes an estimated 6 to 60 billion cases of gastrointestinal illness annually. The majority of these cases occur in rural areas of developing nations where the water supply remains polluted and adequate sanitation is unavailable. A portable, low-cost, and low-maintenance solar unit to disinfect unpotable water has been designed and tested. The solar disinfection unit was tested with both river water and partially processed water from two wastewater treatment plants. In less than 30 min in midday sunlight, the unit eradicated more than 4 log10 U (99.99%) of bacteria contained in highly contaminated water samples. The solar disinfection unit has been field tested by Centro Panamericano de Ingenieria Sanitaria y Ciencias del Ambiente in Lima, Peru. At moderate light intensity, the solar disinfection unit was capable of reducing the bacterial load in a controlled contaminated water sample by 4 log10 U and disinfected approximately 1 liter of water in 30 min. PMID:14766599

Disinfection of contaminated water by using solar irradiation.

PubMed

Caslake, Laurie F; Connolly, Daniel J; Menon, Vilas; Duncanson, Catriona M; Rojas, Ricardo; Tavakoli, Javad

2004-02-01

Contaminated water causes an estimated 6 to 60 billion cases of gastrointestinal illness annually. The majority of these cases occur in rural areas of developing nations where the water supply remains polluted and adequate sanitation is unavailable. A portable, low-cost, and low-maintenance solar unit to disinfect unpotable water has been designed and tested. The solar disinfection unit was tested with both river water and partially processed water from two wastewater treatment plants. In less than 30 min in midday sunlight, the unit eradicated more than 4 log10 U (99.99%) of bacteria contained in highly contaminated water samples. The solar disinfection unit has been field tested by Centro Panamericano de Ingenieria Sanitaria y Ciencias del Ambiente in Lima, Peru. At moderate light intensity, the solar disinfection unit was capable of reducing the bacterial load in a controlled contaminated water sample by 4 log10 U and disinfected approximately 1 liter of water in 30 min.

Solar water disinfection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, R.; Collier, R.

Non-potable drinking water is a major problem for much of the world`s population. It has been estimated that from 15 to 20 million children under the age of 5 die from diarrheal conditions brought on by infected drinking water every year. This is equivalent to a fully-loaded DC-10 crashing every ten minutes of every day, 365 days a year. Heat is one of the most effective methods of disinfecting drinking water. Using conventional means of heating water (heating on an open-flamed stove) results in an extremely energy-intensive process. The main obstacle is that for areas of the world where potablemore » water is a problem, fuel supplies are either too expensive, not available, or the source of devastating environmental problems (deforestation). The apparatus described is a solar-powered water disinfection device that can overcome most if not all of the barriers that presently limit technological solutions to drinking water problems. It uses a parabolic trough solar concentrator with a receiver tube that is also a counterflow heat exchanger. The system is totally self-contained utilizing a photovoltaic-powered water pump, and a standard automotive thermostat for water flow control. The system is designed for simplicity, reliability and the incorporation of technology readily accessible in most areas of the world. Experiments at the Florida Solar Energy Center have demonstrated up to 2,500 liters of safe drinking water per day with 28 square meters of solar concentrator.« less

Effect of μM Fe addition, mild heat and solar UV on sulfate radical-mediated inactivation of bacteria, viruses, and micropollutant degradation in water.

PubMed

Marjanovic, Miloch; Giannakis, Stefanos; Grandjean, Dominique; de Alencastro, Luiz Felippe; Pulgarin, Cesar

2018-09-01

In this work, solar disinfection (SODIS) was enhanced by moderate addition of Fe and sodium peroxydisulfate (PDS), under solar light. A systematic assessment of the activating factors was performed, firstly isolated, then in pairs and concluded in the combined Fe/heat/solar UV-PDS activation process. Solar light was the most effective (single) activator, and its combination with Fe and heat (double activation) yielded high level of synergies (up to S = 2.13). The triple activation was able to reduce the bacterial load up to 6-log in less than 1 h, similarly to the photo-Fenton process done in comparison (SODIS alone: >5 h). Fe-oxides were suitable activators of PDS under the same conditions while the presence of organic matter enhanced bacterial inactivation by the triple activated PDS process. The degradation of a (selected) mixture of micropollutants (i.e. drugs, pesticides) was also achieved in similar order of magnitude, and faster than the photo-Fenton process. Finally, the removal of a viral pathogen indicator (MS2 bacteriophage) was attained at minute-range residence times. The aforementioned facts indicate the suitability of the mild, combined process, as a potential SODIS enhancement, producing safe drinking water for sunny and especially for developing countries. Copyright © 2018 Elsevier Ltd. All rights reserved.

Solar disinfection of water for diarrhoeal prevention in southern India.

PubMed

Rose, A; Roy, S; Abraham, V; Holmgren, G; George, K; Balraj, V; Abraham, S; Muliyil, J; Joseph, A; Kang, G

2006-02-01

To evaluate the efficacy and acceptability of solar irradiation in the prevention of diarrhoeal morbidity in children under 5 years of age, in an urban slum in Vellore, Tamil Nadu. A total of 100 children were assigned to receive drinking water that had been subjected to solar disinfection in polyethylene terephthalate bottles. One hundred age and sex matched controls were also selected. Both groups were followed by weekly home visits for a period of six months for any diarrhoeal morbidity. At the end of the follow up period, the acceptability of the intervention was assessed by interviews, questionnaires, and focus group discussions. There was significant reduction in the incidence, duration, and severity of diarrhoea in children receiving solar disinfected water, despite 86% of the children drinking water other than that treated by the intervention. The incidence of diarrhoea in the intervention group was 1.7 per child-year, and among controls 2.7 per child-year, with an incidence rate ratio of 0.64 (95% CI -0.48 to 0.86). The risk of diarrhoea was reduced by 40% by using solar disinfection. In qualitative evaluation of acceptability, most women felt that solar disinfection was a feasible and sustainable method of disinfecting water. Solar disinfection of water is an inexpensive, effective, and acceptable method of increasing water safety in a resource limited environment, and can significantly decrease diarrhoeal morbidity in children.

Solar disinfection of water for diarrhoeal prevention in southern India

PubMed Central

Rose, A; Roy, S; Abraham, V; Holmgren, G; George, K; Balraj, V; Abraham, S; Muliyil, J; Joseph, A; Kang, G

2006-01-01

Aims To evaluate the efficacy and acceptability of solar irradiation in the prevention of diarrhoeal morbidity in children under 5 years of age, in an urban slum in Vellore, Tamil Nadu. Methods A total of 100 children were assigned to receive drinking water that had been subjected to solar disinfection in polyethylene terephthalate bottles. One hundred age and sex matched controls were also selected. Both groups were followed by weekly home visits for a period of six months for any diarrhoeal morbidity. At the end of the follow up period, the acceptability of the intervention was assessed by interviews, questionnaires, and focus group discussions. Results There was significant reduction in the incidence, duration, and severity of diarrhoea in children receiving solar disinfected water, despite 86% of the children drinking water other than that treated by the intervention. The incidence of diarrhoea in the intervention group was 1.7 per child‐year, and among controls 2.7 per child‐year, with an incidence rate ratio of 0.64 (95% CI −0.48 to 0.86). The risk of diarrhoea was reduced by 40% by using solar disinfection. In qualitative evaluation of acceptability, most women felt that solar disinfection was a feasible and sustainable method of disinfecting water. Conclusions Solar disinfection of water is an inexpensive, effective, and acceptable method of increasing water safety in a resource limited environment, and can significantly decrease diarrhoeal morbidity in children. PMID:16403847

Solar optics-based active panel for solar energy storage and disinfection of greywater.

PubMed

Lee, W; Song, J; Son, J H; Gutierrez, M P; Kang, T; Kim, D; Lee, L P

2016-09-01

Smart city and innovative building strategies are becoming increasingly more necessary because advancing a sustainable building system is regarded as a promising solution to overcome the depleting water and energy. However, current sustainable building systems mainly focus on energy saving and miss a holistic integration of water regeneration and energy generation. Here, we present a theoretical study of a solar optics-based active panel (SOAP) that enables both solar energy storage and photothermal disinfection of greywater simultaneously. Solar collector efficiency of energy storage and disinfection rate of greywater have been investigated. Due to the light focusing by microlens, the solar collector efficiency is enhanced from 25% to 65%, compared to that without the microlens. The simulation of greywater sterilization shows that 100% disinfection can be accomplished by our SOAP for different types of bacteria including Escherichia coli . Numerical simulation reveals that our SOAP as a lab-on-a-wall system can resolve the water and energy problem in future sustainable building systems.

Solar optics-based active panel for solar energy storage and disinfection of greywater

PubMed Central

Lee, W.; Song, J.; Son, J. H.; Gutierrez, M. P.; Kang, T.; Kim, D.; Lee, L. P.

2016-01-01

Smart city and innovative building strategies are becoming increasingly more necessary because advancing a sustainable building system is regarded as a promising solution to overcome the depleting water and energy. However, current sustainable building systems mainly focus on energy saving and miss a holistic integration of water regeneration and energy generation. Here, we present a theoretical study of a solar optics-based active panel (SOAP) that enables both solar energy storage and photothermal disinfection of greywater simultaneously. Solar collector efficiency of energy storage and disinfection rate of greywater have been investigated. Due to the light focusing by microlens, the solar collector efficiency is enhanced from 25% to 65%, compared to that without the microlens. The simulation of greywater sterilization shows that 100% disinfection can be accomplished by our SOAP for different types of bacteria including Escherichia coli. Numerical simulation reveals that our SOAP as a lab-on-a-wall system can resolve the water and energy problem in future sustainable building systems. PMID:27822328

Solar disinfection of drinking water protects against cholera in children under 6 years of age

PubMed Central

Conroy, R; Meegan, M; Joyce, T; McGuigan, K; Barnes, J

2001-01-01

BACKGROUND AND AIMS—We have previously reported a reduction in risk of diarrhoeal disease in children who used solar disinfected drinking water. A cholera epidemic, occurring in an area of Kenya in which a controlled trial of solar disinfection and diarrhoeal disease in children aged under 6 had recently finished, offered an opportunity to examine the protection offered by solar disinfection against cholera.
METHODS—In the original trial, all children aged under 6 in a Maasai community were randomised by household: in the solar disinfection arm, children drank water disinfected by leaving it on the roof in a clear plastic bottle, while controls drank water kept indoors. We revisited all households which had participated in the original trial.
RESULTS—There were 131 households in the trial area, of which 67 had been randomised to solar disinfection (a further 19 households had migrated as a result of severe drought). There was no significant difference in the risk of cholera in adults or in older children in households randomised to solar disinfection; however, there were only three cases of cholera in the 155 children aged under 6 years drinking solar disinfected water compared with 20 of 144controls.
CONCLUSIONS—Results confirm the usefulness of solar disinfection in reducing risk of water borne disease in children. Point of consumption solar disinfection can be done with minimal resources, which are readily available, and may be an important first line response to cholera outbreaks. Its potential in chorine resistant cholera merits further investigation.

 PMID:11567937

Solar disinfection of water reduces diarrhoeal disease: an update

PubMed Central

Conroy, R.; Meegan, M. E.; Joyce, T.; McGuigan, K.; Barnes, J.

1999-01-01

349 Maasai children younger than 6 years old were randomised by alternate household to drink water either left in plastic bottles exposed to sunlight on the roof of the house or kept indoors (control). The trial was run in Maasai by Maasai community elders. Children drinking solar disinfected water had a significantly lower risk of severe diarrhoeal disease over 8705 two weekly follow up visits; two week period prevalence was 48.8% compared with 58.1% in controls, corresponding to an attributable fraction of 16.0%. While this reduction is modest, it was sustained over a year in free living children. It confirms solar disinfection as effective in vivo as a free, low technology, point of consumption method of improving water quality. The continuing use of solar disinfection by the community underlines the value of community participation in research.

 PMID:10490440

High-performance, low-cost solar collectors for disinfection of contaminated water.

PubMed

Vidal, A; Diaz, A I

2000-01-01

Although the germicidal action of sunlight has long been recognized, its potential for practical applications has to be researched more thoroughly. This paper summarizes the progress made toward a commercially practical collector for solar disinfection applications. Nontracking compound parabolic collectors (CPCs), developed originally for capturing solar photons for thermal energy applications, were examined as potential solar photoreactors. A field demonstration of solar disinfection treatment using commercially manufactured solar reactors was conducted. Field tests showed successful destruction of Escherichia coli and Enterococcus faecalis and have provided data for full-scale design of water treatment systems. From above observations, a throughput value of 50 L/m2 h for the low-cost CPC reactor tested was estimated. For a 190 m3/d (0.05 MGD) facility, the estimated total costs for disinfection using UV-A is U.S. $0.19/m3 ($0.70/1000 gal). The use of near-UV sunlight to disinfect water supplies seems promising in rural communities of developing countries where treated water is unavailable.

Synergistic effect of solar radiation and solar heating to disinfect drinking water sources.

PubMed

Rijal, G K; Fujioka, R S

2001-01-01

Waterborne diseases are still common in developing countries as drinking water sources are contaminated and feasible means to reliably treat and disinfect these waters are not available. Many of these developing countries are in the tropical regions of the world where sunlight is plentiful. The objective of this study was to evaluate the effectiveness of combining solar radiation and solar heating to disinfect contaminated water using a modified Family Sol*Saver System (FSP). The non-UV transmittable cover sheet of the former FSP system was replaced with an UV transmittable plastic cover sheet to enable more wavelengths of sunlight to treat the water. Disinfection efficiency of both systems was evaluated based on reduction of the natural populations of faecal coliform, E. coli, enterococci, C. perfringens, total heterotrophic bacteria, hydrogen sulphide producing bacteria and FRNA virus. The results showed that under sunny and partly sunny conditions, water was heated to critical temperature (60 degrees C) in both the FSP systems inactivating more than 3 log (99.9%) of the concentrations of faecal coliform and E. coli to undetectable levels of < 1 CFU/100 mL within 2-5 h exposure to sunlight. However, under cloudy conditions, the two FSP systems did not reduce the concentrations of faecal indicator bacteria to levels of < 1 CFU/100 mL. Nonetheless, sufficient evidence was obtained to show that UV radiation of sunlight plus heat worked synergistically to enhance the inactivation of faecal indicator bacteria. The relative log removal of indicator microorganism in the FSP treated water was total heterotrophic bacteria < C. perfringens < F RNA virus < enterococci < E. coli < faecal coliform. In summary, time of exposure to heat and radiation effects of sunlight were important in disinfecting water by solar units. The data indicated that direct radiation of sunlight worked synergistically with solar heating of the water to disinfect the water. Thus, effective

Solar photocatalytic disinfection with immobilised TiO(2) at pilot-plant scale.

PubMed

Sordo, Carlos; Van Grieken, Rafael; Marugán, Javier; Fernández-Ibáñez, Pilar

2010-01-01

The photocatalytic disinfection efficiency has been investigated for two immobilized TiO(2) catalytic systems (wall reactor and fixed-bed reactor) in a solar pilot plant. Their performances have been compared with the use of a slurry reactor and the solar disinfection without catalyst. The use of photocatalytic TiO(2) wall reactors does no show clear benefits over the solar disinfection process in the absence of catalyst. The reason is that the efficiency of the solar disinfection is so high that the presence of titania in the reactor wall reduces the global efficiency due to the competition for the absorption of photons. As expected, the maximum efficiency was shown by the slurry TiO(2) reactor, due to the optimum contact between bacteria and catalyst. However, it is noticeable that the use of the fixed-bed reactor leads to inactivation rate quite close to that of the slurry, requiring comparable accumulated solar energy of about 6 kJ L(-1) to achieve a 6-log decrease in the concentration of viable bacteria and allowing a total disinfection of the water (below the detection limit of 1 CFU mL(-1)). Not only the high titania surface area of this configuration is responsible for the bacteria inactivation but the important contribution of the mechanical stress has to be considered. The main advantage of the fixed-bed TiO(2) catalyst is the outstanding stability, without deactivation effects after ten reaction cycles, being readily applicable for continuous water treatment systems.

An overview of water disinfection in developing countries and the potential for solar thermal water pasteurization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burch, J.; Thomas, K.E.

This study originated within the Solar Buildings Program at the U.S. Department of Energy. Its goal is to assess the potential for solar thermal water disinfection in developing countries. In order to assess solar thermal potential, the alternatives must be clearly understood and compared. The objectives of the study are to: (a) characterize the developing world disinfection needs and market; (b) identify competing technologies, both traditional and emerging; (c) analyze and characterize solar thermal pasteurization; (d) compare technologies on cost-effectiveness and appropriateness; and (e) identify research opportunities. Natural consequences of the study beyond these objectives include a broad knowledge ofmore » water disinfection problems and technologies, introduction of solar thermal pasteurization technologies to a broad audience, and general identification of disinfection opportunities for renewable technologies.« less

Engineering of solar photocatalytic detoxification and disinfection process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goswami, D.Y.

1995-12-31

Use of solar radiation for photocatalytic detoxification and disinfection is a very fascinating and fast-developing area. Although scientific research on these processes, especially photocatalytic oxidation, has been conducted for at least the last three decades, the development of industrial/commercial applications, engineering systems and engineering design methodologies have occurred only recently. A number of reactor concepts and designs, including concentrating and non-concentrating types and various methods of catalyst deployment have been developed. Some of these reactors have been used in field demonstrations of groundwater and wastewater remediation. Recent research has been focused on improvements of catalysts to increase the reaction rates,more » as well as finding new applications of the process. This paper reviews the latest developments of solar detoxification and disinfection including catalyst development, industrial/commercial applications, reactor design and engineering system design methodologies. 80 refs., 20 figs., 3 tabs.« less

Use of solar radiation for continuous water disinfection in isolated areas.

PubMed

Fabbricino, M; d'Antonio, L

2012-01-01

This study involved investigation of solar water disinfection in continuously working treatment plants with the aim of producing safe drinking water in isolated areas. Results were obtained from experimental work carried out on a pilot plant operating in different configurations. The use of a simple device to increase solar radiation intensity (solar concentrator) was tested, with results showing that it facilitated better performance. A comparison between transparent and black-painted glass reactors was also made, showing no difference between the two casings. Further, the effect of an increase in water temperature was analysed in detail. Temperature was found to play an important role in the disinfection process, even in cases of limited solar radiation intensities, although a synergistic effect of water heating and solar radiation for effective microbial inactivation was confirmed. Reactor design is also discussed, highlighting the importance of having a plug flow to avoid zones that do not contribute to the overall effectiveness of the process.

Use of reflectors to enhance the synergistic effects of solar heating and solar wavelengths to disinfect drinking water sources.

PubMed

Rijal, G K; Fujioka, R S

2003-01-01

Aluminum reflectors were added to solar units designed to inactivate faecal microorganisms (faecal coliform, E. coli, enterococci, FRNA coliphage, C. perfringens) in stream water and diluted sewage by the two mechanisms (solar heat, solar UV) known to inactivate microorganisms. During sunny conditions, solar units with and without reflectors inactivated E. coli to <1 CFU/100 ml to meet drinking water standards. Solar units with reflectors disinfected the water sooner by increasing the water temperature by 8-10 degrees C to 64-75 degrees C. However, FRNA coliphages were still detected in these samples, indicating that this treatment may not inactivate pathogenic human enteric viruses. During cloudy conditions, reflectors only increased the water temperature by 3-4 degrees C to a maximum of 43-49 degrees C and E. coli was not completely inactivated. Under sunny and cloudy conditions, the UV wavelengths of sunlight worked synergistically with increasing water temperatures and were able to disinfect microorganisms at temperatures (45-56 degrees C), which were not effective in inactivating microorganisms. Relative resistance to the solar disinfecting effects were C. perfringens > FRNA coliphages > enterococci > E. coli > faecal coliform.

SODI-COLLOID (Selectable Optical Diagnostics Instrument - Colloid)

NASA Image and Video Library

2011-10-17

ISS029-E-027431 (17 Oct. 2011) --- In the International Space Station?s Destiny laboratory, Japan Aerospace Exploration Agency astronaut Satoshi Furukawa, Expedition 29 flight engineer, activates the Microgravity Science Glovebox (MSG) in preparation for work with the Selectable Optical Diagnostics Instrument ? Colloid (SODI-COLLOID) hardware.

SODI-COLLOID (Selectable Optical Diagnostics Instrument - Colloid)

NASA Image and Video Library

2011-10-17

ISS029-E-027435 (17 Oct. 2011) --- In the International Space Station?s Destiny laboratory, Japan Aerospace Exploration Agency astronaut Satoshi Furukawa, Expedition 29 flight engineer, activates the Microgravity Science Glovebox (MSG) in preparation for work with the Selectable Optical Diagnostics Instrument ? Colloid (SODI-COLLOID) hardware.

Solar disinfection of infectious biomedical waste: a new approach for developing countries.

PubMed

Chitnis, V; Chitnis, S; Patil, S; Chitnis, D

2003-10-18

Poor developing countries cannot afford expensive technologies such as incineration for management of infectious biomedical waste. We assessed solar heating as an alternative technology. We immersed simulated infectious waste with added challenge bacteria in water in a box-type solar cooker, which was left in the sun for 6 h. In 24 sets of observations, the amount of viable bacteria was reduced by about 7 log. We also tested infectious medical waste with a heavy load of bacteria (10(8)-10(9)/g) from our hospital's burn unit for solar heat disinfection in 20 experiments. Our results showed a similar 7 log reduction in the amount of viable bacteria. Solar heating thus seems to be a cheap method to disinfect infectious medical waste in less economically developed countries.

Assessing contribution of DOC from sediments to a drinking-water reservoir using optical profiling

USGS Publications Warehouse

Downing, Bryan D.; Bergamaschi, Brian A.; Evans, David G.; Boss, Emmanuel

2008-01-01

Understanding the sources of dissolved organic carbon (DOC) in drinking-water reservoirs is an important management issue because DOC may form disinfection by-products, interfere with disinfection, or increase treatment costs. DOC may be derived from a host of sources-algal production of DOC in the reservoir, marginal production of DOC from mucks and vascular plants at the margins, and sediments in the reservoir. The purpose of this study was to assess if release of DOC from reservoir sediments containing ferric chloride coagulant was a significant source of DOC to the reservoir. We examined the source-specific contributions of DOC using a profiling system to measure the in situ distribution of optical properties of absorption and fluorescence at various locations in the reservoir. Vertical optical profiles were coupled with discrete water samples measured in the laboratory for DOC concentration and optical properties: absorption spectra and excitation emission matrix spectra (EEMs). Modeling the in situ optical data permitted estimation of the bulk DOC profile in the reservoir as well as separation into source-specific contributions. Analysis of the source-specific profiles and their associated optical characteristics indicated that the sedimentary source of DOC to the reservoir is significant and that this DOC is labile in the reservoir. We conclude that optical profiling is a useful technique for understanding complex biogeochemical processes in a reservoir.

Solar photocatalytic disinfection of agricultural pathogenic fungi (Curvularia sp.) in real urban wastewater.

PubMed

Aguas, Yelitza; Hincapie, Margarita; Fernández-Ibáñez, Pilar; Polo-López, María Inmaculada

2017-12-31

The interest in developing alternative water disinfection methods that increase the access to irrigation water free of pathogens for agricultural purposes is increasing in the last decades. Advanced Oxidation Processes (AOPs) have been demonstrated to be very efficient for the abatement of several kind of pathogens in contaminated water. The purpose of the current study was to evaluate and compare the capability of several solar AOPs for the inactivation of resistant spores of agricultural fungi. Solar photoassisted H 2 O 2 , solar photo-Fenton at acid and near-neutral pH, and solar heterogeneous photocatalysis using TiO 2, with and without H 2 O 2 , have been studied for the inactivation of spores of Curvularia sp., a phytopathogenic fungi worldwide found in soils and crops. Different concentrations of reagents and catalysts were evaluated at bench scale (solar vessel reactors, 200mL) and at pilot plant scale (solar Compound Parabolic Collector-CPC reactor, 20L) under natural solar radiation using distilled water (DW) and real secondary effluents (SE) from a municipal wastewater treatment plant. Inactivation order of Curvularia sp. in distilled water was determined, i.e. TiO 2 /H 2 O 2 /sunlight (100/50mgL -1 )>H 2 O 2 /sunlight (40mgL -1 )>TiO 2 /sunlight (100mgL -1 )>photo-Fenton with 5/10mgL -1 of Fe 2+ /H 2 O 2 at pH3 and near-neutral pH. For the case of SE, at near neutral pH, the most efficient solar process was H 2 O 2 /Solar (60mgL -1 ); nevertheless, the best Curvularia sp. inactivation rate was obtained with photo-Fenton (10/20mgL -1 of Fe 2+ /H 2 O 2 ) requiring a previous water adicification to pH3, within 300 and 210min of solar treatment, respectively. These results show the efficiency of solar AOPs as a feasible option for the inactivation of resistant pathogens in water for crops irrigation, even in the presence of organic matter (average Dissolved Organic Carbon (DOC): 24mgL -1 ), and open a window for future wastewater reclamation and irrigation

A review of engineering development of aqueous phase solar photocatalytic detoxification and disinfection processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goswami, D.Y.

1997-05-01

Scientific research on photocatalytic oxidation of hazardous chemicals has been conducted extensively over the last three decades. Use of solar radiation in photocatalytic detoxification and disinfection has only been explored in the last decade. Developments of engineering scale systems, design methodologies, and commercial and industrial applications have occurred even more recently. A number of reactor concepts and designs including concentrating and nonconcentrating types and methods of catalyst deployment have been developed. Some commercial and industrial field tests of solar detoxification systems have been conducted. This paper reviews the engineering developments of the solar photocatalytic detoxification and disinfection processes, including systemmore » design methodologies.« less

Solar photolysis of soluble microbial products as precursors of disinfection by-products in surface water.

PubMed

Wu, Jie; Ye, Jian; Peng, Huanlong; Wu, Meirou; Shi, Weiwei; Liang, Yongmei; Liu, Wei

2018-06-01

In the Pearl River Delta area, the upstream municipal wastewater is commonly discharged into rivers which are a pivotal source of downstream drinking water. Solar irradiation transforms some of the dissolved organic matter discharged from the wastewater, also affecting the formation of disinfection by-products in subsequent drinking water treatment plants. The effect of simulated solar radiation on soluble microbial products extracted from activated sludge was documented in laboratory experiments. Irradiation was found to degrade macromolecules in the effluent, yielding smaller, more reactive intermediate species which reacted with chlorine or chloramine to form higher levels of noxious disinfection by-products. The soluble microbial products were found to be more active in formation of disinfection by-products regard than naturally-occurring organic matter. The results show that solar irradiation induced the formation of more trihalomethane (THMs), chloral hydrate (CH) and trichloronitromethane (TCNM), causing greater health risks for downstream drinking water. Copyright © 2018 Elsevier Ltd. All rights reserved.

Elimination of disinfection byproduct formation potential in reclaimed water during solar light irradiation.

PubMed

Qian-Yuan, Wu; Chao, Li; Ye, Du; Wen-Long, Wang; Huang, Huang; Hong-Ying, Hu

2016-05-15

Ecological storage of reclaimed water in ponds and lakes is widely applied in water reuse. During reclaimed water storage, solar light can degrade pollutants and improve water quality. This study investigated the effects of solar light irradiation on the disinfection byproduct formation potential in reclaimed water, including haloacetonitriles (HANs), trichloronitromethane (TCNM), trihalomethanes (THMs), haloketones (HKs) and chloral hydrate (CH). Natural solar light significantly decreased the formation potential of HANs, TCNM, and HKs in reclaimed water, but had a limited effect on the formation potential of THMs and CH. Ultraviolet (UV) light in solar radiation played a dominant role in the decrease of the formation potential of HANs, TCNM and HKs. Among the disinfection byproducts, the removal kinetic constant of dichloroacetonitrile (DCAN) with irradiation dose was much larger than those for dichloropropanone (1,1-DCP), trichloropropanone (1,1,1-TCP) and TCNM. During solar irradiation, fluorescence spectra intensities of reclaimed water also decreased significantly. The removal of tyrosine (Tyr)-like and tryptophan (Trp)-like protein fluorescence spectra intensity volumes was correlated to the decrease in DCAN formation potential. Solar irradiation was demonstrated to degrade Trp, Tyr and their DCAN formation potential. The photolysis products of Trp after solar irradiation were detected as kynurenine and tryptamine, which had chloroform, CH and DCAN formation potential lower than those of Trp. Copyright © 2016. Published by Elsevier Ltd.

Disinfection of Multidrug Resistant Escherichia coli by Solar-Photocatalysis using Fe-doped ZnO Nanoparticles.

PubMed

Das, Sourav; Sinha, Sayantan; Das, Bhaskar; Jayabalan, R; Suar, Mrutyunjay; Mishra, Amrita; Tamhankar, Ashok J; Stålsby Lundborg, Cecilia; Tripathy, Suraj K

2017-03-07

Spread of antibiotic resistant bacteria through water, is a threat to global public health. Here, we report Fe-doped ZnO nanoparticles (Fe/ZnO NPs) based solar-photocatalytic disinfection (PCD) of multidrug resistant Escherichia coli (MDR E. coli). Fe/ZnO NPs were synthesized by chemical precipitation technique, and when used as photocatalyst for disinfection, proved to be more effective (time for complete disinfection = 90 min) than ZnO (150 min) and TiO 2 (180 min). Lipid peroxidation and potassium (K + ) ion leakage studies indicated compromisation of bacterial cell membrane and electron microscopy and live-dead staining confirmed the detrimental effects on membrane integrity. Investigations indicated that H 2 O 2 was the key species involved in solar-PCD of MDR E. coli by Fe/ZnO NPs. X-ray diffraction and atomic absorption spectroscopy studies showed that the Fe/ZnO NPs system remained stable during the photocatalytic process. The Fe/ZnO NPs based solar-PCD process proved successful in the disinfection of MDR E. coli in real water samples collected from river, pond and municipal tap. The Fe/ZnO NPs catalyst made from low cost materials and with high efficacy under solar light may have potential for real world applications, to help reduce the spread of resistant bacteria.

USE OF FENTON'S REAGENT AS A DISINFECTANT

EPA Science Inventory

Combined sewage samples obtained from a wastewater treatment facility were disinfected by the Fenton's Reagent of several different compositions. The pre-settled samples contained both suspended solids (SS) and dissolved organic carbon (DOC) at concentrations of 28 and 290 mg/L,...

Hepatitis A Virus Disinfection in Water by Solar Photo-Fenton Systems.

PubMed

Polo, David; García-Fernández, Irene; Fernández-Ibañez, Pilar; Romalde, Jesús L

2018-06-01

This study evaluates and compares the effectiveness of solar photo-Fenton systems for the inactivation of hepatitis A virus (HAV) in water. The effect of solar irradiance, dark- Fenton reaction and three different reactant concentrations (2.5/5, 5/10 and 10/20 mg/L of Fe 2+ /H 2 O 2 ) on the photo-Fenton process were tested in glass bottle reactors (200 mL) during 6 h under natural sunlight. Disinfection kinetics were determined both by RT-qPCR and infectivity assays. Mean water temperatures ranged from 25 to 27.3 °C, with a maximum local noon UV irradiances of 22.36 W/m 2 . Photo-Fenton systems yielded increased viral reduction rates in comparison with the isolated effect under the Fenton reaction in darkness (negligible viral reduction) or the solar radiation (0.25 Log of RNA reduction). With the highest concentration employed (10-20 mg/L Fe 2+ -H 2 O 2 ), an average RNA reduction rate of ~ 1.8 Log (initial concentration of 10 5 pfu/mL) and a reduction of 80% in the infectivity capacity were reached. Results showed a strong synergistic effect between Fe 2+ /H 2 O 2 and sunlight, demonstrating that significant disinfection rates of HAV under photo-Fenton systems may occur with relatively higher efficiency at middle environmental temperatures and without the need for an energy-intensive light source.

Solar-light photocatalytic disinfection using crystalline/amorphous low energy bandgap reduced TiO2

PubMed Central

Kim, Youngmin; Hwang, Hee Min; Wang, Luyang; Kim, Ikjoon; Yoon, Yeoheung; Lee, Hyoyoung

2016-01-01

A generation of reactive oxygen species (ROS) from TiO2 under solar light has been long sought since the ROS can disinfect organic pollutants. We found that newly developed crystalline/amorphous reduced TiO2 (rTiO2) that has low energy bandgap can effectively generate ROS under solar light and successfully remove a bloom of algae. The preparation of rTiO2 is a one-pot and mass productive solution-process reduction using lithium-ethylene diamine (Li-EDA) at room temperature. Interestingly only the rutile phase of TiO2 crystal was reduced, while the anatase phase even in case of both anatase/rutile phased TiO2 was not reduced. Only reduced TiO2 materials can generate ROS under solar light, which was confirmed by electron spin resonance. Among the three different types of Li-EDA treated TiO2 (anatase, rutile and both phased TiO2), the both phased rTiO2 showed the best performance to produce ROS. The generated ROS effectively removed the common green algae Chlamydomonas. This is the first report on algae degradation under solar light, proving the feasibility of commercially available products for disinfection. PMID:27121120

Effect of disinfection upon dissolved organic carbon (DOC) in wastewater: bacterial bioassays.

PubMed

Arana, I; Santorum, P; Muela, A; Barcina, I

2000-08-01

Quantitative and qualitative changes in organic matter content of wastewater effluents attributable to chlorination and ozonation have been analysed using bioassays as well as organic carbon direct measures. Bioassays were carried out using the bacterial populations of wastewater and two Escherichia coli strains as test micro-organisms. Our results indicate that pure strains present some advantages over indigenous bacteria. Although wastewater bacterial populations are better adapted to growth in wastewater, E. coli strains are more sensitive to changes in dissolved organic carbon (DOC) content. Moreover, the use of pure cultures allows estimation of the portion of DOC which can be converted in cell biomass, the assimilable organic carbon (AOC). Finally, the results obtained using prototrophic and the auxotrophic strains of E. coli suggested that ozonation alters the amino acid composition of wastewater while chlorination does not change the quantity nor the quality of the DOC present in effluents.

Enhanced coagulation with powdered activated carbon or MIEX secondary treatment: a comparison of disinfection by-product formation and precursor removal.

PubMed

Watson, Kalinda; Farré, Maria José; Knight, Nicole

2015-01-01

The removal of both organic and inorganic disinfection by-product (DBP) precursors prior to disinfection is important in mitigating DBP formation, with halide removal being particularly important in salinity-impacted water sources. A matrix of waters of variable alkalinity, halide concentration and dissolved organic carbon (DOC) concentration were treated with enhanced coagulation (EC) followed by anion exchange (MIEX resin) or powdered activated carbon (PAC) and the subsequent disinfection by-product formation potentials (DBP-FPs) assessed and compared to DBP-FPs for untreated samples. Halide and DOC removal were also monitored for both treatment processes. Bromide and iodide adsorption by MIEX treatment ranged from 0 to 53% and 4-78%, respectively. As expected, EC and PAC treatments did not remove halides. DOC removal by EC/PAC was 70 ± 10%, while EC/MIEX enabled a DOC removal of 66 ± 12%. Despite the halide removals achieved by MIEX, increases in brominated disinfection by-product (Br-DBP) formation were observed relative to untreated samples, when favourable Br:DOC ratios were created by the treatment. However, the increases in formation were less than what was observed for the EC/PAC treated waters, which caused large increases in Br-DBP formation when high Br-DBP-forming water quality conditions occurred. The formation potential of fully chlorinated DBPs decreased after treatment in all cases.

The role of visible light active TiO2 specimens on the solar photocatalytic disinfection of E. coli.

PubMed

Birben, Nazmiye Cemre; Tomruk, Ayse; Bekbolet, Miray

2017-05-01

Solar photocatalytic disinfection efficiency of novel visible light activated (VLA) photocatalysts was evaluated with the aim of assessing inactivation of Escherichia coli as the pathogen indicator organism present in drinking water. Influence of humic acid (HA) on the photocatalytic disinfection efficiency of the specified VLA TiO 2 specimens i.e., N-doped, Se-doped, and Se-N co-doped TiO 2 was also investigated. Photocatalytic disinfection efficiency was assessed by the enumeration of bacteria following selected irradiation periods. Degradation and compositional changes in organic matter (OM) was also tracked by means of UV-vis and advanced fluorescence spectroscopic (EEM features) parameters. Photocatalytic mineralization of the organic matter was followed by dissolved organic carbon contents. Presence of HA as a model organic compound of natural organic matter (NOM) displayed a retardation effect on solar photocatalytic abatement of E. coli. However, no distinctly different effect was observed under solar photolytic conditions due to the presence of HA. Regrowth of E. coli could not be assessed under the specified experimental conditions. A comparison was introduced with respect to the use of undoped TiO 2 P-25 as the photocatalyst.

Photochemical Mineralization of Terrigenous DOC to Dissolved Inorganic Carbon in Ocean

NASA Astrophysics Data System (ADS)

Aarnos, Hanna; Gélinas, Yves; Kasurinen, Ville; Gu, Yufei; Puupponen, Veli-Mikko; Vähätalo, Anssi V.

2018-02-01

When terrigenous dissolved organic carbon (tDOC) rich in chromophoric dissolved organic matter (tCDOM) enters the ocean, solar radiation mineralizes it partially into dissolved inorganic carbon (DIC). This study addresses the amount and the rates of DIC photoproduction from tDOC and the area of ocean required to photomineralize tDOC. We collected water samples from 10 major rivers, mixed them with artificial seawater, and irradiated them with simulated solar radiation to measure DIC photoproduction and the photobleaching of tCDOM. The linear relationship between DIC photoproduction and tCDOM photobleaching was used to estimate the amount of photoproduced DIC from the tCDOM fluxes of the study rivers. Solar radiation was estimated to mineralize 12.5 ± 3.7 Tg C yr-1 (10 rivers)-1 or 18 ± 8% of tDOC flux. The irradiation experiments also approximated typical apparent spectral quantum yields for DIC photoproduction (ϕλ) over the entire lifetime of the tCDOM. Based on ϕλs and the local solar irradiances in river plumes, the annual areal DIC photoproduction rates from tDOC were calculated to range from 52 ± 4 (Lena River) to 157 ± 2 mmol C m-2 yr-1 (Mississippi River). When the amount of photoproduced DIC was divided by the areal rate, 9.6 ± 2.5 × 106 km2 of ocean was required for the photomineralization of tDOC from the study rivers. Extrapolation to the global tDOC flux yields 45 (31-58) Tg of photoproduced DIC per year in the river plumes that cover 34 (25-43) × 106 km2 of the ocean.

On the factors influencing the performance of solar reactors for water disinfection with photosensitized singlet oxygen.

PubMed

Manjón, Francisco; Villén, Laura; García-Fresnadillo, David; Orellana, Guillermo

2008-01-01

Two solar reactors based on compound parabolic collectors (CPCs) were optimized for water disinfection by photosensitized singlet oxygen (1O2) production in the heterogeneous phase. Sensitizing materials containing Ru(II) complexes immobilized on porous silicone were produced, photochemically characterized, and successfully tested for the inactivation of up to 10(4) CFU mL(-1) of waterborne Escherichia coli (gram-negative) or Enterococcus faecalis (gram-positive) bacteria. The main factors determining the performance of the solar reactors are the type of photosensitizing material, the sensitizer loading, the CPC collector geometry (fin- vs coaxial-type), the fluid rheology, and the balance between concurrent photothermal--photolytic and 1O2 effects on the microorganisms' inactivation. In this way, at the 40 degrees N latitude of Spain, water can be disinfected on a sunny day (0.6-0.8 MJ m(-2) L(-1) accumulated solar radiation dose in the 360-700 nm range, typically 5-6 h of sunlight) with a fin-type reactor containing 0.6 m2 of photosensitizing material saturated with tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) (ca. 2.0 g m(-2)). The optimum rheological conditions require laminar-to-transitional water flow in both prototypes. The fin-type system showed better inactivation efficiency than the coaxial reactor due to a more important photolytic contribution. The durability of the sensitizing materials was tested and the operational lifetime of the photocatalyst is at least three months without any reduction in the bacteria inactivation efficiency. Solar water disinfection with 1O2-generating films is demonstrated to be an effective technique for use in isolated regions of developing countries with high yearly average sunshine.

Application of an electrochemical chlorine-generation system combined with solar energy as appropriate technology for water disinfection.

PubMed

Choi, Jusol; Park, Chan Gyu; Yoon, Jeyong

2013-02-01

Affordable water disinfection is key to reducing the waterborne disease experienced worldwide where resources are limited. A simple electrochemical system that can generate chlorine as a disinfectant from the electrolysis of sodium chloride is an appropriate technology to produce clean water, particularly if driven by solar energy. This study examined the affordability of an electrochemical chlorine generation system using solar energy and developed the necessary design information for its implementation. A two-electrode batch reactor, equipped with commercial IrO(2)-coated electrodes and a solar panel (approximate area 0.2 m(2)), was used to produce chlorine from a 35g/L solution of NaCl. Within 1 h, sufficient chlorine (0.8 g) was generated to produce clean drinking water for about 80 people for 1 day (target microorganism: Escherichia coli; daily drinking water requirement: 2 L per person; chlorine demand: 4 mg/L; solar power: 650 W/m(2) in Seoul, Korea. Small household batteries were demonstrated to be a suitable alternative power source when there is insufficient solar irradiation. Using a 1 m(2) solar panel, the reactor would take only 15 min in Seoul, Korea, or 7 min in the tropics (solar power 1300 W/m(2)), to generate 1 g of chlorine. The solar-powered electrochemical chlorine generation system for which design information is provided here is a simple and affordable way to produce chlorine with which to convert contaminated water into clean drinking water.

Solar disinfection of drinking water contained in transparent plastic bottles: characterizing the bacterial inactivation process.

PubMed

McGuigan, K G; Joyce, T M; Conroy, R M; Gillespie, J B; Elmore-Meegan, M

1998-06-01

A series of experiments is reported to identify and characterize the inactivation process in operation when drinking water, heavily contaminated with a Kenyan isolate of Escherichia coli, is stored in transparent plastic bottles that are then exposed to sunlight. The roles of optical and thermal inactivation mechanisms are studied in detail by simulating conditions of optical irradiance, water turbidity and temperature, which were recorded during a series of solar disinfection measurements carried out in the Kenyan Rift Valley. Optical inactivation effects are observed even in highly turbid water (200 ntu) and at low irradiances of only 10 mW cm-2. Thermal inactivation is found to be important only at water temperatures above 45 degrees C, at which point strong synergy between optical and thermal inactivation processes is observed. The results confirm that, where strong sunshine is available, solar disinfection of drinking water is an effective, low cost method for improving water quality and may be of particular use to refugee camps in disaster areas. Strategies for improving bacterial inactivation are discussed.

Wetlands receiving water treated with coagulants improve water quality by removing dissolved organic carbon and disinfection byproduct precursors.

PubMed

Hansen, Angela M; Kraus, Tamara E C; Bachand, Sandra M; Horwath, William R; Bachand, Philip A M

2018-05-01

Constructed wetlands are used worldwide to improve water quality while also providing critical wetland habitat. However, wetlands have the potential to negatively impact drinking water quality by exporting dissolved organic carbon (DOC) that upon disinfection can form disinfection byproducts (DBPs) like trihalomethanes (THMs) and haloacetic acids (HAAs). We used a replicated field-scale study located on organic rich soils in California's Sacramento-San Joaquin Delta to test whether constructed flow-through wetlands which receive water high in DOC that is treated with either iron- or aluminum-based coagulants can improve water quality with respect to DBP formation. Coagulation alone removed DOC (66-77%) and THM (67-70%) precursors, and was even more effective at removing HAA precursors (77-90%). Passage of water through the wetlands increased DOC concentrations (1.5-7.5mgL -1 ), particularly during the warmer summer months, thereby reversing some of the benefits from coagulant addition. Despite this addition, water exiting the wetlands treated with coagulants had lower DOC and DBP precursor concentrations relative to untreated source water. Benefits of the coagulation-wetland systems were greatest during the winter months (approx. 50-70% reduction in DOC and DBP precursor concentrations) when inflow water DOC concentrations were higher and wetland DOC production was lower. Optical properties suggest DOC in this system is predominantly comprised of high molecular weight, aromatic compounds, likely derived from degraded peat soils. Published by Elsevier B.V.

Selectable Optical Diagnostics Instrument Experiment Diffusion Coefficient Mixture-3 (SODI) DCMix-3 Installation

NASA Image and Video Library

2016-09-13

NASA astronaut Kate Rubins works on Selectable Optical Diagnostics Instrument Experiment Diffusion Coefficient Mixture-3 (SODI) DCMix-3 Installation inside the station’s Microgravity Science Glovebox. The glovebox is one of the major dedicated science facilities inside the Destiny laboratory and provides a sealed environment for conducting science and technology experiments. The glovebox is particularly suited for handling hazardous materials when the crew is present.

Dissolved Organic Carbon and Disinfection By-Product Precursor Release from Managed Peat Soils

USGS Publications Warehouse

Fleck, J.A.; Bossio, D.A.; Fujii, R.

2004-01-01

A wetland restoration demonstration project examined the effects of a permanently flooded wetland on subsidence of peat soils. The project, started in 1997, was done on Twitchell Island, in the Sacramento-San Joaquin Delta of California. Conversion of agricultural land to a wetland has changed many of the biogeochemical processes controlling dissolved organic carbon (DOC) release from the peat soils, relative to the previous land use. Dissolved organic C in delta waters is a concern because it reacts with chlorine, added as a disinfectant in municipal drinking waters, to form carcinogenic disinfection byproducts (DBPs), including trihalomethanes (THMs) and haloacetic acids (HAAs). This study explores the effects of peat soil biogeochemistry on DOC and DBP release under agricultural and wetland management. Results indicate that organic matter source, extent of soil organic matter decomposition, and decomposition pathways all are factors in THM formation. The results show that historical management practices dominate the release of DOC and THM precursors. However, within-site differences indicate that recent management decisions can contribute to changes in DOC quality and THM precursor formation. Not all aromatic forms of carbon are highly reactive and certain environmental conditions produce the specific carbon structures that form THMs. Both HAA and THM precursors are elevated in the DOC released under wetland conditions. The findings of this study emphasize the need to further investigate the roles of organic matter sources, microbial decomposition pathways, and decomposition status of soil organic matter in the release of DOC and DBP precursors from delta soils under varying land-use practices.

Disinfection of the Water Borne Pathogens Escherichia coli and Staphylococcus aureus by Solar Photocatalysis Using Sonochemically Synthesized Reusable Ag@ZnO Core-Shell Nanoparticles.

PubMed

Das, Sourav; Ranjana, Neha; Misra, Ananyo Jyoti; Suar, Mrutyunjay; Mishra, Amrita; Tamhankar, Ashok J; Lundborg, Cecilia Stålsby; Tripathy, Suraj K

2017-07-10

Water borne pathogens present a threat to human health and their disinfection from water poses a challenge, prompting the search for newer methods and newer materials. Disinfection of the Gram-negative bacterium Escherichia coli and the Gram-positive coccal bacterium Staphylococcus aureus in an aqueous matrix was achieved within 60 and 90 min, respectively, at 35 °C using solar-photocatalysis mediated by sonochemically synthesized Ag@ZnO core-shell nanoparticles. The efficiency of the process increased with the increase in temperature and at 55 °C the disinfection for the two bacteria could be achieved in 45 and 60 min, respectively. A new ultrasound-assisted chemical precipitation technique was used for the synthesis of Ag@ZnO core-shell nanoparticles. The characteristics of the synthesized material were established using physical techniques. The material remained stable even at 400 °C. Disinfection efficiency of the Ag@ZnO core-shell nanoparticles was confirmed in the case of real world samples of pond, river, municipal tap water and was found to be better than that of pure ZnO and TiO₂ (Degussa P25). When the nanoparticle- based catalyst was recycled and reused for subsequent disinfection experiments, its efficiency did not change remarkably, even after three cycles. The sonochemically synthesized Ag@ZnO core-shell nanoparticles thus have a good potential for application in solar photocatalytic disinfection of water borne pathogens.

Continuous-flow solar UVB disinfection reactor for drinking water.

PubMed

Mbonimpa, Eric Gentil; Vadheim, Bryan; Blatchley, Ernest R

2012-05-01

Access to safe, reliable sources of drinking water is a long-standing problem among people in developing countries. Sustainable solutions to these problems often involve point-of-use or community-scale water treatment systems that rely on locally-available resources and expertise. This philosophy was used in the development of a continuous-flow, solar UVB disinfection system. Numerical modeling of solar UVB spectral irradiance was used to define temporal variations in spectral irradiance at several geographically-distinct locations. The results of these simulations indicated that a solar UVB system would benefit from incorporation of a device to amplify ambient UVB fluence rate. A compound parabolic collector (CPC) was selected for this purpose. Design of the CPC was based on numerical simulations that accounted for the shape of the collector and reflectance. Based on these simulations, a prototype CPC was constructed using materials that would be available and inexpensive in many developing countries. A UVB-transparent pipe was positioned in the focal area of the CPC; water was pumped through the pipe to allow exposure of waterborne microbes to germicidal solar UVB radiation. The system was demonstrated to be effective for inactivation of Escherichia coli, and DNA-weighted UV dose was shown to govern reactor performance. The design of the reactor is expected to scale linearly, and improvements in process performance (relative to results from the prototype) can be expected by use of larger CPC geometry, inclusion of better reflective materials, and application in areas with greater ambient solar UV spectral irradiance than the location of the prototype tests. The system is expected to have application for water treatment among communities in (developing) countries in near-equatorial and tropical locations. It may also have application for disaster relief or military field operations, as well as in water treatment in areas of developed countries that receive

Disinfection of the Water Borne Pathogens Escherichia coli and Staphylococcus aureus by Solar Photocatalysis Using Sonochemically Synthesized Reusable Ag@ZnO Core-Shell Nanoparticles

PubMed Central

Das, Sourav; Ranjana, Neha; Misra, Ananyo Jyoti; Suar, Mrutyunjay; Mishra, Amrita; Tripathy, Suraj K.

2017-01-01

Water borne pathogens present a threat to human health and their disinfection from water poses a challenge, prompting the search for newer methods and newer materials. Disinfection of the Gram-negative bacterium Escherichia coli and the Gram-positive coccal bacterium Staphylococcus aureus in an aqueous matrix was achieved within 60 and 90 min, respectively, at 35 °C using solar-photocatalysis mediated by sonochemically synthesized Ag@ZnO core-shell nanoparticles. The efficiency of the process increased with the increase in temperature and at 55 °C the disinfection for the two bacteria could be achieved in 45 and 60 min, respectively. A new ultrasound-assisted chemical precipitation technique was used for the synthesis of Ag@ZnO core-shell nanoparticles. The characteristics of the synthesized material were established using physical techniques. The material remained stable even at 400 °C. Disinfection efficiency of the Ag@ZnO core-shell nanoparticles was confirmed in the case of real world samples of pond, river, municipal tap water and was found to be better than that of pure ZnO and TiO2 (Degussa P25). When the nanoparticle- based catalyst was recycled and reused for subsequent disinfection experiments, its efficiency did not change remarkably, even after three cycles. The sonochemically synthesized Ag@ZnO core-shell nanoparticles thus have a good potential for application in solar photocatalytic disinfection of water borne pathogens. PMID:28698514

A community randomised controlled trial evaluating a home-based environmental intervention package of improved stoves, solar water disinfection and kitchen sinks in rural Peru: rationale, trial design and baseline findings.

PubMed

Hartinger, S M; Lanata, C F; Hattendorf, J; Gil, A I; Verastegui, H; Ochoa, T; Mäusezahl, D

2011-11-01

Pneumonia and diarrhoea are leading causes of death in children. There is a need to develop effective interventions. We present the design and baseline findings of a community-randomised controlled trial in rural Peru to evaluate the health impact of an Integrated Home-based Intervention Package in children aged 6 to 35 months. We randomised 51 communities. The intervention was developed through a community-participatory approach prior to the trial. They comprised the construction of improved stoves and kitchen sinks, the promotion of hand washing, and solar drinking water disinfection (SODIS). To reduce the potential impact of non-blinding bias, a psychomotor stimulation intervention was implemented in the control arm. The baseline survey included anthropometric and socio-economic characteristics. In a sub-sample we determined the level of faecal contamination of drinking water, hands and kitchen utensils and the prevalence of diarrhoegenic Escherichia coli in stool specimen. We enrolled 534 children. At baseline all households used open fires and 77% had access to piped water supplies. E. coli was found in drinking water in 68% and 64% of the intervention and control households. Diarrhoegenic E. coli strains were isolated from 45/139 stool samples. The proportion of stunted children was 54%. Randomization resulted in comparable study arms. Recently, several critical reviews raised major concerns on the reliability of open health intervention trials, because of uncertain sustainability and non-blinding bias. In this regard, the presented trial featuring objective outcome measures, a simultaneous intervention in the control communities and a 12-month follow up period will provide valuable evidence. Copyright © 2011 Elsevier Inc. All rights reserved.

Solar Disinfection of MODS Mycobacterial Cultures in Resource-Poor Settings

PubMed Central

Nathavitharana, Ruvandhi; Coronel, Jorge; Moore, David A. J.

2007-01-01

Introduction Safe disposal of TB culture material in which the infectious burden of clinical samples has been greatly amplified is an important challenge in resource-limited settings. The bactericidal capacity of solar cookers has been demonstrated previously for conventional bacteria and contaminated clinical waste. We investigated the use of a simple solar cooker for the sterilization of mycobacterial broth cultures from the microscopic observation drug susceptibility assay (MODS). Methods Simulated TB culture materials were prepared by inoculating 24-well MODS plates with 500 µL of a known concentration of Mycobacterium bovis BCG. In a series of experiments, samples were simultaneously placed inside a box-type solar cooker and control box and removed at timepoints between 15 minutes and 6 hours. Quantitative cultures were performed using retrieved samples to determine sterilization effect. Results All cultures from the control box were positive at or within 1–4 logs of inoculation concentration. Simulated culture plates at concentrations from 103colony-forming-units (CFU)/ml to 107 CFU/ml were completely sterilized after only one hour of cooker exposure, at temperatures between 50–102°C. At 109 CFU/ml (far in excess of diagnostic cultures), it was only possible to recover mycobacterial growth in plates removed after 15 minutes. By 30 minutes all plates were effectively sterilized. Discussion Solar disinfection provides a very effective, safe and low-cost alternative to conventional equipment used for disposal of mycobacterial culture material. Effect of climatic conditions and optimal operating procedure remain to be defined. PMID:17971863

A review of heterogeneous photocatalysis for water and surface disinfection.

PubMed

Byrne, John Anthony; Dunlop, Patrick Stuart Morris; Hamilton, Jeremy William John; Fernández-Ibáñez, Pilar; Polo-López, Inmaculada; Sharma, Preetam Kumar; Vennard, Ashlene Sarah Margaret

2015-03-30

Photo-excitation of certain semiconductors can lead to the production of reactive oxygen species that can inactivate microorganisms. The mechanisms involved are reviewed, along with two important applications. The first is the use of photocatalysis to enhance the solar disinfection of water. It is estimated that 750 million people do not have accessed to an improved source for drinking and many more rely on sources that are not safe. If one can utilize photocatalysis to enhance the solar disinfection of water and provide an inexpensive, simple method of water disinfection, then it could help reduce the risk of waterborne disease. The second application is the use of photocatalytic coatings to combat healthcare associated infections. Two challenges are considered, i.e., the use of photocatalytic coatings to give "self-disinfecting" surfaces to reduce the risk of transmission of infection via environmental surfaces, and the use of photocatalytic coatings for the decontamination and disinfection of medical devices. In the final section, the development of novel photocatalytic materials for use in disinfection applications is reviewed, taking account of materials, developed for other photocatalytic applications, but which may be transferable for disinfection purposes.

THE EFFECTS OF COMBINED OZONATION AND FILTRATION ON DISINFECTION BY-PRODUCT FORMATION. (R830908)

EPA Science Inventory

The effects of combined ozonation and membrane filtration on the removal of the natural organic matter (NOM) and the formation of disinfection by-products (DBPs) were investigated. Ozonation/filtration resulted in a reduction of up to 50% in the dissolved organic carbon (DOC) ...

Solar light irradiation significantly reduced cytotoxicity and disinfection byproducts in chlorinated reclaimed water.

PubMed

Lv, Xiao-Tong; Zhang, Xue; Du, Ye; Wu, Qian-Yuan; Lu, Yun; Hu, Hong-Ying

2017-11-15

Chlorinated reclaimed water is widely used for landscaping and recreational purposes, resulting in human exposure to toxic disinfection byproducts. Although the quality of chlorinated reclaimed water might be affected by sunlight during storage, the effects of solar light irradiation on the toxicity remain unknown. This study investigated the changes in cytotoxicity and total organic halogen (TOX) of chlorinated reclaimed water exposed to solar light. Irradiation with solar light for 12 h was found to significantly reduce the cytotoxicity of chlorinated reclaimed water by about 75%, with ultraviolet light being responsible for the majority of this reduction. Chlorine residual in reclaimed water tended to increase the cytotoxicity, and the synergy between solar light and free chlorine could not enhance the reduction of cytotoxicity. Adding hydroxyl radical scavengers revealed that the contribution of hydroxyl radical to cytotoxicity reduction was limited. Solar light irradiation concurrently reduced TOX. The low molecular weight (<1 kDa) fraction was the major contributor of cytotoxicity and TOX in chlorinated reclaimed water. Detoxification of the low molecular weight fraction by light irradiation was mainly a result of TOX dehalogenation, while detoxification of the high molecular weight (>1 kDa) fraction was probably caused by photoconversion from high toxic TOX to low toxic TOX. Copyright © 2017 Elsevier Ltd. All rights reserved.

The halosol process for water disinfection and dehalogenation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Acra, A.; Jurdi, M.; Mu'allem, H.

Substitution of chlorine and its derivatives as agents to disinfect water and wastewater effluents because of concern for the formation of the mutagenic and carcinogenic trihalomethanes (THM) may be a protracted endeavor. Excess chlorine residuals need to be controlled by dechlorinated agents, e.g., SO{sub 2}, to avoid esthetic objections voiced by consumers and the risk to aquatic environments. We focused on the phenomenon of photodecomposition and aqueons halogen solutions by sunlight. The halosol process, a batch system for solar dehalogenation, was developed into a flow-through system for the halosol disinfection of water. A prototype facility incorporated a solar reactor, throughmore » which chlorinated water flowed, made of borosilicate glass tube with a serpentine shape supported by a frame. Disinfection is induced by two cooperative biocidal agents (a halogen and sunlight) with sequential solar dehalogenation. An overall mean photodechlorination rate, K, of 0.238 m{sup 2}/W-h was obtained. The calculated solar UV-A fluence required to reduce the initial chlorine residuals by 90% and 99% was 9.65 and 19.30 W-h/m{sup 2}. The most effective photodechlorination components of sunlight were in the UV-A region of the spectrum: effectiveness decreased exponentially with wavelength.« less

Preliminary assessment of DOC and THM precursor loads from a freshwater restored wetland, an agricultural field, and a tidal wetland in the Sacramento-San Joaquin River Delta

USGS Publications Warehouse

Fujii, R.; Bergamaschi, B.A.; Ganju, N.K.; Fleck, J.A.; Burow-Fogg, K.R.; Schoellhamer, D.; Deverel, S.J.

2003-01-01

Water exported from the Sacramento-San Joaquin River Delta supplies drinking water to more than 22 million people in California. At certain times of the year, Delta waters contain relatively high concentrations of dissolved organic carbon (DOC) and bromide. During these times, chlorination of Delta water for drinking water disinfection will form disinfection byproducts, such as trihalomethanes (THMs), that can exceed the U.S. Environmental Protection Agency's maximum contaminant level for THMs of 80 mg/L. Important sources of DOC and THM precursors (types of DOC that form THMs when chlorinated) to the Delta include rivers, drainage water from peat islands, water from wetlands and areas with extensive riparian vegetation, and in-channel growth of algae and macrophytes. Due to proposed ecosystem restoration and creation of wetlands in the Delta, there is an urgent need for information on the relative loads of DOC and THM precursors produced from three different land uses: restored wetlands constructed for subsidence mitigation, tidal wetlands, and agricultural operations. We have been conducting research in the Delta to provide this information. A restored wetland and agricultural field located on Twitchell Island, and a tidal wetland on Browns Island have been monitored for flow, DOC, and THM precursors. Initial results indicate that the loads of DOC and THM precursors are similar for the restored wetland (surface water only) and the agricultural field. These land uses produce DOC loads of about 14 and 11 g C/m2/yr, respectively, and THM precursor loads of about 1.7 and 1.0 g THM/m2/yr, respectively. Estimates of DOC and THM precursor loads for the tidal wetland site on Browns Island and seepage associated with the restored wetland are being developed.

[Economic evaluation of social technologies applied to health promotion: water supply by the SODIS System in riverside communities of the Brazilian Amazon].

PubMed

Lobo, Marco Aurélio Arbage; Lima, Dula Maria Bento de; Souza, Cezarina Maria Nobre; Nascimento, Waddle Almeida; Araújo, Leiliane Cristina Cardoso; Santos, Neucy Barreto dos

2013-07-01

The so-called social technologies have been widely used in many places around the world as a viable alternative for low-income populations to gain access to opportunities for employment and income and other aspects related to quality of life, including basic sanitation. This paper conducts a cost-benefit analysis of using a low cost technology for drinking water used in several countries, namely the SODIS system. The study was conducted in riverside communities living in the island area of Belem municipality, located in the Brazilian Amazon. Data were collected through questionnaires answered by families living on three islands: Jutuba, Nova and Urubuoca. The results were positive, considering the cost-benefit analysis of the project, which demonstrates the economic viability of using the SODIS system in the situation investigated.

Combined effects of coagulation and adsorption on ultrafiltration membrane fouling control and subsequent disinfection in drinking water treatment.

PubMed

Xing, Jiajian; Liang, Heng; Cheng, Xiaoxiang; Yang, Haiyan; Xu, Daliang; Gan, Zhendong; Luo, Xinsheng; Zhu, Xuewu; Li, Guibai

2018-06-02

This study investigated the combined effects of coagulation and powdered activated carbon (PAC) adsorption on ultrafiltration (UF) membrane fouling control and subsequent disinfection efficiency through filtration performance, dissolved organic carbon (DOC) removal, fluorescence excitation-emission matrix (EEM) spectroscopy, and disinfectant curve. The fouling behavior of UF membrane was comprehensively analyzed especially in terms of pollutant removal and fouling reversibility to understand the mechanism of fouling accumulation and disinfectant dose reduction. Pre-coagulation with or without adsorption both achieved remarkable effect of fouling mitigation and disinfection dose reduction. The two pretreatments were effective in total fouling control and pre-coagulation combined with PAC adsorption even decreased hydraulically irreversible fouling notably. Besides, pre-coagulation decreased residual disinfectant decline due to the removal of hydrophobic components of natural organic matters (NOM). Pre-coagulation combined with adsorption had a synergistic effect on further disinfectant decline rate reduction and decreased total disinfectant consumption due to additional removal of hydrophilic NOM by PAC adsorption. The disinfectant demand was further reduced after membrane. These results show that membrane fouling and disinfectant dose can be reduced in UF coupled with pretreatment, which could lead to the avoidance of excessive operation cost disinfectant dose for drinking water supply.

Singlet oxygen sensitizing materials based on porous silicone: photochemical characterization, effect of dye reloading and application to water disinfection with solar reactors.

PubMed

Manjón, Francisco; Santana-Magaña, Montserrat; García-Fresnadillo, David; Orellana, Guillermo

2010-06-01

Photogeneration of singlet molecular oxygen ((1)O(2)) is applied to organic synthesis (photooxidations), atmosphere/water treatment (disinfection), antibiofouling materials and in photodynamic therapy of cancer. In this paper, (1)O(2) photosensitizing materials containing the dyes tris(4,4'-diphenyl-2,2'-bipyridine)ruthenium(II) (1, RDB(2+)) or tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) (2, RDP(2+)), immobilized on porous silicone (abbreviated RDB/pSil and RDP/pSil), have been produced and tested for waterborne Enterococcus faecalis inactivation using a laboratory solar simulator and a compound parabolic collector (CPC)-based solar photoreactor. In order to investigate the feasibility of its reuse, the sunlight-exposed RDP/pSil sensitizing material (RDP/pSil-a) has been reloaded with RDP(2+) (RDP/pSil-r). Surprisingly, results for bacteria inactivation with the reloaded material have demonstrated a 4-fold higher efficiency compared to those of either RDP/pSil-a, unused RDB/pSil and the original RDP/pSil. Surface and bulk photochemical characterization of the new material (RDP/pSil-r) has shown that the bactericidal efficiency enhancement is due to aggregation of the silicone-supported photosensitizer on the surface of the polymer, as evidenced by confocal fluorescence lifetime imaging microscopy (FLIM). Photogenerated (1)O(2) lifetimes in the wet sensitizer-doped silicone have been determined to be ten times longer than in water. These facts, together with the water rheology in the solar reactor and the interfacial production of the biocidal species, account for the more effective disinfection observed with the reloaded photosensitizing material. These results extend and improve the operational lifetime of photocatalytic materials for point-of-use (1)O(2)-mediated solar water disinfection.

Solar light (hv) and H2O2/hv photo-disinfection of natural alkaline water (pH 8.6) in a compound parabolic collector at different day periods in Sahelian region.

PubMed

Ndounla, J; Pulgarin, C

2015-11-01

The photo-disinfection of natural alkaline surface water (pH 8.6 ± 0.3) for drinking purposes was carried out under solar radiation treatments. The enteric bacteria studied were the wild total coliforms/Escherichia coli (10(4) CFU/ml) and Salmonella spp. (10(4) CFU/ml) naturally present in the water. The photo-disinfection of a 25-l water sample was carried out in a solar compound parabolic collector (CPC) in the absence and in the presence of hydrogen peroxide (H2O2). The addition of H2O2 (10 mg/L) to the sample water was sufficient to enhance the photo-disinfection and ensure an irreversible lethal action on the wild enteric bacteria contents of the sample. The inactivation kinetic of the system was significantly enhanced compared to the one carried out without H2O2 addition. The effect of the solar radiation parameters on the efficiency of the photo-disinfection were assessed. The pH has increased during the treatment in all the photo-disinfection processes (hv and H2O2/hv). The Salmonella spp strain has shown the best effective inactivate time in alkaline water than the one recorded under acidic or near-neutral conditions. The evolution of some physico-chemical parameters of the water (turbidity, NO2(-), NO3(-), NH4(+), HPO4(2-), and bicarbonate (HCO3(-))) was monitored during the treatment. Finally, the possible mechanistic process involved during the enteric bacteria inactivation was suggested.

Rapid water disinfection using vertically aligned MoS2 nanofilms and visible light

NASA Astrophysics Data System (ADS)

Liu, Chong; Kong, Desheng; Hsu, Po-Chun; Yuan, Hongtao; Lee, Hyun-Wook; Liu, Yayuan; Wang, Haotian; Wang, Shuang; Yan, Kai; Lin, Dingchang; Maraccini, Peter A.; Parker, Kimberly M.; Boehm, Alexandria B.; Cui, Yi

2016-12-01

Solar energy is readily available in most climates and can be used for water purification. However, solar disinfection of drinking water mostly relies on ultraviolet light, which represents only 4% of the total solar energy, and this leads to a slow treatment speed. Therefore, the development of new materials that can harvest visible light for water disinfection, and so speed up solar water purification, is highly desirable. Here we show that few-layered vertically aligned MoS2 (FLV-MoS2) films can be used to harvest the whole spectrum of visible light (∼50% of solar energy) and achieve highly efficient water disinfection. The bandgap of MoS2 was increased from 1.3 to 1.55 eV by decreasing the domain size, which allowed the FLV-MoS2 to generate reactive oxygen species (ROS) for bacterial inactivation in the water. The FLV-MoS2 showed a ∼15 times better log inactivation efficiency of the indicator bacteria compared with that of bulk MoS2, and a much faster inactivation of bacteria under both visible light and sunlight illumination compared with the widely used TiO2. Moreover, by using a 5 nm copper film on top of the FLV-MoS2 as a catalyst to facilitate electron-hole pair separation and promote the generation of ROS, the disinfection rate was increased a further sixfold. With our approach, we achieved water disinfection of >99.999% inactivation of bacteria in 20 min with a small amount of material (1.6 mg l-1) under simulated visible light.

Photophysical and photochemical effects of UV and VUV photo-oxidation and photolysis on PET and PEN

NASA Astrophysics Data System (ADS)

Morgan, Andrew

Polyethylene Terephthalate (PET) is a widely used polymer in the bottling, packaging, and clothing industry. In recent years an increasing global demand for PET has taken place due to the Solar Disinfection (SODIS) process. SODIS is a method of sterilizing fresh water into drinkable water. The PET bottles are used in the process to contain the water during solar irradiation due to its highly transparent optical property. Alongside PET, polyethylene 2,6-napthalate (PEN) is used in bottling and flexible electronic applications. The surface of PEN would need to be modified to control the hydrophilicity and the interaction it exudes as a substrate. The UV light absorption properties of PET and PEN are of great importance for many applications, and thus needs to be studied along with its photochemical resistance. The optical and chemical nature of PET was studied as it was treated by UV photo-oxidation, photo-ozonation, and photolysis under atmospheric pressure. Another investigation was also used to study PEN and PET as they are treated by vacuum UV (VUV) photo-oxidation, VUV photolysis, and remote oxygen reactions. The extent of the photoreactions' effect into the depth of the polymers is examined as treatment conditions are changed. The different experimental methods established the rate of several competing photoreactions on PET and PEN during irradiance, and their effect on the optical quality of the polymers.

Advances in photocatalytic disinfection of bacteria: Development of photocatalysts and mechanisms.

PubMed

Wang, Wanjun; Huang, Guocheng; Yu, Jimmy C; Wong, Po Keung

2015-08-01

Photocatalysis has attracted worldwide attention due to its potential in solar energy conversion. As a "green" advanced oxidation technology, it has been extensively used for water disinfection and wastewater treatment. This article provides a review of the recent progress in solar energy-induced photocatalytic disinfection of bacteria, focusing on the development of highly efficient photocatalysts and their underlying mechanisms in bacterial inactivation. The photocatalysts are classified into TiO2-based and non-TiO2-based systems, as TiO2 is the most investigated photocatalyst. The synthesis methods, modification strategies, bacterial disinfection activities and mechanisms of different types of photocatalysts are reviewed in detail. Emphasis is given to the modified TiO2, including noble metal deposition, non-metal doping, dye sensitization and composite TiO2, along with typical non-TiO2-based photocatalysts for bacterial disinfection, including metal oxides, sulfides, bismuth metallates, graphene-based photocatalysts, carbon nitride-based photocatalysts and natural photocatalysts. A simple and versatile methodology by using a partition system combined with scavenging study is introduced to study the photocatalytic disinfection mechanisms in different photocatalytic systems. This review summarizes the current state of the work on photocatalytic disinfection of bacteria, and is expected to offer useful insights for the future development in the field. Copyright © 2015. Published by Elsevier B.V.

Effect of a constructed wetland on disinfection byproducts: Removal processes and production of precursors

USGS Publications Warehouse

Rostad, C.E.; Martin, B.S.; Barber, L.B.; Leenheer, J.A.; Daniel, S.R.

2000-01-01

The fate of halogenated disinfection byproducts (DBPs) in treatment wetlands and the changes in the DBP formation potential as wastewater treatment plant (WWTP)-derived water moves through the wetlands were investigated. Wetland inlet and outlet samples were analyzed for total organic halide (TOX), trihalomethanes (TH M), haloacetic acids (HAA), dissolved organic carbon (DOC), and UV absorbance. Removal of DBPs by the wetland ranged from 13 to 55% for TOX, from 78 to 97% for THM, and from 67 to 96% for HAA. The 24-h and 7-day nonpurgeable total organic halide (NPTOX), THM, and HAA formation potential yields were determined at the inlet and outlet of these wetlands. The effect of wetlands on the production of DBP precursors and their DBP-formation potential yield from wastewater was dramatic. The wetlands increased DBP yield up to a factor of almost 30. Specific changes in the DOC precursors were identified using 13C NMR spectroscopy.The fate of halogenated disinfection byproducts (DBPs) in treatment wetlands and the changes in the DBP formation potential as wastewater treatment plant (WWTP)-derived water moves through the wetlands were investigated. Wetland inlet and outlet samples were analyzed for total organic halide (TOX), trihalomethanes (THM), haloacetic acids (HAA), dissolved organic carbon (DOC), and UV absorbance. Removal of DBPs by the wetland ranged from 13 to 55% for TOX, from 78 to 97% for THM, and from 67 to 96% for HAA. The 24-h and 7-day nonpurgeable total organic halide (NPTOX), THM, and HAA formation potential yields were determined at the inlet and outlet of these wetlands. The effect of wetlands on the production of DBP precursors and their DBP-formation potential yield from wastewater was dramatic. The wetlands increased DBP yield up to a factor of almost 30. Specific changes in the DOC precursors were identified using 13C NMR spectroscopy.

Conceptual model and experimental framework to determine the contributions of direct and indirect photoreactions to the solar disinfection of MS2, phiX174, and adenovirus.

PubMed

Mattle, Michael J; Vione, Davide; Kohn, Tamar

2015-01-06

Sunlight inactivates waterborne viruses via direct (absorption of sunlight by the virus) and indirect processes (adsorption of sunlight by external chromophores, which subsequently generate reactive species). While the mechanisms underlying these processes are understood, their relative importance remains unclear. This study establishes an experimental framework to determine the kinetic parameters associated with a virus' susceptibility to solar disinfection and proposes a model to estimate disinfection rates and to apportion the contributions of different inactivation processes. Quantum yields of direct inactivation were determined for three viruses (MS2, phiX174, and adenovirus), and second-order rate constants associated with indirect inactivation by four reactive species ((1)O2, OH(•), CO3(•-), and triplet states) were established. PhiX174 exhibited the greatest quantum yield (1.4 × 10(-2)), indicating that it is more susceptible to direct inactivation than MS2 (2.9 × 10(-3)) or adenovirus (2.5 × 10(-4)). Second-order rate constants ranged from 1.7 × 10(7) to 7.0 × 10(9) M(-1) s(-1) and followed the sequence MS2 > adenovirus > phiX174. A predictive model based on these parameters accurately estimated solar disinfection of MS2 and phiX174 in a natural water sample and approximated that of adenovirus within a factor of 6. Inactivation mostly occurred by direct processes, though indirect inactivation by (1)O2 also contributed to the disinfection of MS2 and adenovirus.

Constructed wetlands and solar-driven disinfection technologies for sustainable wastewater treatment and reclamation in rural India: SWINGS project.

PubMed

Álvarez, J A; Ávila, C; Otter, P; Kilian, R; Istenič, D; Rolletschek, M; Molle, P; Khalil, N; Ameršek, I; Mishra, V K; Jorgensen, C; Garfi, A; Carvalho, P; Brix, H; Arias, C A

2017-09-01

SWINGS was a cooperation project between the European Union and India, aiming at implementing state of the art low-cost technologies for the treatment and reuse of domestic wastewater in rural areas of India. The largest wastewater treatment plant consists of a high-rate anaerobic system, followed by vertical and horizontal subsurface flow constructed wetlands with a treatment area of around 1,900 m 2 and a final step consisting of solar-driven anodic oxidation (AO) and ultraviolet (UV) disinfection units allowing direct reuse of the treated water. The implementation and operation of two pilot plants in north (Aligarh Muslim University, AMU) and central India (Indira Gandhi National Tribal University, IGNTU) are shown in this study. The overall performance of AMU pilot plant during the first 7 months of operation showed organic matter removal efficiencies of 87% total suspended solids, 95% 5-day biological oxygen demand (BOD 5 ) and 90% chemical oxygen demand, while Kjeldahl nitrogen removal reached 89%. The UV disinfection unit produces water for irrigation and toilet flushing with pathogenic indicator bacteria well below WHO guidelines. On the other hand, the AO disinfection unit implemented at IGNTU and operated for almost a year has been shown to produce an effluent of sufficient quality to be reused by the local population for agriculture and irrigation.

Effect of DOC on evaporation from small Wisconsin lakes

NASA Astrophysics Data System (ADS)

Watras, C. J.; Morrison, K. A.; Rubsam, J. L.

2016-09-01

Evaporation (E) dominates the loss of water from many small lakes, and the balance between precipitation and evaporation (P-E) often governs water levels. In this study, evaporation rates were estimated for three small Wisconsin lakes over several years using 30-min data from floating evaporation pans (E-pans). Measured E was then compared to the output of mass transfer models driven by local conditions over daily time scales. The three lakes were chosen to span a range of dissolved organic carbon (DOC) concentrations (3-20 mg L-1), a solute that imparts a dark, tea-stain color which absorbs solar energy and limits light penetration. Since the lakes were otherwise similar, we hypothesized that a DOC-mediated increase in surface water temperature would translate directly to higher rates of evaporation thereby informing climate response models. Our results confirmed a DOC effect on surface water temperature, but that effect did not translate to enhanced evaporation. Instead the opposite was observed: evaporation rates decreased as DOC increased. Ancillary data and prior studies suggest two explanatory mechanisms: (1) disproportionately greater radiant energy outflux from high DOC lakes, and (2) the combined effect of wind speed (W) and the vapor pressure gradient (es - ez), whose product [W(es - ez)] was lowest on the high DOC lake, despite very low wind speeds (<1.5 m s-1) and steep forested uplands surrounding all three lakes. Agreement between measured (E-pan) and modeled evaporation rates was reasonably good, based on linear regression results (r2: 0.6-0.7; slope: 0.5-0.7, for the best model). Rankings based on E were similar whether determined by measured or modeled criteria (high DOC < low DOC). Across the 3 lakes and 4 years, E averaged ∼3 mm d-1 (C.V. 9%), but statistically significant differences between lakes resulted in substantial differences in cumulative E that were consistent from year to year. Daily water budgets for these lakes show that inputs

Publishing datasets with eSciDoc and panMetaDocs

NASA Astrophysics Data System (ADS)

Ulbricht, D.; Klump, J.; Bertelmann, R.

2012-04-01

Currently serveral research institutions worldwide undertake considerable efforts to have their scientific datasets published and to syndicate them to data portals as extensively described objects identified by a persistent identifier. This is done to foster the reuse of data, to make scientific work more transparent, and to create a citable entity that can be referenced unambigously in written publications. GFZ Potsdam established a publishing workflow for file based research datasets. Key software components are an eSciDoc infrastructure [1] and multiple instances of the data curation tool panMetaDocs [2]. The eSciDoc repository holds data objects and their associated metadata in container objects, called eSciDoc items. A key metadata element in this context is the publication status of the referenced data set. PanMetaDocs, which is based on PanMetaWorks [3], is a PHP based web application that allows to describe data with any XML-based metadata schema. The metadata fields can be filled with static or dynamic content to reduce the number of fields that require manual entries to a minimum and make use of contextual information in a project setting. Access rights can be applied to set visibility of datasets to other project members and allow collaboration on and notifying about datasets (RSS) and interaction with the internal messaging system, that was inherited from panMetaWorks. When a dataset is to be published, panMetaDocs allows to change the publication status of the eSciDoc item from status "private" to "submitted" and prepare the dataset for verification by an external reviewer. After quality checks, the item publication status can be changed to "published". This makes the data and metadata available through the internet worldwide. PanMetaDocs is developed as an eSciDoc application. It is an easy to use graphical user interface to eSciDoc items, their data and metadata. It is also an application supporting a DOI publication agent during the process of

Comparison of inclined plate sedimentation and dissolved air flotation for the minimisation of subsequent nitrogenous disinfection by-product formation.

PubMed

Chu, Wen-Hai; Gao, Nai-Yun; Templeton, Michael R; Yin, Da-Qiang

2011-04-01

The formation of disinfection by-products (DBPs), including both nitrogenous disinfection by-products (N-DBPs) and carbonaceous disinfection by-products (C-DBPs), was investigated upon chlorination of water samples following two treatment processes: (i) coagulation-inclined plate sedimentation (IPS)-filtration and (ii) coagulation-dissolved air flotation (DAF)-filtration. The removal of algae, dissolved organic nitrogen (DON), dissolved organic carbon (DOC) and UV(254) by coagulation-DAF-filtration was superior to coagulation-IPS-filtration. On average, 53%, 53% and 31% of DOC, DON and UV(254) were removed by coagulation-DAF-filtration process, which were higher than 47%, 31% and 27% of that by coagulation-IPS-filtration process. Additionally, coagulation-IPS-filtration performed less well at removing the low molecular weight organics than coagulation-DAF-filtration process. The concentrations of chloroform, dichloroacetamide (DCAcAm) and dichloroacetonitrile (DCAN) formed during chlorination after coagulation-DAF-filtration reached their maximum values of 13, 1.5 and 4.7μgL(-1), respectively, and were lower than those after coagulation-IPS-filtration with the maximum detected levels of 17, 2.9 and 6.3μgL(-1). However, the trichloronitromethane (TCNM) concentration after the two processes was similar, suggesting that DON may have less of a contribution to TCNM formation than DCAcAm and DCAN. Copyright © 2011 Elsevier Ltd. All rights reserved.

Characterization of dissolved organic matter from surface waters with low to high dissolved organic carbon and the related disinfection byproduct formation potential.

PubMed

Li, Angzhen; Zhao, Xu; Mao, Ran; Liu, Huijuan; Qu, Jiuhui

2014-04-30

In this study, the disinfection byproduct formation potential (DBPFP) of three surface waters with the dissolved organic carbon (DOC) content of 2.5, 5.2, and 7.9mg/L was investigated. The formation and distribution of trihalomethanes and haloacetic acids were evaluated. Samples collected from three surface waters in China were fractionated based on molecular weight and hydrophobicity. The raw water containing more hydrophobic (Ho) fraction exhibited higher formation potentials of haloacetic acid and trihalomethane. The DBPFP of the surface waters did not correlate with the DOC value. The values of DBPFP per DOC were correlated with the specific ultraviolet absorbance (SUVA) for Ho and Hi fractions. The obtained results suggested that SUVA cannot reveal the ability of reactive sites to form disinfection byproducts for waters with few aromatic structures. Combined with the analysis of FTIR and nuclear magnetic resonance spectra of the raw waters and the corresponding fractions, it was concluded that the Ho fraction with phenolic hydroxyl and conjugated double bonds was responsible for the production of trichloromethanes and trichloroacetic acids. The Hi fraction with amino and carboxyl groups had the potential to form dichloroacetic acids and chlorinated trihalomethanes. Copyright © 2014. Published by Elsevier B.V.

The topographic wetness index as a predictor for hot spots of DOC export from catchments

NASA Astrophysics Data System (ADS)

Musolff, Andreas; Oosterwoud, Marieke; Tittel, Jörg; Selle, Benny; Fleckenstein, Jan H.

2015-04-01

Dissolved organic carbon (DOC) concentrations in the discharge of many catchments in Europe and North America are rising. This increase is of concern for the drinking water supply from reservoirs since high DOC concentrations cause additional costs in water treatment and potentially the formation of harmful disinfection by-products. A prerequisite for understanding this increase is the knowledge on the spatial distribution of dominant soil DOC sources within catchments and on mobilization as well as transfer processes to the surface water. A number of studies identified wetland soils as the dominant source with fast mobilization and short transit times to the receiving surface water. However, most studies have either focussed on smaller, hillslope and single catchment or on larger scale multi-catchment assessments. Moreover, information on the distribution of soil types in catchments is not always readily available. This study brings together both types of assessment in a data-driven top-down approach: (i) a detailed survey on DOC concentration and loads over the course of one year within two paired data-rich catchments discharging into a large drinking water reservoir in central Germany and (ii) a database of hydrochemistry and physio-geographic characteristics of 113 catchments draining into 58 reservoirs across Germany over the course of 16 years. The objective is to define hot spots of DOC export within the catchments for both types of assessments (i, ii) and to test the suitability of the topographic wetness index (TWI) as a proxy for well-connected wetland soils at various spatial scales. In the sub-catchments of assessment (i) the spatial variability of concentrations and loads was much smaller than expected. None of the studied sub-catchments was a predominant producer of the total DOC loads exported from the catchments. We found the mean concentrations and loads to be positively correlated with the share of groundwater-dominated soils in the sub

The effect of pyrite on E. coli in water: Proof-of-concept for the elimination of waterborne bacteria by reactive minerals

PubMed Central

Friedlander, Lonia R.; Puri, Neha; Schoonen, Martin A.A.; Karzai, A. Wali

2015-01-01

We present proof-of-concept results for the elimination of waterborne bacteria by reactive minerals. We exposed E.coli MG1655 suspended in water to the reactive mineral pyrite (FeS2) at room temperature and ambient light. This slurry eliminates 99.9% of bacteria in fewer than 4 hours. We also exposed E. coli to pyrite leachate (supernatant liquid from slurry after 24-hours), which eliminates 99.99% of bacteria over the same time-scale. Unlike SOlar water DISinfection (SODIS) our results do not depend on the presence of ultraviolet (UV) light. We confirmed this by testing proposed SODIS additive and known photo-catalyst anatase (TiO2) for antibacterial properties and found that, in contrast to pyrite, it does not eliminate E. coli under our experimental conditions. Previous investigations of naturally antibiotic minerals have focused on the medical applications of antibiotic clays, and thus have not been conducted under experimental conditions resembling those found in water purification. In our examination of the relevant literature, we have not found previously reported evidence for the use of reactive minerals in water sanitization. The results from this proof-of-concept experiment may have important implications for future directions in household water purification research. PMID:25719464

Thermal disinfection of hotels, hospitals, and athletic venues hot water distribution systems contaminated by Legionella species.

PubMed

Mouchtouri, Varvara; Velonakis, Emmanuel; Hadjichristodoulou, Christos

2007-11-01

Legionella spp. (> or = 500 cfu liter(-1)) were detected in 92 of 497 water distribution systems (WDS) examined. Thermal disinfection was applied at 33 WDS. After the first and second application of the disinfection procedure, 15 (45.4%) and 3 (9%) positive for remedial actions WDS were found, respectively. Legionella pneumophila was more resistant to thermal disinfection than Legionella non-pneumophila spp. (relative risk [RR]=5.4, 95% confidence intervals [CI]=1-35). WDS of hotels with oil heater were more easily disinfected than those with electrical or solar heater (RR=0.4 95% CI=0.2-0.8). Thermal disinfection seems not to be efficient enough to eliminate legionellae, unless repeatedly applied and in combination with extended heat flushing, and faucets chlorine disinfection.

Removal of disinfection by-product precursors by coagulation and an innovative suspended ion exchange process.

PubMed

Metcalfe, David; Rockey, Chris; Jefferson, Bruce; Judd, Simon; Jarvis, Peter

2015-12-15

This investigation aimed to compare the disinfection by-product formation potentials (DBPFPs) of three UK surface waters (1 upland reservoir and 2 lowland rivers) with differing characteristics treated by (a) a full scale conventional process and (b) pilot scale processes using a novel suspended ion exchange (SIX) process and inline coagulation (ILCA) followed by ceramic membrane filtration (CMF). Liquid chromatography-organic carbon detection analysis highlighted clear differences between the organic fractions removed by coagulation and suspended ion exchange. Pretreatments which combined SIX and coagulation resulted in significant reductions in dissolved organic carbon (DOC), UV absorbance (UVA), trihalomethane and haloacetic acid formation potential (THMFP, HAAFP), in comparison with the SIX or coagulation process alone. Further experiments showed that in addition to greater overall DOC removal, the processes also reduced the concentration of brominated DBPs and selectively removed organic compounds with high DBPFP. The SIX/ILCA/CMF process resulted in additional removals of DOC, UVA, THMFP, HAAFP and brominated DBPs of 50, 62, 62, 62% and 47% respectively compared with conventional treatment. Copyright © 2015. Published by Elsevier Ltd.

Chlorine dioxide as a post-disinfectant for Dutch drinking water.

PubMed

Wondergem, E; van Dijk-Looijaard, A M

1991-02-01

Chlorine dioxide has some important advantages over chlorine with respect to water quality (no formation of trihalomethanes, no impairment of taste and no odor) and stability when used for oxidation/disinfection of drinking water. In this paper, results are presented of experiments into the consumption and reaction kinetics of chlorine dioxide in a number of (drinking) waters in The Netherlands. It was found that chlorine dioxide consumption is related to the dissolved oxygen content (DOC) of the water and the reaction time. Water samples from a plant that applied ozonation and activated carbon filtration had a very low chlorine dioxide consumption. Other water quality parameters, including pH and CO3(2-), did not have any influence on consumption. The temporary advised Dutch guidelines of 0.2 mg l-1 (dosage) is sufficient for activated carbon treated water. For other Dutch drinking waters, however, none of the 0.2 mg l-1 chlorine dioxide remained after a reaction time of 10 min, as was also found for the water of Dutch pumping stations where chlorine dioxide is at present used for disinfection.

The sensitivity of peat soil and peatland vegetation to drought: release of dissolved organic carbon (DOC) on rewetting

NASA Astrophysics Data System (ADS)

Ritson, Jonathan; Graham, Nigel; Templeton, Michael; Freeman, Christopher; Clark, Joanna

2015-04-01

Organic rich peat soils are a major store of carbon worldwide. Their existence is predicated on high year-round water tables which create an anoxic environment, thus limiting decay, and also to the recalcitrance of plant litter (dead plant material) commonly found in peatland areas. Climate change threatens the stability of peat soils by altering the biogeochemical cycles which control plant decay, lowering water tables so that oxic degradation can occur and by changing habitat niches such that less recalcitrant species can thrive in peatlands. One of the major fluxes of carbon from peatlands is through dissolved organic carbon (DOC) in surface waters. As peatland areas in the UK are often used as source waters for drinking water supply this presents a problem to water utilities as DOC must be effectively removed to limit colour, odour and the formation of potentially carcinogenic by-products on disinfection. Changes in catchment vegetation may occur due to climate change, nutrient deposition and changing bioclimatic envelopes. How different peatland vegetation contribute to DOC flux and how this may change in the future is therefore of interest. A six week laboratory simulation was performed on typical peatland litter (Sphagnum spp., Calluna vulgaris, Molinea caerulea, Juncus effusus) and a peat soil collected from Exmoor National Park, UK. The simulation monitored DOC flux from the decaying litter/soil and considered the impact of different drought severities using the 50th, 25th, 10th and 5th percentiles of the mean July/August monthly rainfall for Exmoor. On rewetting following the drought, all sources produced significantly different amounts of DOC (Tukey HSD p<0.05) in the order Molinia>Juncus>Calluna>Sphagnum>peat. The source also had a significant (ANOVA p<0.001) effect on coagulation removal efficiency, a typical method of removing DOC during drinking water treatment, with Juncus DOC proving the easiest to remove whilst Sphagnum DOC was the most difficult

40 CFR 141.54 - Maximum residual disinfectant level goals for disinfectants.

Code of Federal Regulations, 2014 CFR

2014-07-01

... for disinfectants. MRDLGs for disinfectants are as follows: Disinfectant residual MRDLG(mg/L) Chlorine... 40 Protection of Environment 23 2014-07-01 2014-07-01 false Maximum residual disinfectant level goals for disinfectants. 141.54 Section 141.54 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY...

40 CFR 141.54 - Maximum residual disinfectant level goals for disinfectants.

Code of Federal Regulations, 2012 CFR

2012-07-01

... for disinfectants. MRDLGs for disinfectants are as follows: Disinfectant residual MRDLG(mg/L) Chlorine... 40 Protection of Environment 24 2012-07-01 2012-07-01 false Maximum residual disinfectant level goals for disinfectants. 141.54 Section 141.54 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY...

40 CFR 141.54 - Maximum residual disinfectant level goals for disinfectants.

Code of Federal Regulations, 2013 CFR

2013-07-01

... for disinfectants. MRDLGs for disinfectants are as follows: Disinfectant residual MRDLG(mg/L) Chlorine... 40 Protection of Environment 24 2013-07-01 2013-07-01 false Maximum residual disinfectant level goals for disinfectants. 141.54 Section 141.54 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY...

The two faces of DOC.

PubMed

Wood, Chris M; Al-Reasi, H A; Smith, D Scott

2011-10-01

Dissolved organic carbon (DOC), through its ability to complex metals and thereby reduce their bioavailability, plays a major role in ameliorating metal toxicity in natural waters. Indeed DOC is a key variable in the Biotic Ligand Model (BLM) for predicting metal toxicity on a site-specific basis. However, recent evidence indicates that all DOCs are not alike, but rather heterogeneous in their ability to protect organisms against metal toxicity, at least in fresh water. The degree of protection appears to correlate with optical properties, such that dark, aromatic-rich compounds of allochthonous origin, with greater humic acid content, are more effective in this regard, particularly against Cu, Ag, and Pb toxicity. The specific absorption coefficient of the DOC in the 300-350nm range (SAC(300-350)) has proven to be a simple and effective index of this protective ability. PARAFAC, a multivariate statistical technique for analysis of excitation-emission fluorescence spectroscopy data, also holds promise for quantifying the humic-like and fulvic-like fluorophores, which tend to be positively and negatively correlated with protective ability, respectively. However, what has been largely missing in the toxicological realm is any appreciation that DOC may also affect the physiology of target organisms, such that part of the protection may occur by a mechanism other than metal complexation. Recently published evidence demonstrates that DOC has effects on Na(+) transport, diffusive permeability, and electrical properties of the gills in fish and crustaceans in a manner which will promote Na(+) homeostasis. These actions could thereby protect against metal toxicity by physiological mechanisms. Future research should investigate potential direct interactions of DOC molecules with the branchial epithelium. Incorporation of optical properties of DOC could be used to improve the predictive capabilities of the BLM. 2011 Elsevier B.V. All rights reserved.

Commercial Disinfectants During Disinfection Process Validation: More Failures than Success.

PubMed

Chatterjee, Shiv Sekhar; Chumber, Sushil Kumar; Khanduri, Uma

2016-08-01

Disinfection process validation is mandatory before introduction of a new disinfectant in hospital services. Commercial disinfection brands often question existing hospital policy claiming greater efficacy and lack of toxicity of their products. Inadvertent inadequate disinfection leads to morbidity, patient's economic burden, and the risk of mortality. To evaluate commercial disinfectants for high, intermediate and low-level disinfection so as to identify utility for our routine situations. This laboratory based experiment was conducted at St Stephen Hospital, Delhi during July-September 2013. Twelve commercial disinfectants: Sanidex®, Sanocid®, Cidex®, SekuSept Aktiv®, BIB Forte®, Alprojet W®, Desnet®, Sanihygiene®, Incidin®, D125®, Lonzagard®, and Glutishield® were tested. Time-kill assay (suspension test) was performed against six indicator bacteria (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella Typhi, Bacillus cereus, and Mycobacterium fortuitum). Low and high inoculum (final concentrations 1.5X10(6) and 9X10(6) cfu/ml) of the first five bacteria while only low level of M. fortuitum was tested. Cidex® (2.4% Glutaraldehyde) performed best as high level disinfectant while newer quarternary ammonium compounds (QACs) (Incidin®, D125®, and Lonzagard®) were good at low level disinfection. Sanidex® (0.55% Ortho-pthalaldehyde) though mycobactericidal took 10 minutes for sporicidal activity. Older QAC containing BIB Forte® and Desnet® took 20 minutes to fully inhibit P. aeruginosa. All disinfectants effectively reduced S. Typhi to zero counts within 5 minutes. Cidex® is a good high-level disinfectant while newer QACs (Incidin®, D125®, and Lonzagard®) were capable low-level disinfectants.

Real Time Monitoring of Dissolved Organic Carbon Concentration and Disinfection By-Product Formation Potential in a Surface Water Treatment Plant with Simulaneous UV-VIS Absorbance and Fluorescence Excitation-Emission Mapping

NASA Astrophysics Data System (ADS)

Gilmore, A. M.

2015-12-01

This study describes a method based on simultaneous absorbance and fluorescence excitation-emission mapping for rapidly and accurately monitoring dissolved organic carbon concentration and disinfection by-product formation potential for surface water sourced drinking water treatment. The method enables real-time monitoring of the Dissolved Organic Carbon (DOC), absorbance at 254 nm (UVA), the Specific UV Absorbance (SUVA) as well as the Simulated Distribution System Trihalomethane (THM) Formation Potential (SDS-THMFP) for the source and treated water among other component parameters. The method primarily involves Parallel Factor Analysis (PARAFAC) decomposition of the high and lower molecular weight humic and fulvic organic component concentrations. The DOC calibration method involves calculating a single slope factor (with the intercept fixed at 0 mg/l) by linear regression for the UVA divided by the ratio of the high and low molecular weight component concentrations. This method thus corrects for the changes in the molecular weight component composition as a function of the source water composition and coagulation treatment effects. The SDS-THMFP calibration involves a multiple linear regression of the DOC, organic component ratio, chlorine residual, pH and alkalinity. Both the DOC and SDS-THMFP correlations over a period of 18 months exhibited adjusted correlation coefficients with r2 > 0.969. The parameters can be reported as a function of compliance rules associated with required % removals of DOC (as a function of alkalinity) and predicted maximum contaminant levels (MCL) of THMs. The single instrument method, which is compatible with continuous flow monitoring or grab sampling, provides a rapid (2-3 minute) and precise indicator of drinking water disinfectant treatability without the need for separate UV photometric and DOC meter measurements or independent THM determinations.

The relationship between soil heterotrophic activity, soil dissolved organic carbon (DOC) leachate, and catchment-scale DOC export in headwater catchments

USGS Publications Warehouse

Brooks, P.D.; McKnight, Diane M.; Bencala, K.E.

1999-01-01

Dissolved organic carbon (DOC) from terrestrial sources forms the major component of the annual carbon budget in many headwater streams. In high-elevation catchments in the Rocky Mountains, DOC originates in the upper soil horizons and is flushed to the stream primarily during spring snowmelt. To identify controls on the size of the mobile soil DOC pool available to be transported during the annual melt event, we measured soil DOC production across a range of vegetation communities and soil types together with catchment DOC export in paired watersheds in Summit County, Colorado. Both surface water DOC concentrations and watershed DOC export were lower in areas where pyrite weathering resulted in lower soil pH. Similarly, the amount of DOC leached from organic soils was significantly smaller (p < 0.01) at sites having low soil pH. Scaling point source measurements of DOC production and leaching to the two basins and assuming only vegetated areas contribute to DOC production, we calculated that the amount of mobile DOC available to be leached to surface water during melt was 20.3 g C m−2 in the circumneutral basin and 17.8 g C m−2 in the catchment characterized by pyrite weathering. The significant (r2=0.91 and p < 0.05), linear relationship between over-winter CO2 flux and the amount of DOC leached from upper soil horizons during snowmelt suggests that the mechanism for the difference in production of mobile DOC was heterotrophic processing of soil carbon in snow-covered soil. Furthermore, this strong relationship between over-winter heterotrophic activity and the size of the mobile DOC pool present in a range of soil and vegetation types provides a likely mechanism for explaining the interannual variability of DOC export observed in high-elevation catchments.

Occurrence and exposures to disinfectants and disinfection by-products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cumming, R.B.; Jolley, R.L.

1992-12-31

Disinfection by-products are associated with all chemical disinfectants. The concentration and toxic nature of the disinfection byproducts (DBPs) is a direct function of the chemical nature of the disinfectant itself and/or of the chemical reactions of the disinfectant with reaction substrates in the water, especially organic constituents. A principal advantage of biological and physical water treatment processes, such as filtration, is the lack of chemical reactions producing disinfectant-related DBPs. The use of the highest quality source water available is important for minimization of DBP formation. In lieu of such high quality water, improvement of water quality by removal of DBPmore » precursors through filtration or other means before application of chemical disinfectants is important. Most, if not all, water treatment experts are aware of these simplistic axioms. In view of the increasing knowledge being developed concerning DBPs including the identification of ``new`` DBPs, prudence dictates minimization of DBP formation. Wholesome drinking water is perhaps the biggest economic bargain available to consumers. The cost-effectiveness of water quality improvement should be evaluated with that in mind.« less

Occurrence and exposures to disinfectants and disinfection by-products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cumming, R.B.; Jolley, R.L.

1992-01-01

Disinfection by-products are associated with all chemical disinfectants. The concentration and toxic nature of the disinfection byproducts (DBPs) is a direct function of the chemical nature of the disinfectant itself and/or of the chemical reactions of the disinfectant with reaction substrates in the water, especially organic constituents. A principal advantage of biological and physical water treatment processes, such as filtration, is the lack of chemical reactions producing disinfectant-related DBPs. The use of the highest quality source water available is important for minimization of DBP formation. In lieu of such high quality water, improvement of water quality by removal of DBPmore » precursors through filtration or other means before application of chemical disinfectants is important. Most, if not all, water treatment experts are aware of these simplistic axioms. In view of the increasing knowledge being developed concerning DBPs including the identification of new'' DBPs, prudence dictates minimization of DBP formation. Wholesome drinking water is perhaps the biggest economic bargain available to consumers. The cost-effectiveness of water quality improvement should be evaluated with that in mind.« less

Formation of nitrogenous disinfection by-products in 10 chlorinated and chloraminated drinking water supply systems.

PubMed

Liew, Deborah; Linge, Kathryn L; Joll, Cynthia A

2016-09-01

The presence of nitrogenous disinfection by-products (N-DBPs) in drinking water supplies is a public health concern, particularly since some N-DBPs have been reported to be more toxic than the regulated trihalomethanes and haloacetic acids. In this paper, a comprehensive evaluation of the presence of N-DBPs in 10 drinking water supply systems in Western Australia is presented. A suite of 28 N-DBPs, including N-nitrosamines, haloacetonitriles (HANs), haloacetamides (HAAms) and halonitromethanes (HNMs), were measured and evaluated for relationships with bulk parameters in the waters before disinfection. A number of N-DBPs were frequently detected in disinfected waters, although at generally low concentrations (<10 ng/L for N-nitrosamines and <10 μg/L for other N-DBPs) and below health guideline values where they exist. While there were no clear relationships between N-DBP formation and organic nitrogen in the pre-disinfection water, N-DBP concentrations were significantly correlated with dissolved organic carbon (DOC) and ammonia, and these, in addition to high bromide in one of the waters, led to elevated concentrations of brominated HANs (26.6 μg/L of dibromoacetonitrile). There were significant differences in the occurrence of all classes of N-DBPs between chlorinated and chloraminated waters, except for HNMs, which were detected at relatively low concentrations in both water types. Trends observed in one large distribution system suggest that N-DBPs can continue to form or degrade within distribution systems, and redosing of disinfectant may cause further by-product formation.

Determining sources of dissolved organic carbon and disinfection byproduct precursors to the McKenzie River, Oregon

USGS Publications Warehouse

Kraus, Tamara E.C.; Anderson, Chauncey W.; Morgenstern, Karl; Downing, Bryan D.; Pellerin, Brian A.; Bergamaschi, Brian A.

2010-01-01

This study was conducted to determine the main sources of dissolved organic carbon (DOC) and disinfection byproduct (DBP) precursors to the McKenzie River, Oregon (USA). Water samples collected from the mainstem, tributaries, and reservoir outflows were analyzed for DOC concentration and DBP formation potentials (trihalomethanes [THMFPs] and haloacetic acids [HAAFPs]). In addition, optical properties (absorbance and fluorescence) of dissolved organic matter (DOM) were measured to provide insight into DOM composition and assess whether optical properties are useful proxies for DOC and DBP precursor concentrations. Optical properties indicative of composition suggest that DOM in the McKenzie River mainstem was primarily allochthonous - derived from soils and plant material in the upstream watershed. Downstream tributaries had higher DOC concentrations than mainstem sites (1.6 ?? 0.4 vs. 0.7 ?? 0.3 mg L-1) but comprised <5% of mainstem flows and had minimal effect on overall DBP precursor loads. Water exiting two large upstream reservoirs also had higher DOC concentrations than the mainstem site upstream of the reservoirs, but optical data did not support in situ algal production as a source of the added DOC during the study. Results suggest that the first major rain event in the fall contributes DOM with high DBP precursor content. Although there was interference in the absorbance spectra in downstream tributary samples, fluorescence data were strongly correlated to DOC concentration (R 2 = 0.98), THMFP (R2 = 0.98), and HAAFP (R2 = 0.96). These results highlight the value of using optical measurements for identifying the concentration and sources of DBP precursors in watersheds, which will help drinking water utilities improve source water monitoring and management programs. Copyright ?? 2010 by the American Society of Agronomy.

Water disinfection agents and disinfection by-products

NASA Astrophysics Data System (ADS)

Ilavský, J.; Barloková, D.; Kapusta, O.; Kunštek, M.

2017-10-01

The aim of this work is to describe factors of water quality change in the distribution network and legislative requirements in Slovakia for disinfectants and disinfection byproducts (DBPs). In the experimental part, the time dependence of the application of the chlorine dioxide and sodium hypochlorite on the formation of some by-products of disinfection for drinking water from WTP Hriňová is studied. We monitored trihalomethanes, free chlorine, chlorine dioxide and chlorites.

Disinfection of gloves: feasible, but pay attention to the disinfectant/glove combination.

PubMed

Scheithauer, S; Häfner, H; Seef, R; Seef, S; Hilgers, R D; Lemmen, S

2016-11-01

Compliance with hand hygiene is complicated by indications for hand disinfection in rapid succession during the care of one patient. In such situations, disinfection of gloves could facilitate better workflow and optimize compliance rates. We analysed the efficacy of disinfecting gloves by comparing an individual effect of five different hand disinfectant solutions in combination with three different glove types. The investigation was performed in accordance with DIN EN 1500:2013. For all combinations, ten analyses were performed, including (1) right/left-hand examination disinfection efficacy after the first and fifth contamination with E. coli K12 NCTC 10538, (2) recovery rates after contamination, (3) reduction efficacy, (4) fingertip immersion culture, and (5) check for tightness. Disinfection of the ungloved hands was taken as an additional benchmark. The disinfection efficacy for all disinfectant/glove combinations was better with rather than without gloves. For eight combinations, the disinfection efficacy was always >5.0 log 10 . There were significant differences within the gloves (P=0.0021) and within the disinfectant product (P=0.0023), respectively. In detail, Nitril Blue Eco-Plus performed significantly better than Vasco Braun (P=0.0017) and Latex Med Comfort (P=0.0493). Descoderm showed a significantly worse performance than Promanum pure (P=0.043). In the check for tightness, only the Vasco Braun gloves showed no leaks in all samples. There were relevant qualitative differences pertaining to the comfort of disinfecting gloves. The disinfection efficacy for the different disinfectant/glove combinations was greater than for the ungloved hands. However, various disinfectant/glove combinations produce relevant differences as regards disinfection efficacy. Copyright © 2016 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

Health effects of drinking water disinfectants and disinfection by-products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Condie, L.W.; Bercz, J.P.

This paper summarizes toxicological studies conducted with drinking water disinfectants. Toxicological effects, which are associated with the disinfectants themselves as well as with the by-products formed when disinfectants react with organic material present in water, are considered. The health impact of chemical reactions occurring between residual disinfectants and nutrients in the gastrointestinal tract is also discussed. 40 references, 5 tables.

Electrochemical disinfection of toilet wastewater using wastewater electrolysis cell

PubMed Central

Huang, Xiao; Qu, Yan; Cid, Clément A.; Finke, Cody; Hoffmann, Michael R.; Lim, Keahying; Jiang, Sunny C.

2016-01-01

The paucity of proper sanitation facilities has contributed to the spread of waterborne diseases in many developing countries. The primary goal of this study was to demonstrate the feasibility of using a wastewater electrolysis cell (WEC) for toilet wastewater disinfection. The treated wastewater was designed to reuse for toilet flushing and agricultural irrigation. Laboratory-scale electrochemical (EC) disinfection experiments were performed to investigate the disinfection efficiency of the WEC with four seeded microorganisms (Escherichia coli, Enterococcus, recombinant adenovirus serotype 5, and bacteriophage MS2). In addition, the formation of organic disinfection byproducts (DBPs) trihalomethanes (THMs) and haloacetic acids (HAA5) at the end of the EC treatment was also investigated. The results showed that at an applied cell voltage of +4 V, the WEC achieved 5-log10 reductions of all four seeded microorganisms in real toilet wastewater within 60 min. In contrast, chemical chlorination (CC) disinfection using hypochlorite [NaClO] was only effective for the inactivation of bacteria. Due to the rapid formation of chloramines, less than 0.5-log10 reduction of MS2 was observed in toilet wastewater even at the highest [NaClO] dosage (36 mg/L, as Cl2) over a 1 h reaction. Experiments using laboratory model waters showed that free reactive chlorine generated in situ during EC disinfection process was the main disinfectant responsible for the inactivation of microorganisms. However, the production of hydroxyl radicals [•OH], and other reactive oxygen species by the active bismuth-doped TiO2 anode were negligible under the same electrolytic conditions. The formation of THMs and HAA5 were found to increase with higher applied cell voltage. Based on the energy consumption estimates, the WEC system can be operated using solar energy stored in a DC battery as the sole power source. PMID:26854604

Reduction of disinfection by-product precursors in reservoir water by coagulation and ultrafiltration.

PubMed

Wang, Feng; Gao, Baoyu; Ma, Defang; Yue, Qinyan; Li, Ruihua; Wang, Qianwen

2016-11-01

In this study, reservoir water intended for drinking water supply was treated by (i) ultrafiltration (UF) (ii) coagulation (CW) (iii) coagulation combined with ultrafiltration (CW-UF). To probe the influences of three treatment processes on disinfection byproduct (DBP) precursors in source water, the changes of dissolved organic matter (DOM) amounts and physicochemical properties, and disinfection byproduct (DBP) formation characteristics during chlorine disinfection were investigated. Both carbonaceous DBP (C-DBP) and nitrogenous DBP (N-DBP) formation and speciation were analyzed. The influence of chlorine dose, contact time on DBP formation and speciation were also studied to optimize the disinfection conditions to minimize the DBP formation. Compared with UF and CW alone, CW-UF improved the dissolved organic carbon (DOC) removal from about 20 % to 59 %. The three-dimensional excitation and emission matrix (3DEEM) fluorescence spectroscopy analysis showed that CW-UF had high removal efficiency in microbial products (Region IV), fulvic acid-like (Region III) and humic acid-like (Region V). The total C-DBP was determined by the formation of trihalomethanes and trichloromethane was the most abundant species (40 %). The most abundant N-DBP species was dichloroacetonitrile (32.5 %), followed by trichloroactetonitrile. CW-UF effectively reduced the risk of DBPs in drinking water supply by reducing 30.8 % and 16.9 % DBPs formation potential compared with UF and CW alone. Increasing contact time improved the yields of both C-DBPs and N-DBPs. Chlorine dosage had slight influence on DBP yield in this study.

Formation and control of disinfection byproducts and toxicity during reclaimed water chlorination: A review.

PubMed

Du, Ye; Lv, Xiao-Tong; Wu, Qian-Yuan; Zhang, Da-Yin; Zhou, Yu-Ting; Peng, Lu; Hu, Hong-Ying

2017-08-01

Chlorination is essential to the safety of reclaimed water; however, this process leads to concern regarding the formation of disinfection byproducts (DBPs) and toxicity. This study reviewed the formation and control strategies for DBPs and toxicity in reclaimed water during chlorination. Both regulated and emerging DBPs have been frequently detected in reclaimed water during chlorination at a higher level than those in drinking water, indicating they pose a greater risk to humans. Luminescent bacteria and Daphnia magna acute toxicity, anti-estrogenic activity and cytotoxicity generally increased after chlorination because of the formation of DBPs. Genotoxicity by umu-test and estrogenic activity were decreased after chlorination because of destruction of toxic chemicals. During chlorination, water quality significantly impacted changes in toxicity. Ammonium tended to attenuate toxicity changes by reacting with chlorine to form chloramine, while bromide tended to aggravate toxicity changes by forming hypobromous acid. During pretreatment by ozonation and coagulation, disinfection byproduct formation potential (DBPFP) and toxicity formation potential (TFP) occasionally increase, which is accompanied by DOC removal; thus, the decrease of DOC was limited to indicate the decrease of DBPFP and TFP. It is more important to eliminate the key fraction of precursors such as hydrophobic acid and hydrophilic neutrals. During chlorination, toxicities can increase with the increasing chlorine dose and contact time. To control the excessive toxicity formation, a relatively low chlorine dose and short contact time were required. Quenching chlorine residual with reductive reagents also effectively abated the formation of toxic compounds. Copyright © 2017. Published by Elsevier B.V.

Reductions of dissolved organic matter and disinfection by-product precursors in full-scale wastewater treatment plants in winter.

PubMed

Xue, Shuang; Jin, Wujisiguleng; Zhang, Zhaohong; Liu, Hong

2017-07-01

The reductions of dissolved organic matter (DOM) and disinfection byproduct precursors in four full-scale wastewater treatment plants (WWTPs) (Liaoning Province, China) where different biological treatment processes were employed in winter were investigated. The total removal efficiencies of dissolved organic carbon (DOC), ultraviolet light at 254 nm (UV-254), trihalomethane formation potential (THMFP), and haloacetic acid formation potential (HAAFP) were in the range of 70.3-76.0%, 49.6-57.3%, 54.4-65.0%, and 53.7-63.8% in the four WWTPs, respectively. The biological treatment was the predominant process responsible for the removal of DOC, THMFP, and HAAFP in WWTPs. Differences in the reduction of UV-254 were not significant (p > 0.05) among biochemical reaction pool, secondary sedimentation tank, and disinfection tank. Biological aerated filter and suspended carrier activated sludge processes achieved higher DOM removal than the conventional active sludge and anaerobic-anoxic-oxic processes. Hydrophobic neutral and hydrophilic fraction were removed to a higher degree through biological treatment than the other three DOM fractions. HAAFP removal was more efficient than THMFP reduction during biological treatment. During primary treatment, fluorescent materials in secondary sedimentation tanks were preferentially removed, as compared to the bulk DOM. Humic-like fluorescent compounds were not readily eliminated during biological treatment. The fluorescent materials were more susceptible to chlorine than nonfluorescent compounds. Copyright © 2017. Published by Elsevier Ltd.

Dynamics of dissolved organic matter during four storm events in two forest streams: source, export, and implications for harmful disinfection byproduct formation.

PubMed

Yang, Liyang; Hur, Jin; Lee, Sonmin; Chang, Soon-Woong; Shin, Hyun-Sang

2015-06-01

Dynamics of river dissolved organic matter (DOM) during storm events have profound influences on the downstream aquatic ecosystem and drinking water safety. This study investigated temporal variations in DOM during four storm events in two forest headwater streams (the EH and JH brooks, South Korea) and the impacts on the disinfection byproducts (DBPs) formation potential. The within-event variations of most DOM quantity parameters were similar to the flow rate in the EH but not in the larger JH brook. The dissolved organic carbon (DOC) showed clockwise and counterclockwise hysteresis with the flow rate in the EH and JH brooks, respectively, indicating the importance of both flow path and DOM source pool size in determining the effects of storm events. The stream DOM became less aromatic/humified from the first to the last event in both brooks, probably due to the increasing fresh plant pool and the decreasing leaf litter pool during the course of rainy season. The DOC export during each event increased 1.3-2.7- and 1.1-7.0-fold by stormflows in the EH and JH brooks, respectively. The leaf litter and soil together was the major DOM source, particularly during early events. The enhanced DOM export probably increases the risks of DBPs formation in disinfection, as indicated by a strong correlation observed between DOC and trihalomethanes formation potential (THMFP). High correlations between two humic-like fluorescent components and THMFP further suggested the potential of assessing THMFP with in situ fluorescence sensors during storms.

9 CFR 96.9 - Casings admitted on disinfection; sealing; transfer and disinfection.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Casings admitted on disinfection; sealing; transfer and disinfection. 96.9 Section 96.9 Animals and Animal Products ANIMAL AND PLANT HEALTH... STATES § 96.9 Casings admitted on disinfection; sealing; transfer and disinfection. Foreign animal...

9 CFR 96.9 - Casings admitted on disinfection; sealing; transfer and disinfection.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Casings admitted on disinfection; sealing; transfer and disinfection. 96.9 Section 96.9 Animals and Animal Products ANIMAL AND PLANT HEALTH... STATES § 96.9 Casings admitted on disinfection; sealing; transfer and disinfection. Foreign animal...

9 CFR 96.9 - Casings admitted on disinfection; sealing; transfer and disinfection.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Casings admitted on disinfection; sealing; transfer and disinfection. 96.9 Section 96.9 Animals and Animal Products ANIMAL AND PLANT HEALTH... STATES § 96.9 Casings admitted on disinfection; sealing; transfer and disinfection. Foreign animal...

New formaldehyde base disinfectants.

NASA Technical Reports Server (NTRS)

Trujillo, R.; Lindell, K. F.

1973-01-01

Preparations of formaldehyde in various organic liquids - ethylene glycol, glycerol, and propylene glycol - serve as effective disinfectants towards microbial vegetative cells and spores. This disinfection is a temperature-dependent process and is manifest when these formaldehyde base disinfectants are dissolved in water. The irritating vapors associated with formaldehyde disinfection are not present in either of these new formaldehyde base disinfectants or in aqueous solutions of them.

Quality and disinfection trials of consumption water in storage reservoirs for rural area in the Marrakech region (Assif El Mal).

PubMed

Aziz, Faissal; Mandi, Laila; Boussaid, Abdellatif; Boraam, Fatima; Ouazzani, Naaila

2013-03-01

Traditional reservoirs for water storage are important systems of water supply in rural areas of Morocco. These reservoirs are fed by rainwater and/or directly from rivers through open channels; the stored water is used without any treatment as drinking water by the surrounding population. The present study aimed to assess the physicochemical and bacteriological quality of stored water and the corresponding sediment in six traditional reservoirs (R1 to R6) located in the rural municipality of Assif El Mal. We tested two inexpensive methods of disinfecting the stored water: chlorination and solar disinfection in bottles. The results show a rise of organic and mineral concentrations. Regarding bacteriological quality, a critical contamination level was detected (8 × 10(5) CFU/100 ml in water and 9 × 10(7) CFU/g in sediment) according to the 2002 Moroccan Standards for drinking water (0 CFU/100 ml). In the disinfection tests, chlorine disinfection removed all studied germs after just 1 hour, and the solar exposure process removed the majority of bacteria (after 3 hours) except those with a resistant form (Clostridia).

40 CFR 141.54 - Maximum residual disinfectant level goals for disinfectants.

Code of Federal Regulations, 2011 CFR

2011-07-01

... for disinfectants. MRDLGs for disinfectants are as follows: Disinfectant residual MRDLG(mg/L) Chlorine 4 (as Cl 2). Chloramines 4 (as Cl 2). Chlorine dioxide 0.8 (as ClO2) [63 FR 69465, Dec. 16, 1998] ...

40 CFR 141.54 - Maximum residual disinfectant level goals for disinfectants.

Code of Federal Regulations, 2010 CFR

2010-07-01

... for disinfectants. MRDLGs for disinfectants are as follows: Disinfectant residual MRDLG(mg/L) Chlorine 4 (as Cl 2). Chloramines 4 (as Cl 2). Chlorine dioxide 0.8 (as ClO2) [63 FR 69465, Dec. 16, 1998] ...

The Earth System (ES-DOC) Project

NASA Astrophysics Data System (ADS)

Greenslade, Mark; Murphy, Sylvia; Treshansky, Allyn; DeLuca, Cecilia; Guilyardi, Eric; Denvil, Sebastien

2014-05-01

ESSI1.3 New Paradigms, Modelling, and International Collaboration Strategies for Earth System Sciences Earth System Documentation (ES-DOC) is an international project supplying tools & services in support of earth system documentation creation, analysis and dissemination. It is nurturing a sustainable standards based documentation eco-system that aims to become an integral part of the next generation of exa-scale dataset archives. ES-DOC leverages open source software and places end-user narratives at the heart of all it does. ES-DOC has initially focused upon nurturing the Earth System Model (ESM) documentation eco-system. Within this context ES-DOC leverages emerging documentation standards and supports the following projects: Coupled Model Inter-comparison Project Phase 5 (CMIP5); Dynamical Core Model Inter-comparison Project (DCMIP); National Climate Predictions and Projections Platforms Quantitative Evaluation of Downscaling Workshop. This presentation will introduce the project to a wider audience and demonstrate the range of tools and services currently available for use. It will also demonstrate how international collaborative efforts are essential to the success of ES-DOC.

Examining the interrelationship between DOC, bromide and chlorine dose on DBP formation in drinking water--a case study.

PubMed

Bond, Tom; Huang, Jin; Graham, Nigel J D; Templeton, Michael R

2014-02-01

During drinking water treatment aqueous chlorine and bromine compete to react with natural organic matter (NOM). Among the products of these reactions are potentially harmful halogenated disinfection by-products, notably four trihalomethanes (THM4) and nine haloacetic acids (HAAs). Previous research has concentrated on the role of bromide in chlorination reactions under conditions of a given NOM type and/or concentration. In this study different concentrations of dissolved organic carbon (DOC) from U.K. lowland water were reacted with varying amounts of bromide and chlorine in order to examine the interrelationship between the three reactants in the formation of THM4, dihaloacetic acids (DHAAs) and trihaloacetic acids (THAAs). Results showed that, in general, molar yields of THM4 increased with DOC, bromide and chlorine concentrations, although yields did fluctuate versus chlorine dose. In contrast both DHAA and THAA yields were mainly independent of changes in bromide and chlorine dose at low DOC (1 mg·L(-1)), but increased with chlorine dose at higher DOC concentrations (4 mg·L(-1)). Bromine substitution factors reached maxima of 0.80, 0.67 and 0.65 for the THM4, DHAAs and THAAs, respectively, at the highest bromide/chlorine ratio studied. These results suggest that THM4 formation kinetics depend on both oxidation and halogenation steps, whereas for DHAAs and THAAs oxidation steps are more important. Furthermore, they indicate that high bromide waters may prove more problematic for water utilities with respect to THM4 formation than for THAAs or DHAAs. While mass concentrations of all three groups increased in response to increased bromide incorporation, only the THMs also showed an increase in molar yield. Overall, the formation behaviour of DHAA and THAA was more similar than that of THM4 and THAA. © 2013.

Electrochemical disinfection of toilet wastewater using wastewater electrolysis cell.

PubMed

Huang, Xiao; Qu, Yan; Cid, Clément A; Finke, Cody; Hoffmann, Michael R; Lim, Keahying; Jiang, Sunny C

2016-04-01

The paucity of proper sanitation facilities has contributed to the spread of waterborne diseases in many developing countries. The primary goal of this study was to demonstrate the feasibility of using a wastewater electrolysis cell (WEC) for toilet wastewater disinfection. The treated wastewater was designed to reuse for toilet flushing and agricultural irrigation. Laboratory-scale electrochemical (EC) disinfection experiments were performed to investigate the disinfection efficiency of the WEC with four seeded microorganisms (Escherichia coli, Enterococcus, recombinant adenovirus serotype 5, and bacteriophage MS2). In addition, the formation of organic disinfection byproducts (DBPs) trihalomethanes (THMs) and haloacetic acids (HAA5) at the end of the EC treatment was also investigated. The results showed that at an applied cell voltage of +4 V, the WEC achieved 5-log10 reductions of all four seeded microorganisms in real toilet wastewater within 60 min. In contrast, chemical chlorination (CC) disinfection using hypochlorite [NaClO] was only effective for the inactivation of bacteria. Due to the rapid formation of chloramines, less than 0.5-log10 reduction of MS2 was observed in toilet wastewater even at the highest [NaClO] dosage (36 mg/L, as Cl2) over a 1 h reaction. Experiments using laboratory model waters showed that free reactive chlorine generated in situ during EC disinfection process was the main disinfectant responsible for the inactivation of microorganisms. However, the production of hydroxyl radicals [OH], and other reactive oxygen species by the active bismuth-doped TiO2 anode were negligible under the same electrolytic conditions. The formation of THMs and HAA5 were found to increase with higher applied cell voltage. Based on the energy consumption estimates, the WEC system can be operated using solar energy stored in a DC battery as the sole power source. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Simultaneous E. coli inactivation and NOM degradation in river water via photo-Fenton process at natural pH in solar CPC reactor. A new way for enhancing solar disinfection of natural water.

PubMed

Moncayo-Lasso, Alejandro; Sanabria, Janeth; Pulgarin, César; Benítez, Norberto

2009-09-01

Bacteria inactivation and natural organic matter oxidation in river water was simultaneously conducted via photo-Fenton reaction at "natural" pH ( approximately 6.5) containing 0.6 mg L(-1) of Fe(3+) and 10 mg L(-1) of H(2)O(2). The experiments were carried out by using a solar compound parabolic collector on river water previously filtered by a slow sand filtration system and voluntarily spiked with Escherichia coli. Fifty five percent of 5.3 mg L(-1) of dissolved organic carbon was mineralized whereas total disinfection was observed without re-growth after 24h in the dark.

Disinfection Addition and Disinfection Changes: What It Means to the LCR

EPA Science Inventory

This slide presentation’s general points are: Many protective pipe scales are vey dependent on ORP, and hence, state of disinfection. Adding disinfection to anoxic systems will likely cause big chemistry changes in DS and corrosion. Changing disinfectants could cause major l...

Prechlorination of algae-laden water: The effects of transportation time on cell integrity, algal organic matter release, and chlorinated disinfection byproduct formation.

PubMed

Qi, Jing; Lan, Huachun; Liu, Ruiping; Miao, Shiyu; Liu, Huijuan; Qu, Jiuhui

2016-10-01

The prechlorination-induced algal organic matter (AOM) released from Microcystis aeruginosa (M. aeruginosa) cells has been reported to serve as a source of precursors for chlorinated disinfection byproducts (DBPs). However, previous studies have mainly focused on the precursors either extracted directly from the cell suspension or derived immediately after algal suspension prechlorination. This study aims to investigate the impacts of water transportation time after algal suspension prechlorination on cell integrity, AOM release, and DBP formation during the dissolved phase chlorination. The damage to cell integrity after prechlorination was indicated to depend not only on chlorine dose but also on transportation time. The highest dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) values were observed at 2 mg/L chlorine preoxidation before transportation, but were obtained at 0.4 mg/L chlorine after 480-min simulated transportation. The variation of DON with transportation time was indicated to be mainly influenced by the small molecular weight nitrogenous organic compounds, such as amino acids. Additionally, formation of the corresponding chlorinated carbonaceous disinfection byproducts (C-DBPs) and nitrogenous disinfection byproducts (N-DBPs) during the dissolved phase chlorination showed the same variation tendency as DOC and DON respectively. The highest C-DBP (98.4 μg/L) and N-DBP (5.5 μg/L) values were obtained at 0.4 mg/L chlorine preoxidation after 480-min simulated transportation. Therefore, when prechlorination is applied for algae-laden water pretreatment, not only chlorine dose but also transportation time needs to be considered with regard to their effects on cell integrity, AOM release, and chlorinated DBP formation. Copyright © 2016. Published by Elsevier Ltd.

Long-term decomposition of DOC from experimental diatom blooms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fry, B.; Hopkinson, C.S. Jr.; Nolin, A.

1996-09-01

Decomposition of {sup 13}C-labeled dissolved organic carbon (DOC) produced in two marine diatom blooms was followed for 2.5 yr with large volume (20 liter) incubations performed in the dark. The {sup 13}C tracer was used to partition decomposition dynamics of the fresh diatom-derived DOC and the turnover of background DOC from Woods Hole Harbor. DOC from Woods Hole harbor proved largely refractory, with DOC concentrations falling from 122 to {approximately} 100 {mu}M C in 2.5 yr. DOC from the diatom blooms was more labile, but was also incompletely mineralized, with 25-35% remaining after 2.5 yr. Neither nutrients nor labile carbonmore » (dextrose) added at 1.5 yr significantly stimulated DOC mineralization. The experiments indicate that DOC produced in short-term blooms can be surprisingly resistant to microbial attack. 21 refs., 1 fig., 1 tab.« less

Does Litter Impart A Detectable Chemical Signal on Soil DOC? DOC Fluorescence Signatures in Soils Undergoing Long-Term Litter Manipulations

NASA Astrophysics Data System (ADS)

Lajtha, K.; Strid, A.; Lee, B. S.

2015-12-01

Soil dissolved organic carbon (DOC) is a small but crucial part of the forest carbon cycle. Characterizing the relationship between organic matter inputs to soil and DOC chemistry is crucial to understanding the ultimate fate of root carbon, fallen wood and needles. Chemical differences in the DOC pool may help to explain whether fractions are sorbed to mineral surfaces and contribute to accumulation of soil organic carbon, respired as CO2, or exported. Soil solution DOC was sampled from the detrital input and removal treatment (DIRT) plots located in the H.J. Andrews Experimental Forest, OR to determine whether detrital inputs impart a detectable signal on DOC in mineral soil. Multiple types of fresh litter extracts, along with lysimeter and soil extracts from DIRT treatment plots were characterized using UV-Vis and fluorescence spectroscopy coupled with the Cory and McKnight (2005) parallel factor analysis (PARAFAC) model. Principal component analysis of 13 unique fluorophores distinguished using PARAFAC show that litter and soil extracts (needles, wood of decomposition Class 1, Class 3 and Class 5, O-horizon, and A-horizon) each have distinct fluorescence signatures. However, while litter-leached DOC chemistry varies by litter type, neither lysimeter-collected DOC or soil extracts show statistically significant differences in fluorescence signatures among treatments, even after 17 years of litter manipulations. The lack of observed differences among DIRT treatments suggests a "Soil Blender" hypothesis whereby both abiotic and biotic mechanisms effectively homogenize organic carbon constituents within the dissolved pool. The results of this work emphasize the ability of sorption and biodegradation to homogenize soil DOC and demonstrate that fluorescence can be an effective fingerprinting technique for soil DOC composition.

Investigating Forest Harvest Effects on DOC Concentration and Quality: An In Situ, High Resolution Approach to Quantifying DOC Export Dynamics

NASA Astrophysics Data System (ADS)

Jollymore, A. J.; Johnson, M. S.; Hawthorne, I.

2013-12-01

Justification: Forest harvest effects on water quality can signal alterations in hydrologic and ecologic processes incurred as a result of forest harvest activities. Organic matter (OM), specifically dissolved organic carbon (DOC), plays a number of important roles mediating UV-light penetration, redox reactivity and microbial activity within aquatic ecosystems. Quantification of DOC is typically pursued via grab sampling followed by chemical or spectrophotometric analysis, limiting the temporal resolution obtained as well as the accuracy of export calculations. The advent of field-deployable sensors capable of measuring DOC concentration and certain quality characteristics in situ provides the ability to observe dynamics at temporal scales necessary for accurate calculation of DOC flux, as well as the observation of dynamic changes in DOC quality on timescales impossible to observe through grab sampling. Methods: This study utilizes a field deployable UV-Vis spectrophotometer (spectro::lyzer, s::can, Austria) to investigate how forest harvest affects DOC export. The sensor was installed at an existing hydrologic monitoring site at the outlet of a headwater stream draining a small (91 hectare) second growth Douglasfir-dominated catchment near Campbell River on Vancouver Island, British Columbia. Measurement began late in 2009, prior to forest harvest and associated activities such as road building (which commenced in October 2010 and ended in early 2011), and continues to present. During this time - encompassing the pre, during and post-harvest conditions - the absorbance spectrum of stream water from 200 to 750 nm was measured. DOC concentration and spectroscopic indices related to DOC quality (including SUVA, which relates to the concentration of aromatic carbon, and spectral slope) were subsequently calculated for each spectra obtained at 30-minute intervals. Results and conclusions: High frequency measurements of DOC show that overall export of OM increased in

Evaluation of the efficiency of the photo Fenton disinfection of natural drinking water source during the rainy season in the Sahelian region.

PubMed

Ndounla, J; Pulgarin, C

2014-09-15

The photo-disinfection of water from two different wells (W1, pH: 4.6-5.1 ± 0.02) and (W2 pH: 5.6-5.7 ± 0.02) was carried out during the rainy season at Ouagadougou-Burkina Faso, West Africa. The weather variation during the rainy season significantly affects the photo-disinfection processes (solar disinfection and photo-Fenton). The dilution of the water by rainwater highly affected the chemical composition of the wells' water used in this study; very low iron contents Compared to the ones recorded during the dry season were recorded in all water samples. Both photo-disinfection processes were used to treat 25 L of water in a compound parabolic collector (CPC). None of them have shown the total inactivation of both wild enteric bacteria strains (total coliforms/E. coli and Salmonella spp.) involved in the treatment. However, the total coliforms/E. coli strains were totally inactivated during the exposure under most of the photo-Fenton treatment. Also, the remaining strains, especially those of Salmonella spp. were achieved during the subsequent 24h of dark storage under the action of the Fenton process. Under uniquely solar radiation, total inactivation was recorded only in the total coliforms/E. coli strains. The impact of the available irradiance on the efficiency of the photo-Fenton disinfection of natural water was highlighted during the exposure under high intermittent solar radiation. The impact of the HCO3(-) concentration of both wells' water on the evolution of the pH during the photo-disinfection was recorded. Drastic decrease was noticed after the initial fast increase in presence of low HCO3(-) concentration while a steady state was observed after the increase in presence of higher concentration. The redox activities of the nitrogen components of the water during both photo-disinfection processes have led to increased concentration of nitrite in all the cases and variations were noticed in that of nitrate and ammonia. Copyright © 2014 Elsevier B

CDOM-DOC relationship in contrasted coastal waters: implication for DOC retrieval from ocean color remote sensing observation.

PubMed

Vantrepotte, Vincent; Danhiez, François-Pierre; Loisel, Hubert; Ouillon, Sylvain; Mériaux, Xavier; Cauvin, Arnaud; Dessailly, David

2015-01-12

Increasing our knowledge on dissolved organic carbon (DOC) spatio-temporal distribution in the coastal ocean represents a crucial challenge for better understanding the role of these ecosystems in the global oceanic carbon cycle. The assessment of DOC concentration from the absorption properties of the colored part of the dissolved organic matter (a(cdom)) was investigated from an extensive data set covering a variety of coastal environments. Our results confirmed that variation in the a(cdom)(412) to DOC ratio (a*(cdom)(412)) can be depicted from the CDOM spectral slope in the UV domain (S(275-295)). They also evidenced that regional first order variation in both a*(cdom)(412) and S(275-295) are highly correlated to variation in a(cdom)(412). From these observations, generalized relationships for estimating a*(cdom)(412) from S(275-295) or a(cdom)(412) were parameterized from our development sites (N = 158; English Channel, French Guiana, Hai Phong Bay) and tested against an independent data set covering others coastal regions (N = 223; French Polynesia, Rhone River estuary, Gulf of Maine, Chesapeake Bay, Southern Middle Atlantic Bight) demonstrating the possibility to derive DOC estimates from in situ CDOM optical properties with an average accuracy of ~16% over very contrasted coastal environments (with DOC ranging from 50 to 250 µmol.L(-1)). The applicability of these generalized approaches was evaluated in the context of ocean color remote sensing observation emphasizing the limits of S(275-295)-based formulations and the potential for a(cdom)-based approaches to represent a compelling alternative for assessing synoptic DOC distribution.

Status report on analytical methods to support the disinfectant/disinfection by-products regulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1992-08-01

The U.S. EPA is developng national regulations to control disinfectants and disinfection by-products in public drinking water supplies. Twelve disinfectants and disinfection by-products are identified for possible regulation under this rule. The document summarizes the analytical methods that EPA intends to propose as compliance monitoring methods. A discussion of surrogate measurements that are being considered for inclusion in the regulation is also provided.

Earth System Documentation (ES-DOC) Preparation for CMIP6

NASA Astrophysics Data System (ADS)

Denvil, S.; Murphy, S.; Greenslade, M. A.; Lawrence, B.; Guilyardi, E.; Pascoe, C.; Treshanksy, A.; Elkington, M.; Hibling, E.; Hassell, D.

2015-12-01

During the course of 2015 the Earth System Documentation (ES-DOC) project began its preparations for CMIP6 (Coupled Model Inter-comparison Project 6) by further extending the ES-DOC tooling ecosystem in support of Earth System Model (ESM) documentation creation, search, viewing & comparison. The ES-DOC online questionnaire, the ES-DOC desktop notebook, and the ES-DOC python toolkit will serve as multiple complementary pathways to generating CMIP6 documentation. It is envisaged that institutes will leverage these tools at different points of the CMIP6 lifecycle. Institutes will be particularly interested to know that the documentation burden will be either streamlined or completely automated.As all the tools are tightly integrated with the ES-DOC web-service, institutes can be confident that the latency between documentation creation & publishing will be reduced to a minimum. Published documents will be viewable with the online ES-DOC Viewer (accessible via citable URL's). Model inter-comparison scenarios will be supported using the ES-DOC online Comparator tool. The Comparator is being extended to:• Support comparison of both Model descriptions & Simulation runs;• Greatly streamline the effort involved in compiling official tables.The entire ES-DOC ecosystem is open source and built upon open standards such as the Common Information Model (CIM) (versions 1 and 2).

Solar Eclipse Computer API: Planning Ahead for August 2017

NASA Astrophysics Data System (ADS)

Bartlett, Jennifer L.; Chizek Frouard, Malynda; Lesniak, Michael V.; Bell, Steve

2016-01-01

With the total solar eclipse of 2017 August 21 over the continental United States approaching, the U.S. Naval Observatory (USNO) on-line Solar Eclipse Computer can now be accessed via an application programming interface (API). This flexible interface returns local circumstances for any solar eclipse in JavaScript Object Notation (JSON) that can be incorporated into third-party Web sites or applications. For a given year, it can also return a list of solar eclipses that can be used to build a more specific request for local circumstances. Over the course of a particular eclipse as viewed from a specific site, several events may be visible: the beginning and ending of the eclipse (first and fourth contacts), the beginning and ending of totality (second and third contacts), the moment of maximum eclipse, sunrise, or sunset. For each of these events, the USNO Solar Eclipse Computer reports the time, Sun's altitude and azimuth, and the event's position and vertex angles. The computer also reports the duration of the total phase, the duration of the eclipse, the magnitude of the eclipse, and the percent of the Sun obscured for a particular eclipse site. On-line documentation for using the API-enabled Solar Eclipse Computer, including sample calls, is available (http://aa.usno.navy.mil/data/docs/api.php). The same Web page also describes how to reach the Complete Sun and Moon Data for One Day, Phases of the Moon, Day and Night Across the Earth, and Apparent Disk of a Solar System Object services using API calls.For those who prefer using a traditional data input form, local circumstances can still be requested that way at http://aa.usno.navy.mil/data/docs/SolarEclipses.php. In addition, the 2017 August 21 Solar Eclipse Resource page (http://aa.usno.navy.mil/data/docs/Eclipse2017.php) consolidates all of the USNO resources for this event, including a Google Map view of the eclipse track designed by Her Majesty's Nautical Almanac Office (HMNAO). Looking further ahead, a

40 CFR 141.72 - Disinfection.

Code of Federal Regulations, 2010 CFR

2010-07-01

... PRIMARY DRINKING WATER REGULATIONS Filtration and Disinfection § 141.72 Disinfection. A public water... the direct influence of surface water and provides filtration treatment must provide disinfection...) Disinfection requirements for public water systems which provide filtration. Each public water system that...

Conventional and advanced oxidation processes used in disinfection of treated urban wastewater.

PubMed

Rodríguez-Chueca, J; Ormad, M P; Mosteo, R; Sarasa, J; Ovelleiro, J L

2015-03-01

The purpose of the current study is to compare the inactivation of Escherichia coli in wastewater effluents using conventional treatments (chlorination) and advanced oxidation processes (AOPs) such as UV irradiation, hydrogen peroxide (H2O2)/solar irradiation, and photo-Fenton processes. In addition, an analysis of the operational costs of each treatment is carried out taking into account the optimal dosages of chemicals used. Total inactivation of bacteria (7.5 log) was achieved by means of chlorination and UV irradiation. However, bacterial regrowth was observed 6 hours after the completion of UV treatment, obtaining a disinfection value around 3 to 4 log. On the other hand, the combination H2O2/solar irradiation achieved a maximum inactivation of E. coli of 3.30 ± 0.35 log. The photo-Fenton reaction achieved a level of inactivation of 4.87 ± 0.10 log. The order of disinfection, taking into account the reagent/cost ratio of each treatment, is as follows: chlorination > UV irradiation > photo-Fenton > H2O2/sunlight irradiation.

Quality of drinking-water at source and point-of-consumption--drinking cup as a high potential recontamination risk: a field study in Bolivia.

PubMed

Rufener, Simonne; Mäusezahl, Daniel; Mosler, Hans-Joachim; Weingartner, Rolf

2010-02-01

In-house contamination of drinking-water is a persistent problem in developing countries. This study aimed at identifying critical points of contamination and determining the extent of recontamination after water treatment. In total, 81 households were visited, and 347 water samples from their current sources of water, transport vessels, treated water, and drinking vessels were analyzed. The quality of water was assessed using Escherichia coli as an indicator for faecal contamination. The concentration of E. coli increased significantly from the water source [median=0 colony-forming unit (CFU)/100 mL, interquartile range (IQR: 0-13)] to the drinking cup (median=8 CFU/100 mL; IQR: 0-550; n=81, z=-3.7, p<0.001). About two-thirds (34/52) of drinking vessels were contaminated with E. coli. Although boiling and solar disinfection of water (SODIS) improved the quality of drinking-water (median=0 CFU/100 mL; IQR: 0-0.05), recontamination at the point-of-consumption significantly reduced the quality of water in the cups (median=8, IQR: 0-500; n=45, z=-2.4, p=0.015). Home-based interventions in disinfection of water may not guarantee health benefits without complementary hygiene education due to the risk of posttreatment contamination.

40 CFR 141.72 - Disinfection.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 23 2014-07-01 2014-07-01 false Disinfection. 141.72 Section 141.72... PRIMARY DRINKING WATER REGULATIONS Filtration and Disinfection § 141.72 Disinfection. A public water... disinfection treatment specified in paragraph (a) of this section beginning December 30, 1991, unless the State...

40 CFR 141.72 - Disinfection.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 24 2012-07-01 2012-07-01 false Disinfection. 141.72 Section 141.72... PRIMARY DRINKING WATER REGULATIONS Filtration and Disinfection § 141.72 Disinfection. A public water... disinfection treatment specified in paragraph (a) of this section beginning December 30, 1991, unless the State...

Dental unit waterlines disinfection using hypochlorous acid-based disinfectant

PubMed Central

Shajahan, Irfana Fathima; Kandaswamy, D; Srikanth, Padma; Narayana, L Lakshmi; Selvarajan, R

2016-01-01

Objective: The purpose of the study was to investigate the efficacy of a new disinfectant to disinfect the dental unit waterlines. Materials and Methods: New dental unit waterlines were installed in 13 dental chairs, and biofilm was allowed to grow for 10 days. Disinfection treatment procedure was carried out in the 12 units, and one unit was left untreated. The dental unit waterlines were removed and analyzed using the scanning electron microscope (SEM) (TESCAN VEGA3 SBU). Result: On examination, SEM images showed that there was no slime layer or bacterial cells seen in any of the 12 cut sections obtained from the treated dental waterlines which mean that there was no evident of biofilm formation. Untreated dental unit waterlines showed a microbial colonization with continuous filamentous organic matrix. There was significant biofilm formation in the control tube relative to the samples. Conclusion: The tested disinfectant was found to be effective in the removal of biofilm from the dental unit waterlines. PMID:27563184

Can pulsed xenon ultraviolet light systems disinfect aerobic bacteria in the absence of manual disinfection?

PubMed

Jinadatha, Chetan; Villamaria, Frank C; Ganachari-Mallappa, Nagaraja; Brown, Donna S; Liao, I-Chia; Stock, Eileen M; Copeland, Laurel A; Zeber, John E

2015-04-01

Whereas pulsed xenon-based ultraviolet light no-touch disinfection systems are being increasingly used for room disinfection after patient discharge with manual cleaning, their effectiveness in the absence of manual disinfection has not been previously evaluated. Our study indicates that pulsed xenon-based ultraviolet light systems effectively reduce aerobic bacteria in the absence of manual disinfection. These data are important for hospitals planning to adopt this technology as adjunct to routine manual disinfection. Published by Elsevier Inc.

DOC quantity and quality in northeastern USA catchments

NASA Astrophysics Data System (ADS)

Shanley, J. B.; Sebestyen, S. D.; Aiken, G.; Pellerin, B. A.

2011-12-01

At the Sleepers River Research Watershed in Vermont we have studied interactions of dissolved organic carbon (DOC) cycling and hydrological processes for nearly 20 years to determine how and when DOC is transported through the landscape. Stream DOC concentration in this cool temperate forested catchment varies from ~1 to ~15 mg L-1 and is transport-limited; concentrations increase with increasing flow, even under the wettest conditions, suggesting shifting but non-depletable sources. Specific UV absorbance (SUVA) also increases consistently with flow. Source strength does vary seasonally, however, evidenced by higher DOC for a given flow during autumn leaf fall relative to spring snowmelt. Recent high-frequency optical sensor measurements have revealed fine-scale structure in the temporal DOC pattern not possible from discrete sampling. We observe a consistent counterclockwise hysteresis and diurnal cycles with seasonally variable amplitude. In this presentation we infer DOC sources and processes through analysis of antecedent moisture conditions and concurrent variations in nitrate, dissolved organic nitrogen, and SUVA. With sensors and sampling in place at several other research catchments, we are investigating the similarity of patterns across the northeastern USA.

Inactivation and regrowth of multidrug resistant bacteria in urban wastewater after disinfection by solar-driven and chlorination processes.

PubMed

Fiorentino, Antonino; Ferro, Giovanna; Alferez, María Castro; Polo-López, Maria Inmaculada; Fernández-Ibañez, Pilar; Rizzo, Luigi

2015-07-01

Solar disinfection and solar-driven advanced oxidation processes (AOPs) (namely H2O2/sunlight, TiO2/sunlight, H2O2/TiO2/sunlight, solar photo-Fenton) were evaluated in the inactivation of indigenous antibiotic-resistant bacteria (ARB) in real urban wastewater. A multidrug resistant (MDR) Escherichia coli strain isolated from the effluent of the biological process of an urban wastewater treatment plant was the target ARB. The higher inactivation rates (residual density under detection limit, 2 CFUm L(-1)) were achieved with H2O2/TiO2/sunlight (cumulative energy per unit of volume (QUV) in the range 3-5 kJ L(-1), depending on H2O2/TiO2 ratio) and H2O2/sunlight (QUV of 8 kJ L(-1)) processes. All investigated processes did not affect antibiotic resistance of survived colonies. Moreover, H2O2/sunlight was compared with conventional chlorination process to evaluate bacterial regrowth potential and particularly the proportion of indigenous MDR E. coli with respect to total indigenous E. coli population. Chlorination (1.0 mg Cl2 L(-1)) was more effective than H2O2/sunlight (50 mg H2O2 L(-1)) to achieve total inactivation of MDR E. coli (15 min Vs 90 min) but less effective in controlling their regrowth (24 h Vs 48 h). Interestingly, the percentage of MDR E. coli in H2O2/sunlight treated samples decreased as incubation time increased; the opposite was observed for chlorinated samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Rapid disinfection of E-Coliform contaminated water using WO3 semiconductor catalyst by laser-induced photo-catalytic process.

PubMed

Gondal, Mohammed A; Khalil, Amjad

2008-04-01

Laser-induced photo-catalysis process using WO(3) semiconductor catalyst was applied for the study of disinfection effectiveness of E-coliform-contaminated water. For this purpose, wastewater polluted with E-coliform bacteria was exposed to 355 nm UV radiations generated by third harmonic of Nd: YAG laser in special glass cell with and without WO(3) catalyst. E-Coliform quantification was performed by direct plating method to obtain the efficiency of each disinfection treatment. The dependence of disinfection process on laser irradiation energy, amount of catalyst and duration of laser irradiation was also investigated. The disinfection with WO(3) was quite efficient inactivating E-coliforms. For inactivation of E-coliforms, less than 8 minutes' laser irradiation was required, so that, the treated water complies with the microbial standards for drinking water. This study opens the possibility of application of this simple method in rural areas of developing countries using solar radiation.

Degradation potentials of dissolved organic carbon (DOC) from thawed permafrost peat

PubMed Central

Panneer Selvam, Balathandayuthabani; Lapierre, Jean-François; Guillemette, Francois; Voigt, Carolina; Lamprecht, Richard E.; Biasi, Christina; Christensen, Torben R.; Martikainen, Pertti J.; Berggren, Martin

2017-01-01

Global warming can substantially affect the export of dissolved organic carbon (DOC) from peat-permafrost to aquatic systems. The direct degradability of such peat-derived DOC, however, is poorly constrained because previous permafrost thaw studies have mainly addressed mineral soil catchments or DOC pools that have already been processed in surface waters. We incubated peat cores from a palsa mire to compare an active layer and an experimentally thawed permafrost layer with regard to DOC composition and degradation potentials of pore water DOC. Our results show that DOC from the thawed permafrost layer had high initial degradation potentials compared with DOC from the active layer. In fact, the DOC that showed the highest bio- and photo-degradability, respectively, originated in the thawed permafrost layer. Our study sheds new light on the DOC composition of peat-permafrost directly upon thaw and suggests that past estimates of carbon-dioxide emissions from thawed peat permafrost may be biased as they have overlooked the initial mineralization potential of the exported DOC. PMID:28378792

Predictive models for water sources with high susceptibility for bromine-containing disinfection by-product formation: implications for water treatment.

PubMed

Watson, Kalinda; Farré, Maria José; Birt, James; McGree, James; Knight, Nicole

2015-02-01

This study examines a matrix of synthetic water samples designed to include conditions that favour brominated disinfection by-product (Br-DBP) formation, in order to provide predictive models suitable for high Br-DBP forming waters such as salinity-impacted waters. Br-DBPs are known to be more toxic than their chlorinated analogues, in general, and their formation may be favoured by routine water treatment practices such as coagulation/flocculation under specific conditions; therefore, circumstances surrounding their formation must be understood. The chosen factors were bromide concentration, mineral alkalinity, bromide to dissolved organic carbon (Br/DOC) ratio and Suwannee River natural organic matter concentration. The relationships between these parameters and DBP formation were evaluated by response surface modelling of data generated using a face-centred central composite experimental design. Predictive models for ten brominated and/or chlorinated DBPs are presented, as well as models for total trihalomethanes (tTHMs) and total dihaloacetonitriles (tDHANs), and bromide substitution factors for the THMs and DHANs classes. The relationships described revealed that increasing alkalinity and increasing Br/DOC ratio were associated with increasing bromination of THMs and DHANs, suggesting that DOC lowering treatment methods that do not also remove bromide such as enhanced coagulation may create optimal conditions for Br-DBP formation in waters in which bromide is present.

9 CFR 71.11 - Cresylic disinfectant as permitted disinfectant; specifications.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Cresylic disinfectant as permitted disinfectant; specifications. 71.11 Section 71.11 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND...

9 CFR 71.11 - Cresylic disinfectant as permitted disinfectant; specifications.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Cresylic disinfectant as permitted disinfectant; specifications. 71.11 Section 71.11 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND...

9 CFR 71.11 - Cresylic disinfectant as permitted disinfectant; specifications.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Cresylic disinfectant as permitted disinfectant; specifications. 71.11 Section 71.11 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND...

9 CFR 71.11 - Cresylic disinfectant as permitted disinfectant; specifications.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Cresylic disinfectant as permitted disinfectant; specifications. 71.11 Section 71.11 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE INTERSTATE TRANSPORTATION OF ANIMALS (INCLUDING POULTRY) AND...

Influence of ultrasound enhancement on chlorine dioxide consumption and disinfection by-products formation for secondary effluents disinfection.

PubMed

Zhou, Xiaoqin; Zhao, Junyuan; Li, Zifu; Lan, Juanru; Li, Yajie; Yang, Xin; Wang, Dongling

2016-01-01

Chlorine dioxide (ClO2) has been promoted as an alternative disinfectant because of its high disinfection efficiency and less formation of organic disinfection by-products (DBPs). However, particle-associated microorganisms could be protected during the disinfection process, which decreases the disinfection efficiency or increases the required dosage. Besides, the formation of inorganic disinfection by-products is a significant concern in environment health. Ultrasound (US)-combined disinfection methods are becoming increasingly attractive because they are efficient and environmentally friendly. In this study, US was introduced as an enhancement method to identify its influence on ClO2 demand reduction and to minimize the production of potential DBPs for secondary effluents disinfection. Fecal coliform was used as an indicator, and DBPs, including trichloromethane (TCM), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), chlorite (ClO2(-)), and chlorate (ClO3(-)), were analyzed to observe the potential DBPs formation. Results show that US pretreatment could reduce half of ClO2 dosage compared with ClO2 disinfection alone for the same disinfection efficiency, and that an input power density of 2.64 kJ/L pretreatment with the 1.5mg/L ClO2 was enough to meet the discharge requirement in China (i.e., fecal coliform below 1000 CFU/L for Class 1A) for secondary effluent disinfection, and the ClO2(-) concentration in the disinfection effluent was only 1.37 mg/L at the same time. Furthermore, the different effects of US on the two processes (US as pretreatment and simultaneous US/ClO2 disinfection) were also analyzed, including deagglomerating, cell damage, and synergistic disinfection as well as degasing/sonolysis. It was proved that the production of TCM, DCAA, and TCAA was insignificantly influenced with the introduction of US, but US pretreatment did reduce the production of ClO2(-) and ClO3(-) effectually. In general, US pretreatment could be a better option for

Estimating Retrospective Exposure of Household Humidifier Disinfectants

PubMed Central

Park, Dong-Uk; Friesen, Melissa C; Roh, Hyun-Suk; Choi, Ye-Yong; Ahn, Jong-Ju; Lim, Heung-Kyu; Kim, Sun-Kyung; Koh, Dong-Hee; Jung, Hye-Jung; Lee, Jong-Hyeon; Cheong, Hae-Kwan; Lim, Sin-Ye; Leem, Jong-Han; Kim, Yong-Hwa; Paek, Do-Myung

2014-01-01

We conducted a comprehensive humidifier disinfectant exposure characterization for 374 subjects with lung disease who presumed their disease was related to humidifier disinfectant use (patient group) and for 303 of their family members (family group) for an ongoing epidemiological study. We visited the homes of the registered patients to investigate disinfectant use characteristics. Probability of exposure to disinfectants was determined from the questionnaire and supporting evidence from photographs demonstrating the use of humidifier disinfectant, disinfectant purchase receipts, any residual disinfectant and the consistency of their statements. Exposure duration was estimated as cumulative disinfectant use hours from the questionnaire. Airborne disinfectant exposure intensity (μg/m3) was estimated based on the disinfectant volume (mL) and frequency added to the humidifier per day, disinfectant bulk level (μg/mL), the volume of the room (m3) with humidifier disinfectant, and the degree of ventilation. Overall, the distribution patterns of the intensity, duration and cumulative exposure to humidifier disinfectants for the patient group were higher than those of the family group, especially for pregnant women and patients ≤ 6 years old. Further study is underway to evaluate the association between the disinfectant exposure estimated here with clinically diagnosed lung disease. PMID:25557769

Estimating retrospective exposure of household humidifier disinfectants.

PubMed

Park, D U; Friesen, M C; Roh, H S; Choi, Y Y; Ahn, J J; Lim, H K; Kim, S K; Koh, D H; Jung, H J; Lee, J H; Cheong, H K; Lim, S Y; Leem, J H; Kim, Y H; Paek, D M

2015-12-01

We conducted a comprehensive humidifier disinfectant exposure characterization for 374 subjects with lung disease who presumed their disease was related to humidifier disinfectant use (patient group) and for 303 of their family members (family group) for an ongoing epidemiological study. We visited the homes of the registered patients to investigate disinfectant use characteristics. Probability of exposure to disinfectants was determined from the questionnaire and supporting evidence from photographs demonstrating the use of humidifier disinfectant, disinfectant purchase receipts, any residual disinfectant, and the consistency of their statements. Exposure duration was estimated as cumulative disinfectant use hours from the questionnaire. Airborne disinfectant exposure intensity (μg/m(3)) was estimated based on the disinfectant volume (ml) and frequency added to the humidifier per day, disinfectant bulk level (μg/ml), the volume of the room (m(3)) with humidifier disinfectant, and the degree of ventilation. Overall, the distribution patterns of the intensity, duration, and cumulative exposure to humidifier disinfectants for the patient group were higher than those of the family group, especially for pregnant women and patients ≤6 years old. Further study is underway to evaluate the association between the disinfectant exposures estimated here with clinically diagnosed lung disease. Retrospective exposure to household humidifier disinfectant as estimated here can be used to evaluate associations with clinically diagnosed lung disease due to the use of humidifier disinfectant in Korea. The framework, with modifications to account for dispersion and use patterns, can also be potentially adapted to assessment of other household chemical exposures. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Point-of-use water disinfection using ultraviolet and visible light-emitting diodes.

PubMed

Lui, Gough Yumu; Roser, David; Corkish, Richard; Ashbolt, Nicholas J; Stuetz, Richard

2016-05-15

Improvements in point-of-use (POU) drinking water disinfection technologies for remote and regional communities are urgently needed. Conceptually, UV-C light-emitting diodes (LEDs) overcome many drawbacks of low-pressure mercury tube based UV devices, and UV-A or visible light LEDs also show potential. To realistically evaluate the promise of LED disinfection, our study assessed the performance of a model 1.3 L reactor, similar in size to solar disinfection bottles. In all, 12 different commercial or semi-commercial LED arrays (270-740 nm) were compared for their ability to inactivate Escherichia coli K12 ATCC W3110 and Enterococcus faecalis ATCC 19433 over 6h. Five log10 and greater reductions were consistently achieved using the 270, 365, 385 and 405 nm arrays. The output of the 310 nm array was insufficient for useful disinfection while 430 and 455 nm performance was marginal (≈ 4.2 and 2.3-log10s E. coli and E. faecalis over the 6h). No significant disinfection was observed with the 525, 590, 623, 660 and 740 nm arrays. Delays in log-phase inactivation of E. coli were observed, particularly with UV-A wavelengths. The radiation doses required for >3-log10 reduction of E. coli and E. faecalis differed by 10 fold at 270 nm but only 1.5-2.5 fold at 365-455 nm. Action spectra, consistent with the literature, were observed with both indicators. The design process revealed cost and technical constraints pertaining to LED electrical efficiency, availability and lifetime. We concluded that POU LED disinfection using existing LED technology is already technically possible. UV-C LEDs offer speed and energy demand advantages, while UV-A/violet units are safer. Both approaches still require further costing and engineering development. Our study provides data needed for such work. Copyright © 2016 Elsevier B.V. All rights reserved.

Biofilms Reduce Solar Disinfection of Cryptosporidium parvum Oocysts

PubMed Central

Hargreaves, B. R.; Jellison, K. L.

2012-01-01

Solar radiation reduces Cryptosporidium infectivity. Biofilms grown from stream microbial assemblages inoculated with oocysts were exposed to solar radiation. The infectivity of oocysts attached at the biofilm surface and oocysts suspended in water was about half that of oocysts attached at the base of a 32-μm biofilm. PMID:22467508

Alternative Electrode Materials and Ceramic Filter Minimize Disinfection Byproducts in Point-of-Use Electrochemical Water Treatment

PubMed Central

Yoon, Yeojoon; Jung, Youmi; Kwon, Minhwan; Cho, Eunha; Kang, Joon-Wun

2013-01-01

Abstract Effects of various electrodes and prefiltration to minimize disinfection byproducts (DBPs) in electrochemical water disinfection was evaluated. The target microorganism, Escherichia coli O157:H7, was effectively inactivated even applying a solar-charged storage battery for the electrolysis process. Extent of microbial inactivation decreased with lower water temperature and higher pH in the free chlorine disinfection system. The RuO2/Ti electrode was most efficient because it produced the lowest concentration of chlorate and the highest generation of free chlorine. Prefiltration using a ceramic filter inhibited formation of halogenated DBPs because it removed precursors of DBPs. For safe point-of-use water treatment, the use of a hybrid prefiltration stage with the electrolysis system is strongly recommended to reduce risks from DBPs. The system is particularly suited to use in developing regions. PMID:24381482

Comparing Stream DOC Fluxes from Sensor- and Sample-Based Approaches

NASA Astrophysics Data System (ADS)

Shanley, J. B.; Saraceno, J.; Aulenbach, B. T.; Mast, A.; Clow, D. W.; Hood, K.; Walker, J. F.; Murphy, S. F.; Torres-Sanchez, A.; Aiken, G.; McDowell, W. H.

2015-12-01

DOC transport by streamwater is a significant flux that does not consistently show up in ecosystem carbon budgets. In an effort to quantify stream DOC flux, we analyzed three to four years of high-frequency in situ fluorescing dissolved organic matter (FDOM) concentrations and turbidity measured by optical sensors at the five diverse forested and/or alpine headwater sites of the U.S. Geological Survey (USGS) Water, Energy, and Biogeochemical Budgets (WEBB) program. FDOM serves as a proxy for DOC. We also took discrete samples over a range of hydrologic conditions, using both manual weekly and automated event-based sampling. After compensating FDOM for temperature effects and turbidity interference - which was successful even at the high-turbidity Luquillo, PR site -- we evaluated the DOC-FDOM relation based on discrete sample DOC analyses matched to corrected FDOM at the time of sampling. FDOM was a moderately robust predictor of DOC, with r2 from 0.60 to more than 0.95 among sites. We then formed continuous DOC time series by two independent approaches: (1) DOC predicted from FDOM; and (2) the composite method, based on modeled DOC from regression on stream discharge, season, air temperature, and time, forcing the model to observations and adjusting modeled concentrations between observations by linearly-interpolated model residuals. DOC flux from each approach was then computed directly as concentration times discharge. DOC fluxes based on the sensor approach were consistently greater than the sample-based approach. At Loch Vale, CO (2.5 years) and Panola Mountain GA (1 year), the difference was 5-17%. At Sleepers River, VT (3 years), preliminary differences were greater than 20%. The difference is driven by the highest events, but we are investigating these results further. We will also present comparisons from Luquillo, PR, and Allequash Creek, WI. The higher sensor-based DOC fluxes could result from their accuracy during hysteresis, which is difficult to model

DISINFECTION OF NEW WATER MAINS

EPA Science Inventory

The 'AWWA Standard for Disinfecting Water Mains' (AWWA C601-68) has fallen into disuse by a number of water utilities because of repeated bacteriological failures following initial disinfection with the recommended high-dose chlorination. Other methods of disinfection, including ...

The Comparison of Different Heterotrophic Bacteria on the Decomposition of DOC molecule

NASA Astrophysics Data System (ADS)

Xie, R.; Zheng, Q.; Jiao, N.

2016-02-01

Marine dissolved organic carbon (DOC) pool is one of the largest reservoirs of organic carbon on Earth. Heterotrophic bacteria are the primary biotic force regulating the fate of marine DOC. Comparison of genomic data, microbes belonging to different clades have diverse DOC molecule utilization genes. That's give us a hint that different microbial groups may have their own pattern to decompose DOC, biosynthesize diverse DOC molecule and contribute to the in situ DOC reservoirs in the ocean. The interaction between marine microbes and DOC molecule is hotspots in current research. We will choose some important microbial groups (e.g., Roseobacter, Altermonas, Halomonas, SAR11 and CFB) to identify their contribution to environmental DOC pool and their specific recalcitrant DOC component using ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Combined with the composition of hydrolases, lyases and ligases in their genomes, we try to establish a linkage between the specific DOC composition and microbial genetic information. Future more the environmental metagenomic data would help us understand the relationship between the endemic DOC composition and microbial communities in the environment.

An environmental disinfection odyssey: evaluation of sequential interventions to improve disinfection of Clostridium difficile isolation rooms.

PubMed

Sitzlar, Brett; Deshpande, Abhishek; Fertelli, Dennis; Kundrapu, Sirisha; Sethi, Ajay K; Donskey, Curtis J

2013-05-01

OBJECTIVE. Effective disinfection of hospital rooms after discharge of patients with Clostridium difficile infection (CDI) is necessary to prevent transmission. We evaluated the impact of sequential cleaning and disinfection interventions by culturing high-touch surfaces in CDI rooms after cleaning. DESIGN. Prospective intervention. SETTING. A Veterans Affairs hospital. INTERVENTIONS. During a 21-month period, 3 sequential tiered interventions were implemented: (1) fluorescent markers to provide monitoring and feedback on thoroughness of cleaning facility-wide, (2) addition of an automated ultraviolet radiation device for adjunctive disinfection of CDI rooms, and (3) enhanced standard disinfection of CDI rooms, including a dedicated daily disinfection team and implementation of a process requiring supervisory assessment and clearance of terminally cleaned CDI rooms. To determine the impact of the interventions, cultures were obtained from CDI rooms after cleaning and disinfection. RESULTS. The fluorescent marker intervention improved the thoroughness of cleaning of high-touch surfaces (from 47% to 81% marker removal; P < .0001). Relative to the baseline period, the prevalence of positive cultures from CDI rooms was reduced by 14% (P=.024), 48% (P <.001), and 89% (P=.006) with interventions 1, 2, and 3, respectively. During the baseline period, 67% of CDI rooms had positive cultures after disinfection, whereas during interventions periods 1, 2, and 3 the percentages of CDI rooms with positive cultures after disinfection were reduced to 57%, 35%, and 7%, respectively. CONCLUSIONS. An intervention that included formation of a dedicated daily disinfection team and implementation of a standardized process for clearing CDI rooms achieved consistent CDI room disinfection. Culturing of CDI rooms provides a valuable tool to drive improvements in environmental disinfection.

Diel fluctuations of viscosity-driven riparian inflow affect streamflow DOC concentration

NASA Astrophysics Data System (ADS)

Schwab, Michael P.; Klaus, Julian; Pfister, Laurent; Weiler, Markus

2018-04-01

Diel fluctuations of stream water DOC concentrations are generally explained by a complex interplay of different instream processes. We measured the light absorption spectrum of water and DOC concentrations in situ and with high frequency by means of a UV-Vis spectrometer during 18 months at the outlet of a forested headwater catchment in Luxembourg (0.45 km2). We generally observed diel DOC fluctuations with a maximum in the afternoon during days that were not affected by rainfall-runoff events. We identified an increased inflow of terrestrial DOC to the stream in the afternoon, causing the DOC maxima in the stream. The terrestrial origin of the DOC was derived from the SUVA-254 (specific UV absorbance at 254 nm) index, which is a good indicator for the aromaticity of DOC. In the studied catchment, the most likely process that can explain the diel DOC input variations towards the stream is the so-called viscosity effect. The water temperature in the upper parts of the saturated riparian zone is increasing during the day, leading to a lower viscosity and therefore a higher hydraulic conductivity. Consequently, more water from areas that are rich in terrestrial DOC passes through the saturated riparian zone and contributes to streamflow in the afternoon. We believe that not only diel instream processes, but also viscosity-driven diel fluctuations of terrestrial DOC input should be considered to explain diel DOC patterns in streams.

Understanding DOC Mobilization Dynamics Through High Frequency Measurements in a Headwater Catchment

NASA Astrophysics Data System (ADS)

Werner, B.; Musolff, A.; Lechtenfeld, O.; de Rooij, G. H.; Fleckenstein, J. H.

2017-12-01

Increasing dissolved organic carbon (DOC) exports from headwater catchments impact the quality of downstream waters and pose challenges to water supply. The importance of riparian zones for DOC export from catchments in humid, temperate climates has generally been acknowledged, but the hydrological controls and biogeochemical factors that govern mobilization of DOC from riparian zones remain elusive. By analyzing high-frequency time series of UV-VIS based water quality we therefore aim at a better understanding on temporal dynamics of DOC mobilization and exports. In a first step a one year high frequency (15 minutes) data set from a headwater catchment in the Harz Mountains (Germany) was systematically analyzed for event-based patterns in DOC concentrations. Here, a simplistic linear model was generated to explain DOC concentration level and variability in the stream. Furthermore, spectral (e.g. slopes and SUVA254) and molecular (FT-ICR-MS) characterization of DOC was used to fingerprint in-stream DOC during events. Continuous DOC concentrations were best predicted (R², NSE = 0.53) by instantaneous discharge (Q) and antecede wetness conditions of the last 30 days (AWC30 = Precip.30/PET30) as well as mean air temperature (Tmean30) and mean discharge (Qmean30) of the preceding 30 days. Analyses of 36 events revealed seasonal trends for the slope, intercept and R² of linear log(DOC)-log(Q) regressions that can be best explained by the mean air temperature of the preceding 15 days. Continuously available optical DOC quality parameters SUVA254 and spectral slope (275 nm - 295 nm) systematically changed with shifts in discharge and in DOC concentration. This is underlined by selected FT-ICR-MS measurements indicating higher DOC aromaticity and oxygen content at high flow conditions. The change of DOC quality parameters during events indicate a shift in the activated source zones: DOC with a different quality was mobilized during high flow conditions when higher

Inverse coupling of DOC and nitrate export from soils and streams

NASA Astrophysics Data System (ADS)

Goodale, Christine

2013-04-01

Over the last two decades, nitrate concentrations in surface waters have decreased across the Northeastern United States and parts of northern Europe. Many hypotheses have been proposed to explain this decrease, but the cause remains unclear. One control may be associated with increasing abundance of dissolved organic carbon (DOC), which in turn may be a result of soil recovery from acidification. Compared across catchments, surface water NO3- decreases sharply with increasing DOC concentration. Here, we used measurements of soil and solution nitrate, DOC, and their isotopic composition (13C-DOC, 15N- and 18O-NO3) to test several related hypotheses that changing acidification affects the release of DOC and bio-available DOC (bDOC) from soil, and that variation in stocks of soil C and release of bDOC partly control NO3- export from forested catchments in New York State, USA. We examined whether DOC and NO3- are both driven by soil C processes that produce inverse coupling at the scale of soil cores as well as across catchments, through comparison of soil and surface water chemistry across nine catchments selected from long-term monitoring networks in the Catskill and Adirondack Mountains. In addition, we conducted a series of soil core leaching experiments to examine the role of acidification and recovery in driving the net production of DOC and NO3- from soils. Over 8 months, soil cores were leached biweekly with simulated rainfall solutions of varying pH (3.6 to 7.0) from additions of H2SO4, CaCO3 and NaOH. These experiments did not yield a pH-induced change in DOC quantity, but did show a change in DOC quality, in that acidified cores released more bio-available DOC with less depleted 13C-DOC than cores with experimentally increased pH. All cores leached substantial amounts of nitrate. Together, these lab- and field comparisons are being used to identify the role of soil production and consumption processes in driving cross-watershed differences in DOC and NO3

Effect of Disinfectants on Glucose Monitors

PubMed Central

Mahoney, John J; Lim, Christine G

2012-01-01

Background Monitoring blood glucose levels is an integral part of routine diabetes management. To minimize the risk of transmission of bloodborne pathogens during monitoring, the Centers for Disease Control and Prevention (CDC) recommends that glucose meters be disinfected after each use whenever they are used to test multiple patients. The objective of this study is to assess the compatibility of some common disinfectants with certain blood glucose meter systems. Methods We tested six disinfectants for adverse impact on meter performance or the exterior meter surfaces. The disinfectants tested were 0.525% sodium hypochlorite, 20% 2-propanol and 10% ethanol, 17.2% isopropanol, 55% isopropanol, 70% isopropanol, and hydrogen peroxide. To assess meter performance, we tested OneTouch® Ultra® blood glucose monitoring systems with control solution before and after application of either water or disinfectant. To assess the effect on exterior meter surfaces, we performed a soaking test to simulate long-term exposure to disinfectant. Results Paired t-test results showed that the control solution data associated with disinfectant and with water application were not significantly different for each meter type. However, most of the meter types were adversely affected by hydrogen peroxide and/or by the higher concentrations of alcohol-based disinfectants. Conclusions Although none of the six disinfectants affected meter performance, hydrogen peroxide and isopropanol >20% adversely affected the exterior surfaces of the tested meters. When complying with CDC instructions for meter disinfection, users should use caution and choose disinfectants that have been validated by the meter manufacturer. PMID:22401326

Effect of disinfectants on glucose monitors.

PubMed

Mahoney, John J; Lim, Christine G

2012-01-01

Monitoring blood glucose levels is an integral part of routine diabetes management. To minimize the risk of transmission of bloodborne pathogens during monitoring, the Centers for Disease Control and Prevention (CDC) recommends that glucose meters be disinfected after each use whenever they are used to test multiple patients. The objective of this study is to assess the compatibility of some common disinfectants with certain blood glucose meter systems. We tested six disinfectants for adverse impact on meter performance or the exterior meter surfaces. The disinfectants tested were 0.525% sodium hypochlorite, 20% 2-propanol and 10% ethanol, 17.2% isopropanol, 55% isopropanol, 70% isopropanol, and hydrogen peroxide. To assess meter performance, we tested OneTouch® Ultra® blood glucose monitoring systems with control solution before and after application of either water or disinfectant. To assess the effect on exterior meter surfaces, we performed a soaking test to simulate long-term exposure to disinfectant. Paired t-test results showed that the control solution data associated with disinfectant and with water application were not significantly different for each meter type. However, most of the meter types were adversely affected by hydrogen peroxide and/or by the higher concentrations of alcohol-based disinfectants. Although none of the six disinfectants affected meter performance, hydrogen peroxide and isopropanol >20% adversely affected the exterior surfaces of the tested meters. When complying with CDC instructions for meter disinfection, users should use caution and choose disinfectants that have been validated by the meter manufacturer. © 2012 Diabetes Technology Society.

There's An App For That: Planning Ahead for the Solar Eclipse in August 2017

NASA Astrophysics Data System (ADS)

Chizek Frouard, Malynda R.; Lesniak, Michael V.; Bell, Steve

2017-01-01

With the total solar eclipse of 2017 August 21 over the continental United States approaching, the U.S. Naval Observatory (USNO) on-line Solar Eclipse Computer can now be accessed via an Android application, available on Google Play.Over the course of the eclipse, as viewed from a specific site, several events may be visible: the beginning and ending of the eclipse (first and fourth contacts), the beginning and ending of totality (second and third contacts), the moment of maximum eclipse, sunrise, or sunset. For each of these events, the USNO Solar Eclipse 2017 Android application reports the time, Sun's altitude and azimuth, and the event's position and vertex angles. The app also lists the duration of the total phase, the duration of the eclipse, the magnitude of the eclipse, and the percent of the Sun obscured for a particular eclipse site.All of the data available in the app comes from the flexible USNO Solar Eclipse Computer Application Programming Interface (API), which produces JavaScript Object Notation (JSON) that can be incorporated into third-party Web sites or custom applications. Additional information is available in the on-line documentation (http://aa.usno.navy.mil/data/docs/api.php).For those who prefer using a traditional data input form, the local circumstances can still be requested at http://aa.usno.navy.mil/data/docs/SolarEclipses.php.In addition the 2017 August 21 Solar Eclipse Resource page (http://aa.usno.navy.mil/data/docs/Eclipse2017.php) consolidates all of the USNO resources for this event, including a Google Map view of the eclipse track designed by Her Majesty's Nautical Almanac Office (HMNAO).Looking further ahead, a 2024 April 8 Solar Eclipse Resource page (http://aa.usno.navy.mil/data/docs/Eclipse2024.php) is also available.

Enhancement effects of ultrasound on secondary wastewater effluent disinfection by sodium hypochlorite and disinfection by-products analysis.

PubMed

Zhou, Xiaoqin; Zhao, Junyuan; Li, Zifu; Song, Jianing; Li, Xueying; Yang, Xin; Wang, Dongling

2016-03-01

Since fecal coliforms was introduced as a standard indicator of pollutants in effluents of municipal wastewater treatment plants in China in 2003, chlorine had been widely used in many wastewater treatment plants. However, concerns about the disinfection by-products (DBPs) of chlorine have been increasing. One of the effective way to reduce the production of DBPs is to reduce the effective chlorine dosage by improving the utilization rate of disinfectant. Ultrasound (US) is proved to be effective in wastewater treatment for its multiple chemical and physical effects produced by cavitation, which could favor the disinfection process accordingly. For the purpose of improving disinfection efficiency with the help of US, following points are addressed in the current study: (1) investigate the enhancement effects of US on the disinfection efficiency of sodium hypochlorite (NaClO) for real secondary effluents of municipal wastewater treatment plants; (2) evaluate the possibility of using US specific energy consumption (kJ/L) as an parameter for disinfection efficiency evaluation; and (3) quantify the reduction in chlorine-DBPs through US application. Results demonstrated that sonication could reduce two-thirds (US pretreatment) or one-third (simultaneous US and NaClO disinfection) of the required concentrations of NaClO (available chlorine) for 4 log reduction of fecal coliforms, which could meet the Class 1A (fecal coliforms less than 1000 CFU/L) discharge standard of China. In addition, US pretreatment with NaClO disinfection performed better enhancement in disinfection efficiency compared with simultaneous US and NaClO disinfection. Furthermore, analysis on DBPs showed that US application as pretreatment could obviously reduce the contents of trichloromethane (TCM) and trichloroacetic acid (TCAA) by more than 85% and 50%, respectively, compared with NaClO disinfection alone for the same disinfection efficiency. Meanwhile, the experimental results also showed that the

Enhanced dissipation of oxyfluorfen, ethalfluralin, trifluralin, propyzamide, and pendimethalin in soil by solarization and biosolarization.

PubMed

Fenoll Serrano, José; Ruiz, Encarnación; Hellín, Pilar; Lacasa, Alfredo; Flores, Pilar

2010-02-24

This study was conducted to assess the effects of solarization and biosolarization on the degradation of oxyfluorfen, ethalfluralin, trifluralin, propyzamide, and pendimethalin. The experimental design consisted of 17 L pots filled with clay-loam soil, which were contaminated with the studied herbicides. Then, soil disinfection treatments were applied during the summer season, including a control without disinfection (C), solarization (S), and biosolarization (BS). Soil from five pots per treatment was sampled periodically up to 90 days. Herbicide dissipation rates were higher in both S and BS treatments with regard to the control. Similar dissipation rates were observed under S and BS for most of the herbicides studied, except oxyfluorfen and pendimethalin, which were degraded to a greater extent in the BS than in the S treatment. The obtained results showed that both solarization and biosolarization can be considered, in addition to soil disinfection techniques, such as bioremediation tools for herbicide-polluted soils.

Bactericidal activity of TiO[sub 2] photocatalyst in aqueous media. Toward a solar-assisted water disinfection system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei, C.; Lin, W.Y.; Zainal, Z.

Irradiation of suspensions of Escherichia coli ([approximately] 10[sup 6] cells/mL) and TiO[sub 2] (anatase) with UV-visible light of wave-lengths longer than 380 nm resulted in the killing of the bacteria within minutes. Oxygen was found to be a prerequisite for the bactericidal properties of the photocatalyst. Bacterial killing was found to adhere to first-order kinetics. The rate constant was proportional to the square root of the concentration of TiO[sub 2] and proportional to the incident light intensity in the range [approximately] 180- [approximately] 1660 [mu]E s[sup [minus]1] m[sup [minus]2]. The trends in these simulated laboratory experiments were mimicked by outdoormore » tests conducted under the summer noonday sun in Texas. The implications of these results as well as those of previous investigations in terms of practical applicability to solar-assisted water treatment and disinfection at remote sites are discussed relative to water technologies currently considered as viable as alternatives to chlorination. 24 refs., 8 figs.« less

Acid-induced changes in DOC quality in an experimental whole-lake manipulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donahue, W.F.; Schindler, D.W.; Page, S.J.

1998-10-01

Fluorescence analyses of archived water samples were used to typify dissolved organic carbon (DOC) quality in experimentally acidified lakes and reference lakes at the Experimental Lakes Area, in northwestern Ontario. Carbon-specific DOC fluorescence (CSF) during peak acidification was 40--50% of that for a high-DOC reference lake and similar to a low-DOC reference lake. Reference lakes showed similar but smaller decreases in CSF during several years of prolonged drought in the late 1980s. During the 1990s, recovery from acidification resulted in increased CSF, whereas reference lakes remained unchanged during the same time period. In addition to causing decreased [DOC], acidification causesmore » changes in fluorescence-peak geometry that indicate a switch in DOC quality from allochthonous to autochthonous-like during acidification. The acid-induced change in DOC quality was likely due to increased chemical oxidation or precipitation of the UV-absorbent aromatic portions of allochthonous DOC molecules, leaving more UV-transparent aliphatic chains. The change in the nature of DOC following acidification and drought may have an important role in physical, biological, and chemical processes within these lakes. With recovery from acidification, DOC quality has also recovered.« less

Physico-chemical Analysis, Microbial Isolation, Sensitivity Test of the Isolates and Solar Disinfection of Water Running in Community Taps and River Kandutura in Nakuru North Sub-county, Kenya

PubMed Central

Waithaka, Paul N; Maingi, John Muthini; Nyamache, Anthony Kebira

2015-01-01

Nakuru North sub-county is a peri-urban area which has both dry and wet seasons. Its residents rely mostly on untreated water sources for daily water needs due to unreliable water supply from the urban council. However, this water has not been evaluated on its quality despite residents solely depending on it. This study was aimed at determining the physico-chemical and bacteriological quality of water drawn from River Kandutura and water taps in Nakuru North sub-county. In addition, the study was aimed at carrying out sensitivity test of the isolates to antibiotics and determining effectiveness of solar disinfection in water treatment. A total of 510 water samples; river (255) and taps (255) were collected and analyzed between January and December 2013. Antimicrobial sensitivity test was carried out using Kirby Bauer disk diffusion test. Out of five hundred and ten (510) samples examined for microorganisms, 36.86 % (188/510) were positive for E. coli, Shigella and Salmonella. Water used by Nakuru North sub-county residents is highly contaminated thus posing public health risk. Solar disinfection experiment indicated a possibility of effective decontamination of water up on exposure to sun light for 3-5 h. E. coli showed the highest resistance (26.3 %) followed by Salmonella (17.4 %) while Shigella showed the least (17.1 %). However, there was no significant deference (p=0.98) in resistance among total coliforms, Total heterotrophic and Salmonella at 0.05 level of significant. There is a need to enforce laws and policies on proper waste disposal as part of water pollution control. PMID:26464611

The Earth System Documentation (ES-DOC) Software Process

NASA Astrophysics Data System (ADS)

Greenslade, M. A.; Murphy, S.; Treshansky, A.; DeLuca, C.; Guilyardi, E.; Denvil, S.

2013-12-01

Earth System Documentation (ES-DOC) is an international project supplying high-quality tools & services in support of earth system documentation creation, analysis and dissemination. It is nurturing a sustainable standards based documentation eco-system that aims to become an integral part of the next generation of exa-scale dataset archives. ES-DOC leverages open source software, and applies a software development methodology that places end-user narratives at the heart of all it does. ES-DOC has initially focused upon nurturing the Earth System Model (ESM) documentation eco-system and currently supporting the following projects: * Coupled Model Inter-comparison Project Phase 5 (CMIP5); * Dynamical Core Model Inter-comparison Project (DCMIP); * National Climate Predictions and Projections Platforms Quantitative Evaluation of Downscaling Workshop. This talk will demonstrate that ES-DOC implements a relatively mature software development process. Taking a pragmatic Agile process as inspiration, ES-DOC: * Iteratively develops and releases working software; * Captures user requirements via a narrative based approach; * Uses online collaboration tools (e.g. Earth System CoG) to manage progress; * Prototypes applications to validate their feasibility; * Leverages meta-programming techniques where appropriate; * Automates testing whenever sensibly feasible; * Streamlines complex deployments to a single command; * Extensively leverages GitHub and Pivotal Tracker; * Enforces strict separation of the UI from underlying API's; * Conducts code reviews.

Modeling nonlinear responses of DOC transport in boreal catchments in Sweden

NASA Astrophysics Data System (ADS)

Kasurinen, Ville; Alfredsen, Knut; Ojala, Anne; Pumpanen, Jukka; Weyhenmeyer, Gesa A.; Futter, Martyn N.; Laudon, Hjalmar; Berninger, Frank

2016-07-01

Stream water dissolved organic carbon (DOC) concentrations display high spatial and temporal variation in boreal catchments. Understanding and predicting these patterns is a challenge with great implications for water quality projections and carbon balance estimates. Although several biogeochemical models have been used to estimate stream water DOC dynamics, model biases common during both rain and snow melt-driven events. The parsimonious DOC-model, K-DOC, with 10 calibrated parameters, uses a nonlinear discharge and catchment water storage relationship including soil temperature dependencies of DOC release and consumption. K-DOC was used to estimate the stream water DOC concentrations over 5 years for eighteen nested boreal catchments having total area of 68 km2 (varying from 0.04 to 67.9 km2). The model successfully simulated DOC concentrations during base flow conditions, as well as, hydrological events in catchments dominated by organic and mineral soils reaching NSEs from 0.46 to 0.76. Our semimechanistic model was parsimonious enough to have all parameters estimated using statistical methods. We did not find any clear differences between forest and mire-dominated catchments that could be explained by soil type or tree species composition. However, parameters controlling slow release and consumption of DOC from soil water behaved differently for small headwater catchments (less than 2 km2) than for those that integrate larger areas of different ecosystem types (10-68 km2). Our results emphasize that it is important to account for nonlinear dependencies of both, soil temperature, and catchment water storage, when simulating DOC dynamics of boreal catchments.

Google Docs in an Out-of-Class Collaborative Writing Activity

ERIC Educational Resources Information Center

Zhou, Wenyi; Simpson, Elizabeth; Domizi, Denise Pinette

2012-01-01

Google Docs, an online word processing application, is a promising tool for collaborative learning. However, many college instructors and students lack knowledge to effectively use Google Docs to enhance teaching and learning. Goals of this study include (1) assessing the effectiveness of using Google Docs in an out-of-class collaborative writing…

Sensitivity to disinfection of bacterial indicator organisms for monitoring the Salmonella Enteritidis status of layer farms after cleaning and disinfection.

PubMed

Dewaele, I; Ducatelle, R; Herman, L; Heyndrickx, M; De Reu, K

2011-06-01

The present study evaluated Escherichia coli, Enterococcus faecalis, and Enterococcus hirae as potential indicator organisms for the possible Salmonella Enteritidis (SE) presence in layer farms after cleaning and disinfection by comparing their susceptibility to disinfection. A quantitative suspension disinfection test according to European Standard EN1656 was performed using disinfection products CID20 and Virocid (both from CID Lines, Ieper, Belgium). In a preliminary test, the sensitivity to both disinfection products was compared between ATCC strains of SE, E. coli, En. faecalis, and En. hirae. The sensitivity of SE to disinfection was most comparable to that of E. coli. A second disinfection test compared the elimination of E. coli to SE ATCC strains as well as field strains. Results showed no significant effect regarding the strain (P > 0.05 for CID20 and Virocid), meaning that no difference was detected in sensitivity toward disinfection. When comparing the sensitivity in general at species level for all concentrations of disinfectant used, no significant difference was found between E. coli and SE in sensitivity to Virocid (P > 0.05). In conclusion, because of its similar response to disinfection in a suspension disinfection test, E. coli could be used as an indicator for possible Salmonella presence after cleaning and disinfection.

Removal of terrestrial DOC in aquatic ecosystems of a temperate river network

USGS Publications Warehouse

Wollheim, W.M.; Stewart, R. J.; Aiken, George R.; Butler, Kenna D.; Morse, Nathaniel B.; Salisbury, J.

2015-01-01

Surface waters play a potentially important role in the global carbon balance. Dissolved organic carbon (DOC) fluxes are a major transfer of terrestrial carbon to river systems, and the fate of DOC in aquatic systems is poorly constrained. We used a unique combination of spatially distributed sampling of three DOC fractions throughout a river network and modeling to quantify the net removal of terrestrial DOC during a summer base flow period. We found that aquatic reactivity of terrestrial DOC leading to net loss is low, closer to conservative chloride than to reactive nitrogen. Net removal occurred mainly from the hydrophobic organic acid fraction, while hydrophilic and transphilic acids showed no net change, indicating that partitioning of bulk DOC into different fractions is critical for understanding terrestrial DOC removal. These findings suggest that river systems may have only a modest ability to alter the amounts of terrestrial DOC delivered to coastal zones.

DISINFECTION BY-PRODUCT FORMATION BY ALTERNATIVE DISINFECTANTS AND REMOVAL BY GRANULAR ACTIVATED CARBON

EPA Science Inventory

The effects of the use of the alternative disinfectants on the formation of halogenated disinfection by–products (DBPs) including total organic halide, trihalomethanes, haloacetic acids, haloacetonitriles, haloketones, chloral hydrate, and chloropicrin, were examined along ...

Assessing the relative bioavailability of DOC in regional groundwater systems

USGS Publications Warehouse

Chapelle, Francis H.; Bradley, Paul M.; Journey, Celeste A.; McMahon, Peter B.

2013-01-01

It has been hypothesized that the degree to which a hyperbolic relationship exists between concentrations of dissolved organic carbon (DOC) and dissolved oxygen (DO) in groundwater may indicate the relative bioavailability of DOC. This hypothesis was examined for 73 different regional aquifers of the United States using 7745 analyses of groundwater compiled by the National Water Assessment (NAWQA) program of the U.S. Geological Survey. The relative reaction quotient (RRQ), a measure of the curvature of DOC concentrations plotted versus DO concentrations and regressed to a decaying hyperbolic equation, was used to assess the relative bioavailability of DOC. For the basalt aquifer of Oahu, Hawaii, RRQ values were low (0.0013 mM−2), reflecting a nearly random relationship between DOC and DO concentrations. In contrast, on the island of Maui, treated sewage effluent injected into a portion of the basalt aquifer resulted in pronounced hyperbolic DOC-DO behavior and a higher RRQ (142 mM−2). RRQ values for the 73 aquifers correlated positively with mean concentrations of ammonia, dissolved iron, and manganese, and correlated negatively with mean pH. This indicates that greater RRQ values are associated with greater concentrations of the final products of microbial reduction reactions. RRQ values and DOC concentrations were negatively correlated with the thickness of the unsaturated zone (UNST) and depth to the top of the screened interval. Finally, RRQ values were positively correlated with mean annual precipitation (MAP), and the highest observed RRQ values were associated with aquifers receiving MAP rates ranging between 900 and 1300 mm/year. These results are uniformly consistent with the hypothesis that the hyperbolic behavior of DOC-DO plots, as quantified by the RRQ metric, can be an indicator of relative DOC bioavailability in groundwater systems.

DISINFECTION BY-PRODUCT FORMATION BY ALTERNATIVE DISINFECTANTS AND REMOVAL BY GRANULAR ACTIVATED CARBON

EPA Science Inventory

The effects of the use of the alternative disinfectants on the formation of halogenated disinfection by-products (DBPS) including total organic halide, trihalomethanes, haloacetic acids, haloacentonitriles, haloketones, chloral hydrate, and chloropicrin, were examined along with ...

[Disinfecting contact tonometers - a systematic review].

PubMed

Neubauer, A S; Heeg, P; Kampik, A; Hirneiss, C

2009-05-01

The aim of this study is to provide the best available evidence on how to disinfect contact Goldman tonometers. A systematic review of all articles on disinfection of contact tonometers was conducted. Articles published up to July 2008 were identified in Medline, Embase and references from included articles. Two observers participated in the data retrieval and assessment of the studies identified. A total of 89 articles was retrieved, of which 58 could be included. Of those, 18 were clinical studies, 17 experimental microbiological studies, 8 expert assessments or guidelines and 15 reviews, surveys, descriptions of new methods. The clinical studies illustrate the importance of the problem, possible side effects of some disinfection methods but yield inconclusive results regarding efficacy. Experimental studies investigated a variety of bacterial and virological questions as well as material damage by disinfection. Both chlorine-based and hydrogen peroxide-based liquid disinfection were shown to be effective if applied for 5 min. Inconsistent results exist for alcohol wipes and UV disinfection - material damage has been described for both. The US guidelines and most expert recommendations are supported by evidence of the existing data. Chlorine-based and hydrogen peroxide-based liquid disinfections for 5 minutes are effective and relatively safe for disinfecting contact tonometers.

Dynamics, chemical properties and bioavailability of DOC in an early successional catchment

NASA Astrophysics Data System (ADS)

Risse-Buhl, U.; Hagedorn, F.; Dümig, A.; Gessner, M. O.; Schaaf, W.; Nii-Annang, S.; Gerull, L.; Mutz, M.

2013-07-01

The dynamics of dissolved organic carbon (DOC) have been intensively studied in mature ecosystems, but little is known about DOC dynamics and the significance of DOC as a substrate for microbial activity in early-successional catchments. We determined the concentration, chemical composition, source, radiocarbon age, and bioavailability of DOC along the hydrological flow path from soil solution to a downstream pond in a recently constructed catchment (Chicken Creek Catchment, Germany). Soil solution, upwelling ground water, stream water, subsurface water in an alluvial fan, and pond water all had high DOC concentrations (averages: 6.0-11.6 mg DOC L-1), despite small carbon stocks in both vegetation and soil of the catchment. Solid-state CPMAS 13C NMR of DOC in upwelling ground water revealed a higher proportion of aromatic compounds (32%) and a lower proportion of carbohydrates (33%) than in pond water (18% and 45%, respectively). The average 14C age of DOC in upwelling ground water was 2600 to 2900 yr, while organic matter of the Quaternary substrate of the catchment had a 14C age of 3000 to 16 000 yr. Both the 14C age data and 13C NMR spectra suggest that DOC partly derived from organic matter of the Quaternary substrate (about 40 to 90% of the C in the DOC), indicating that both recent and old C of the DOC can support microbial activity during early ecosystem succession. However, in a 70 day incubation experiment, only about 11% of the total DOC was found to be bioavailable. This proportion was irrespective of the water type. Origin of the microbial communities within the catchment (enriched from soil, stream sediment or pond water) also had only a marginal effect on overall DOC utilization.

Drivers of inverse DOC-nitrate loss patterns in forest soils and streams

NASA Astrophysics Data System (ADS)

Goodale, C. L.

2013-12-01

Nitrate loss from forested catchments varies greatly across sites and over time, with few reliable correlates. One of the few recurring patterns, however, is the negative nonlinear relationship that occurs regularly between surface water nitrate and dissolved organic carbon (DOC) concentrations: that is, nitrate declines sharply as DOC concentrations increase, and high nitrate levels occur only at low DOC concentrations. Several hypotheses have been proposed to explain this pattern, but its cause has remained speculative. It is likely to be driven by C- or N-limitation of biological processes such as assimilation or denitrification, but the identity of which biological process or the main landscape position of their activity are not known. We examined whether DOC and nitrate are both driven by soil C content, at scales of both soil blocks and across catchments, by measuring soil, soil extract, and surface water chemistry across nine catchments selected from long-term monitoring networks in the Catskill and Adirondack Mountains. We measured soil C and N status and solution nitrate, DOC, bioavailable DOC (bDOC), and isotopic composition (13C-DOC, 15N- and 18O-NO3) to examine whether variation in stocks of soil C partly controls DOC and nitrate loss from forested catchments in New York State. These measurements showed that surface soil C and C:N ratio together determine soil production of DOC and nitrate, reflecting assimilative demand for N by heterotrophic microbes. Yet, they also show that these processes do not produce the inverse DOC-NO3 curve observed at the catchment scale. Rather, catchment-scale DOC-nitrate patterns are more likely to be governed by the balance between excess nitrate production and its bDOC-mediated loss to denitrification.

Electrochemical alternatives for drinking water disinfection.

PubMed

Martínez-Huitle, Carlos A; Brillas, Enric

2008-01-01

Chlorination is the most common method worldwide for the disinfection of drinking water. However, the identification of potentially toxic products from this method has encouraged the development of alternative disinfection technologies. Among them, electrochemical disinfection has emerged as one of the more feasible alternatives to chlorination. This article reviews electrochemical systems that can contribute to drinking water disinfection and underscores the efficiency of recently developed diamond films in chlorine-free electrochemical systems.

9 CFR 96.9 - Casings admitted on disinfection; sealing; transfer and disinfection.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Casings admitted on disinfection; sealing; transfer and disinfection. 96.9 Section 96.9 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EXPORTATION AND IMPORTATION OF ANIMALS (INCLUDING POULTRY) AND...

9 CFR 96.9 - Casings admitted on disinfection; sealing; transfer and disinfection.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Casings admitted on disinfection; sealing; transfer and disinfection. 96.9 Section 96.9 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EXPORTATION AND IMPORTATION OF ANIMALS (INCLUDING POULTRY) AND...

Disinfectants used for environmental disinfection and new room decontamination technology.

PubMed

Rutala, William A; Weber, David J

2013-05-01

Environmental contamination plays an important role in the transmission of several key health care-associated pathogens. Effective and thorough cleaning/disinfecting of the patient environment is essential. Room decontamination units (such as ultraviolet-C and hydrogen peroxide systems) aid in reducing environmental contamination after terminal room cleaning and disinfection. Copyright © 2013 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Dynamics, chemical properties and bioavailability of DOC in an early successional catchment

NASA Astrophysics Data System (ADS)

Risse-Buhl, U.; Hagedorn, F.; Dümig, A.; Gessner, M. O.; Schaaf, W.; Nii-Annang, S.; Gerull, L.; Mutz, M.

2013-01-01

The dynamics of dissolved organic carbon (DOC) have been intensively studied in mature ecosystems, but little is known about DOC dynamics and the significance of DOC as a substrate for microbial activity in early-successional catchments. We determined the concentration, chemical composition, source, radiocarbon age, and bioavailability of DOC along the hydrological flow path from soil solution to a downstream pond in a recently constructed catchment (Chicken Creek Catchment, Germany). Soil solution, upwelling ground water, subsurface water in an alluvial fan, and pond water all had high DOC concentrations (averages of 6.0-11.6 mg DOC L-1), despite small carbon stocks in either vegetation or soil of the early-successional catchment. The mean 14C age of DOC in upwelling ground water was 2600 to 2800 yr. Solid-state CPMAS 13C NMR revealed a higher proportion of aromatic compounds (32%) and a lower proportion of carbohydrates (33%) in upwelling ground water than in pond water (18% and 45%, respectively). The 14C age and 13C NMR spectra suggest that DOC was partly mobilized from charred organic matter of the Quaternary substrate. In an experimental 70-days incubation experiment, 20% of the total DOC was found to be bioavailable, irrespective of the water type. Origin of microbial communities (enriched from soil, stream sediment or pond water) had only marginal effects on overall DOC utilization. Overall, these data suggest that the old DOC can support microbial activity during early ecosystem succession to some extent, although the largest fraction is recalcitrant DOC that is exported from the catchment once it has been mobilized.

Improving stethoscope disinfection at a children's hospital.

PubMed

Zaghi, Justin; Zhou, Jing; Graham, Dionne A; Potter-Bynoe, Gail; Sandora, Thomas J

2013-11-01

Stethoscopes are contaminated with pathogenic bacteria and pose a risk for transmission of infections, but few clinicians disinfect their stethoscope after every use. We sought to improve stethoscope disinfection rates among pediatric healthcare providers by providing access to disinfection materials and visual reminders to disinfect stethoscopes. Prospective intervention study. Inpatient units and emergency department of a major pediatric hospital. Physicians and nurses with high anticipated stethoscope use. Baskets filled with alcohol prep pads and a sticker reminding providers to regularly disinfect stethoscopes were installed outside of patient rooms. Healthcare providers' stethoscope disinfection behaviors were directly observed before and after the intervention. Multivariable logistic regression models were created to identify independent predictors of stethoscope disinfection. Two hundred twenty-six observations were made in the preintervention period and 261 in the postintervention period (83% were of physicians). Stethoscope disinfection compliance increased significantly from a baseline of 34% to 59% postintervention (P < .001). In adjusted analyses, the postintervention period was associated with improved disinfection among both physicians (odds ratio [OR], 2.3 [95% confidence interval (CI), 1.4-3.5]) and nurses (OR, 14.3 [95% CI, 4.6-44.6]). Additional factors independently associated with disinfection included subspecialty unit (vs general pediatrics; OR, 0.5 [95% CI, 0.3-0.8]) and contact precautions (OR, 2.3 [95% CI, 1.2-4.1]). Providing stethoscope disinfection supplies and visible reminders outside of patient rooms significantly increased stethoscope disinfection rates among physicians and nurses at a children's hospital. This simple intervention could be replicated at other healthcare facilities. Future research should assess the impact on patient infections.

UV disinfection in drinking water supplies.

PubMed

Hoyer, O

2000-01-01

UV disinfection has become a practical and safely validatable disinfection procedure by specifying the requirements for testing and monitoring in DVGW standard W 294. A standardized biodosimetric testing procedure and monitoring with standardized UV sensors is introduced and successfully applied. On-line monitoring of irradiance can be counterchecked with handheld reference sensors and makes it possible that UV systems can be used for drinking water disinfection with the same level of confidence and safety as is conventional chemical disinfection.

The Earth System Documentation (ES-DOC) project

NASA Astrophysics Data System (ADS)

Murphy, S.; Greenslade, M. A.; Treshansky, A.; DeLuca, C.; Guilyardi, E.; Denvil, S.

2013-12-01

Earth System Documentation (ES-DOC) is an international project supplying high quality tools and services in support of Earth system documentation creation, analysis and dissemination. It is nurturing a sustainable standards based documentation ecosystem that aims to become an integral part of the next generation of exa-scale dataset archives. ES-DOC leverages open source software, and applies a software development methodology that places end-user narratives at the heart of all it does. ES-DOC has initially focused upon nurturing the Earth System Model (ESM) documentation eco-system. Within this context ES-DOC leverages the emerging Common Information Model (CIM) metadata standard, which has supported the following projects: ** Coupled Model Inter-comparison Project Phase 5 (CMIP5); ** Dynamical Core Model Inter-comparison Project (DCMIP-2012); ** National Climate Predictions and Projections Platforms (NCPP) Quantitative Evaluation of Downscaling Workshop (QED-2013). This presentation will introduce the project to a wider audience and will demonstrate the current production level capabilities of the eco-system: ** An ESM documentation Viewer embeddable into any website; ** An ESM Questionnaire configurable on a project by project basis; ** An ESM comparison tool reusable across projects; ** An ESM visualization tool reusable across projects; ** A search engine for speedily accessing published documentation; ** Libraries for streamlining document creation, validation and publishing pipelines.

Decontamination formulations for disinfection and sterilization

DOEpatents

Tucker, Mark D.; Engler, Daniel E.

2007-09-18

Aqueous decontamination formulations that neutralize biological pathogens for disinfection and sterilization applications. Examples of suitable applications include disinfection of food processing equipment, disinfection of areas containing livestock, mold remediation, sterilization of medical instruments and direct disinfection of food surfaces, such as beef carcasses. The formulations include at least one reactive compound, bleaching activator, inorganic base, and water. The formulations can be packaged as a two-part kit system, and can have a pH value in the range of 7-8.

Bench-scale evaluation of water disinfection by visible-to-UVC upconversion under high-intensity irradiation.

PubMed

Cates, Ezra L; Kim, Jae-Hong

2015-12-01

The feasibility of applying visible-to-UVC upconversion (UC) luminescence to enhance the kinetics of solar water disinfection was evaluated using Lu7O5F9:Pr(3+) ceramics incorporated into a solar reactor containing E. coli suspensions. Inactivation was assessed in batch conditions using both laser and lens-concentrated sunlight excitation conditions. Under 840-mW argon laser excitation, the UC efficiency was estimated to be 1 order of magnitude greater than previously reported under lamp excitation and UVC emitted by the reactors resulted in 3.6-log inactivation in 20 min. However, experiments using ~1500 mW of concentrated natural sunlight showed no additional inactivation that could be attributed to UC within the timescale studied. Due to the fundamental and practical limitations of solar focusing, the optical concentration ratio employed herein prevented the excitation beam from achieving the power densities required to attain UC efficiencies comparable to the laser experiments. We also observed that the high intensity of both the laser and sunlight induced rapid photoreactivation by the bacteria, which detracted from net disinfection performance. The results suggest that current UC materials perform inadequately for environmental application; nonetheless, valuable qualitative and quantitative insight was gained that more explicitly defines materials development goals and considerations for application of UC to environmental technology. Copyright © 2015 Elsevier B.V. All rights reserved.

ISACS-DOC: Monitoring and Diagnostic System for AKARI and HINODE

NASA Astrophysics Data System (ADS)

Mizutani, Mitsue; Hirose, Toshinori; Takaki, Ryoji; Honda, Hideyuki

ISACS-DOC (Intelligent Satellite Control Software-DOCtor), which is an automatic monitoring and diagnostic system for scientific satellites or spacecraft, aims to rapidly and accurately capture important changes and sign of anomaly during daily satellite operations. After three systems for deep space missions, the new generation of ISACS-DOC with a higher speed processing performance had been developed for the satellites in earth orbit, AKARI and HINODE. This paper reports on the newest ISACS-DOC about enhanced functions, operating status, and an approach to create standards to build and keep up the knowledge data base. Continuous enhancements through the actual operations are the advantage of ISACS-DOC.

Enhanced DOC removal using anion and cation ion exchange resins.

PubMed

Arias-Paic, Miguel; Cawley, Kaelin M; Byg, Steve; Rosario-Ortiz, Fernando L

2016-01-01

Hardness and DOC removal in a single ion exchange unit operation allows for less infrastructure, is advantageous for process operation and depending on the water source, could enhance anion exchange resin removal of dissolved organic carbon (DOC). Simultaneous application of cationic (Plus) and anionic (MIEX) ion exchange resin in a single contact vessel was tested at pilot and bench scales, under multiple regeneration cycles. Hardness removal correlated with theoretical predictions; where measured hardness was between 88 and 98% of the predicted value. Comparing bench scale DOC removal of solely treating water with MIEX compared to Plus and MIEX treated water showed an enhanced DOC removal, where removal was increased from 0.5 to 1.25 mg/L for the simultaneous resin application compared to solely applying MIEX resin. A full scale MIEX treatment plant (14.5 MGD) reduced raw water DOC from 13.7 mg/L to 4.90 mg/L in the treated effluent at a bed volume (BV) treatment rate of 800, where a parallel operation of a simultaneous MIEX and Plus resin pilot (10 gpm) measured effluent DOC concentrations of no greater than 3.4 mg/L, even at bed volumes of treatment 37.5% greater than the full scale plant. MIEX effluent compared to simultaneous Plus and MIEX effluent resulted in differences in fluorescence intensity that correlated to decreases in DOC concentration. The simultaneous treatment of Plus and MIEX resin produced water with predominantly microbial character, indicating the enhanced DOC removal was principally due to increased removal of terrestrially derived organic matter. The addition of Plus resin to a process train with MIEX resin allows for one treatment process to remove both DOC and hardness, where a single brine waste stream can be sent to sewer at a full-scale plant, completely removing lime chemical addition and sludge waste disposal for precipitative softening processes. Published by Elsevier Ltd.

To disinfect or not to disinfect in postharvest research on the fungal decay of apple?

PubMed

Naets, Matthias; van Dael, Mattias; Vanstreels, Els; Daelemans, Dirk; Verboven, Pieter; Nicolaï, Bart; Keulemans, Wannes; Geeraerd, Annemie

2018-02-02

Postharvest losses of fruit and vegetables can reach up to 30%, the main cause being microbial decay. For apple fruit, mostly fungal pathogens, such as Penicillium expansum, Colletotrichum spp., Neofabraea spp. and Botrytis cinerea, are important. As such losses are unsustainable in many ways, it is necessary that research is conducted to prevent them. Generally, for plants and fruit grown under non-sterile field conditions, disinfection is carried out prior to the start of a phytopathological experiment. The motivation for this practice is the removal of background contamination so that it will not affect the experimental outcome and its interpretation. In literature, a plethora of disinfection methods exists, differing in disinfectant, strength and duration. The following two disinfectants are commonly used: sodium hypochlorite (NaOCl) and ethanol. This article presents a targeted investigation into the effects of these two disinfectants on apple fruit surface and physiology. The results clearly demonstrate that both were affected by both disinfectants. NaOCl caused oxidative damage to the apple's wax layer, causing it to crack. Ethanol affected a redistribution of the wax on the fruit surface and altered the wax composition and/or metabolism. Both NaOCl and ethanol treatment resulted in an increased respiration rate. Therefore, apple and possibly other fruit should not be disinfected in phytopathological studies. A negative control, as is typically used, is not solving this issue, as we clearly demonstrate that the living tissue shows metabolic effects following disinfection, and hence the study objects are changed, hampering a clear interpretation of the experimental outcomes. Moreover, fungal inoculation during experiments is typically taking place at rather large levels in wounded tissue (as infection success is the exception), outnumbering the variable levels of background population, if present. Copyright © 2017 Elsevier B.V. All rights reserved.

Engineered biofiltration for the removal of disinfection by-product precursors and genotoxicity.

PubMed

McKie, Michael J; Taylor-Edmonds, Liz; Andrews, Susan A; Andrews, Robert C

2015-09-15

Disinfection by-products (DBPs) are formed when naturally occurring organic matter reacts with chlorine used in drinking water treatment, and DBPs formed in chlorinated drinking water samples have been shown to cause a genotoxic response. The objective of the current study was to further understand the principles of biofiltration and the resulting impacts on the formation of DBPs and genotoxicity. Pilot-scale systems were utilized to assess the performance of engineered biofilters enhanced with hydrogen peroxide, in-line coagulants, and nutrients when compared to passively operated biofilters and conventional treatment (coagulation, flocculation, sedimentation, non-biological filtration). Organic fractionation was completed using liquid chromatography-organic carbon detection (LC-OCD). Water samples were chlorinated after collection and examined for the removal of trihalomethane (THM), haloacetic acid (HAA), and adsorbable organic halide (AOX) precursors. Additionally, the formation potential of two halogenated furanones, 3-chloro-4(dichloromethyl)-2(5H)-furanone (MX) and mucochloric acid (MCA), and genotoxicity was determined. Biofiltration was shown to preferentially remove more DBP precursors than dissolved organic carbon (DOC). Formation potential of the unregulated DBPs, including MX and MCA, and genotoxic response was shown to be correlated to THM formation. These results infer that monitoring for THMs and HAAs provide insight to the formation of more mutagenic DBPs such as halogenated furanones, and that biofiltration may preferentially remove precursors to DBPs at a rate exceeding the removal of DOC. Copyright © 2015 Elsevier Ltd. All rights reserved.

Insights and issues with simulating terrestrial DOC loading of Arctic river networks

USGS Publications Warehouse

Kicklighter, David W.; Hayes, Daniel J.; McClelland, James W.; Peterson, Bruce J.; McGuire, A. David; Melillo, Jerry M.

2013-01-01

Terrestrial carbon dynamics influence the contribution of dissolved organic carbon (DOC) to river networks in addition to hydrology. In this study, we use a biogeochemical process model to simulate the lateral transfer of DOC from land to the Arctic Ocean via riverine transport. We estimate that, over the 20th century, the pan-Arctic watershed has contributed, on average, 32 Tg C/yr of DOC to river networks emptying into the Arctic Ocean with most of the DOC coming from the extensive area of boreal deciduous needle-leaved forests and forested wetlands in Eurasian watersheds. We also estimate that the rate of terrestrial DOC loading has been increasing by 0.037 Tg C/yr2 over the 20th century primarily as a result of climate-induced increases in water yield. These increases have been offset by decreases in terrestrial DOC loading caused by wildfires. Other environmental factors (CO2 fertilization, ozone pollution, atmospheric nitrogen deposition, timber harvest, agriculture) are estimated to have relatively small effects on terrestrial DOC loading to Arctic rivers. The effects of the various environmental factors on terrestrial carbon dynamics have both offset and enhanced concurrent effects on hydrology to influence terrestrial DOC loading and may be changing the relative importance of terrestrial carbon dynamics on this carbon flux. Improvements in simulating terrestrial DOC loading to pan-Arctic rivers in the future will require better information on the production and consumption of DOC within the soil profile, the transfer of DOC from land to headwater streams, the spatial distribution of precipitation and its temporal trends, carbon dynamics of larch-dominated ecosystems in eastern Siberia, and the role of industrial organic effluents on carbon budgets of rivers in western Russia.

Modelling impacts of temperature, and acidifying and eutrophying deposition on DOC trends

NASA Astrophysics Data System (ADS)

Sawicka, Kasia; Rowe, Ed; Evans, Chris; Monteith, Don; Vanguelova, Elena; Wade, Andrew; Clark, Joanna

2017-04-01

Surface water dissolved organic carbon (DOC) concentrations in large parts of the northern hemisphere have risen over the past three decades, raising concern about enhanced contributions of carbon to the atmosphere and seas and oceans. The effect of declining acid deposition has been identified as a key control on DOC trends in soil and surface waters, since pH and ionic strength affect sorption and desorption of DOC. However, since DOC is derived mainly from recently-fixed carbon, and organic matter decomposition rates are considered sensitive to temperature, uncertainty persists regarding the extent to the relative importance of different drivers that affect these upward trends. We ran the dynamic model MADOC (Model of Acidity and Soil Organic Carbon) for a range of UK soils (podzols, gleysols and peatland), for which the time-series were available, to consider the likely relative importance of decreased deposition of sulphate and chloride, accumulation of reactive N, and higher temperatures, on DOC production in different soils. Modelled patterns of DOC change generally agreed favourably with measurements collated over 10-20 years, but differed markedly between sites. While the acidifying effect of sulphur deposition appeared to be the predominant control on the observed soil water DOC trends in all the soils considered other than a blanket peat, the model suggested that over the long term, the effects of nitrogen deposition on N-limited soils may have been sufficient to elevate the DOC recovery trajectory significantly. The second most influential cause of rising DOC in the model simulations was N deposition in ecosystems that are N-limited and respond with stimulated plant growth. Although non-marine chloride deposition made some contribution to acidification and recovery, it was not amongst the main drivers of DOC change. Warming had almost no effect on modelled historic DOC trends, but may prove to be a significant driver of DOC in future via its influence

Environmental cleaning and disinfection.

PubMed

Traverse, Michelle; Aceto, Helen

2015-03-01

The guidelines in this article provide veterinarians, veterinary technicians, and veterinary health care workers with an overview of evidence-based recommendations for the best practices associated with environmental cleaning and disinfection of a veterinary clinic that deals with small animals. Hospital-associated infections and the control and prevention programs necessary to alleviate them are addressed from an environmental perspective. Measures of hospital cleaning and disinfection include understanding mechanisms and types of contamination in veterinary settings, recognizing areas of potential concern, addressing appropriate decontamination techniques and selection of disinfectants, the management of potentially contaminated equipment, laundry, and waste management, and environmental surveillance strategies. Copyright © 2015 Elsevier Inc. All rights reserved.

Humidifier disinfectants, unfinished stories

PubMed Central

Choi, Yeyong

2016-01-01

Once released into the air, humidifier disinfectants became tiny nano-size particles, and resulted in chemical bronchoalveolitis. Families had lost their most beloved members, and even some of them became broken. Based on an estimate of two million potential victims who had experienced adverse effects from the use of humidifier disinfectants, we can say that what we have observed was only the tip of the iceberg. Problems of entire airways, as well as other systemic effects, should be examined, as we know these nano-size particles can irritate cell membranes and migrate into systemic circulation. The story of humidifier disinfectant is not finished yet. PMID:26987713

Optimization of fixed titanium dioxide film on PET bottles and visual indicator for water disinfection

NASA Astrophysics Data System (ADS)

Heredia-Munoz, Manuel Antonio

Water is perhaps the most important resource that sustains human life. According to the World Health Organization (WHO), almost two billion people do not have access to the required water that is needed to satisfy their daily needs and one billion do not have access to clean sources of water for consumption, most of them living in isolated and poor areas around the globe. Poor quality water increases the risk of cholera, typhoid fever and dysentery, and other water-borne illness making this problem a real crisis that humankind is facing. Several water disinfection technologies have been proposed as solutions for this problem. Solar water disinfection using TiO2 coated PET bottles was the alternative that is studied in this work. This technology does not only inactivate bacteria but also disintegrates organic chemicals that can be present in water. The objectives of this work address the optimization of the TiO 2 coated PET bottles technologies. The improvement on the bottle coating process, using two coats of 10% W/V of TiO2 in a solution of vinegar and sodium bicarbonate to form the TiO2 film, the use of a different indigo carmine (1.25 X 10-1mg/pill) concentration in the pill indicator of contamination, the increase of the disinfection rate through shaking the bottles, degradation under intermittent UV radiation and the effect of bottle size on photocatalytic water disinfection were among the most important findings. A new mathematical model that describes better photocatalytic water disinfection in TiO2 coated bottles and simulates water disinfection under different working conditions was another important achievement. These results can now be used to design a strategy for disseminating this technology in areas where it is required and, in that way, generate the greatest positive impact on the people needing safe drinking water.

[Genotoxicity of drinking water during chlorine and chloramine disinfection and the influence of disinfection conditions using the umu-test].

PubMed

Liu, Qing; Zhang, Li-Ping; Liu, Wen-Jun; Nie, Xue-Biao; Zhang, Su-Xia; Zhang, Shun

2010-01-01

In this study, the effects of disinfectant dosage, reaction time and the ratio of Cl2 to N of disinfectant on genotoxicity of effluent of ozone-biological activated carbon (O3-BAC) during chlorine or chloramine disinfection were investigated using umu-test. It was found that, the genotoxicity of effluent of O3-BAC before disinfection ranged from 20-70 ng/L, and it increased after disinfection by chlorine or chloramines. With the same reaction time(24 h), genotoxicity after chlorination (40-95 ng/L) was higher than that after chloramination (20-40 ng/L) under same initial dosage. For chlorination, with initial dosage increasing from 0 mg/L to 10 mg/L, genotoxicity increased firstly, and got the maximum value at about 0.5-1 mg/L dosage, then decreased and got the minimum value at about 3-5 mg/L dosage, and finally increased again. For chloramination, genotoxicity didn't change that much. With the dosage of 3 mg/L and reaction time increasing from 0 h to 72 h, no matter for chlorine or chloramines disinfection, genotoxicity of effluent of O3-BAC both increased firstly, and got the maximum value at about 2 h, then decreased and got the minimum value at about 18 h, and finally increased again, and genotoxicity after chlorine disinfection (83-120 ng/L) was higher than that after chloramines disinfection (20-62 ng/L) under same reaction time. Further more, effects of the different ratios of Cl2 to N of disinfectant on genotoxicity of effluent of O3-BAC were also studied. Results of this study demonstrate that under test conditions, chloramine disinfection is safer than chlorine disinfection in the aspect of genotoxicity for drinking water, and the changes of genotoxicity are different from those of total HAAs.

Comparing irradiation parameters on disinfecting enterrecoccus faecalis in root canal disinfection

NASA Astrophysics Data System (ADS)

Sarp, Ayşe. S.; Gülsoy, Murat

2016-02-01

Although conventional method carries all the debris, studies on persisting infections in root canals show bacteria and their toxins spread from the root canal and contaminate the apical region. Thus developes apical periodontitis or symptoms, and loss of tooth. Even if the treatment has adequate success, anatomy of root canal system can be very complexwith accessory canals. The disinfecting effect of laser radiation has only recently been used in dentistry. Laser irradiation has a bactericidal effect. Each wavelength has its own advantages and limitations according to their different absorption characteristics, depending on their 'absorption coefficient'. The sterilizing efficiency of two types of wavelengths, a new fiber laser 1940- nm Thulium fiber Laser and an 2940 nm Er:YAG Laser were compared in this study. Irradiation with a power of 0.50 W with 1940- nm Thulium fiber Laser disinfected 95,15% of bacteria, however irradiation with same laser power with Er:YAG Laser caused a reduction of 96,48 %. But there was no significant difference in the disinfection effect of two different laser groups ( p < 0.05, Mann- U-Whitney Test). In addition to this, Er :YAG Laser caused three times more reduction from its own positive control group where 1940- nm Thulium fiber Laser caused 2,5 times effective disinfection.

The mechanics of endoscope disinfection.

PubMed

Babb, J R; Bradley, C R

1991-06-01

The decontamination of flexible fibreoptic endoscopes has considerably improved in recent years. This is mainly due to the introduction of instruments with more accessible channels, the use of automated washer disinfectors and a greater awareness of the problems associated with disinfection. Unfortunately the most widely used and effective disinfectant is 2% glutaraldehyde and this is toxic, irritant and sensitizing. With the implementation of Control of Substances Hazardous to Health legislation, strict environmental controls are required to reduce skin contact and vapour inhalation. Alcohol is probably the most suitable alternative disinfectant at present but it is flammable and cannot be used in automated systems. Other agents are either insufficiently effective or corrosive. Autoclavable or heat tolerant rigid endoscopes are now available but flexible endoscopes will not tolerate heat disinfection temperatures.

Predictors of stethoscope disinfection among pediatric health care providers.

PubMed

Muniz, Jeanette; Sethi, Rosh K V; Zaghi, Justin; Ziniel, Sonja I; Sandora, Thomas J

2012-12-01

Stethoscopes are contaminated with bacteria, but predictors of stethoscope disinfection frequency are unknown. We sought to describe health care provider stethoscope disinfection attitudes and practices and determine predictors of frequent disinfection. We used an anonymous online survey of nurses, nurse practitioners, and physicians at a pediatric hospital. We assessed frequency and methods of disinfection, perceptions of contamination, and barriers to disinfection. Multivariate logistic regression models were used to identify independent predictors of disinfecting after every use. One thousand four hundred one respondents completed the survey: 76% believed that infection transmission occurs via stethoscopes, but only 24% reported disinfecting after every use. In multivariate analyses, belief that infection transmission occurs via stethoscopes significantly increased the odds of disinfection after every use (odds ratio [OR], 2.06 [95% confidence interval (CI): 1.38-3.06]). The odds of disinfection after every use were significantly decreased in those who perceived the following barriers: lack of time (OR, 0.31 [95% CI: 0.18-0.54]), lack of access to disinfection material (OR, 0.41 [95% CI: 0.29-0.57]), or lack of visual reminders to disinfect (OR, 0.22 [95% CI: 0.14-0.34]). Only a minority of pediatric health care providers reported disinfecting their stethoscopes after every use. Increasing access to disinfection materials and visual reminders in health care facilities may improve stethoscope disinfection practices. Copyright © 2012 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

Emergency Disinfection of Drinking Water

EPA Pesticide Factsheets

How to boil and disinfect water to kill most disease-causing microorganisms during emergency situations where regular water service has been interrupted and local authorities recommend using only bottled water, boiled water, or disinfected water.

Reliability and Validity of the Dyadic Observed Communication Scale (DOCS).

PubMed

Hadley, Wendy; Stewart, Angela; Hunter, Heather L; Affleck, Katelyn; Donenberg, Geri; Diclemente, Ralph; Brown, Larry K

2013-02-01

We evaluated the reliability and validity of the Dyadic Observed Communication Scale (DOCS) coding scheme, which was developed to capture a range of communication components between parents and adolescents. Adolescents and their caregivers were recruited from mental health facilities for participation in a large, multi-site family-based HIV prevention intervention study. Seventy-one dyads were randomly selected from the larger study sample and coded using the DOCS at baseline. Preliminary validity and reliability of the DOCS was examined using various methods, such as comparing results to self-report measures and examining interrater reliability. Results suggest that the DOCS is a reliable and valid measure of observed communication among parent-adolescent dyads that captures both verbal and nonverbal communication behaviors that are typical intervention targets. The DOCS is a viable coding scheme for use by researchers and clinicians examining parent-adolescent communication. Coders can be trained to reliably capture individual and dyadic components of communication for parents and adolescents and this complex information can be obtained relatively quickly.

[Experiments for physiologic improvement of disinfectants].

PubMed

Beyer, C; Wozniak, K D; Höhne, K; Laub, R

1990-11-01

The use of customary trade disinfectants lead to occupational disease no. 80 in many employers of public health. For that reason our aim is to improve the skin compatibility of this disinfectants. Its possible to achieve a pH-shift to a more physiological level eighter by buffer salt addition or by neutralization. Following this, disinfectants were investigated in a microbiological test.

The Relationship Between DOC Partition Coefficient and Mineral Soil C:N Ratio

NASA Astrophysics Data System (ADS)

Aitkenhead-Peterson, J. A.; McDowell, W. H.

2001-12-01

Since our recent publication showing that soil C:N predicts DOC flux at local and global scales, an effort has been made to understand mechanisms controlling the relationship between the two variables. We have approached this at multiple scales, using soil batch experiments, soil column experiments, and long-term field manipulations. We present here the results from our batch adsorption experiment. Mineral soils from tropical (wet and moist) and temperate (coniferous and hardwood) forests were used to assess DOC adsorption by the initial mass isotherm approach. We found that the DOC partition co-efficient (m) which represents a soil's tendency to adsorb DOC is strongly and inversely related to mineral soil C:N ratio (R2 = 0.99 n = 10 p < 0.001). The intercept of the mass isotherm, or the desorption term, was positively related to mineral soil C:N ratio (R2 = 0.80 n = 10 p < 0.01), but we found that desorption of DOC was more closely correlated with equilibrium DOC concentration (R2 = 0.97 n = 10 p < 0.001) than with mineral soil C:N. The mass isotherm approach is also useful in calculating the reactive soil pool (RSP), the fraction of the soil pool of organic carbon that may be lost to leaching. The RSP was not significantly related to mineral soil C:N, but tropical soils tended to have a larger RSP than temperate soils. Although some of the tropical soils came from areas where the natural forest had been cleared, used for plantations and then abandoned, the relationship between DOC adsorption and mineral soil C:N was not compromised. Watershed soil C:N ratio is an excellent predictor of DOC export because soil C:N is related to physiochemical adsorption processes in mineral soils and biotic production of DOC in organic soil horizons. It appears that soil C:N is a relatively robust predictor of soil solution DOC concentration and surface water DOC export for ecosystems undergoing environmental stress.

A Toxicological Perspective on Disinfection ByProducts

EPA Science Inventory

Disinfection of water is essential for reduction of microbes harmful to human health and chemical disinfection is considered one of the major public health triumphs of the 20th Century. An unintended consequence of disinfection with oxidizing chemicals is formation of disinfectio...

Cleaning and Disinfection of Bacillus cereus Biofilm.

PubMed

Deal, Amanda; Klein, Dan; Lopolito, Paul; Schwarz, John Spencer

2016-01-01

Methodology has been evolving for the testing of disinfectants against bacterial single-species biofilms, as the difficulty of biofilm remediation continues to gain much-needed attention. Bacterial single-species biofilm contamination presents a real risk to good manufacturing practice-regulated industries. However, mixed-species biofilms and biofilms containing bacterial spores remain an even greater challenge for cleaning and disinfection. Among spore-forming microorganisms frequently encountered in pharmaceutical manufacturing areas, the spores of Bacillus cereus are often determined to be the hardest to disinfect and eradicate. One of the reasons for the low degree of susceptibility to disinfection is the ability of these spores to be encapsulated within an exopolysachharide biofilm matrix. In this series of experiments, we evaluated the disinfectant susceptibility of B. cereus biofilms relative to disassociated B. cereus spores and biofilm from a non-spore-forming species. Further, we assessed the impact that pre-cleaning has on increasing that susceptibility. Methodology has been evolving for the testing of disinfectants against bacterial single-species biofilms, as the difficulty of biofilm remediation continues to gain much-needed attention. Bacterial single-species biofilm contamination presents a real risk to good manufacturing practice-regulated industries. However, mixed-species biofilms and biofilms containing bacterial spores remain an even greater challenge for cleaning and disinfection. Among spore-forming microorganisms frequently encountered in pharmaceutical manufacturing areas, the spores of Bacillus cereus are often determined to be the hardest to disinfect and eradicate. One of the reasons for the low degree of susceptibility to disinfection is the ability of these spores to be encapsulated within an exopolysachharide biofilm matrix. In this series of experiments, we evaluated the disinfectant susceptibility of B. cereus biofilms relative to

Seasonal Changes of DOC Composition of Rivers in Temperate Monsoon Climates

NASA Astrophysics Data System (ADS)

Oh, N. H.; Shin, Y.; Lee, E. J.; Hur, J.

2014-12-01

The spatial and seasonal dynamics of dissolved organic carbon (DOC) composition and biodegradability were investigated for the five largest rivers in the Republic of Korea during the years 2012 - 2013 using dark incubation experiments and spectroscopic measurements, including parallel factor analysis (PARAFAC). The DOC concentrations of the rivers in relatively steep and forest-dominated basins were <~2 mg L-1, and remained relatively constant over the seasons. In contrast, those of the rivers influenced by urban and agricultural activities rose up to 5.4 mg L-1, which was decreased to ~2 mg L-1 during the summer monsoon period, indicating that increased precipitation had the effect of dilution. Among the fluorescence components, terrestrial humic-like components were dominant in all the rivers except for one, where tyrosine- or tryptophan-like compounds were the major component. However, terrestrial humic-like components became dominant in all five of the rivers after high precipitation which occurred during the monsoon season, during which ~76% of the annual precipitation was received. Considering that 64% of South Korea is forested, our results suggest that the forests could be a large source of riverine DOC, elevating the DOC loads during monsoon rainfall. Although more DOC could be degraded when DOC input increased, regardless of its sources, the percent biodegradability was reduced with increased proportions of terrestrially derived and aromatic compounds. These results suggest that the relatively stable and terrestrial humic-like compounds released during the monsoon rainfall could reduce the potential of microbial respiration of riverine DOC and evasion of river CO2 to the atmosphere, despite of the increase in the DOC load.

The removal of disinfection by-product precursors from water with ceramic membranes.

PubMed

Harman, B I; Koseoglu, H; Yigit, N O; Sayilgan, E; Beyhan, M; Kitis, M

2010-01-01

The main objective of this work was to investigate the effectiveness of ceramic ultrafiltration (UF) membranes with different pore sizes in removing natural organic matter (NOM) from model solutions and drinking water sources. A lab-scale, cross-flow ceramic membrane test unit was used in all experiments. Two different single-channel tubular ceramic membrane modules were tested with average pore sizes of 4 and 10 nm. The impacts of membrane pore size and pressure on permeate flux and the removals of UV(280 nm) absorbance, specific UV absorbance (SUVA(280 nm)), and dissolved organic carbon (DOC) were determined. Prior to experiments with model solutions and raw waters, clean water flux tests were conducted. UV(280) absorbance reductions ranged between 63 and 83% for all pressures and membranes tested in the raw water. More than 90% of UV(280) absorbance reduction was consistently achieved with both membranes in the model NOM solutions. Such high UV absorbance reductions are advantageous due to the fact that UV absorbing sites of NOM are known to be one of the major precursors to disinfection by-products (DBP) such as trihalomethanes and haloacetic acids. For both UF membranes, the ranges of DOC removals in the raw water and model NOM solutions were 55-73% and 79-91%, respectively. SUVA(280) value of the raw water decreased from 2 to about 1.5 L/mg-m by both membranes. For the model solutions, SUVA(280) values were consistently reduced to < or =1 L/mg-m levels after membrane treatment. As the SUVA(280) value of the NOM source increased, the extent of SUVA(280) reduction and DOC removal by the tested ceramic UF membranes also increased. The results overall indicated that ceramic UF membranes, especially the one with 4 nm average pore size, appear to be effective in removing organic matter and DBP precursors from drinking water sources with relatively high and sustainable permeate flux values.

Quantifying tropical peatland dissolved organic carbon (DOC) using UV-visible spectroscopy.

PubMed

Cook, Sarah; Peacock, Mike; Evans, Chris D; Page, Susan E; Whelan, Mick J; Gauci, Vincent; Kho, Lip Khoon

2017-05-15

UV-visible spectroscopy has been shown to be a useful technique for determining dissolved organic carbon (DOC) concentrations. However, at present we are unaware of any studies in the literature that have investigated the suitability of this approach for tropical DOC water samples from any tropical peatlands, although some work has been performed in other tropical environments. We used water samples from two oil palm estates in Sarawak, Malaysia to: i) investigate the suitability of both single and two-wavelength proxies for tropical DOC determination; ii) develop a calibration dataset and set of parameters to calculate DOC concentrations indirectly; iii) provide tropical researchers with guidance on the best spectrophotometric approaches to use in future analyses of DOC. Both single and two-wavelength model approaches performed well with no one model significantly outperforming the other. The predictive ability of the models suggests that UV-visible spectroscopy is both a viable and low cost method for rapidly analyzing DOC in water samples immediately post-collection, which can be important when working at remote field sites with access to only basic laboratory facilities. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Re-evaluation of colorimetric Cl- data from natural waters with DOC

USGS Publications Warehouse

Norton, S.A.; Handlet, M.J.; Kahl, J.S.; Peters, N.E.

1996-01-01

Colorimetric Cl- data from natural solutions that contain dissolved organic carbon (DOC) may be biased high. We evaluated aquatic Cl- concentrations in ecosystem compartments at the Bear Brook Watershed, Maine, and from lakes in Maine, using ion chromatography and colorimetry. DOC imparts a positive interference on colorimetric Cl- results proportional to DOC concentrations at approximately 0.8 ??eq Cl-/L per mg DOC/L. The interference is not a function of Cl- concentration. The resulting bias in concentrations of Cl- may be 50% or more of typical environmental values for Cl- in areas remote from atmospheric deposition of marine aerosols. Such biased data in the literature appear to have led to spurious conclusions about recycling of Cl- by forests, the usefulness of Cl- as a conservative tracer in watershed studies, and calculations of elemental budgets, ion balance, charge density of DOC, and dry deposition factors.

Possible monitoring requirements for the disinfectants and disinfection by-products (D/DBP) regulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1993-01-01

The monitoring requirements presented in the report were developed by EPA before a negotiated Disinfectants and Disinfection By-Products (D/DBP) rule was considered. The framework described herein may be substantially changed as a result of the negotiated rulemaking process. The document is useful to consider in developing various monitoring options during the negotiated rulemaking process.

Disinfection of Human Teeth for Educational Purposes.

ERIC Educational Resources Information Center

Tate, William H.; White, Robert S.

1991-01-01

A study investigated the efficacy of glutaraldehyde and several other disinfectants for disinfecting teeth to be used for teaching and research, as an alternative to autoclaving for teeth with amalgam restorations. Results indicate that formalin was the only disinfectant that penetrated tooth pulp chambers in effective antimicrobial…

Formulation of glutaraldehyde disinfectant for alginate impressions.

PubMed

Unemori, M; Matsuya, Y; Matsuya, S; Akashi, A; Mizuno, K; Akamine, A

1999-12-01

The effect of buffer agents incorporated in glutaraldehyde disinfectants on the surface quality of dental models was examined by the measurement of surface roughness, X-ray diffraction analysis and SEM observation. Seven experimental glutaraldehyde disinfectants were prepared using two buffer agents, potassium acetate alone or potassium acetate and sodium hydrogen carbonate in combination. Four kinds of sulfate--zinc, calcium, potassium and magnesium sulfate--were added to these disinfectants in order to accelerate the hydration of calcium sulfate hemihydrate. The impressions treated with the experimental disinfectants for 1 h produced stone surfaces which had significantly lower surface roughness values than those treated with the commercial disinfectants (p < 0.05). The X-ray diffraction analysis and SEM observation showed that these superior surfaces were produced as a result of significant reductions in the amount of residual calcium sulfate hemihydrate. Replacement of buffer agents in commercial glutaraldehyde disinfectants with chemicals such as those studied in the present study will improve the surface quality of dental stone.

Sepsis, parenteral vaccination and skin disinfection.

PubMed

Cook, Ian F

2016-10-02

ASBSTRACT Disinfection should be required for all skin penetrative procedures including parenteral administration of vaccines. This review analyses medically attended infectious events following parenteral vaccination in terms of their microbiological aetiology and pathogenesis. Like 'clean' surgical site infections, the major pathogens responsible for these events were Staphylococcal species, implicating endogenous con-tamination as a significant source of infection. As 70% isopropyl alcohol swabbing has been shown to effectively disinfect the skin, it would be medico-legally difficult to defend a case of sepsis with the omission of skin disinfection unless the very low risk of this event was adequately explained to the patient and documented prior to vaccination. There was a significant cost-benefit for skin disinfection and cellulitis. Skin disinfection in the context of parenteral vaccination represents a new paradigm of medical practice; the use of a low cost intervention to prevent an event of very low prevalence but of significant cost.

Sepsis, parenteral vaccination and skin disinfection

PubMed Central

Cook, Ian F.

2016-01-01

ASBSTRACT Disinfection should be required for all skin penetrative procedures including parenteral administration of vaccines. This review analyses medically attended infectious events following parenteral vaccination in terms of their microbiological aetiology and pathogenesis. Like ‘clean’ surgical site infections, the major pathogens responsible for these events were Staphylococcal species, implicating endogenous con-tamination as a significant source of infection. As 70% isopropyl alcohol swabbing has been shown to effectively disinfect the skin, it would be medico-legally difficult to defend a case of sepsis with the omission of skin disinfection unless the very low risk of this event was adequately explained to the patient and documented prior to vaccination. There was a significant cost-benefit for skin disinfection and cellulitis. Skin disinfection in the context of parenteral vaccination represents a new paradigm of medical practice; the use of a low cost intervention to prevent an event of very low prevalence but of significant cost. PMID:27295449

Differences in influence patterns between groups predicting the adoption of a solar disinfection technology for drinking water in Bolivia.

PubMed

Moser, Stephanie; Mosler, Hans-Joachim

2008-08-01

The lack of safe drinking water is one of the major problems faced by developing countries. The consequences of contaminated water are diseases such as diarrhea, one of the main causes of infant mortality. Because of its simplicity, solar water-disinfection technology provides a good way of treating water at the household level. Despite its obvious advantages and considerable promotional activities, this innovation has had rather a slow uptake. We conducted a field survey in which 644 households in Bolivia were interviewed in order to gain insights on motivations that resulted in adopting the technology. The aim was to examine possible differences in the predictors for adopting this technology during the diffusion process using the theory of innovation diffusion. Our findings indicate that early adoption was predicted by increased involvement in the topic of drinking water and that adoption in the middle of the diffusion process was predicted by increased involvement by opinion leaders and by recognition of a majority who supported the technology. Finally, late adoption was predicted by recognition that a majority had already adopted. Suggestions for future promotional strategies are outlined.

Fingerprinting Dissolved Organic Carbon (DOC) Sources with Specific UV Absorbance (SUVA) and Fluorescence

NASA Astrophysics Data System (ADS)

van Verseveld, W. J.; Lajtha, K.; McDonnell, J. J.

2007-12-01

DOC is an important water quality constituent because it is an important food source for stream biota, it plays a significant role in metal toxicity and transport, and protects aquatic organisms by absorbing visible and UV light. However, sources of stream DOC and changes in DOC quality at storm and seasonal scales remain poorly understood. We characterized DOC concentrations and SUVA (as an indicator of aromaticity) at the plot, hillslope and catchment scale during and between five storm events over the period Fall 2004 until Spring 2005, in WS10, H.J. Andrews, Oregon, USA. This study site has hillslopes that issue directly into the stream. This enabled us to compare a trenched hillslope response to the stream response without the influence of a riparian zone. The main result of this study was that SUVA in addition to DOC was needed to fingerprint sources of DOC. Stream water and lateral subsurface flow showed a clockwise DOC and SUVA hysteresis pattern. Both organic horizon water and transient groundwater were characterized by high DOC concentrations and SUVA values, while DOC concentrations and SUVA values in soil water decreased with depth in the soil profile. This indicates transient groundwater was an important contributor to high DOC concentrations and SUVA values during storm events. During the falling limb of the hydrograph deep soil water and seepage groundwater based on SUVA values contributed significantly to lateral subsurface flow and stream water. Preliminary results showed that fluorescence of stream water and lateral subsurface flow continuously measured with a fluorometer was significantly related to UV-absorbance during a December storm event. Finally, SUVA of lateral subsurface flow was lower than SUVA of stream water at the seasonal scale, indicating a difference in mixing of water sources at the hillslope and catchment scale. Overall, our results show that SUVA and fluorescence are useful tracers for fingerprinting DOC sources.

DISINFECTION

EPA Science Inventory

The primary goal of the disinfection process in drinking water treatment is the inactivation of microbial pathogens. These pathogens comprise a diverse group of organisms which serve as the etiological agents of waterborne disease. Included in this group are bacterial, viral and ...

Sanitizers and Disinfectants Guide. Revised

ERIC Educational Resources Information Center

Healthy Schools Network, Inc., 2012

2012-01-01

Sanitizers and disinfectants can play an important role in protecting public health. They are designed to kill "pests," including infectious germs and other microorganisms such as bacteria, viruses, and fungi. Unfortunately, sanitizers and disinfectants also contain chemicals that are "pesticides." Exposure to persistent toxic…

DISINFECTION BYPRODUCTS: THE NEXT GENERATION

EPA Science Inventory

Disinfection of drinking water is rightly hailed as a major public health triumph of the 20th Century. Before widespread disinfection of drinking water in the U.S. and Europe, millions of people died from infectious waterborne diseases, such as typhoid and cholera. The microbia...

Hospital disinfection: efficacy and safety issues.

PubMed

Dettenkofer, Markus; Block, Colin

2005-08-01

To review recent publications relevant to hospital disinfection (and cleaning) including the reprocessing of medical instruments. The key question as to whether the use of disinfectants on environmental surfaces rather than cleaning with detergents only reduces nosocomial infection rates still awaits conclusive studies. New disinfectants, mainly peroxygen compounds, show good sporicidal properties and will probably replace more problematical substances such as chlorine-releasing agents. The safe reprocessing of medical devices requires a well-coordinated approach, starting with proper cleaning. New methods and substances show promising activity for preventing the transmission of prions. Different aspects of virus inactivation have been studied, and the transmissibility, e.g. of norovirus, shows the need for sound data on how different disinfectant classes perform. Biofilms or other forms of surface-adherent organisms pose an extraordinary challenge to decontamination. Although resistance to biocides is generally not judged to be as critical as antibiotic resistance, scientific data support the need for proper use, i.e. the avoidance of widespread application, especially in low concentrations and in consumer products. Chemical disinfection of heat-sensitive instruments and targeted disinfection of environmental surfaces are established components of hospital infection control. To avoid danger to staff, patients and the environment, prudent use as well as established safety precautions are required. New technologies and products should be evaluated with sound methods. As emerging resistant pathogens will challenge healthcare facilities in the future even more than at present, there is a need for well-designed studies addressing the role of disinfection in hospital infection control.

The role of surface disinfection in infection prevention

PubMed Central

Gebel, Jürgen; Exner, Martin; French, Gary; Chartier, Yves; Christiansen, Bärbel; Gemein, Stefanie; Goroncy-Bermes, Peter; Hartemann, Philippe; Heudorf, Ursel; Kramer, Axel; Maillard, Jean-Yves; Oltmanns, Peter; Rotter, Manfred; Sonntag, Hans-Günther

2013-01-01

Background: The Rudolf Schuelke Foundation addresses topics related to hygiene, infection prevention and public health. In this context a panel of scientists from various European countries discussed “The Role of Surface Disinfection in Infection Prevention”. The most important findings and conclusions of this meeting are summarised in the present consensus paper. Aim: Although the relevance of surface disinfection is increasingly being accepted, there are still a number of issues which remain controversial. In particular, the following topics were addressed: Transferral of microbes from surface to patients as a cause of infection, requirements for surface disinfectants, biocidal resistance and toxicity, future challenges. Methods and findings: After discussion and review of current scientific literature the authors agreed that contaminated surfaces contribute to the transmission of pathogens and may thus pose an infection hazard. Targeted surface disinfection based on a risk profile is seen as an indispensable constituent in a multibarrier approach of universal infection control precautions. Resistance and cross-resistance depend on the disinfectant agent as well as on the microbial species. Prudent implementation of surface disinfection regimens tested to be effective can prevent or minimize adverse effects. Conclusions: Disinfection must be viewed as a holistic process. There is a need for defining standard principles for cleaning and disinfection, for ensuring compliance with these principles by measures such as written standard operating procedures, adequate training and suitable audit systems. Also, test procedures must be set up in order to demonstrate the efficacy of disinfectants including new application methods such as pre-soaked wipes for surface disinfection. PMID:23967396

Proteobacteria become predominant during regrowth after water disinfection.

PubMed

Becerra-Castro, Cristina; Macedo, Gonçalo; Silva, Adrian M T; Manaia, Célia M; Nunes, Olga C

2016-12-15

Disinfection processes aim at reducing the number of viable cells through the generation of damages in different cellular structures and molecules. Since disinfection involves unspecific mechanisms, some microbial populations may be selected due to resilience to treatment and/or to high post-treatment fitness. In this study, the bacterial community composition of secondarily treated urban wastewater and of surface water collected in the intake area of a drinking water treatment plant was compared before and 3-days after disinfection with ultraviolet radiation, ozonation or photocatalytic ozonation. The aim was to assess the dynamics of the bacterial communities during regrowth after disinfection. In all the freshly collected samples, Proteobacteria and Bacteroidetes were the predominant phyla (40-50% and 20-30% of the reads, respectively). Surface water differed from wastewater mainly in the relative abundance of Actinobacteria (17% and <5% of the reads, respectively). After 3-days storage at light and room temperature, disinfected samples presented a shift of Gammaproteobacteria (from 8 to 10% to 33-65% of the reads) and Betaproteobacteria (from 14 to 20% to 31-37% of the reads), irrespective of the type of water and disinfection process used. Genera such as Pseudomonas, Acinetobacter or Rheinheimera presented a selective advantage after water disinfection. These variations were not observed in the non-disinfected controls. Given the ubiquity and genome plasticity of these bacteria, the results obtained suggest that disinfection processes may have implications on the microbiological quality of the disinfected water. Copyright © 2016 Elsevier B.V. All rights reserved.

42 CFR 71.42 - Disinfection of imports.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 42 Public Health 1 2011-10-01 2011-10-01 false Disinfection of imports. 71.42 Section 71.42 Public... FOREIGN QUARANTINE Requirements Upon Arrival at U.S. Ports: Sanitary Inspection § 71.42 Disinfection of imports. When the cargo manifest of a carrier lists articles which may require disinfection under the...

42 CFR 71.42 - Disinfection of imports.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 42 Public Health 1 2013-10-01 2013-10-01 false Disinfection of imports. 71.42 Section 71.42 Public... FOREIGN QUARANTINE Requirements Upon Arrival at U.S. Ports: Sanitary Inspection § 71.42 Disinfection of imports. When the cargo manifest of a carrier lists articles which may require disinfection under the...

42 CFR 71.42 - Disinfection of imports.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 42 Public Health 1 2012-10-01 2012-10-01 false Disinfection of imports. 71.42 Section 71.42 Public... FOREIGN QUARANTINE Requirements Upon Arrival at U.S. Ports: Sanitary Inspection § 71.42 Disinfection of imports. When the cargo manifest of a carrier lists articles which may require disinfection under the...

42 CFR 71.42 - Disinfection of imports.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 42 Public Health 1 2014-10-01 2014-10-01 false Disinfection of imports. 71.42 Section 71.42 Public... FOREIGN QUARANTINE Requirements Upon Arrival at U.S. Ports: Sanitary Inspection § 71.42 Disinfection of imports. When the cargo manifest of a carrier lists articles which may require disinfection under the...

42 CFR 71.42 - Disinfection of imports.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 42 Public Health 1 2010-10-01 2010-10-01 false Disinfection of imports. 71.42 Section 71.42 Public... FOREIGN QUARANTINE Requirements Upon Arrival at U.S. Ports: Sanitary Inspection § 71.42 Disinfection of imports. When the cargo manifest of a carrier lists articles which may require disinfection under the...

Modeling rates of DOC degradation using DOM composition and hydroclimatic variables

NASA Astrophysics Data System (ADS)

Moody, C. S.; Worrall, F.

2017-05-01

The fluvial fluxes of dissolved organic carbon (DOC) from peatlands form an important part of that ecosystem's carbon cycle, contributing approximately 35% of the overall peatland carbon budget. The in-stream processes acting on the DOC, such as photodegradation and biodegradation, can lead to DOC loss and thus contribute CO2 to the atmosphere. The aim of this study was to understand what controls the rates of DOC degradation. Water samples from a headwater, peat-covered catchment, were collected over a 23 month period and analyzed for the DOC degradation rate and dissolved organic matter (DOM) composition in the context of hydroclimatic monitoring. Measures of DOM composition included 13C solid-state nuclear magnetic resonance spectroscopy, bomb calorimetry, and elemental analysis. Regression analysis showed that there was a significant role for the composition of the DOM in controlling degradation with degradation rates significantly increasing with the proportion of aldehyde and carboxylic acid functional groups but decreasing with the proportion of N-alkyl functional groups. The highest rates of DOC degradation occurred when aldehyde functionality was at its greatest and this occurred on the recession limb of storm hydrographs. Including this knowledge into models of fluvial carbon fate for an 818 km2 catchment gave an annual average DOC removal rate of 67% and 50% for total organic carbon, slightly lower than previously predicted. The compositional controls suggest that DOM is primarily being used as a ready energy source to the aquatic ecosystem rather than as a nutrient source.

Genotoxicity of the disinfection by-products resulting from peracetic acid- or hypochlorite-disinfected sewage wastewater.

PubMed

Crebelli, R; Conti, L; Monarca, S; Feretti, D; Zerbini, I; Zani, C; Veschetti, E; Cutilli, D; Ottaviani, M

2005-03-01

Wastewater disinfection is routinely carried out to prevent the spread of human pathogens present in wastewater effluents. To this aim, chemical and physical treatments are applied to the effluents before their emission in water bodies. In this study, the influence of two widely used disinfectants, peracetic acid (PAA) and sodium hypochlorite (NaClO), on the formation of mutagenic by-products was investigated. Wastewater samples were collected before and after disinfection, in winter and in summer, at a pilot plant installed in a municipal wastewater-treatment plant. Samples were adsorbed using silica C18 cartridges and the concentrates were tested for mutagenicity in the Salmonella typhimurium reversion test with strains TA98 and TA100. Non-concentrated water samples were tested with two plant genotoxicity assays (the Allium cepa root anaphase aberration test and the Tradescantia/micronucleus test). Mutagenicity assays in bacteria and in Tradescantia showed borderline mutagenicity in some of the wastewater samples, independent of the disinfection procedure applied. Negative results were obtained in the A. cepa anaphase aberration test. These results indicate that, in the conditions applied, wastewater disinfection with PAA and NaClO does not lead to the formation of significant amounts of genotoxic by-products.

Disinfection in the laboratory: theory and practice in disinfection policy in late C19th and early C20th England.

PubMed

Whyte, Rebecca

2015-03-01

This article examines the relationship between theory and practice in nineteenth century English public health disinfection practice. Disinfection undertaken by local authorities and practised on objects, spaces and people became an increasingly common public health practice in the last quarter of the nineteenth century, and was part of a newly developed public health system of 'stamping out' disease as described by Hardy. Despite disinfection's key role in public health policy, it has thus far not received significant investigation or historiographical attending. This article explores the development of disinfection policy at local level, highlighting that despite commentators assumptions that increasingly exacting standards of disinfection required professional oversight rather than that of the 'amateur' public, there was a significant gap between laboratory based knowledge and evidence derived from practical experience. Laboratory conditions could not replicate those found in day-to-day disinfection, and there were myriad debates about how to create a mutually understandable scientific standard for testing. Despite increasing efforts to bring local disinfection in line with new ideas promulgated by central government and disinfection researchers, the mismatches between the two meant that there was greater divergence. This tension lay at the heart of the changes in disinfection theory and practice in the second half of the nineteenth century, and illustrate the complexities of the impact of germ theory on public health policy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Do prevailing XAD extraction methods used to generate extracts from disinfected water adequately link extract toxicology to disinfected water chemistry?

EPA Science Inventory

Motivation: It is common to use XAD resins to extract disinfection byproducts (DBPs) from disinfected water. The resulting extract is used in toxicological assays to study the effects of DBP mixtures and has been considered representative of the original disinfected water. Howeve...

In vitro study on the disinfectability of two split-septum needle-free connection devices using different disinfection procedures

PubMed Central

Engelhart, Steffen; Exner, Martin; Simon, Arne

2015-01-01

This in vitro study investigated the external disinfection of two needle-free connection devices (NFC) using Octeniderm® (spraying and wiping technique) vs. Descoderm® pads (wiping technique). The split-septum membrane of the NFC was contaminated with >105 CFU K. pneumoniae or S. epidermidis. The efficacy of the disinfection at 30 sec. exposure time was controlled by taking a swab sample and by flushing the NFC with sterile 0.9% sodium chloride solution. Disinfection with octenidine dihydrochloride 0.1 g, 1-Propanol 30.0 g, and 2-Propanol 45.0 g in 100 g solution was highly effective (CFU reduction ≥4 log) against both microorganisms, whereas the use of 63.1 g 2-Propanol in 100 ml solution led to residual contamination with S. epidermidis. Our investigation underlines that (i) in clinical practice disinfection of NFCs before use is mandatory, and that (ii) details of disinfection technique are of utmost importance regarding their efficacy. Our investigation revealed no significant differences between both split-septum NFC types. Clinical studies are needed to confirm a possible superiority of disinfectants with long-lasting residual antimicrobial activity. PMID:26693394

7 CFR 301.89-12 - Cleaning, disinfection, and disposal.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 7 Agriculture 5 2013-01-01 2013-01-01 false Cleaning, disinfection, and disposal. 301.89-12... Cleaning, disinfection, and disposal. (a) Mechanized harvesting equipment that has been used to harvest... and, if disinfection is determined to be necessary by an inspector, disinfected in accordance with...

7 CFR 301.89-12 - Cleaning, disinfection, and disposal.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 5 2011-01-01 2011-01-01 false Cleaning, disinfection, and disposal. 301.89-12... Cleaning, disinfection, and disposal. (a) Mechanized harvesting equipment that has been used to harvest... and, if disinfection is determined to be necessary by an inspector, disinfected in accordance with...

7 CFR 301.89-12 - Cleaning, disinfection, and disposal.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 7 Agriculture 5 2012-01-01 2012-01-01 false Cleaning, disinfection, and disposal. 301.89-12... Cleaning, disinfection, and disposal. (a) Mechanized harvesting equipment that has been used to harvest... and, if disinfection is determined to be necessary by an inspector, disinfected in accordance with...

7 CFR 301.89-12 - Cleaning, disinfection, and disposal.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 7 Agriculture 5 2014-01-01 2014-01-01 false Cleaning, disinfection, and disposal. 301.89-12... Cleaning, disinfection, and disposal. (a) Mechanized harvesting equipment that has been used to harvest... and, if disinfection is determined to be necessary by an inspector, disinfected in accordance with...

[DESIDENT CaviCide a new disinfectant].

PubMed

Severa, J; Klaban, V

2009-01-01

The properties of the new disinfection agent DESIDENT CaviCide, such as characteristics, disinfection efficiency, biological degradability and ecotoxicity are described. Also areas and forms of usage this biocidal agent are mentioned.

Disinfection.

ERIC Educational Resources Information Center

Gould, J. P.; Haas, C. N.

1978-01-01

Presents a literature review of wastewater disinfection for 1978. This review covers areas such as: (1) mechanisms of inactivation of negative microorganisms by chlorine and ozone; and (2) the effects of various treatment on over-all water quality. A list of 61 references is also presented. (HM)

DRINKING WATER DISINFECTION BY-PRODUCTS: WHAT IS KNOWN

EPA Science Inventory

Chlorine, ozone, chlorine dioxide, and chloramine are currently the major disinfectants being used to disinfect drinking water. Although the alternative disinfectants (ozone, chlorine dioxide, and chloramine) are increasing in popularity in the United States, chlorine is still us...

9 CFR 53.5 - Disinfection or destruction of materials.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Disinfection or destruction of....5 Disinfection or destruction of materials. (a) In order to prevent the spread of disease, materials... cost of disinfection would exceed the value of the materials or disinfection would be impracticable for...

9 CFR 53.5 - Disinfection or destruction of materials.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Disinfection or destruction of....5 Disinfection or destruction of materials. (a) In order to prevent the spread of disease, materials... cost of disinfection would exceed the value of the materials or disinfection would be impracticable for...

9 CFR 53.5 - Disinfection or destruction of materials.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Disinfection or destruction of....5 Disinfection or destruction of materials. (a) In order to prevent the spread of disease, materials... cost of disinfection would exceed the value of the materials or disinfection would be impracticable for...

9 CFR 53.5 - Disinfection or destruction of materials.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Disinfection or destruction of....5 Disinfection or destruction of materials. (a) In order to prevent the spread of disease, materials... cost of disinfection would exceed the value of the materials or disinfection would be impracticable for...

40 CFR 141.543 - How is the disinfection benchmark calculated?

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 24 2012-07-01 2012-07-01 false How is the disinfection benchmark... Disinfection-Systems Serving Fewer Than 10,000 People Disinfection Benchmark § 141.543 How is the disinfection benchmark calculated? If your system is making a significant change to its disinfection practice, it must...

40 CFR 141.543 - How is the disinfection benchmark calculated?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 23 2014-07-01 2014-07-01 false How is the disinfection benchmark... Disinfection-Systems Serving Fewer Than 10,000 People Disinfection Benchmark § 141.543 How is the disinfection benchmark calculated? If your system is making a significant change to its disinfection practice, it must...

40 CFR 141.543 - How is the disinfection benchmark calculated?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 24 2013-07-01 2013-07-01 false How is the disinfection benchmark... Disinfection-Systems Serving Fewer Than 10,000 People Disinfection Benchmark § 141.543 How is the disinfection benchmark calculated? If your system is making a significant change to its disinfection practice, it must...

40 CFR 141.543 - How is the disinfection benchmark calculated?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 23 2011-07-01 2011-07-01 false How is the disinfection benchmark... Disinfection-Systems Serving Fewer Than 10,000 People Disinfection Benchmark § 141.543 How is the disinfection benchmark calculated? If your system is making a significant change to its disinfection practice, it must...

G-DOC Plus - an integrative bioinformatics platform for precision medicine.

PubMed

Bhuvaneshwar, Krithika; Belouali, Anas; Singh, Varun; Johnson, Robert M; Song, Lei; Alaoui, Adil; Harris, Michael A; Clarke, Robert; Weiner, Louis M; Gusev, Yuriy; Madhavan, Subha

2016-04-30

G-DOC Plus is a data integration and bioinformatics platform that uses cloud computing and other advanced computational tools to handle a variety of biomedical BIG DATA including gene expression arrays, NGS and medical images so that they can be analyzed in the full context of other omics and clinical information. G-DOC Plus currently holds data from over 10,000 patients selected from private and public resources including Gene Expression Omnibus (GEO), The Cancer Genome Atlas (TCGA) and the recently added datasets from REpository for Molecular BRAin Neoplasia DaTa (REMBRANDT), caArray studies of lung and colon cancer, ImmPort and the 1000 genomes data sets. The system allows researchers to explore clinical-omic data one sample at a time, as a cohort of samples; or at the level of population, providing the user with a comprehensive view of the data. G-DOC Plus tools have been leveraged in cancer and non-cancer studies for hypothesis generation and validation; biomarker discovery and multi-omics analysis, to explore somatic mutations and cancer MRI images; as well as for training and graduate education in bioinformatics, data and computational sciences. Several of these use cases are described in this paper to demonstrate its multifaceted usability. G-DOC Plus can be used to support a variety of user groups in multiple domains to enable hypothesis generation for precision medicine research. The long-term vision of G-DOC Plus is to extend this translational bioinformatics platform to stay current with emerging omics technologies and analysis methods to continue supporting novel hypothesis generation, analysis and validation for integrative biomedical research. By integrating several aspects of the disease and exposing various data elements, such as outpatient lab workup, pathology, radiology, current treatments, molecular signatures and expected outcomes over a web interface, G-DOC Plus will continue to strengthen precision medicine research. G-DOC Plus is available

Peracetic Acid as a Green Disinfectant for Combined Sewer ...

EPA Pesticide Factsheets

This cooperative research and development agreement between U.S. EPA, Solvay, MSDGC, and CB&I is evaluating the potential of PAA for disinfection of Muddy Creek CSO wastewater and comparing that with sodium hypochlorite disinfection. This presentation will document the effectiveness of sodium hypochlorite and PAA for the inactivation of E. coli in CSO wastewater using laboratory bench-scale jar tests and Muddy Creek field site studies based on the following items:•Storage, shelf life, and application of the disinfectants.•Effectiveness of the disinfectants in the inactivation of E. coli.•Formation of harmful byproducts by the disinfectants.•Operation and maintenance costs, including the cost of the disinfectant, its storage, application, and neutralizing agent for the disinfectant to maintain the Ohio EPA guideline for residual disinfectant at the discharge point. Like many cities in the USA, Cincinnati, Ohio is attempting to find the best way to meet state and federal requirements concerning combined sewer overflow (CSO) wastewater. The Muddy Creek CSO treatment facility was constructed to provide treatment for CSO Numbers 198 and 216 from the Westwood Trunk sewer. The Metropolitan Sewer District of Greater Cincinnati (MSDGC) is currently using sodium hypochlorite for disinfection in this treatment facility. Because of degradation of hypochlorite during storage and the formation of chlorinated disinfection byproducts (DBPs), MSDGC is evaluating alternat

Photochemical Transformation and Bacterial Utilization of Dissolved Organic Matter and Disinfection Byproduct Precursors from Foliar Litter

NASA Astrophysics Data System (ADS)

Chow, A. T.; Wong, P.; O'Geen, A. T.; Dahlgren, R. A.

2009-12-01

Foliar litter is an important terrestrial source of dissolved organic matter (DOM) in surface water. DOM is a public health concern since it is a precursor of carcinogenic disinfection byproducts (DBPs) during drinking water treatment. Chemical characterization of in-situ water samples for their impact on water treatment may be misleading because DOM characteristics can be altered from their original composition during downstream transport to water treatment plants. In this study, we collected leachate from four fresh litters and decomposed duffs from four dominant vegetation components of California oak woodlands: blue oak (Quercus douglassi), live oak (Quercus wislizenii), foothill pine (Pinus sabiniana), and annual grasses to evaluate their DOM degradability and the reactivity of altered DOM towards DBP formation. Samples were filtered through a sterilized membrane (0.2 micron) and exposed to natural sunlight and Escherichia coli K-12 independently for 14 days. Generally speaking, leachate from decomposed duff was relatively resistant towards biodegradation compared to that from fresh litter, but the former was more susceptible to photo-transformation. Photo-bleaching caused a 30% decrease in ultra-violet absorbance at 254 nm (UVA) but no significant changes in dissolved organic carbon (DOC) concentration. This apparent loss of aromatic carbon in DOM, in terms of specific UVA, did not result in a decrease of specific trihalomethane (THM) formation potential, although aromatic carbon is considered as a major reactive site for THM formation. In addition, there were significant increases (p < 0.05) of chloral hydrate after the 14-day exposure, suggesting that the photolytic products could be a precursor of chloral hydrate. In contrast, samples inoculated with E. coli did not show a significant effect on the DOC concentration, UVA or DBP formation, although the colony counts indicated a 2-log cell growth during the 14-day incubation. Results suggest photolysis is a

MODELING DISINFECTANT RESIDUALS IN DRINKING-WATER STORAGE TANKS

EPA Science Inventory

The factors leading to the loss of disinfectant residual in well-mixed drinking-water storage tanks are studied. Equations relating disinfectant residual to the disinfectant's reation rate, the tank volume, and the fill and drain rates are presented. An analytical solution for ...

40 CFR 141.172 - Disinfection profiling and benchmarking.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection-Systems Serving 10,000 or More People § 141.172 Disinfection profiling and benchmarking. (a... 40 Protection of Environment 22 2010-07-01 2010-07-01 false Disinfection profiling and...

Design and bidding of UV disinfection equipment -- Case study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akyurek, M.

1998-07-01

Ultraviolet (UV) disinfection systems are being widely considered for application to treated wastewaters, in lieu of conventional chlorination facilities. The number of UV systems operating in the US was approximately 50 in 1984. In 1990 there were over 500 systems, a ten-fold increase. The use of UV disinfection has increased since 1990, and will likely to increase in the future. It is anticipated that as many chlorine disinfection facilities reach their useful life, most of them will be replaced with UV disinfection systems. Several manufacturers offer different UV disinfection equipment. Each offers something different for the designer. There are alsomore » different approaches used in estimating the number of lamps needed for the disinfection system. The lack of standardization in determination of the number of lamps for a UV system poses problems for the designer. Such was the case during the design of the disinfection system for the Watertown, SD Wastewater Treatment Plant (WWRP). The purpose of this paper is to present a case study for the design and bidding of UV disinfection equipment.« less

Susceptibility of Vaccinia Virus to Chemical Disinfectants

PubMed Central

de Oliveira, Tércia Moreira Ludolfo; Rehfeld, Izabelle Silva; Coelho Guedes, Maria Isabel Maldonado; Ferreira, Jaqueline Maria Siqueira; Kroon, Erna Geessien; Lobato, Zélia Inês Portela

2011-01-01

Vaccinia virus (VACV) is the cause of bovine vaccinia (BV), an emerging zoonotic disease that affects dairy cows and milkers. Some chemical disinfectants have been used on farms affected by BV to disinfect cow teats and milkers' hands. To date, there is no information about the efficacy of disinfectants against VACV. Therefore, this study aimed to assess the virucidal activity of some active disinfectants commonly used in the field. Sodium hypochlorite, quaternary ammonium combined with chlorhexidine, and quaternary ammonium combined with glutaraldehyde were effective in inactivating the virus at all concentrations tested. Iodine and quaternary ammonium as the only active component were partially effective. The presence of bovine feces as organic matter and light decreased the effectiveness of sodium hypochlorite. These results show that an appropriated disinfection and asepsis of teats and hands may be helpful in the control and prevention of BV and other infections with VACV. PMID:21734141

40 CFR 141.172 - Disinfection profiling and benchmarking.

Code of Federal Regulations, 2011 CFR

2011-07-01

... benchmarking. 141.172 Section 141.172 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Disinfection-Systems Serving 10,000 or More People § 141.172 Disinfection profiling and benchmarking. (a... sanitary surveys conducted by the State. (c) Disinfection benchmarking. (1) Any system required to develop...

Candida auris: Disinfectants and Implications for Infection Control.

PubMed

Ku, Tsun S N; Walraven, Carla J; Lee, Samuel A

2018-01-01

Candida auris is a rapidly emerging pathogen and is able to cause severe infections with high mortality rates. It is frequently misidentified in most clinical laboratories, thus requiring more specialized identification techniques. Furthermore, several clinical isolates have been found to be multidrug resistant and there is evidence of nosocomial transmission in outbreak fashion. Appropriate infection control measures will play a major role in controlling the management and spread of this pathogen. Unfortunately, there are very few data available on the effectiveness of disinfectants against C. auris . Chlorine-based products appear to be the most effective for environmental surface disinfection. Other disinfectants, although less effective than chlorine-based products, may have a role as adjunctive disinfectants. A cleaning protocol will also need to be established as the use of disinfectants alone may not be sufficient for maximal decontamination of patient care areas. Furthermore, there are fewer data on the effectiveness of antiseptics against C. auris for patient decolonization and hand hygiene for healthcare personnel. Chlorhexidine gluconate has shown some efficacy in in vitro studies but there are reports of patients with persistent colonization despite twice daily body washes with this disinfectant. Hand hygiene using soap and water, with or without chlorhexidine gluconate, may require the subsequent use of alcohol-based hand sanitizer for maximal disinfection. Further studies will be needed to validate the currently studied disinfectants for use in real-world settings.

Disinfection aboard cruise liners and naval units: formation of disinfection by-products using chlorine dioxide in different qualities of drinking water.

PubMed

Ufermann, Petra; Petersen, Hauke; Exner, Martin

2011-12-01

The world-wide deployment of cruise liners and naval units has caused an increased need for the disinfection of drinking water. The main cause for this is the unknown quality of drinking water in foreign harbours--besides the formation of bio-films due to the climatically disadvantageous conditions in the operational area. Water conduits on board are currently disinfected with calcium hypochlorite in case of microbiological contamination. Chemical and physical analyses after disinfection with calcium hypochlorite have shown that organic by-products consisting of trihalomethanes develop in considerable amounts during disinfection. Furthermore, the method is susceptible to handling errors and thus often leads to insufficient disinfection results. Hitherto, the use of other disinfection methods allowed by government regulations, especially chlorine dioxide, is not widely spread. Unlike disinfection with calcium hypochlorite, chlorine dioxide does not lead to the formation of trihalomethanes. Typical disinfection by-products (DBP) are the anions chlorite and chlorate, which are formed in oxidative processes. The formation conditions of these anions have not yet been elucidated. For this reason, the probability of the generation of inorganic by-products after disinfection with chlorine dioxide has been determined, and their occurrence in drinking water on board has been examined with respect to a possible correlation between water quality and the formation of chlorate and chlorite. Therefore, a chromatographic method was developed and validated in order to determine the periodical development of chlorate and chlorite from chorine dioxide in purified water at different pH-values as well as in actual drinking water samples from water conduits on board. The formation of the by-products chlorite and chlorate after disinfection with chlorine dioxide is influenced neither by pH-value nor by chemical properties of the disinfected water. Considering the examined conditions

Ultraviolet disinfection of potable water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolfe, R.L.

Because of upcoming surface and groundwater regulations regarding the control of microbiological and chemical contaminants, there is a need to evaluate the feasibility and effectiveness of ultraviolet (UV) radiation for primary disinfection of potable water supplies. Data is presented on microbicidal wavelengths of UV and distribution of energy output for low and medium-pressure arc lamps. Both systems were found to perform equally well for inactivating microorganisms, but each had distinct advantages in different applications. Approximate dosages for 90% inactivation of selected microorganisms by UV is presented in a table. Cost analysis for disinfection is presented in two tables as wellmore » as the advantages and disadvantages of UV disinfection. 38 refs.« less

Proteomic Adaptations to Starvation Prepare Escherichia coli for Disinfection Tolerance

PubMed Central

Du, Zhe; Nandakumar, Renu; Nickerson, Kenneth; Li, Xu

2015-01-01

Despite the low nutrient level and constant presence of secondary disinfectants, bacterial re-growth still occurs in drinking water distribution systems. The molecular mechanisms that starved bacteria use to survive low-level chlorine-based disinfectants are not well understood. The objective of this study is to investigate these molecular mechanisms at the protein level that prepare starved cells for disinfection tolerance. Two commonly used secondary disinfectants chlorine and monochloramine, both at 1 mg/L, were used in this study. The proteomes of normal and starved Escherichia coli (K12 MG1655) cells were studied using quantitative proteomics. Over 60-min disinfection, starved cells showed significantly higher disinfection tolerance than normal cells based on the inactivation curves for both chlorine and monochloramine. Proteomic analyses suggest that starvation may prepare cells for the oxidative stress that chlorine-based disinfection will cause by affecting glutathione metabolism. In addition, proteins involved in stress regulation and stress responses were among the ones up-regulated under both starvation and chlorine/monochloramine disinfection. By comparing the fold changes under different conditions, it is suggested that starvation prepares E. coli for disinfection tolerance by increasing the expression of enzymes that can help cells survive chlorine/monochloramine disinfection. Protein co-expression analyses show that proteins in glycolysis and pentose phosphate pathway that were up-regulated under starvation are also involved in disinfection tolerance. Finally, the production and detoxification of methylglyoxal may be involved in the chlorine-based disinfection and cell defense mechanisms. PMID:25463932

Peracetic acid for secondary effluent disinfection: a comprehensive performance assessment.

PubMed

Antonelli, M; Turolla, A; Mezzanotte, V; Nurizzo, C

2013-01-01

The paper is a review of previous research on secondary effluent disinfection by peracetic acid (PAA) integrated with new data about the effect of a preliminary flash-mixing step. The process was studied at bench and pilot scale to assess its performance for discharge in surface water and agricultural reuse (target microorganisms: Escherichia coli and faecal coliform bacteria). The purposes of the research were: (1) determining PAA decay and disinfection kinetics as a function of operating parameters, (2) evaluating PAA suitability as a disinfectant, (3) assessing long-term disinfection efficiency, (4) investigating disinfected effluent biological toxicity on some aquatic indicator organisms (Vibrio fischeri, Daphnia magna and Selenastrum capricornutum), (5) comparing PAA with conventional disinfectants (sodium hypochlorite, UV irradiation). PAA disinfection was capable of complying with Italian regulations on reuse (10 CFU/100 mL for E. coli) and was competitive with benchmarks. No regrowth phenomena were observed, as long as needed for agricultural reuse (29 h after disinfection), even at negligible concentrations of residual disinfectant. The toxic effect of PAA on the aquatic environment was due to the residual disinfectant in the water, rather than to chemical modification of the effluent.

[Experimental evaluation of the spraying disinfection efficiency on dental models].

PubMed

Zhang, Yi; Fu, Yuan-fei; Xu, Kan

2013-08-01

To evaluate the disinfect effect after spraying a new kind of disinfectant on the dental plaster models. The germ-free plaster samples, which were smeared with bacteria compound including Staphylococcus aureus, Escherichia coli, Saccharomyces albicans, Streptococcus mutans and Actinomyces viscosus were sprayed with disinfectants (CaviCide) and glutaraldehyde individually. In one group(5 minutes later) and another group(15 minutes later), the colonies were counted for statistical analysis after sampling, inoculating, and culturing which were used for evaluation of disinfecting efficiency. ANOVA was performed using SPSS12.0 software package. All sample bacteria were eradicated after spraying disinfectants(CaviCide) within 5 minutes and effective bacteria control was retained after 15 minutes. There was significant difference between the disinfecting efficiency of CaviCide and glutaraldehyde. The effect of disinfection with spraying disinfectants (CaviCide) on dental models is quick and effective.

Recent advances in drinking water disinfection: successes and challenges.

PubMed

Ngwenya, Nonhlanhla; Ncube, Esper J; Parsons, James

2013-01-01

Drinking water is the most important single source of human exposure to gastroenteric diseases, mainly as a result of the ingestion of microbial contaminated water. Waterborne microbial agents that pose a health risk to humans include enteropathogenic bacteria, viruses, and protozoa. Therefore, properly assessing whether these hazardous agents enter drinking water supplies, and if they do, whether they are disinfected adequately, are undoubtedly aspects critical to protecting public health. As new pathogens emerge, monitoring for relevant indicator microorganisms (e.g., process microbial indicators, fecal indicators, and index and model organisms) is crucial to ensuring drinking water safety. Another crucially important step to maintaining public health is implementing Water Safety Plans (WSPs), as is recommended by the current WHO Guidelines for Drinking Water Quality. Good WSPs include creating health-based targets that aim to reduce microbial risks and adverse health effects to which a population is exposed through drinking water. The use of disinfectants to inactivate microbial pathogens in drinking water has played a central role in reducing the incidence of waterborne diseases and is considered to be among the most successful interventions for preserving and promoting public health. Chlorine-based disinfectants are the most commonly used disinfectants and are cheap and easy to use. Free chlorine is an effective disinfectant for bacteria and viruses; however, it is not always effective against C. parvum and G. lamblia. Another limitation of using chlorination is that it produces disinfection by-products (DBPs), which pose potential health risks of their own. Currently, most drinking water regulations aggressively address DBP problems in public water distribution systems. The DBPs of most concern include the trihalomethanes (THMs), the haloacetic acids (HAAs), bromate, and chlorite. However, in the latest edition of the WHO Guidelines for Drinking Water Quality

MUTAGENICITY OF DRINKING WATER FOLLOWING DISINFECTION

EPA Science Inventory

Many drinking water utilities in the USA are considering alternatives to chlorine for disinfection in order to comply with federal regulations regarding disinfection by-products. An evaluation is thus needed of the potential risks associated with the use of alternative disinfecta...

Integrated Disinfection By-Products Mixtures Research: Disinfection of Drinking Waters by Chlorination and Ozonation/Postchlorination Treatment Scenarios

EPA Science Inventory

This article describes disinfection of the same source water by two commonly used disinfection treatment scenarios for purposes of subsequent concentration, chemical analysis, and toxicological evaluation. Accompanying articles in this issue of the Journal of Toxicology and Envir...

[Control of disinfection in buildings used for poultry raising].

PubMed

Maris, P

1989-01-01

During a 2-year survey in turkey breeding farms, it was possible to compare six disinfection procedures by monitoring 14 first disinfections following the breeding house cleaning and 14 second disinfections prior to animal return. By swabbing all the germs from asbestos concrete surfaces, we noted that in the case of first disinfection the chloramine T-based product was more effective than phenol or quaternary ammonium-aldehyde-based products. For the second disinfection, it was demonstrated that a minimal dose of 15 kg of formaldehyde was necessary for disinfection to be satisfactory; 12 to 15 kg paraformaldehyde was as effective as 40 to 60 liters of 30-35% formol for buildings, the ground surface of which covered between 1,000 and 1,300 m2.

Changes in the character of DOC in streams during storms in two Midwestern watersheds with contrasting land uses

USGS Publications Warehouse

Vidon, P.; Wagner, L.E.; Soyeux, E.

2008-01-01

Dissolved organic carbon (DOC) dynamics in streams is important, yet few studies focus on DOC dynamics in Midwestern streams during storms. In this study, stream DOC dynamics during storms in two Midwestern watersheds with contrasting land uses, the change in character of stream DOC during storms, and the usability of DOC as a hydrologic tracer in artificially drained landscapes of the Midwest are investigated. Major cation/DOC concentrations, and DOC specific UV absorbance (SUVA) and fluorescence index (FI) were monitored at 2-4 h intervals during three spring storms. Although DOC is less aromatic in the mixed land use watershed than in the agricultural watershed, land use has little impact on stream DOC concentration during storms. For both watersheds, DOC concentration follows discharge, and SUVA and FI values indicate an increase in stream DOC aromaticity and lignin content during storms. The comparison of DOC/major cation flushing dynamics indicates that DOC is mainly exported via overland flow/macropore flow. In both watersheds, the increase in DOC concentration in the streams during storms corresponds to a shift in the source of DOC from DOC originating from mineral soil layers of the soil profile at baseflow, to DOC originating from surficial soil layers richer in aromatic substances and lignin during storms. Results also suggest that DOC, SUVA and FI could be used as hydrologic tracers in artificially drained landscapes of the Midwest. These results underscore the importance of sampling streams for DOC during high flow periods in order to understand the fate of DOC in streams. ?? 2008 Springer Science+Business Media B.V.

DETECTION OF INFECTIOUS ADENOVIRUS IN TERTIARY TREATED AND UV DISINFECTED WASTEWATER DURING A UV DISINFECTION PILOT STUDY

EPA Science Inventory

An infectious enteric adenovirus was isolated from urban wastewater receiving tertiary treatment and ultraviolet (UV) disinfection. A pilot study was undertaken to investigate the efficacy of UV disinfection (low pressure, high intensity radiation) of total and fecal coliform bac...

Products identified at an alternative disinfection pilot plant.

PubMed Central

Lykins, B W; Koffskey, W

1986-01-01

Many drinking water utilities have recently changed or are seriously considering changing their disinfection practice from chlorine to some alternative treatment process. However, most of these utilities are changing their disinfectants without evaluating chemical impacts. Therefore, a research cooperative agreement was developed with Jefferson Parish, LA, to evaluate four parallel streams treated with four different disinfectants (chlorine, monochloramine, chlorine dioxide, and ozone.) These streams, along with a fifth parallel stream, which was not treated with a disinfectant (control), were passed through both sand and granular activated carbon (GAC). Ozonation reduced the total organic carbon (TOC) and total organic halide (TOX) concentration by 0.3 mg/L and 10 micrograms/L, respectively. The average concentration of TOC for the other disinfectants was comparable to that associated with the nondisinfected stream (3.3 mg/L). The average instantaneous TOX concentration for chlorine dioxide, chloramine, and chlorine disinfection after 30 min contact time increased by 60, 92, and 238 micrograms/L, respectively, from a nondisinfected concentration of 25 micrograms/L. The volatile organics most affected by disinfection (chlorination) were the trihalomethanes. No significant change in concentration was noted after disinfection for the other volatile organics evaluated, such as 1,2-dichlorethane, dichloromethane, trichloroethylene, 1,1,2-trichloroethane, and carbon tetrachloride. Ozonation produced an average concentration reduction of 11 to 84% for most of the nonvolatiles evaluated. Conversely, a concentration increase of 43 to 100% was noted, after chlorination, for some of the nonvolatile organics. PMID:3816717

Products identified at an alternative disinfection pilot plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lykins, B.W. Jr.; Koffskey, W.

1986-11-01

Many drinking water utilities have recently changed or are seriously considering changing their disinfection practice from chlorine to some alternative treatment process. However, most of these utilities are changing their disinfectants without evaluating chemical impacts. Therefore, a research cooperative agreement was developed with Jefferson Parish, LA, to evaluate four parallel streams treated with four different disinfectants (chlorine, monochloramine, chlorine dioxide, and ozone.) These streams, along with a fifth parallel stream, which was not treated with a disinfectant (control), were passed through both sand and granular activated carbon (GAC). Ozonation reduced the total organic carbon (TOC) and total organic halide (TOX)more » concentration by 0.3 mg/L and 10 micrograms/L, respectively. The average concentration of TOC for the other disinfectants was comparable to that associated with the nondisinfected stream (3.3 mg/L). The average instantaneous TOX concentration for chlorine dioxide, chloramine, and chlorine disinfection after 30 min contact time increased by 60, 92, and 238 micrograms/L, respectively, from a nondisinfected concentration of 25 micrograms/L. The volatile organics most affected by disinfection (chlorination) were the trihalomethanes. No significant change in concentration was noted after disinfection for the other volatile organics evaluated, such as 1,2-dichlorethane, dichloromethane, trichloroethylene, 1,1,2-trichloroethane, and carbon tetrachloride. Ozonation produced an average concentration reduction of 11 to 84% for most of the nonvolatiles evaluated. Conversely, a concentration increase of 43 to 100% was noted, after chlorination, for some of the nonvolatile organics.« less

Candida auris: Disinfectants and Implications for Infection Control

PubMed Central

Ku, Tsun S. N.; Walraven, Carla J.; Lee, Samuel A.

2018-01-01

Candida auris is a rapidly emerging pathogen and is able to cause severe infections with high mortality rates. It is frequently misidentified in most clinical laboratories, thus requiring more specialized identification techniques. Furthermore, several clinical isolates have been found to be multidrug resistant and there is evidence of nosocomial transmission in outbreak fashion. Appropriate infection control measures will play a major role in controlling the management and spread of this pathogen. Unfortunately, there are very few data available on the effectiveness of disinfectants against C. auris. Chlorine-based products appear to be the most effective for environmental surface disinfection. Other disinfectants, although less effective than chlorine-based products, may have a role as adjunctive disinfectants. A cleaning protocol will also need to be established as the use of disinfectants alone may not be sufficient for maximal decontamination of patient care areas. Furthermore, there are fewer data on the effectiveness of antiseptics against C. auris for patient decolonization and hand hygiene for healthcare personnel. Chlorhexidine gluconate has shown some efficacy in in vitro studies but there are reports of patients with persistent colonization despite twice daily body washes with this disinfectant. Hand hygiene using soap and water, with or without chlorhexidine gluconate, may require the subsequent use of alcohol-based hand sanitizer for maximal disinfection. Further studies will be needed to validate the currently studied disinfectants for use in real-world settings. PMID:29706945

Nonlinear and threshold-dominated runoff generation controls DOC export in a small peat catchment

NASA Astrophysics Data System (ADS)

Birkel, C.; Broder, T.; Biester, H.

2017-03-01

We used a relatively simple two-layer, coupled hydrology-biogeochemistry model to simultaneously simulate streamflow and stream dissolved organic carbon (DOC) concentrations in a small lead and arsenic contaminated upland peat catchment in northwestern Germany. The model procedure was informed by an initial data mining analysis, in combination with regression relationships of discharge, DOC, and element export. We assessed the internal model DOC processing based on stream DOC hysteresis patterns and 3-hourly time step groundwater level and soil DOC data for two consecutive summer periods in 2013 and 2014. The parsimonious model (i.e., few calibrated parameters) showed the importance of nonlinear and rapid near-surface runoff generation mechanisms that caused around 60% of simulated DOC load. The total load was high even though these pathways were only activated during storm events on average 30% of the monitoring time—as also shown by the experimental data. Overall, the drier period 2013 resulted in increased nonlinearity but exported less DOC (115 kg C ha-1 yr-1 ± 11 kg C ha-1 yr-1) compared to the equivalent but wetter period in 2014 (189 kg C ha-1 yr-1 ± 38 kg C ha-1 yr-1). The exceedance of a critical water table threshold (-10 cm) triggered a rapid near-surface runoff response with associated higher DOC transport connecting all available DOC pools and subsequent dilution. We conclude that the combination of detailed experimental work with relatively simple, coupled hydrology-biogeochemistry models not only allowed the model to be internally constrained but also provided important insight into how DOC and tightly coupled pollutants or trace elements are mobilized.

Proteomic adaptations to starvation prepare Escherichia coli for disinfection tolerance.

PubMed

Du, Zhe; Nandakumar, Renu; Nickerson, Kenneth W; Li, Xu

2015-02-01

Despite the low nutrient level and constant presence of secondary disinfectants, bacterial re-growth still occurs in drinking water distribution systems. The molecular mechanisms that starved bacteria use to survive low-level chlorine-based disinfectants are not well understood. The objective of this study is to investigate these molecular mechanisms at the protein level that prepare starved cells for disinfection tolerance. Two commonly used secondary disinfectants chlorine and monochloramine, both at 1 mg/L, were used in this study. The proteomes of normal and starved Escherichia coli (K12 MG1655) cells were studied using quantitative proteomics. Over 60-min disinfection, starved cells showed significantly higher disinfection tolerance than normal cells based on the inactivation curves for both chlorine and monochloramine. Proteomic analyses suggest that starvation may prepare cells for the oxidative stress that chlorine-based disinfection will cause by affecting glutathione metabolism. In addition, proteins involved in stress regulation and stress responses were among the ones up-regulated under both starvation and chlorine/monochloramine disinfection. By comparing the fold changes under different conditions, it is suggested that starvation prepares E. coli for disinfection tolerance by increasing the expression of enzymes that can help cells survive chlorine/monochloramine disinfection. Protein co-expression analyses show that proteins in glycolysis and pentose phosphate pathway that were up-regulated under starvation are also involved in disinfection tolerance. Finally, the production and detoxification of methylglyoxal may be involved in the chlorine-based disinfection and cell defense mechanisms. Copyright © 2014 Elsevier Ltd. All rights reserved.

Application of a high-level peracetic acid disinfection protocol to re-process antibiotic disinfected skin allografts.

PubMed

Lomas, R J; Huang, Q; Pegg, D E; Kearney, J N

2004-01-01

Skin allografts, derived from cadaveric donors, are widely used for the treatment of burns and ulcers. Prior to use in clinical situations, these allografts are disinfected using a cocktail of antibiotics and then cryopreserved. Unfortunately, this antibiotic disinfection procedure fails to decontaminate a significant proportion and these contaminated grafts can not be used clinically. We have investigated whether it is possible to apply a second, more potent disinfection procedure to these contaminated grafts and effectively to re-process them for clinical use. Cadaveric skin grafts, treated with antibiotics and cryopreserved, were thawed and a peracetic acid (PAA) disinfection protocol applied. The grafts were then preserved in a high concentration of glycerol or propylene glycol, and properties thought to be essential for successful clinical performance assessed. The cytotoxicity of the grafts was assessed using both extract and contact assays; damage to the skin collagen was assessed using a collagenase susceptibility assay and the capacity of the grafts to elicit an inflammatory response in vitro was assessed by quantifying the production of the pro-inflammatory cytokine TNF-alpha by human peripheral blood mononuclear phagocytes. PAA disinfection, in conjunction with either glycerol or propylene glycol preservation, did not render the grafts cytotoxic, pro-inflammatory, or increase their susceptibility to collagenase digestion. The rates of penetration of glycerol and propylene glycol into the re-processed skin were comparable to those of fresh skin. This study has demonstrated that PAA disinfection combined with immersion in high concentrations of either glycerol or propylene glycol was an effective method for re-processing contaminated skin allografts, and may justify their clinical use.

9 CFR 52.7 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2010 CFR

2010-01-01

... cleaning and disinfection, unless an official pseudorabies epidemiologist determines that a shorter or... and disinfection, except for cleaning and disinfection of the conveyances used to transport the swine... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Disinfection of premises, conveyances...

40 CFR 141.543 - How is the disinfection benchmark calculated?

Code of Federal Regulations, 2010 CFR

2010-07-01

...) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Enhanced Filtration and Disinfection-Systems Serving Fewer Than 10,000 People Disinfection Benchmark § 141.543 How is the disinfection... 40 Protection of Environment 22 2010-07-01 2010-07-01 false How is the disinfection benchmark...

40 CFR 141.709 - Developing the disinfection profile and benchmark.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 23 2011-07-01 2011-07-01 false Developing the disinfection profile... Cryptosporidium Disinfection Profiling and Benchmarking Requirements § 141.709 Developing the disinfection profile and benchmark. (a) Systems required to develop disinfection profiles under § 141.708 must follow the...

40 CFR 141.709 - Developing the disinfection profile and benchmark.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 23 2014-07-01 2014-07-01 false Developing the disinfection profile... Cryptosporidium Disinfection Profiling and Benchmarking Requirements § 141.709 Developing the disinfection profile and benchmark. (a) Systems required to develop disinfection profiles under § 141.708 must follow the...

40 CFR 141.709 - Developing the disinfection profile and benchmark.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 24 2012-07-01 2012-07-01 false Developing the disinfection profile... Cryptosporidium Disinfection Profiling and Benchmarking Requirements § 141.709 Developing the disinfection profile and benchmark. (a) Systems required to develop disinfection profiles under § 141.708 must follow the...

40 CFR 141.709 - Developing the disinfection profile and benchmark.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 24 2013-07-01 2013-07-01 false Developing the disinfection profile... Cryptosporidium Disinfection Profiling and Benchmarking Requirements § 141.709 Developing the disinfection profile and benchmark. (a) Systems required to develop disinfection profiles under § 141.708 must follow the...

Effects of wastewater disinfection on waterborne bacteria and viruses

USGS Publications Warehouse

Blatchley, E. R.; Gong, W.-L.; Alleman, J.E.; Rose, J.B.; Huffman, D.E.; Otaki, M.; Lisle, J.T.

2007-01-01

Wastewater disinfection is practiced with the goal of reducing risks of human exposure to pathogenic microorganisms. In most circumstances, the efficacy of a wastewater disinfection process is regulated and monitored based on measurements of the responses of indicator bacteria. However, inactivation of indicator bacteria does not guarantee an acceptable degree of inactivation among other waterborne microorganisms (e.g., microbial pathogens). Undisinfected effluent samples from several municipal wastewater treatment facilities were collected for analysis. Facilities were selected to provide a broad spectrum of effluent quality, particularly as related to nitrogenous compounds. Samples were subjected to bench-scale chlorination and dechlorination and UV irradiation under conditions that allowed compliance with relevant discharge regulations and such that disinfectant exposures could be accurately quantified. Disinfected samples were subjected to a battery of assays to assess the immediate and long-term effects of wastewater disinfection on waterborne bacteria and viruses. In general, (viable) bacterial populations showed an immediate decline as a result of disinfectant exposure; however, incubation of disinfected samples under conditions that were designed to mimic the conditions in a receiving stream resulted in substantial recovery of the total bacterial community. The bacterial groups that are commonly used as indicators do not provide an accurate representation of the response of the bacterial community to disinfectant exposure and subsequent recovery in the environment. UV irradiation and chlorination/dechlorination both accomplished measurable inactivation of indigenous phage; however, the extent of inactivation was fairly modest under the conditions of disinfection used in this study. UV irradiation was consistently more effective as a virucide than chlorination/dechlorination under the conditions of application, based on measurements of virus (phage

Inactivation of an enterovirus by airborne disinfectants

PubMed Central

2013-01-01

Background The activity of airborne disinfectants on bacteria, fungi and spores has been reported. However, the issue of the virucidal effect of disinfectants spread by fogging has not been studied thoroughly. Methods A procedure has been developed to determine the virucidal activity of peracetic acid-based airborne disinfectants on a resistant non-enveloped virus poliovirus type 1. This virus was laid on a stainless carrier. The products were spread into the room by hot fogging at 55°C for 30 minutes at a concentration of 7.5 mL.m-3. Poliovirus inoculum, supplemented with 5%, heat inactivated non fat dry organic milk, were applied into the middle of the stainless steel disc and were dried under the air flow of a class II biological safety cabinet at room temperature. The Viral preparations were recovered by using flocked swabs and were titered on Vero cells using the classical Spearman-Kärber CPE reading method, the results were expressed as TCID50.ml-1. Results The infectious titer of dried poliovirus inocula was kept at 105 TCID50.mL-1 up to 150 minutes at room temperature. Dried inocula exposed to airborne peracetic acid containing disinfectants were recovered at 60 and 120 minutes post-exposition and suspended in culture medium again. The cytotoxicity of disinfectant containing medium was eliminated through gel filtration columns. A 4 log reduction of infectious titer of dried poliovirus inocula exposed to peracetic-based airborne disinfectant was obtained. Conclusion This study demonstrates that the virucidal activity of airborne disinfectants can be tested on dried poliovirus. PMID:23587047

Optical monitoring of Disinfection By-product Precursors with Fluorescence Excitation-Emission Mapping (F-EEM): Practical Application Issues for Drinking, Waste and Reuse Water Industry

NASA Astrophysics Data System (ADS)

Gilmore, A. M.

2012-12-01

Drinking water, wastewater and reuse plants must deal with regulations associated with bacterial contamination and halogen disinfection procedures that can generate harmful disinfection by-products (DBPs) including trihalomethanes (THMs), haloacetic acids (HOAAs) and other compounds. The natural fluorescent chromophoric dissolved organic matter (CDOM) is regulated as the major DBP precursor. This study outlines the advantages and current limitations associated with optical monitoring of water treatment processes using tcontemporary Fluorescence Excitation-Emission Mapping (F-EEM). The F-EEM method coupled with practical peak indexing and multi-variate analyses is potentially superior in terms of cost, speed and sensitivity over conventional total organic carbon (TOC) meters and specific UV-absorbance (SUVA) measurements. Hence there is strong interest in developing revised environmental regulations around the F-EEM technique instruments which can incidentally simultaneously measure the SUVA and DOC parameters. Importantly, the F-EEM technique, compared to the single-point TOC and SUVA signals can resolve CDOM classes distinguishing those that strongly cause DBPs. The F-EEM DBP prediction method can be applied to surface water sources to evaluate DBP potential as a function of the point sources and reservoir depth profiles. It can also be applied in-line to rapidly adjust DOC removal processes including sedimentation-flocculation, microfiltration, reverse-osmosis, and ozonation. Limitations and interferences for F-EEMs are discussed including those common to SUVA and TOC in contrast to the advantages including that F-EEMs are less prone to interferences from inorganic carbon and metal contaminations and require little if any chemical preparation. In conclusion, the F-EEM method is discussed in terms of not only the DBP problem but also as a means of predicting (concurrent to DBP monitoring) organic membrane fouling in water-reuse and desalination plants.

Character, quality and bioavailability of Dissolved Organic Carbon (DOC) in a boreal stream network (Invited)

NASA Astrophysics Data System (ADS)

Laudon, H.; Berggren, M.; Agren, A.; Jansson, M.

2010-12-01

The conceptual understanding of the role of terrestrially derived dissolved organic carbon (DOC) in freshwaters has been changing rapidly. While it was once considered mainly a pool of recalcitrant compounds, DOC is now better known for its interactivity and ability to affect both the biogeochemistry and ecology of streams, rivers and lakes. Here we summarize the recent work from the multi-investigatory project conducted in the Krycklan Catchment Study in Sweden with an emphasis on the spatial and temporal variability of the character and bioavailability of DOC. In total, 15 streams and their adjacent soils have been investigated. The streams cover a forest-wetland gradient, spanning from 0% to 69% wetland coverage (hence with a 100% to 31% forest cover). Lower values of the ratio between absorbance measured at 254 nm and 365 nm (A254/A365), in both soil plots and streams, indicated that wetland-derived DOC has a higher average molecular weight than forest DOC. Higher SUVA254 (DOC specific ultraviolet absorption at 254 nm) in wetland runoff indicated more aromatic DOC from wetlands than forests. In accordance, low molecular weight non-aromatic compounds such as free organic acids (OA), amino acids (AA) and carbohydrates (CH) had higher quantities in the forested streams. We have shown that a variety of the OA, AA and CH compounds can be significantly assimilated by bacteria, meeting 15-100% of the bacterial carbon demand and explaining most of the observed variance in bacterial growth efficiency. We can now also show that in small homogenous catchments, the hydrological functioning provides a first order control on the temporal variability of stream water DOC and its quality. As a consequence, streams with heterogeneous catchments undergo a temporal switch in the DOC source. In a typical boreal catchment of 10-20% wetlands, DOC originates predominantly from wetland sources during low flow conditions whereas the major source of DOC originates from forested areas of

Relative importance of multiple factors on terrestrial loading of DOC to Arctic river networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kicklighter, David W.; Hayes, Daniel J; Mcclelland, James W

2014-01-01

Terrestrial carbon dynamics influence the contribution of dissolved organic carbon (DOC) to river networks in addition to controlling carbon fluxes between the land surface and the atmosphere. In this study, we use a biogeochemical process model to simulate the lateral transfer of DOC from land to the Arctic Ocean via riverine transport. We estimate that the pan-arctic watershed has contributed, on average, 32 Tg C/yr of DOC to the Arctic Ocean over the 20th century with most coming from the extensive area of boreal deciduous needle-leaved forests and forested wetlands in Eurasian watersheds. We also estimate that the rate ofmore » terrestrial DOC loading has been increasing by 0.037 Tg C/yr2 over the 20th century primarily as a result of increases in air temperatures and precipitation. These increases have been partially compensated by decreases in terrestrial DOC loading caused by wildfires. Other environmental factors (CO2 fertilization, ozone pollution, atmospheric nitrogen deposition, timber harvest, agriculture) are estimated to have relatively small effects on terrestrial DOC loading to arctic rivers. The effects of the various environmental factors on terrestrial carbon dynamics have both compensated and enhanced concurrent effects on hydrology to influence terrestrial DOC loading. Future increases in riverine DOC concentrations and export may occur from warming-induced increases in terrestrial DOC production associated with enhanced microbial metabolism and the exposure of additional organic matter from permafrost degradation along with decreases in water yield associated with warming-induced increases in evapotranspiration. Improvements in simulating terrestrial DOC loading to pan-arctic rivers in the future will require better information on the spatial distribution of precipitation and its temporal trends, carbon dynamics of larch-dominated ecosystems in eastern Siberia, and the role of industrial organic effluents on carbon budgets of rivers in

Acute occupational disinfectant-related illness among youth, 1993-1998.

PubMed Central

Brevard, Theresa A; Calvert, Geoffrey M; Blondell, Jerome M; Mehler, Louise N

2003-01-01

Working youths face many safety and health risks. Among these risks are those posed by disinfectant exposures. In this study we describe acute occupational disinfectant-related illness among youth. Data on U.S. children younger than 18 years with acute occupational disinfectant-related illnesses between 1993 and 1998 were collected from the Toxic Exposure Surveillance System and from the California Department of Pesticide Regulation. We analyzed data from persons with exposures who met the case definition for acute occupational disinfectant-related illness. The case definition required onset of new adverse health effects that were both temporally related to a disinfectant exposure and consistent with the known toxicology of the disinfectant. We calculated incidence rates of acute occupational disinfectant-related illness among youths 15-17 years old and incidence rate ratios to compare these rates with those of adults 25-44 years old. We found 307 children with disinfectant-related illnesses. The average annual incidence rate was 16.8/billion hours worked with a relative risk compared with adults of 4.14 (95% confidence interval, 3.66-4.68). Most illnesses were of mild severity (78%). There were no fatalities. Hypochlorites (e.g., bleach) were responsible for 45% of the illnesses. Among the 206 cases where the responsible disinfectant's U.S. Environmental Protection Agency toxicity category was known, 80% were in category I (highest toxicity level). These findings suggest the need for greater efforts to prevent adolescent acute occupational disinfectant-related illness. This may require strengthening regulations and enforcement as well as increased educational efforts directed at employers, youths, parents, school officials, and physicians. Better mechanisms for reporting and tracking chemical illnesses among working adolescents are also needed. PMID:14527846

Ultra violet disinfection: A 3-year history

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tubesing, R.R.; Lindeke, D.R.

1998-07-01

The Stillwater Wastewater Treatment Facility is one of nine wastewater treatment facilities operated by the Metropolitan Council Environmental Services in the Minneapolis-St. Paul Metropolitan Area. The facility services the cities of Stillwater, Oak Park Heights, and Bayport. In 1993, an ultra violet disinfection facility began operation to provide the disinfection for the Facility. This presentation discusses the reasons for using ultra violet disinfection in lieu of chlorination/dechlorination facilities, the operating performance, and operating cost factors.

Studies on Disinfection By-Products and Drinking Water

USGS Publications Warehouse

Rostad, Colleen E.

2007-01-01

Drinking water is disinfected with chemicals to remove pathogens, such as Giardia and Cryptosproridium, and prevent waterborne diseases such as cholera and typhoid. During disinfection, by-products are formed at trace concentrations. Because some of these by-products are suspected carcinogens, drinking water utilities must maintain the effectiveness of the disinfection process while minimizing the formation of by-products.

Disinfecting capabilities of oxychlorine compounds.

PubMed Central

Noss, C I; Olivieri, V P

1985-01-01

The bacterial virus f2 was inactivated by chlorine dioxide at acidic, neutral, and alkaline pH values. The rate of inactivation increased with increasing pH. Chlorine dioxide disproportionation products, chlorite and chlorate, were not active disinfectants. As chlorine dioxide solutions were degraded under alkaline conditions, they displayed reduced viricidal effectiveness, thereby confirming the chlorine dioxide free radical as the active disinfecting species. PMID:3911893

40 CFR 141.540 - Who has to develop a disinfection benchmark?

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 23 2014-07-01 2014-07-01 false Who has to develop a disinfection... Disinfection-Systems Serving Fewer Than 10,000 People Disinfection Benchmark § 141.540 Who has to develop a disinfection benchmark? If you are a subpart H system required to develop a disinfection profile under §§ 141...

40 CFR 141.540 - Who has to develop a disinfection benchmark?

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 24 2013-07-01 2013-07-01 false Who has to develop a disinfection... Disinfection-Systems Serving Fewer Than 10,000 People Disinfection Benchmark § 141.540 Who has to develop a disinfection benchmark? If you are a subpart H system required to develop a disinfection profile under §§ 141...

40 CFR 141.540 - Who has to develop a disinfection benchmark?

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 23 2011-07-01 2011-07-01 false Who has to develop a disinfection... Disinfection-Systems Serving Fewer Than 10,000 People Disinfection Benchmark § 141.540 Who has to develop a disinfection benchmark? If you are a subpart H system required to develop a disinfection profile under §§ 141...

EPIDEMIOLOGIC STUDIES OF DISINFECTANTS AND DISINFECTANT BY-PRODUCTS

EPA Science Inventory

This article provides a review of the epidemiologic evidence for human health effects that may be associated with the disinfection of drinking water. An epidemiologic study attempts to link human health effects with exposure to a specific agent (e.g., DBCM), agents (e.g., THMs or...

TOXICOLOGIC AND CHEMICAL EVALUATION OF ALTERNATIVE DISINFECTION TREATMENT SCENARIOS

EPA Science Inventory

More than 500 disinfecting byproducts have been identified. They result from the reaction of the disinfectants with the natural organic matter present in source waters. The concentrations and bromo/chloro speciation of these disinfection byproducts (DBPs) are influenced by source...

OPTIMAL SCHEDULING OF BOOSTER DISINFECTION IN WATER DISTRIBUTION SYSTEMS

EPA Science Inventory

Booster disinfection is the addition of disinfectant at locations distributed throughout a water distribution system. Such a strategy can reduce the mass of disinfectant required to maintain a detectable residual at points of consumption in the distribution system, which may lea...

THE TOXICOLOGY OF COMPLEX MIXTURES OF DISINFECTION BY-PRODUCTS

EPA Science Inventory

Chemical disinfection of water is a major public health advance that has decreased dramatically water-borne disease. Chemical disinfectants react with naturally occurring organic and inorganic matter in water to produce a wide variety of disinfection byproducts (DBPs). DBP num...

Review of water disinfection techniques

NASA Technical Reports Server (NTRS)

Colombo, Gerald V.; Sauer, Richard L.

1987-01-01

Throughout the history of manned space flight the supply of potable water to the astronauts has presented unique problems. Of particular concern has been the microbiological quality of the potable water. This has required the development of both preflight water system servicing procedures to disinfect the systems and inflight disinfectant addition and monitoring devices to ensure continuing microbiological control. The disinfectants successfully used to date have been aqueous chlorine or iodine. Because of special system limitations the use of iodine has been the most successful for inflight use and promises to be the agent most likely to be used in the future. Future spacecraft potable, hygiene, and experiment water systems will utilize recycled water. This will present special problems for water quality control. NASA is currently conducting research and development to solve these problems.

Web-based Loansome Doc, librarians, and end users: results from a survey of the Southeast Region.

PubMed

Paden, S L; Batson, A L; Wallace, R L

2001-07-01

The study examines how Loansome Doc services are implemented and used by libraries in the Southeast Region and describe end users' experiences with and attitudes toward Loansome Doc. 251 active DOCLINE libraries and 867 Loansome Doc users were surveyed. Roughly one half of the libraries offered Loansome Doc services. Of those that did not, most indicated no plans to offer it in the future. The majority had a small number of end users and experienced minimal increases in interlibrary loan activity. Problems were relatively rare. Satisfaction with Loansome Doc was high among all types of libraries. End users were usually physicians or other health care professionals who requested articles for research and patient care. Most learned about Loansome Doc through PubMed or Internet Grateful Med. End users appeared to be largely self-taught or received informal instruction in Loansome Doc. Loansome Doc filled document requests in a timely manner, and end users reported being satisfied with the service. Greater promotion of what Loansome Doc is and how it can benefit libraries can increase the number of participating libraries. While satisfaction of Loansome Doc end users is high, satisfaction could be increased with more help on the PubMed screen, more library training, and faster delivery methods.

Assessing the contribution of wetlands and subsided islands to dissolved organic matter and disinfection byproduct precursors in the Sacramento-San Joaquin River Delta: A geochemical approach

USGS Publications Warehouse

Kraus, T.E.C.; Bergamaschi, B.A.; Hernes, P.J.; Spencer, R.G.M.; Stepanauskas, R.; Kendall, C.; Losee, R.F.; Fujii, R.

2008-01-01

This study assesses how rivers, wetlands, island drains and open water habitats within the Sacramento-San Joaquin River Delta affect dissolved organic matter (DOM) content and composition, and disinfection byproduct (DBP) formation. Eleven sites representative of these habitats were sampled on six dates to encompass seasonal variability. Using a suite of qualitative analyses, including specific DBP formation potential, absorbance, fluorescence, lignin content and composition, C and N stable isotopic compositions, and structural groupings determined using CPMAS (cross polarization, magic angle spinning) 13C NMR, we applied a geochemical fingerprinting approach to characterize the DOM from different Delta habitats, and infer DOM and DBP precursor sources and estimate the relative contribution from different sources. Although river input was the predominant source of dissolved organic carbon (DOC), we observed that 13-49% of the DOC exported from the Delta originated from sources within the Delta, depending on season. Interaction with shallow wetlands and subsided islands significantly increased DOC and DBP precursor concentrations and affected DOM composition, while deep open water habitats had little discernable effect. Shallow wetlands contributed the greatest amounts of DOM and DBP precursors in the spring and summer, in contrast to island drains which appeared to be an important source during winter months. The DOM derived from wetlands and island drains had greater haloacetic acid precursor content relative to incoming river water, while two wetlands contributed DOM with greater propensity to form trihalomethanes. These results are pertinent to restoration of the Delta. Large scale introduction of shallow wetlands, a proposed restoration strategy, could alter existing DOC and DBP precursor concentrations, depending on their hydrologic connection to Delta channels. ?? 2008 Elsevier Ltd.

Defining unnecessary disinfection procedures for single-dose and multiple-dose vials.

PubMed

Buckley, T; Dudley, S M; Donowitz, L G

1994-11-01

Recommendations in the literature conflict on the necessity of disinfecting single-use vials prior to aspiration of fluid. Interventions to disinfect the stopper surface on multiple-dose vials vary considerably. To determine the necessity of alcohol disinfection of the stopper on single-dose vials and to compare povidone-iodine and alcohol versus alcohol-only disinfection of the stopper prior to each needle penetration on multiple-dose vials. The rubber stopper surfaces of 100 single-dose vials were cultured for the presence of bacteria. To determine the efficacy of two procedures for disinfection of multiple-dose vials, 87 stopper surfaces routinely disinfected with both povidone-iodine and alcohol were cultured for bacteria. After a change in practice, 100 multiple-dose vials routinely disinfected with alcohol only were cultured for the presence of bacteria. Of the cultures done on single-dose vial stoppers, 99% were sterile. A comparison of the two disinfection techniques for multiple-dose vials revealed that 83 (95%) of the 87 vials prepped with both povidone-iodine and alcohol were sterile, compared with all stoppers disinfected with alcohol only. This study shows the lack of necessity of any disinfection procedure on the rubber stopper of single-dose vials and the efficacy of alcohol only for disinfecting the stopper of multiple-dose vials.

Diagnosis of Processes Controlling Dissolved Organic Carbon (DOC) Export in a Subarctic Region by a Dynamic Ecosystem Model

NASA Astrophysics Data System (ADS)

Tang, J.

2015-12-01

Permafrost thawing in high latitudes allows more soil organic carbon (SOC) to become hydrologically accessible. This can increase dissolved organic carbon (DOC) exports and carbon release to the atmosphere as CO2 and CH4, with a positive feedback to regional and global climate warming. However, this portion of carbon loss through DOC export is often neglected in ecosystem models. In this paper, we incorporate a set of DOC-related processes (DOC production, mineralization, diffusion, sorption-desorption and leaching) into an Arctic-enabled version of the dynamic ecosystem model LPJ-GUESS (LPJ-GUESS WHyMe) to mechanistically model the DOC export, and to link this flux to other ecosystem processes. The extended LPJ-GUESS WHyMe with these DOC processes is applied to the Stordalen catchment in northern Sweden. The relative importance of different DOC-related processes for mineral and peatland soils for this region have been explored at both monthly and annual scales based on a detailed variance-based Sobol sensitivity analysis. For mineral soils, the annual DOC export is dominated by DOC fluxes in snowmelt seasons and the peak in spring is related to the runoff passing through top organic rich layers. Two processes, DOC sorption-desorption and production, are found to contribute most to the annual variance in DOC export. For peatland soils, the DOC export during snowmelt seasons is constrained by frozen soils and the processes of DOC production and mineralization, determining the magnitudes of DOC desorption in snowmelt seasons as well as DOC sorption in the rest of months, play the most important role in annual variances of DOC export. Generally, the seasonality of DOC fluxes is closely correlated with runoff seasonality in this region. The current implementation has demonstrated that DOC-related processes in the framework of LPJ-GUESS WHyMe are at an appropriate level of complexity to represent the main mechanism of DOC dynamics in soils. The quantified contributions

Disinfection by electrohydraulic treatment.

PubMed

Allen, M; Soike, K

1967-04-28

Electrohydraulic treatment was applied to suspensions of Escherichia coli, spores of Bacillus subtilis var. niger, Saccharomyces cerevisiae, and bacteriophage T2 at an input energy that, in most cases, was below the energy required to sterilize. The input energy was held relatively constant for each of these microorganisms, but the capacitance and voltage were varied. Data are presented which show the degree of disinfection as a function of capacitance and voltage. In all cases, the degree of disinfection for a given input energy increases as both capacitance and voltage are lowered.

40 CFR 141.53 - Maximum contaminant level goals for disinfection byproducts.

Code of Federal Regulations, 2010 CFR

2010-07-01

... disinfection byproducts. 141.53 Section 141.53 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Maximum Contaminant Level... disinfection byproducts. MCLGs for the following disinfection byproducts are as indicated: Disinfection...

Concentration and age of DOC transported from thawing permafrost soils into Arctic headwater streams

NASA Astrophysics Data System (ADS)

Romano, E. L.; Wickland, K.; Ebert, C.; Schuur, E.

2017-12-01

As Arctic permafrost stability decreases due to global climate change, hydrologic dynamics in catchments underlain by permafrost are expected to shift. The thickness of seasonally thawed surface soils is an important driver of the extent to which carbon (C) that was previously stored as frozen soil organic carbon (SOC) will be transported laterally as dissolved organic carbon (DOC). The concentration and radiocarbon (14C) age of newly thawed DOC that moves downslope through tundra soils and is delivered to headwater streams is an important indicator of changing C dynamics. Understanding the timing and quantity of C loss in this form is imperative for greenhouse gas emission and soil C stock estimates, as well as predicting the impact of permafrost thaw on aquatic ecosystems. In this study we examined the relationship between DOC concentrations, 14C-DOC, and active layer thickness (ALT) in thawing soils over time. Water samples were collected once in July 2016 and weekly in 2017 from late May to late August from wells within a long-term tundra soil warming experiment (n=36), located in a discontinuous permafrost zone in Interior Alaska. Preliminary data from 2016 shows average maximum ALT at wells within the warming treatment of 68.9 cm, while wells from control averaged 86.6 cm. 2016 water sample data from wells within the warming treatment showed higher mean DOC concentrations (103.1 ± 32.5 mg/L) and older 14C-DOC values (-28.7 ± 21.1 ‰) than samples from the control (44.5 ± 3.0 mg/L and 11.3 ± 8.6 ‰). To assess inter-annual changes in DOC delivery to local headwater streams, DOC concentration and 14C-DOC were also measured on water samples taken in late summer of 2007, 2008, and 2016 from streams within the watershed surrounding the experimental sites. Weekly sampling in 2017 allowed analysis of seasonal patterns of DOC concentration for that year. Values increased slightly over time at some stream sites (ranging from 4-33 mg/L in 2012 to 2-80 mg/L in

Linking pulses of atmospheric deposition to DOC release in an upland peat-covered catchment

NASA Astrophysics Data System (ADS)

Worrall, F.; Burt, T. P.; Adamson, J. K.

2008-12-01

Changes in atmospheric deposition have been proposed as one possible explanation of the widespread increase in DOC concentration observed in many Northern Hemisphere catchments. This study uses detailed, long-term, monthly monitoring records of pH, conductivity SO4, and DOC in precipitation, soil water, and runoff chemistry from an upland peat-covered catchment in northern England. By deriving impulse transfer functions this study explores whether changes in deposition lead to significant changes in the occurrence of each component in the soil and runoff water; especially significant changes in DOC. The study shows that (1) impulses in the deposition of acidity have no significant effect upon pH or DOC in soil water or runoff. (2) DOC in soil water and runoff is responsive to impulses in SO4 and conductivity, but only when those impulses are changes in soil water chemistry and not when they are in atmospheric deposition. (3) The effects of changes in SO4 and/or conductivity can easily be overemphasized if memory effects are not accounted for, and their effect is limited to only 1 or 2 months after a severe drought. This study can support the view that changes in ionic strength can result in changes in DOC concentration in soil water or runoff, but the system studied is unresponsive to changes in atmospheric deposition. Impulses in soil water SO4 do not lead to increases in DOC concentrations, and so this mechanism does not provide an explanation for DOC increases.

Determination of an organic-acid analog of DOC for use in copper toxicity studies on salmonids

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacRae, R.K.; Meyer, J.S.; Hansen, J.A.

1995-12-31

Concentrations of dissolved copper in streams draining mine sites often exceed concentrations shown to cause acute and chronic mortality in salmonids. However, toxicity and impaired behaviors may be modified by dissolved organic carbon (DOC) and other inorganic components present in the site water. The effects of DOC on copper speciation, and thus bioavailability and toxicity, were determined by titrating stream waters with copper, using a cupric ion-specific electrode to detect free copper concentrations. Effects of various competing cations (e.g., Ca{sup +2}, Co{sup +2}) on copper-DOC binding were also evaluated. Titration results were evaluated using Scatchard and non-linear regression analyses tomore » quantify the strength and capacity of copper-DOC binding. Inorganic speciation was determined using the geochemical model MINEQL{sup +}. Results of these titrations indicated the presence of two or three distinct copper binding components in site water DOC. Three commercially available organic acids where then chosen to mimic the binding characteristics of natural DOC. This DOC-analog was used successfully in fish toxicity studies to evaluate the influence of DOC on copper bioavailability. Geochemical models were developed to predict copper speciation in both laboratory test waters and site waters, for any typical combination of water chemistry parameters (pH, alkalinity, [DOC], etc.). A combined interpretation of fish toxicity and modeling results indicate that some DOC-bound copper was bioavailable.« less

Color stability comparison of silicone facial prostheses following disinfection.

PubMed

Goiato, Marcelo Coelho; Pesqueira, Aldiéris Alves; dos Santos, Daniela Micheline; Zavanelli, Adriana Cristina; Ribeiro, Paula do Prado

2009-04-01

The purpose of this study was to evaluate the color stability of two silicones for use in facial prostheses, under the influence of chemical disinfection and storage time. Twenty-eight specimens were obtained half made from Silastic MDX 4-4210 silicone and the other half from Silastic 732 RTV silicone. The specimens were divided into four groups: Silastic 732 RTV and MDX 4-4210 with disinfection three times a week with Efferdent and Sliastic 732 RTV and MDX 4-4210 disinfected with neutral soap. Color stability was analyzed by spectrophotometry, immediately and 2 months after making the specimens. After obtaining the results, ANOVA and Tukey test with 1% reliability were used for statistical analysis. Statistical differences between mean color values were observed. Disinfection with Efferdent did not statistically influence the mean color values. The factors of storage time and disinfection statistically influenced color stability; disinfection acts as a bleaching agent in silicone materials.

Conductive diamond sono-electrochemical disinfection (CDSED) for municipal wastewater reclamation.

PubMed

Llanos, Javier; Cotillas, Salvador; Cañizares, Pablo; Rodrigo, Manuel A

2015-01-01

In the present work, the disinfection of actual effluents from a municipal wastewater treatment plant (WWTP) by a conductive diamond sono-electrochemical process was assessed. First, efficiency of single electrodisinfection process with diamond anodes (without the contribution of ultrasounds) was studied, finding that the total disinfection can be attained at current charges applied below 0.02kAhm(-3). It was also found that the main disinfection mechanism is the attack of Escherichia coli (E. coli) by the disinfectants produced in the electrochemical cell and that the production of chlorates is avoided when working at current densities not higher than 1.27Am(-2). Next, a marked synergistic effect was found when coupling ultrasound (US) irradiation to the electrochemical system (sono-electrochemical disinfection). This increase in the disinfection rate was found to be related to the suppression of the agglomeration of E. coli cells and the enhancement in the production of disinfectant species. Copyright © 2014 Elsevier B.V. All rights reserved.

Formation and Occurrence of Disinfection By-Products

EPA Science Inventory

Disinfection by-products (DBPs) are formed when disinfectants such as chlorine, ozone, chlorine dioxide, or chloramines react with naturally occurring organic matter, anthropogenic contaminants, bromide, and iodide during the production of drinking water. There is concern about D...

9 CFR 91.41 - Cleaning and disinfecting of aircraft.

Code of Federal Regulations, 2010 CFR

2010-01-01

... of this chapter. The time at which the cleaning and disinfection is performed must be approved by the inspector, who will give approval only if he or she determines that the cleaning and disinfection will be... time, the inspector shall determine whether further cleaning and disinfection are necessary. The...

9 CFR 51.31 - Disinfecting premises, conveyances, and materials.

Code of Federal Regulations, 2010 CFR

2010-01-01

... representative. Cleaning and disinfecting must be completed within 15 days from the date the animals were removed from the premises, except that the Veterinarian in Charge may extend the time limit for disinfection to... circumstances occur that prevent or hinder disinfection of the premises, conveyances, and materials within 30...

9 CFR 91.41 - Cleaning and disinfecting of aircraft.

Code of Federal Regulations, 2011 CFR

2011-01-01

... of this chapter. The time at which the cleaning and disinfection is performed must be approved by the inspector, who will give approval only if he or she determines that the cleaning and disinfection will be... time, the inspector shall determine whether further cleaning and disinfection are necessary. The...

9 CFR 91.41 - Cleaning and disinfecting of aircraft.

Code of Federal Regulations, 2013 CFR

2013-01-01

... of this chapter. The time at which the cleaning and disinfection is performed must be approved by the inspector, who will give approval only if he or she determines that the cleaning and disinfection will be... time, the inspector shall determine whether further cleaning and disinfection are necessary. The...

9 CFR 91.41 - Cleaning and disinfecting of aircraft.

Code of Federal Regulations, 2014 CFR

2014-01-01

... of this chapter. The time at which the cleaning and disinfection is performed must be approved by the inspector, who will give approval only if he or she determines that the cleaning and disinfection will be... time, the inspector shall determine whether further cleaning and disinfection are necessary. The...

9 CFR 91.41 - Cleaning and disinfecting of aircraft.

Code of Federal Regulations, 2012 CFR

2012-01-01

... of this chapter. The time at which the cleaning and disinfection is performed must be approved by the inspector, who will give approval only if he or she determines that the cleaning and disinfection will be... time, the inspector shall determine whether further cleaning and disinfection are necessary. The...

Hydrological controls on DOC  :  nitrate resource stoichiometry in a lowland, agricultural catchment, southern UK

NASA Astrophysics Data System (ADS)

Heppell, Catherine M.; Binley, Andrew; Trimmer, Mark; Darch, Tegan; Jones, Ashley; Malone, Ed; Collins, Adrian L.; Johnes, Penny J.; Freer, Jim E.; Lloyd, Charlotte E. M.

2017-09-01

The role that hydrology plays in governing the interactions between dissolved organic carbon (DOC) and nitrogen in rivers draining lowland, agricultural landscapes is currently poorly understood. In light of the potential changes to the production and delivery of DOC and nitrate to rivers arising from climate change and land use management, there is a pressing need to improve our understanding of hydrological controls on DOC and nitrate dynamics in such catchments. We measured DOC and nitrate concentrations in river water of six reaches of the lowland river Hampshire Avon (Wiltshire, southern UK) in order to quantify the relationship between BFI (BFI) and DOC : nitrate molar ratios across contrasting geologies (Chalk, Greensand, and clay). We found a significant positive relationship between nitrate and BFI (p < 0. 0001), and a significant negative relationship between DOC and BFI (p < 0. 0001), resulting in a non-linear negative correlation between DOC : nitrate molar ratio and BFI. In the Hampshire Avon, headwater reaches which are underlain by clay and characterized by a more flashy hydrological regime are associated with DOC : nitrate ratios > 5 throughout the year, whilst groundwater-dominated reaches underlain by Chalk, with a high BFI have DOC : nitrate ratios in surface waters that are an order of magnitude lower (< 0.5). Our analysis also reveals significant seasonal variations in DOC : nitrate transport and highlights critical periods of nitrate export (e.g. winter in sub-catchments underlain by Chalk and Greensand, and autumn in drained, clay sub-catchments) when DOC : nitrate molar ratios are low, suggesting low potential for in-stream uptake of inorganic forms of nitrogen. Consequently, our study emphasizes the tight relationship between DOC and nitrate availability in agricultural catchments, and further reveals that this relationship is controlled to a great extent by the hydrological setting.

Impact of disinfection on drinking water biofilm bacterial community.

PubMed

Mi, Zilong; Dai, Yu; Xie, Shuguang; Chen, Chao; Zhang, Xiaojian

2015-11-01

Disinfectants are commonly applied to control the growth of microorganisms in drinking water distribution systems. However, the effect of disinfection on drinking water microbial community remains poorly understood. The present study investigated the impacts of different disinfectants (chlorine and chloramine) and dosages on biofilm bacterial community in bench-scale pipe section reactors. Illumina MiSeq sequencing illustrated that disinfection strategy could affect both bacterial diversity and community structure of drinking water biofilm. Proteobacteria tended to predominate in chloraminated drinking water biofilms, while Firmicutes in chlorinated and unchlorinated biofilms. The major proteobacterial groups were influenced by both disinfectant type and dosage. In addition, chloramination had a more profound impact on bacterial community than chlorination. Copyright © 2015. Published by Elsevier B.V.

Long-term trends in dissolved iron and DOC concentration linked to nitrate depletion in riparian soils

NASA Astrophysics Data System (ADS)

Musolff, Andreas; Selle, Benny; Fleckenstein, Jan H.; Oosterwoud, Marieke R.; Tittel, Jörg

2016-04-01

The instream concentrations of dissolved organic carbon (DOC) are rising in many catchments of the northern hemisphere. Elevated concentrations of DOC, mainly in the form of colored humic components, increase efforts and costs of drinking water purification. In this study, we evaluated a long-term dataset of 110 catchments draining into German drinking water reservoirs in order to assess sources of DOC and drivers of a potential long-term change. The average DOC concentrations across the wide range of different catchments were found to be well explained by the catchment's topographic wetness index. Higher wetness indices were connected to higher average DOC concentrations, which implies that catchments with shallow topography and pronounced riparian wetlands mobilize more DOC. Overall, 37% of the investigated catchments showed a significant long-term increase in DOC concentrations, while 22% exhibited significant negative trends. Moreover, we found that increasing trends in DOC were positively correlated to trends in dissolved iron concentrations at pH≤6 due to remobilization of DOC previously sorbed to iron minerals. Both, increasing trends in DOC and dissolve iron were found to be connected to decreasing trends and low concentrations of nitrate (below ~6 mg/L). This was especially observed in forested catchments where atmospheric N-depositions were the major source for nitrate availability. In these catchments, we also found long-term increases of phosphate concentrations. Therefore, we argue that dissolved iron, DOC and phosphate were jointly released under iron-reducing conditions when nitrate as a competing electron acceptor was too low in concentrations to prevent the microbial iron reduction. In contrast, we could not explain the observed increasing trends in DOC, iron and phosphate concentrations by the long-term trends of pH, sulfate or precipitation. Altogether this study gives strong evidence that both, source and long-term increases in DOC are

The disinfection of drinking water. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

The current status of theoretically possible methods for disinfecting drinking water is reviewed. The specific biocidal activity of each of the disinfectants is considered, as well as information (or lack of it) on the practical application and reliability of the methods.

Silver disinfection in water distribution systems

NASA Astrophysics Data System (ADS)

Silvestry Rodriguez, Nadia

Silver was evaluated as disinfectant to maintain water quality in water distribution system. It was used to inhibit growth of two opportunistic bacteria in planktonik form and in biofilm formation in Robbins devices with stainless steel and PVC surfaces. The results of this work show that silver is a potential secondary disinfectant to be used in water distribution systems.

Soil-solution partitioning of DOC in acid organic soils: Results from a UK field acidification and alkalization experiment

NASA Astrophysics Data System (ADS)

Oulehle, Filip; Jones, Timothy; Burden, Annette; Evans, Chris

2013-04-01

Dissolved organic carbon (DOC) is an important component of the global carbon (C) cycle and has profound impacts on water chemistry and metabolism in lakes and rivers. Reported increases of DOC concentration in surface waters across Europe and Northern America have been attributed to several drivers; from changing climate and land-use to eutrophication and declining acid deposition. The last of these suggests that acidic deposition suppressed the solubility of DOC, and that this historic suppression is now being reversed by reducing emissions of acidifying pollutants. We studied a set of four parallel acidification and alkalization experiments in organic rich soils which, after three years of manipulation, have shown clear soil solution DOC responses to acidity change. We tested whether these DOC concentration changes were related to changes in the acid/base properties of DOC. Based on laboratory determination of DOC site density (S.D. = amount of carboxylic groups per milligram DOC) and charge density (C.D. = organic acid anion concentration per milligram DOC) we found that the change in DOC soil-solution partitioning was tightly related to the change in degree of dissociation (α = C.D./S.D. ratio) of organic acids (R2=0.74, p<0.01). Carbon turnover in soil organic matter (SOM), determined by soil respiration and β-D-glucosidase enzyme activity measurements, also appears to have some impact on DOC leaching, via constraints on the actual supply of available DOC from SOM; when the turnover rate of C in SOM is low, the effect of α on DOC leaching is reduced. Thus, differences in the magnitude of DOC changes seen across different environments might be explained by interactions between physicochemical restrictions of DOC soil-solution partitioning, and SOM carbon turnover effects on DOC supply.

Bacterial Spores Survive Treatment with Commercial Sterilants and Disinfectants

PubMed Central

Sagripanti, Jose-Luis; Bonifacino, Aylin

1999-01-01

This study compared the activity of commercial liquid sterilants and disinfectants on Bacillus subtilis spores deposited on three types of devices made of noncorrodible, corrodible, or polymeric material. Products like Renalin, Exspor, Wavicide-01, Cidexplus, and cupric ascorbate were tested under conditions specified for liquid sterilization. These products, at the shorter times indicated for disinfection, and popular disinfectants, like Clorox, Cavicide, and Lysol were also studied. Data obtained with a sensitive and quantitative test suggest that commercial liquid sterilants and disinfectants are less effective on contaminated surfaces than generally acknowledged. PMID:10473448

Bacterial spores survive treatment with commercial sterilants and disinfectants.

PubMed

Sagripanti, J L; Bonifacino, A

1999-09-01

This study compared the activity of commercial liquid sterilants and disinfectants on Bacillus subtilis spores deposited on three types of devices made of noncorrodible, corrodible, or polymeric material. Products like Renalin, Exspor, Wavicide-01, Cidexplus, and cupric ascorbate were tested under conditions specified for liquid sterilization. These products, at the shorter times indicated for disinfection, and popular disinfectants, like Clorox, Cavicide, and Lysol were also studied. Data obtained with a sensitive and quantitative test suggest that commercial liquid sterilants and disinfectants are less effective on contaminated surfaces than generally acknowledged.

Silver-based Antibacterial Surfaces for Drinking Water Disinfection - An overview

EPA Science Inventory

Risks associated with current disinfection techniques, including the formation of disinfection by-products and multi-drug resistant bacterial species, have prompted the exploration of advanced disinfection methods. One such technique employs silver nanoparticles incorporation on ...

Efficacy of a variety of disinfectants against Listeria spp.

PubMed

Best, M; Kennedy, M E; Coates, F

1990-02-01

The efficacy of 14 disinfectants against Listeria innocua and two strains of Listeria monocytogenes in the presence of organic matter was studied. Quantitative efficacy tests were used. Many of the disinfectants tested were not as effective on Listeria spp. when the test organisms were dried onto the surface of steel disks (carrier tests) as they were when the organisms were placed in suspension (suspension test). The presence of whole serum and milk (2% fat) further reduced the disinfectant capacities of most of the formulations studied. Only three disinfectants (povidone-iodine, chlorhexidine gluconate, and glutaraldehyde) were effective in the carrier test in the presence of serum; however, all three were ineffective when challenged with milk (2% fat). Only one solution, sodium dichloroisocyanurate, was effective in the presence of milk. All but four formulations (chloramine-T, phosphoric acid, an iodophor, and formaldehyde) were effective in the suspension tests, regardless of the organic load. L. monocytogenes was observed to be slightly more resistant to disinfection than L. innocua was. There was no difference in disinfectant susceptibility between the two strains of L. monocytogenes. These findings emphasize the need for caution in selecting an appropriate disinfectant for use on contaminated surfaces, particularly in the presence of organic material.

Nanosilver as a disinfectant in dental unit waterlines ...

EPA Pesticide Factsheets

Dental unit water lines (DUWL) are susceptible to biofilm development and bacterial growth leading to water contamination, causing health and ecological effects. This study monitors the interactions between a commonly used nanosilver disinfectant (ASAP-AGX-32, an antimicrobial cleaner for dental units, 0.0032% Ag) and biofilm development in DUWL. To simulate the disinfection scenario, an in-house DUWL model was assembled and biofilm accumulation was allowed. Subsequent to biofilm development, the disinfection process was performed according to the manufacturer's instructions. The pristine nanosilver particles in the cleaner measured between 3 and 5 nm in diameter and were surrounded by a stabilizing polymer. However, the polymeric stabilizing agent diminished over the disinfection process, initiating partial AgNPs aggregation. Furthermore, surface speciation of the pristine AgNPs were identified as primarily AgO, and after the disinfection process, transformations to AgCl were observed. The physicochemical characteristics of AgNPs are known to govern their fate, and transport and environmental implications. Hence, knowledge of the AgNPs characteristics after the disinfection process (usage scenario) is of significance. This study demonstrates the adsorption of AgNPs onto biofilm surfaces and, therefore, will assist in illustration of the toxicity mechanisms of AgNPs to bacteria and biofilms. This work can be an initial step in better understanding how

Solar Fenton and solar TiO2 catalytic treatment of ofloxacin in secondary treated effluents: evaluation of operational and kinetic parameters.

PubMed

Michael, I; Hapeshi, E; Michael, C; Fatta-Kassinos, D

2010-10-01

Two different technical approaches based on advanced oxidation processes (AOPs), solar Fenton homogeneous photocatalysis (hv/Fe(2+)/H(2)O(2)) and heterogeneous photocatalysis with titanium dioxide (TiO(2)) suspensions were studied for the chemical degradation of the fluoroquinolone ofloxacin in secondary treated effluents. A bench-scale solar simulator in combination with an appropriate photochemical batch reactor was used to evaluate and select the optimal oxidation conditions of ofloxacin spiked in secondary treated domestic effluents. The concentration profile of the examined substrate during degradation was determined by UV/Vis spectrophotometry. Mineralization was monitored by measuring the dissolved organic carbon (DOC). The concentrations of Fe(2+) and H(2)O(2) were the key factors for the solar Fenton process, while the most important parameter of the heterogeneous photocatalysis was proved to be the catalyst loading. Kinetic analyses indicated that the photodegradation of ofloxacin can be described by a pseudo-first-order reaction. The rate constant (k) for the solar Fenton process was determined at different Fe(2+) and H(2)O(2) concentrations whereas the Langmuir-Hinshelwood (LH) kinetic expression was used to assess the kinetics of the heterogeneous photocatalytic process. The conversion of ofloxacin depends on several parameters based on the various experimental conditions, which were investigated. A Daphnia magna bioassay was used to evaluate the potential toxicity of the parent compound and its photo-oxidation by-products in different stages of oxidation. In the present study solar Fenton has been demonstrated to be more effective than the solar TiO(2) process, yielding complete degradation of the examined substrate and DOC reduction of about 50% in 30 min of the photocatalytic treatment. Copyright © 2010 Elsevier Ltd. All rights reserved.

Z-DOC: a serious game for Z-plasty procedure training.

PubMed

Shewaga, Robert; Knox, Aaron; Ng, Gary; Kapralos, Bill; Dubrowski, Adam

2013-01-01

We present Z-DOC, a (prototype) serious game for training plastic surgery residents the steps comprising the Z-plasty surgical procedure. Z-DOC employs touch-based interactions and promotes competition amongst multiple players/users thus promote engagement and motivation. It is hypothesized that by learning the Z-plasty procedure in an interactive, engaging, and fun gaming environment, trainees will have a much better understanding of the procedure than by traditional learning modalities.

Robust evaluation of performance monitoring options for ozone disinfection in water recycling using Bayesian analysis.

PubMed

Carvajal, Guido; Branch, Amos; Michel, Philipp; Sisson, Scott A; Roser, David J; Drewes, Jörg E; Khan, Stuart J

2017-11-01

Ozonation of wastewater has gained popularity because of its effectiveness in removing colour, UV absorbance, trace organic chemicals, and pathogens. Due to the rapid reaction of ozone with organic compounds, dissolved ozone is often not measurable and therefore, the common disinfection controlling parameter, concentration integrated over contact time (CT) cannot be obtained. In such cases, alternative parameters have been shown to be useful as surrogate measures for microbial removal including change in UV 254 absorbance (ΔUVA), change in total fluorescence (ΔTF), or O 3 :TOC (or O 3 :DOC). Although these measures have shown promise, a number of caveats remain. These include uncertainties in the associations between these measurements and microbial inactivation. Furthermore, previous use of seeded microorganisms with higher disinfection sensitivity compared to autochthonous microorganisms could lead to overestimation of appropriate log credits. In our study, secondary treated wastewater from a full-scale plant was ozonated in a bench-scale reactor using five increasing ozone doses. During the experiments, removal of four indigenous microbial indicators representing viruses, bacteria and protozoa were monitored concurrent with ΔUVA, ΔTF, O 3 :DOC and PARAFAC derived components. Bayesian methods were used to fit linear regression models, and the uncertainty in the posterior predictive distributions and slopes provided a comparison between previously reported results and those reported here. Combined results indicated that all surrogate parameters were useful in predicting the removal of microorganisms, with a better fit to the models using ΔUVA, ΔTF in most cases. Average adjusted determination coefficients for fitted models were high (R 2 adjusted >0.47). With ΔUVA, one unit decrease in LRV corresponded with a UVA mean reduction of 15-20% for coliforms, 59% for C. perfringens spores, and 11% for somatic coliphages. With ΔTF, a one unit decrease in LRV

ULTRAVIOLET DISINFECTION STUDIES WITH CCL LISTED MICROORGANISMS

EPA Science Inventory

Resistance to ultraviolet (UV) disinfection is an essential aspect regarding all microbial groups listed on the CCL. The U.S. drinking water industry is interested in including UV light treatment as an amendment to conventional treatment for disinfecting water supplies. UV disi...

Ultraviolet (UV) Disinfection for Drinking Water Systems

EPA Science Inventory

UV disinfection is an effective process for inactivating many microbial pathogens in water with potential to serve as stand-alone treatment or in combination with other disinfectants. USEPA provided guidance on the validation of UV reactors nearly a decade ago. Since then, lesson...

The Next Generation of Disinfection By-Products

EPA Science Inventory

The disinfection of drinking water has been rightly hailed as a public health triumph of the 20th century. Millions of people worldwide receive quality drinking water every day from their public water systems. However, chemical disinfection has also produced an unintended health ...

Clinical and cost effectiveness of eight disinfection methods for terminal disinfection of hospital isolation rooms contaminated with Clostridium difficile 027.

PubMed

Doan, L; Forrest, H; Fakis, A; Craig, J; Claxton, L; Khare, M

2012-10-01

Clostridium difficile spores can survive in the environment for months or years, and contaminated environmental surfaces are important sources of nosocomial C. difficile transmission. To compare the clinical and cost effectiveness of eight C. difficile environmental disinfection methods for the terminal cleaning of hospital rooms contaminated with C. difficile spores. This was a novel randomized prospective study undertaken in three phases. Each empty hospital room was disinfected, then contaminated with C. difficile spores and disinfected with one of eight disinfection products: hydrogen peroxide vapour (HPV; Bioquell Q10) 350-700 parts per million (ppm); dry ozone at 25 ppm (Meditrox); 1000 ppm chlorine-releasing agent (Actichlor Plus); microfibre cloths (Vermop) used in combination with and without a chlorine-releasing agent; high temperature over heated dry atomized steam cleaning (Polti steam) in combination with a sanitizing solution (HPMed); steam cleaning (Osprey steam); and peracetic acid wipes (Clinell). Swabs were inoculated on to C. difficile-selective agar and colony counts were performed pre and post disinfection for each method. A cost-effectiveness analysis was also undertaken comparing all methods to the current method of 1000 ppm chlorine-releasing agent (Actichlor Plus). Products were ranked according to the log(10) reduction in colony count from contamination phase to disinfection. The three statistically significant most effective products were hydrogen peroxide (2.303); 1000 ppm chlorine-releasing agent (2.223) and peracetic acid wipes (2.134). The cheaper traditional method of using a chlorine-releasing agent for disinfection was as effective as modern methods. Copyright © 2012 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

Overcoming the problem of residual microbial contamination in dental suction units left by conventional disinfection using novel single component suction handpieces in combination with automated flood disinfection.

PubMed

Boyle, M A; O'Donnell, M J; Russell, R J; Galvin, N; Swan, J; Coleman, D C

2015-10-01

Decontaminating dental chair unit (DCU) suction systems in a convenient, safe and effective manner is problematic. This study aimed to identify and quantify the extent of the problems using 25 DCUs, methodically eliminate these problems and develop an efficient approach for reliable, effective, automated disinfection. DCU suction system residual contamination by environmental and human-derived bacteria was evaluated by microbiological culture following standard aspiration disinfection with a quaternary ammonium disinfectant or alternatively, a novel flooding approach to disinfection. Disinfection of multicomponent suction handpieces, assembled and disassembled, was also studied. A prototype manual and a novel automated Suction Tube Cleaning System (STCS) were developed and tested, as were novel single component suction handpieces. Standard aspiration disinfection consistently failed to decontaminate DCU suction systems effectively. Semi-confluent bacterial growth (101-500 colony forming units (CFU) per culture plate) was recovered from up to 60% of suction filter housings and from up to 19% of high and 37% of low volume suction hoses. Manual and automated flood disinfection of DCU suction systems reduced this dramatically (ranges for filter cage and high and low volume hoses of 0-22, 0-16 and 0-14CFU/plate, respectively) (P<0.0001). Multicomponent suction handpieces could not be adequately disinfected without prior removal and disassembly. Novel single component handpieces, allowed their effective disinfection in situ using the STCS, which virtually eliminated contamination from the entire suction system. Flood disinfection of DCU suction systems and single component handpieces radically improves disinfection efficacy and considerably reduces potential cross-infection and cross-contamination risks. DCU suction systems become heavily contaminated during use. Conventional disinfection does not adequately control this. Furthermore, multicomponent suction handpieces

Impact of managed moorland burning on DOC concentrations in soil solutions and stream waters

NASA Astrophysics Data System (ADS)

Palmer, Sheila; Wearing, Catherine; Johnson, Kerrylyn; Holden, Joseph; Brown, Lee

2013-04-01

In the UK uplands, prescribed burning of moorland vegetation is a common practice to maintain suitable habitats for game birds. Many of these landscapes are in catchments covered by significant deposits of blanket peat (typically one metre or more in depth). There is growing interest in the effect of land management on the stability of these peatland carbon stores, and their contribution to dissolved and particulate organic carbon in surface waters (DOC and POC, respectively) and subsequent effects on stream biogeochemistry and ecology. Yet there are surprisingly few published catchment-scale studies on the effect of moorland burning on DOC and POC. As part of the EMBER project, stream chemistry data were collected approximately monthly in ten upland blanket peat catchments in the UK, five of which acted as controls and were not subject to burning. The other five catchments were subject to a history of prescribed burning, typically in small patches (300-900 m2) in rotations of 8-25 years. Soil solution DOC was also monitored at four depths at two intensively studied sites (one regularly burned and one control). At the two intensive sites, soil solution DOC was considerably higher at the burned site, particularly in surface solutions where concentrations in excess of 100 mg/L were recorded on several occasions (median 37 mg/L over 18 months). The high soil solution DOC concentrations at the burned site occurred in the most recently burned plots (less than 2 years prior to start of sampling) and the lowest DOC concentrations were observed in plots burned 15-25 years previously. On average, median stream DOC and POC concentrations were approximately 43% and 35% higher respectively in burned catchments relative to control catchments. All streams exhibited peak DOC in late summer/early autumn with higher peak DOC concentrations in burned catchments (20-66 mg/L) compared to control catchments (18-54 mg/L). During winter months, DOC concentrations were low in control

Disinfection byproduct precursor dynamics and water treatability during an extreme flooding event in a coastal blackwater river in southeastern United States.

PubMed

Ruecker, A; Uzun, H; Karanfil, T; Tsui, M T K; Chow, A T

2017-12-01

Coastal blackwater rivers, characterized by high concentrations of natural organic matter, are source water for millions of people in the southeastern US. In October 2015, large areas of coastal South Carolina were flooded by Hurricane Joaquin. This so-called "thousand-year" rainfall mobilized and flushed large amounts of terrestrial organic matter and associated pollutants (e.g. mercury) into source water, affecting water quality and safety of municipal water supply. To understand the dynamics of water quality and water treatability during this extreme flood, water samples were collected from Waccamaw River (a typical blackwater river in the southeastern US) during rising limb, peak discharge, falling limb, and base flow. Despite decreasing water flow after peak discharge, dissolved organic carbon (DOC) levels (increased by up to 125%), and formation potentials of trihalomethanes and haloacetic acids (increased by up to 150%) remained high for an extended period of time (>eight weeks after peak discharge), while variation in the N-nitrosodimethylamine (NDMA) FP was negligible. Coagulation with alum and ferric at optimal dosage significantly reduced concentrations of DOC by 51-76%, but up to 10 mg/L of DOC still remained in treated waters. For an extended period of time, elevated levels of THMs (71-448 μg/L) and HAAs (88-406 μg/L) were quantified in laboratory chlorination experiments under uniform formation conditions (UFC), exceeding the United States Environmental Protection Agency's (USEPA) maximum contaminant level of 80 and 60 μg/L, respectively. Results demonstrated that populations in coastal cities are at high risk with disinfection by-products (DBPs) under the changing climate. Copyright © 2017 Elsevier Ltd. All rights reserved.

UV Disinfection of Wastewater and Combined Sewer Overflows.

PubMed

Gibson, John; Drake, Jennifer; Karney, Bryan

2017-01-01

Municipal wastewater contains bacteria, viruses, and other pathogens that adversely affect the environment, human health, and economic activity. One way to mitigate these effects is a final disinfection step using ultraviolet light (UVL). The advantages of UVL disinfection, when compared to the more traditional chlorine, include no chlorinated by-products, no chemical residual, and relatively compact size. The design of most UV reactors is complex. It involves lamp selection, power supply design, optics, and hydraulics. In general, medium pressure lamps are more compact, powerful, and emit over a wider range of light than the more traditional low pressure lamps. Low pressure lamps, however, may be electrically more efficient. In UV disinfection, the fraction of surviving organisms (e.g. E. coli) will decrease exponentially with increasing UV dose. However, the level of disinfection that can be achieved is often limited by particle-associated organisms. Efforts to remove or reduce the effects of wastewater particles will often improve UV disinfection effectiveness. Regrowth, photoreactivation, or dark repair after UV exposure are sometimes cited as disadvantages of UV disinfection. Research is continuing in this area, however there is little evidence that human pathogens can photoreactivate in environmental conditions, at doses used in wastewater treatment. The UV disinfection of combined sewer overflows, a form of wet weather pollution, is challenging and remains largely at the research phase. Pre-treatment of combined sewer overflows (CSOs) with a cationic polymer to induce fast settling, and a low dose of alum to increase UV transmittance, has shown promise at the bench scale.

Synergistic integration of sonochemical and electrochemical disinfection with DSA anodes.

PubMed

Cotillas, Salvador; Llanos, Javier; Castro-Ríos, Katherin; Taborda-Ocampo, Gonzalo; Rodrigo, Manuel A; Cañizares, Pablo

2016-11-01

This work focuses on the disinfection actual urban wastewater by the combination of ultrasound (US) irradiation and electrodisinfection with Dimensionally Stable Anodes (DSA). First, the inactivation of Escherichia coli (E. coli) during the sonochemical disinfection was studied at increasing ultrasound power. Results showed that it was not possible to achieve a complete disinfection, even at the highest US power (200 W) dosed by the experimental device used. Next, the electrodisinfection with DSA anodes at different current densities was studied, finding that it was necessary a minimum current density of 11.46 A m(-2) to reach the complete disinfection. Finally, an integrated sonoelectrodisinfection process was studied. Results showed a synergistic effect when coupling US irradiation with DSA electrodisinfection, with a synergy coefficient higher than 200% of the disinfection rate attained for the highest US power applied. In this process, hypochlorite and chloramines were identified as the main reagents for the disinfection process (neither chlorate nor perchlorate were detected), and the presence of trihalomethanes was far below acceptable values. Confirming this synergistic effect with DSA anodes opens the door to novel efficient disinfection processes, limiting the occurrence of hazardous disinfection by-products. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effectiveness of disinfectants used in cooling towers against Legionella pneumophila.

PubMed

García, M T; Pelaz, C

2008-01-01

Legionella persists in man-made aquatic installations despite preventive treatments. More information about disinfectants could improve the effectiveness of treatments. This study tests the susceptibility of Legionella pneumophila serogroup (sg) 1 against 8 disinfectants used in cooling tower treatments. We determined the minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC) and bactericidal effect of sodium hypochlorite (A), hydrogen peroxide with silver nitrate (B), didecyldimethylammonium chloride (C), benzalkonium chloride (D), tributyltetradecylphosphonium chloride (E), tetrahydroxymethylphosphonium sulfide (F), 2,2-dibromonitropropionamide (G) and chloromethylisothiazolone (H) against 28 L. pneumophila sg 1 isolates. MIC and MBC values were equivalent. Bacteria are less susceptible to disinfectants F, B, D and A than to H, E, C and G. All disinfectants induced a bactericidal effect. The effect rate is dose dependent for G, H, F and B; the effect is fast for the rest of disinfectants at any concentration. The bactericidal activity of disinfectants A, G and F depends on the susceptibility test used. All disinfectants have bactericidal activity against L. pneumophila sg 1 at concentrations used in cooling tower treatments. Results depend on the assay for some products.

CHLORINE DISINFECTION STUDIES OF ENCEPHALITOZOON (SEPTATA) INTESTINALIS

EPA Science Inventory

A reproducible standardized assay was designed to determine two infective doses for E.intestinalis, the TCID50 and the MID. These doses can be used to assess the potential effectiveness of chlorine disinfection and can also be used to assess other disinfection parameters and ant...

Process Inference from High Frequency Temporal Variations in Dissolved Organic Carbon (DOC) Dynamics Across Nested Spatial Scales

NASA Astrophysics Data System (ADS)

Tunaley, C.; Tetzlaff, D.; Lessels, J. S.; Soulsby, C.

2014-12-01

In order to understand aquatic ecosystem functioning it is critical to understand the processes that control the spatial and temporal variations in DOC. DOC concentrations are highly dynamic, however, our understanding at short, high frequency timescales is still limited. Optical sensors which act as a proxy for DOC provide the opportunity to investigate near-continuous DOC variations in order to understand the hydrological and biogeochemical processes that control concentrations at short temporal scales. Here we present inferred 15 minute stream water DOC data for a 12 month period at three nested scales (1km2, 3km2 and 31km2) for the Bruntland Burn, a headwater catchment in NE Scotland. High frequency data were measured using FDOM and CDOM probes which work by measuring the fluorescent component and coloured component, respectively, of DOC when exposed to ultraviolet light. Both FDOM and CDOM were strongly correlated (r2 >0.8) with DOC allowing high frequency estimations. Results show the close coupling of DOC with discharge throughout the sampling period at all three spatial scales. However, analysis at the event scale highlights anticlockwise hysteresis relationships between DOC and discharge due to the delay in DOC being flushed from the increasingly large areas of peaty soils as saturation zones expand and increase hydrological connectivity. Lag times vary between events dependent on antecedent conditions. During a 10 year drought period in late summer 2013 it was apparent that very small changes in discharge on a 15 minute timescale result in high increases in DOC. This suggests transport limitation during this period where DOC builds up in the soil and is not flushed regularly, therefore any subsequent increase in discharge results in large DOC peaks. The high frequency sensors also reveal diurnal variability during summer months related to the photo-oxidation, evaporative and biological influences of DOC during the day. This relationship is less

Sterilization, high-level disinfection, and environmental cleaning.

PubMed

Rutala, William A; Weber, David J

2011-03-01

Failure to perform proper disinfection and sterilization of medical devices may lead to introduction of pathogens, resulting in infection. New techniques have been developed for achieving high-level disinfection and adequate environmental cleanliness. This article examines new technologies for sterilization and high-level disinfection of critical and semicritical items, respectively, and because semicritical items carry the greatest risk of infection, the authors discuss reprocessing semicritical items such as endoscopes and automated endoscope reprocessors, endocavitary probes, prostate biopsy probes, tonometers, laryngoscopes, and infrared coagulation devices. In addition, current issues and practices associated with environmental cleaning are reviewed. Copyright © 2011. Published by Elsevier Inc.

Chlorine disinfection of grey water for reuse: effect of organics and particles.

PubMed

Winward, Gideon P; Avery, Lisa M; Stephenson, Tom; Jefferson, Bruce

2008-01-01

Adequate disinfection of grey water prior to reuse is important to prevent the potential transmission of disease-causing microorganisms. Chlorine is a widely utilised disinfectant and as such is a leading contender for disinfection of grey water intended for reuse. This study examined the impact of organics and particles on chlorine disinfection of grey water, measured by total coliform inactivation. The efficacy of disinfection was most closely linked with particle size. Larger particles shielded total coliforms from inactivation and disinfection efficacy decreased with increasing particle size. Blending to extract particle-associated coliforms (PACs) following chlorine disinfection revealed that up to 91% of total coliforms in chlorinated grey water were particle associated. The organic concentration of grey water affected chlorine demand but did not influence the disinfection resistance of total coliforms when a free chlorine residual was maintained. Implications for urban water reuse are discussed and it is recommended that grey water treatment systems target suspended solids removal to ensure removal of PACs prior to disinfection.

Temperature sensitivity of DOC production and transformation in organic soils of the Yukon River Basin, Alaska

NASA Astrophysics Data System (ADS)

O'Donnell, J.; Butler, K. D.; Aiken, G.

2012-12-01

The flux of dissolved organic carbon (DOC) from terrestrial to aquatic ecosystems represents a critical component of the high-latitude carbon balance. In the Yukon River basin (YRB), DOC fluxes have declined in recent decades, likely in response to regional permafrost thaw and increased groundwater discharge to river flow. Despite improved flux estimates for many arctic rivers, considerable uncertainty exists regarding the potential response of DOC fluxes to projected warming. To improve estimates of future DOC dynamics, it is important to develop a process-based approach whereby empirical constraints are placed on source and sink terms in both soil and river systems. Here, we examine variability in DOC production and microbially mediated transformations as a function of both temperature and organic matter (OM) composition in soils of the YRB. We conducted "tea" experiments by incubating three organic-soil types that vary with depth and decomposition extent (live/dead moss, fibric OM and humic OM) at two temperatures (4 vs. 20 °C). Leachate samples were collected periodically over a 30-day incubation and characterized for DOC concentration, optical properties (specific UV absorbance at 254 nm or SUVA254, fluorescence), and major chemical fractions using XAD8/XAD4 resins. We observed a non-linear increase in DOC production over time, characterized by a rapid initial release of DOC from soils followed by a slower rise in DOC concentration in subsequent weeks. Mean DOC concentration was described by a significant interaction between organic-soil type and temperature, indicating a strong relationship between temperature sensitivity of net DOC production and the decomposition extent of soil OM. On average across all sampling dates, DOC concentrations were highest in leachate from fibric OM (13.4 to 17.8 mgC L-1), and lowest in leachate from humic OM (3.5 to 8.5 mgC L-1). However, the temperature sensitivity of net DOC production was highest in the humic OM treatment

Characterization of soluble microbial products as precursors of disinfection byproducts in drinking water supply.

PubMed

Liu, Jin-Lin; Li, Xiao-Yan; Xie, Yue-Feng; Tang, Hao

2014-02-15

Water pollution by wastewater discharge can cause the problem of disinfection byproducts (DBPs) in drinking water supply. In this study, DBP formation characteristics of soluble microbial products (SMPs) as the main products of wastewater organic biodegradation were investigated. The results show that SMPs can act as DBP precursors in simulated wastewater biodegradation process. Under the experimental conditions, stabilized SMPs had DBPFP (DBP formation potential) yield of around 5.6 μmol mmol(-1)-DOC (dissolved organic carbon) and DBP speciation profile different from that of the conventional precursor, natural organic matter (NOM). SMPs contained polysaccharides, proteins, and humic-like substances, and the latter two groups can act as reactive DBP precursors. SMP fraction with molecular weight of <1 kDa accounted for 85% of the organic carbon and 65% of the DBP formation. As small SMP molecules are more difficult to remove by conventional water treatment processes, more efforts are needed to control wastewater-derived DBP problem in water resource management. Copyright © 2013 Elsevier B.V. All rights reserved.

Effectiveness of disinfectant treatments for inactivating Piscirickettsia salmonis.

PubMed

Muniesa, A; Escobar-Dodero, J; Silva, N; Henríquez, P; Bustos, P; Perez, A M; Mardones, F O

2018-03-08

This short communication investigated in vitro differences between commercial disinfectants types (n = 36), doses of application, and time of action in the elimination of Piscirickettsia salmonis, the most important bacterium affecting farmed salmon in Chile. Seven different treatments were examined, including active and inactive chlorine dioxides, glutaraldehyde, hypochlorite disinfectants and detergents, peracetic acid, peroxides and other miscellaneous methods A 3 replicate set of each of the sample groups was stored at 20 °C and 95% relative humidity and retested after 1, 5 and 30 min with varying doses (low, recommended and high doses). Multiple comparison tests were performed for the mean log CFU/ml among different disinfectant types, dose (ppm) and time of exposure (minutes) on the reduction of P. salmonis. Overall, disinfection using peracetic acid, peroxides, and both active and inactive chlorine dioxides caused significantly higher reduction of >7.5 log CFU/ml in samples, compared to other tested sanitizers. The lowest reduction was obtained after disinfection with hypochlorite detergents. As expected, as doses and time of action increase, there was a significant reduction of the overall counts of P. salmonis. However, at lowest doses, only use of paracetic acids resulted in zero counts. Implementation of effective protocols, making use of adequate disinfectants, may enhance biosecurity, and ultimately, mitigate the impact of P. salmonis in farmed salmon. Copyright © 2018. Published by Elsevier B.V.

Disinfection and Sterilization in Health Care Facilities: An Overview and Current Issues.

PubMed

Rutala, William A; Weber, David J

2016-09-01

When properly used, disinfection and sterilization can ensure the safe use of invasive and noninvasive medical devices. The method of disinfection and sterilization depends on the intended use of the medical device: critical items (contact sterile tissue) must be sterilized before use; semicritical items (contact mucous membranes or nonintact skin) must be high-level disinfected; and noncritical items (contact intact skin) should receive low-level disinfection. Cleaning should always precede high-level disinfection and sterilization. Current disinfection and sterilization guidelines must be strictly followed. Copyright © 2016 Elsevier Inc. All rights reserved.

ToxicDocs (www.ToxicDocs.org): from history buried in stacks of paper to open, searchable archives online.

PubMed

Rosner, David; Markowitz, Gerald; Chowkwanyun, Merlin

2018-02-01

As a result of a legal mechanism called discovery, the authors accumulated millions of internal corporate and trade association documents related to the introduction of new products and chemicals into workplaces and commerce. What did these private entities discuss among themselves and with their experts? The plethora of documents, both a blessing and a curse, opened new sources and interesting questions about corporate and regulatory histories. But they also posed an almost insurmountable challenge to historians. Thus emerged ToxicDocs, possible only with a technological innovation known as "Big Data." That refers to the sheer volume of new digital data and to the computational power to analyze them. Users will be able to identify what firms knew (or did not know) about the dangers of toxic substances in their products-and when. The database opens many areas to inquiry including environmental studies, business history, government regulation, and public policy. ToxicDocs will remain a resource free and open to all, anywhere in the world.

9 CFR 52.7 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Disinfection of premises, conveyances... SWINE DESTROYED BECAUSE OF PSEUDORABIES § 52.7 Disinfection of premises, conveyances, and materials. All... cleaning and disinfection, unless an official pseudorabies epidemiologist determines that a shorter or...

9 CFR 52.7 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Disinfection of premises, conveyances... SWINE DESTROYED BECAUSE OF PSEUDORABIES § 52.7 Disinfection of premises, conveyances, and materials. All... cleaning and disinfection, unless an official pseudorabies epidemiologist determines that a shorter or...

9 CFR 52.7 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Disinfection of premises, conveyances... SWINE DESTROYED BECAUSE OF PSEUDORABIES § 52.7 Disinfection of premises, conveyances, and materials. All... cleaning and disinfection, unless an official pseudorabies epidemiologist determines that a shorter or...

9 CFR 52.7 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Disinfection of premises, conveyances... SWINE DESTROYED BECAUSE OF PSEUDORABIES § 52.7 Disinfection of premises, conveyances, and materials. All... cleaning and disinfection, unless an official pseudorabies epidemiologist determines that a shorter or...

[Estimation of DOC concentrations using CDOM absorption coefficients: a case study in Taihu Lake].

PubMed

Jiang, Guang-Jia; Ma, Rong-Hua; Duan, Hong-Tao

2012-07-01

Dissolved organic carbon (DOC) is the largest organic carbon stock in water ecosystems, which plays an important role in the carbon cycle in water. Chromophoric dissolved organic matter (CDOM), an important water color variation, is the colored fraction of DOC and its absorption controls the instruction of light under water. The available linkage between DOC concentration and CDOM absorptions enables the determination of DOC accumulations using remote sensing reflectance or radiance in lake waters. The present study explored the multi-liner relationship between CDOM absorptions [a(g) (250) and a(g) (365)] and DOC concentrations in Taihu Lake, based on the available data in 4 cruises (201005, 201101, 201103, 201105) (totally 183 sampling sites). Meanwhile, the results were validated with the data of the experiment carried out from August 29 to September 2, 2011 in Taihu Lake (n = 27). Furthermore, a universal pattern of modeling from remote sensing was built for lake waters. The results demonstrated that this method provided more satisfying estimation of DOC concentrations in Taihu Lake. Except the data obtained in January 2011, the fitted results of which were not conductive to the winter dataset (201101) in Taihu Lake, due to the diverse sources and sinks of DOC and CDOM, the multi-liner relationship was robust for the data collected in the other three cruises (R2 = 0.64, RMSE = 14.31%, n = 164), which was validated using the 201108 sampling dataset (R2 = 0.67, RMSE = 10.58%, n = 27). In addition, the form of the statistic model is universal, to some extent, for other water areas, however, there is difference in the modeling coefficients. Further research should be focused on the parameterization using local data from different lakes, which provides effective methodology for the estimation of DOC concentrations in lakes and other water regions.

The effectiveness of photocatalytic ionisation disinfection of filter materials.

PubMed

Pietrzak, Katarzyna; Gutarowska, Beata

2013-01-01

The purpose of this study was to determine the effectiveness of photocatalytic ionisation as a disinfection method for filter materials contaminated by microorganisms, and to assess how air relative humidity (RH), time and microbe type influence the effectiveness of this disinfection. In the quantitative analysis of a used car air filter, bacterial contamination equalled 1.2 x 10(5) cfu/cm2, fungal contamination was 3.8 x 10(6) cfu/cm2, and the isolated microorganisms were Aspergillus niger, Bacillus megaterium, Cladosporium herbarum, Cryptococcus laurenti, Micrococcus sp., Rhodotorula glutinis and Staphylococcus cohnii. In the model experiment, three isolates (C. herbarum, R. glutinis, S. cohnii) and 3 ATCC species (A. niger, E. coli, S. aureus) were used for photocatalytic ionisation disinfection. The conditions of effective photocatalytic ionisation disinfection (R > or = 99.9%) were established as 2-3 h at RH = 77% (bacteria) and 6-24 h at RH = 53% (fungi). RH has an influence on the effectiveness of the photocatalytic disinfection process; the highest effectiveness was obtained for bacteria at RH = 77%, with results 5% higher than for RH = 49%. The studies show that the sensitivity of microorganisms to photocatalytic ionisation disinfection is ordered as follows: Gram-positive bacteria (S. cohnii, S. aureus), Gram-negative bacteria (E. coli), yeasts (R. glutinis), and moulds (C. herbarum, A. niger). Of all the mathematical models used for the description of death dynamics after photocatalytic ionisation disinfection, the Chick-Watson model is the most useful, but for more resistant microorganisms, the delayed Chick-Watson model is highly recommended. It therefore seems, that the presented disinfection method of photocatalytic ionisation can be successfully used to clean filtration materials.

Implementing Gmail Docs and Blogs for Enhancing Motivation towards Writing in English

ERIC Educational Resources Information Center

Gomez Zapata, Julian Esteban

2010-01-01

This action research paper dealt with how to increase motivation towards writing in English through blogs and Gmail docs in a private school in Medellín, Colombia. It was necessary to explore the concepts of "social interaction," "motivation" and "reasons for writing" to understand how blogs and Gmail docs favored…

Solar photo-oxidative disinfection of drinking water: preliminary field observations.

PubMed

Reed, R H; Mani, S K; Meyer, V

2000-06-01

The feasibility of using solar photo-oxidation to inactivate faecal bacterial contaminants in drinking water has been evaluated under field conditions in India and South Africa. Freshly drawn samples from all six test water sources were low in dissolved oxygen, at 13-40% of the air saturation value. However, vigorous mixing followed by exposure to full-strength sunlight in transparent plastic containers (1-25 l capacity) caused a rapid decrease in the counts of faecal indicator bacteria, giving complete inactivation within 3-6 h, with no evidence of reactivation. These results demonstrate that solar photo-oxidation may provide a practical, low-cost approach to the improvement of drinking water quality in developing countries with consistently sunny climates.

9 CFR 53.7 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2010 CFR

2010-01-01

... least 7 days following such cleaning and disinfection, unless the Administrator determines that a... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Disinfection of premises, conveyances... LIVESTOCK OR POULTRY § 53.7 Disinfection of premises, conveyances, and materials. All premises, including...

Carbon Isotope Composition as an Indicator of DOC Sources to a Stream During Events in a Temperate Forested Catchment

NASA Astrophysics Data System (ADS)

Doctor, D. H.; Sebestyen, S. D.; Aiken, G. R.; Shanley, J. B.; Kendall, C.; Boyer, E. W.

2006-12-01

Increased DOC flux in streams and rivers is commonly observed during high runoff regimes, however DOC concentrations alone do not provide information about multiple sources or pathways of DOC to streams. In an effort to gain this information, we measured DOC concentrations and stable carbon isotope composition (δ13C-DOC) on samples collected at high-frequency during events at Sleepers River Research Watershed in Vermont, USA. During snowmelt and storm events, peaks in stream DOC concentration (up to 10.5 mg/L) were coincident with peaks in flow. Stream water δ13C-DOC measurements ranged between -23.7‰ and - 28.9‰ and indicated changing sources of DOC during events; the highest δ13C-DOC values occurred consistently at the lowest flows, and the lowest δ13C-DOC values occurred with peaks in discharge. Water samples collected from shallow wells and stacked soil lysimeters showed the highest DOC concentrations in the most shallow (<0.5 m) lysimeter waters, and the lowest concentrations in the deeper (>1.5 m) well waters. Wells and lysimeters exhibited a range of δ13C-DOC values similar to those observed in the stream; however, samples collected from shallow horizons at nested wells and lysimeters consistently showed lower δ13C-DOC values than those from greater depths. Maple leaf litter collected from across the watershed provided an end-member of fresh organic material, with average δ13C composition of -31.3±0.7‰ (n=57), which is lower than the lowest measured DOC values in any of the stream, well, or lysimeter waters. A subset of stream waters were fractionated onto XAD4 and XAD8 resins; the hydrophobic acid fraction (XAD8) had consistently lower δ13C values than the transphilic acid fraction (XAD4), and both of these were lower than those of the bulk DOC. Samples with lower δ13C-DOC values also exhibited higher SUVA-254 values, i.e. greater aromaticity. Thus, lower δ13C-DOC values are interpreted as an indicator of relatively "fresh", more aromatic

The catheter hub disinfection cap as esophageal foreign body.

PubMed

Tawfik, Kareem O; Myer, Charles M; Shikary, Tasneem; Goldschneider, Kenneth R

2015-12-01

Disinfection caps are increasingly being used to prevent catheter-associated bloodstream infections. These devices, designed for continuous passive disinfection of catheter hubs, are typically small and often brightly colored. As such, they have the potential to become pediatric airway and esophageal foreign bodies. We report two patients who developed esophageal foreign body following ingestion of disinfection caps. Given the increasing use of these devices, it is imperative that health care providers be aware of this potential iatrogenic problem. We propose that the use of disinfection caps may not be appropriate in pediatric patients with risk factors for foreign body ingestion. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

Simultaneous control of microorganisms and disinfection by-products by sequential chlorination.

PubMed

Chen, Chao; Zhang, Xiao-Jian; He, Wen-Jie; Han, Hong-Da

2007-04-01

To introduce a new sequential chlorination disinfection process in which short-term free chlorine and chloramine are sequentially added. Pilot tests of this sequential chlorination were carried out in a drinking water plant. The sequential chlorination disinfection process had the same or better efficiency on microbe (including virus) inactivation compared with the free chlorine disinfection process. There seemed to be some synergetic disinfection effect between free chlorine and monochloramine because they attacked different targets. The sequential chlorination disinfection process resulted in 35.7%-77.0% TTHM formation and 36.6%-54.8% THAA5 formation less than the free chlorination process. The poorer the water quality was, the more advantage the sequential chlorination disinfection had over the free chlorination. This process takes advantages of free chlorine's quick inactivation of microorganisms and chloramine's low disinfection by-product (DBP) yield and long-term residual effect, allowing simultaneous control of microbes and DBPs in an effective and economic way.

Inactivation of fecal bacteria in drinking water by solar heating.

PubMed

Joyce, T M; McGuigan, K G; Elmore-Meegan, M; Conroy, R M

1996-02-01

We report simulations of the thermal effect of strong equatorial sunshine on water samples contaminated with high populations of fecal coliforms. Water samples, heavily contaminated with a wild-type strain of Escherichia coli (starting population = 20 x 10(5) CFU/ml), are heated to those temperatures recorded for 2-liter samples stored in transparent plastic bottles and exposed to full Kenyan sunshine (maximum water temperature, 55 degrees C). The samples are completely disinfected within 7 h, and no viable E. coli organisms are detected at either the end of the experiment or a further 12 h later, showing that no bacterial recovery has occurred. The feasibility of employing solar disinfection for highly turbid, fecally contaminated water is discussed.

Lens material and formulation of multipurpose solutions affects contact lens disinfection.

PubMed

Santos, Lívia; Oliveira, Rosário; Oliveira, M Elisabete C D Real; Azeredo, Joana

2011-08-01

To assess the disinfection efficacy of multipurpose solutions (MPS) against different bacterial species adhered either to silicon hydrogel or to conventional hydrogel contact lenses (CLs). The influences of the MPS formulation and the chemical composition of the lens material were investigated. This investigation followed the standard 14729, which establishes the guidelines for assessing CL disinfecting solutions. Two commercially available (Opti-Free(®) Express(®) and Renu(®) Multiplus) solutions and one recalled solution (Complete(®) MoisturePlus™) were used in this study. After disinfection, the number of survivors was estimated by the colony forming units' method. The lens material appears to influence disinfection. The conventional hydrogel polymacon exhibited the highest disinfection scores, a fact that should be related with the lack of electrostatic attraction towards the biocides and its hydrophilicity. The MPS formulation appears to have influence in disinfection efficacy as well. For most adhered bacteria, Opti-Free(®) was capable of reducing cell concentration in 4-log. Disinfection results from multivariate factors and this study confirmed that the lens material and the MPS play a very important role in the disinfection efficacy of CL. Copyright © 2011. Published by Elsevier Ltd.

Basic Information about Chloramines and Drinking Water Disinfection

EPA Pesticide Factsheets

Chloramines are disinfectants used to treat drinking water. Chloramines are most commonly formed when ammonia is added to chlorine to treat drinking water. Chloramines provide longer-lasting disinfection as the water moves through pipes to consumers.

9 CFR 51.8 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2010 CFR

2010-01-01

... facilities, conveyances, or other materials on the premises that would require such cleaning and disinfection... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Disinfection of premises, conveyances... ANIMALS DESTROYED BECAUSE OF BRUCELLOSIS Indemnity for Cattle, Bison, and Swine § 51.8 Disinfection of...

Greywater as a sustainable water source: A photocatalytic treatment technology under artificial and solar illumination.

PubMed

Tsoumachidou, Sophia; Velegraki, Theodora; Antoniadis, Apostolos; Poulios, Ioannis

2017-06-15

Greywater considers being a highly reclaimable water source particularly important for water-stressed nations. In this work, heterogeneous photocatalysis using artificial and solar illumination has been applied for the mineralization of simulated light greywater (effluents from dishwashers and kitchen sinks were excluded from the study). The effects on the process' efficiency of TiO 2 P25 catalyst's concentration, initial concentration of H 2 O 2 and Fe 3+ , pH of the solution, as well as the type of radiation, were evaluated in a bench-scale Pyrex reactor and a pilot-scale slurry fountain photoreactor. The treatment efficiency has been followed through the evolution of the organic matter content expresses as dissolved organic carbon (DOC). Best results were obtained with the photo-Fenton-assisted TiO 2 photocatalytic process with 72% DOC removal after 210 min of bench scale treatment, while under the same photocatalytic conditions in the pilot reactor the DOC removal reached almost 64%. Moreover, the decrease in toxicity, phytotoxicity and biodegradability of the simulated wastewater has been observed after solar-induced photocatalytic treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Neutralization efficiency of alcohol based products used for rapid hand disinfection

PubMed

Chojecka, Agnieszka; Tarka, Patryk; Kierzkowska, Anna; Nitsch-Osuch, Aneta; Kanecki, Krzysztof

Alcohols are the most commonly used active substances in preparations for quick hand disinfection. They should be bactericidal in very short contact time. PN-EN 13727 + A2: 2015-12 standard, for testing hygienic and surgical handrub disinfection preparations, provides mandatory test conditions of disinfectants in contact times with the range of 30 s to 60 s (hygienic handrub disinfection) and 60 s to 5 min (surgical handrub disinfection). A short contact times for hand hygiene products require a short time of neutralization process. For contact times less than or equal to 10 minutes, the estimated neutralization time is 10 s ± 1 s. Neutralization is a process that abolishes the action of disinfectants. Correct application of this process allows for proper use of disinfectants in practice and its biocidal effect. Objectives. Verification of the effectiveness of 10-second neutralization time of alcohol based preparations for hygienic handrub disinfection Neutralization of two products with different ethanol content (89% and 70%) for hygienic handrub disinfection according to PN-EN 13727 + A2: 2015-12 was investigated. The effectiveness of the neutralizer was assessed by determining toxicity of neutralizer, activity of residual effects of the tested products and their derivatives produced during neutralization (10 s) for test organisms (Staphylococcus aureus ATCC 6538; Pseudomonas aeruginosa ATCC 15442; Enterococcus hirae ATCC 10541; Escherichia coli K12 NCTC 10538) The 10-second neutralization time was sufficient to eliminate the residual activity of products for hygienic handrub disinfection with differentiated ethanol concentration. The neutralizer used did not show toxicity to bacteria and did not produce toxic products with tested preparations after neutralization Conclusions. The use of 10-second neutralization time allows in a precise way designate the contact times for hygienic handrub disinfection products

A Novel Source of DOC and DON to Watershed Soils

NASA Astrophysics Data System (ADS)

Aitkenhead-Peterson, J. A.

2017-12-01

A source of dissolved organic carbon (DOC) and nitrogen (DON) to soils and groundwater is that emanating from decomposing mammals. Although there is an increase in human donor facilities (body farms) in the USA and in mass mortality events (MME) worldwide, this injection of DOC and DON into watershed soils has received little attention. Studies at two human donor facilities in Texas, USA have revealed that the purge fluid associated with decomposition is extremely high in DOC and DON and migrates down the soil profile. Two studies were carried out 1) The southeast Texas Applied Forensic Science (STAFS) facility on an Alfisol with a saturated hydraulic conductivity of 331 mm hr-1 and 83% sand and 2) the Forensic Anthropology Research Facility (FARF) on Mollisols with a saturated hydraulic conductivity of 3.6-9.7 mm hr-1 and 28-33% sand. The numbers of days since donors were laid in the environment ranged from 219-680 d at STAFS and 306-960 d at FACTS. Purge can occur between 5 and 30 d dependent on the time of year the body is placed and the resultant phenomenon is termed cadaver decomposition island (CDI). Soil cores were taken at 5 cm increments to a depth of 30 cm in the sandy soil and 15 cm in the clayey/rocky soil. In the sandy soils, DOC concentrations were significantly higher in all the CDI soils when compared to control soils at depths of 15, 20, 25 and 30 cm and ranged from 121.7 µg g-1 (30 cm) to 167.6 µg g-1 (15 cm) in control soils and 461.9 µg g-1 (30 cm) to 660.4 µg g-1 (15 cm) in CDI soils, representing a three- to four-fold increase in DOC relative to control soils. DON in all CDI soils was not significantly higher than control soils until 30 cm depth and ranged from 9.9-32.3 µg g-1 in CDI soils and 121.7 µg g-1 in control soil, representing a two- to seven-fold increase in DON relative to control soils. DOC concentrations in control soils at the FARF site at 15 cm ranged 215-365 µg g-1 while in the CDI soils DOC was higher (range: 270

The History And Future Directions Of Biosolids Disinfection

EPA Science Inventory

This paper reviews the history of disinfection practices, emphasizing their application to human fecal material and the residuals from wastewater treatment. It discusses development of the current US sewage sludge disinfection regulations and their associated practices; discusse...

Chemical cleaning/disinfection and ageing of organic UF membranes: a review.

PubMed

Regula, C; Carretier, E; Wyart, Y; Gésan-Guiziou, G; Vincent, A; Boudot, D; Moulin, P

2014-06-01

Membrane separation processes have become a basic unit operation for process design and product development. These processes are used in a variety of separation and concentration steps, but in all cases, the membranes must be cleaned regularly to remove both organic and inorganic material deposited on the surface and/or into the membrane bulk. Cleaning/disinfection is a vital step in maintaining the permeability and selectivity of the membrane in order to get the plant to its original capacity, to minimize risks of bacteriological contamination, and to make acceptable products. For this purpose, a large number of chemical cleaning/disinfection agents are commercially available. In general, these cleaning/disinfection agents have to improve the membrane flux to a certain extent. However, they can also cause irreversible damages in membrane properties and performances over the long term. Until now, there is considerably less literature dedicated to membrane ageing than to cleaning/disinfection. The knowledge in cleaning/disinfection efficiency has recently been improved. But in order to develop optimized cleaning/disinfection protocols there still remains a challenge to better understand membrane ageing. In order to compensate for the lack of correlated cleaning/disinfection and ageing data from the literature, this paper investigates cleaning/disinfection efficiencies and ageing damages of organic ultrafiltration membranes. The final aim is to provide less detrimental cleaning/disinfection procedures and to propose some guidelines which should have been taken into consideration in term of membrane ageing studies. To carry out this study, this article will detail the background of cleaning/disinfection and aging membrane topics in a first introductive part. In a second part, key factors and endpoints of cleaning/disinfection and aging membranes will be discussed deeply: the membrane role and the cleaning parameters roles, such as water quality, storing conditions

75 FR 12496 - Proposed Information Collection; Comment Request; DOC National Environmental Policy Act...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-16

... DEPARTMENT OF COMMERCE Office of the Secretary Proposed Information Collection; Comment Request; DOC National Environmental Policy Act Environmental Questionnaire and Checklist AGENCY: Office of the...) Environmental Questionnaire and Checklist (EQC) was developed to assist DOC in complying with NEPA by...

Temporal Variability of Stemflow Dissolved Organic Carbon (DOC) Concentrations and Quality from Morphologically Contrasting Deciduous Canopies

NASA Astrophysics Data System (ADS)

van Stan, J. T.; Levia, D. F.; Inamdar, S. P.; Mitchell, M. J.; Mage, S. M.

2010-12-01

Dissolved organic carbon (DOC) inputs from canopy-derived hydrologic fluxes play a significant role in the terrestrial carbon budgets of forested ecosystems. However, no studies known to the authors have examined the variability of both DOC concentrations and quality for stemflow across time scales, nor has any study to date evaluated the effects of canopy structure on stemflow DOC characteristics. This investigation seeks to rectify this knowledge gap by examining the variability of stemflow DOC concentrations and quality across contrasting canopy morphologies and time scales (seasonal, storm and intrastorm). Bulk and intrastorm stemflow samples from a less dense, rough-barked, more plagiophile (Liriodendron tulipifera L. (tulip poplar)) and a denser, thin-barked, more erectophile (Fagus grandifolia Ehrh. (American beech)) canopy were collected and analyzed for DOC quality using metrics derived from UV-vis spectroscopy (E2:E3 ratio, SUVA254, select spectral slope (S), and spectral slope ratios (SR)). Our results suggest that stemflow DOC concentrations and quality change as crown architectural traits enhance or diminish hydrologic retention time within the canopy. The architecture of L. tulipifera canopies likely retards the flow of intercepted water, increasing chemical exchange with bark and foliar surfaces. UV-vis metrics indicated that this increased chemical exchange, particularly with bark surfaces, generally enhanced aromatic hydrocarbon content and increased molecular weight. Because leaf presence influenced DOC quality, stemflow DOC characteristics also varied seasonally in response to canopy condition. At the inter- and intrastorm scale, stemflow DOC concentration and quality varied with meteorological and antecedent canopy conditions. Since recent studies have linked stemflow production to preferential subsurface transport of dissolved chemistries, trends in DOC speciation and fluxes described in this study may impact soil environments within wooded

New disinfection and sterilization methods.

PubMed Central

Rutala, W. A.; Weber, D. J.

2001-01-01

New disinfection methods include a persistent antimicrobial coating that can be applied to inanimate and animate objects (Surfacine), a high-level disinfectant with reduced exposure time (ortho-phthalaldehyde), and an antimicrobial agent that can be applied to animate and inanimate objects (superoxidized water). New sterilization methods include a chemical sterilization process for endoscopes that integrates cleaning (Endoclens), a rapid (4-hour) readout biological indicator for ethylene oxide sterilization (Attest), and a hydrogen peroxide plasma sterilizer that has a shorter cycle time and improved efficacy (Sterrad 50). PMID:11294738

Efficient water disinfection with Ag2WO4-doped mesoporous g-C3N4 under visible light.

PubMed

Li, Yi; Li, Yanan; Ma, Shuanglong; Wang, Pengfei; Hou, Qianlei; Han, Jingjing; Zhan, Sihui

2017-09-15

Ag 2 WO 4 /g-C 3 N 4 composite photocatalyst was synthesized by polymerization of thiourea and ammonia chloride combined with the deposition-precipitation method, which was applied as an efficient visible-light driven photocatalyst for inactivating Escherichia coli (E. coli). The physicochemical properties of these photocatalysts were systematically characterized by various techniques such as SEM, TEM, XRD, FT-IR, BET, UV-vis DRS and PL. The synthesized photocatalysts exhibited outstandingly enhanced photocatalytic disinfection efficiency compared with that of pure g-C 3 N 4 and Ag 2 WO 4 under visible light. Furthermore, the optimal mass ratio of the Ag 2 WO 4 to g-C 3 N 4 was 5wt%, and a number of live bacteria could be completely inactivated with Ag 2 WO 4 (5%)/g-C 3 N 4 (100μg/mL) after 90min under visible light irradiation. The high disinfection efficiency is due to the synergetic effect between g-C 3 N 4 and Ag 2 WO 4 , including a good distribution of Ag 2 WO 4 particles on the surface of g-C 3 N 4 and an improved separation rate of photogenerated electron-hole pairs. The enhanced disinfection mechanism was also investigated using photogenerated current densities and electrochemical impedance spectroscopy (EIS). Considering the bulk availability and excellent disinfection activity of Ag 2 WO 4 /g-C 3 N 4 composite, it is a promising solar-driven photocatalyst for cleaning the microbial contaminated water. Copyright © 2017 Elsevier B.V. All rights reserved.

Optimum Disinfection Properties and Commercially Available Disinfectants

DTIC Science & Technology

1989-07-01

organic constituents that display a chlorine demand.) d. Upon addition to water, the agent should dissolve quickly and release its active ingredient(s...trione pH dependence alkaline pH favored Temperature dependence high at low residual Palatability Taste and odor claimed to be lartgly absent Color...CryptosgortdLjM at various temperature and pH levels. 2. A field procedwu for masueing disinfectant residual is ".eded for chlorin dioaide. 3. Stability

9 CFR 51.8 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Disinfection of premises, conveyances... ANIMALS DESTROYED BECAUSE OF BRUCELLOSIS Indemnity for Cattle, Bison, and Swine § 51.8 Disinfection of... for disinfection to 30 days when request for such extension is received by him prior to the expiration...

9 CFR 51.8 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Disinfection of premises, conveyances... ANIMALS DESTROYED BECAUSE OF BRUCELLOSIS Indemnity for Cattle, Bison, and Swine § 51.8 Disinfection of... for disinfection to 30 days when request for such extension is received by him prior to the expiration...

9 CFR 51.8 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Disinfection of premises, conveyances... ANIMALS DESTROYED BECAUSE OF BRUCELLOSIS Indemnity for Cattle, Bison, and Swine § 51.8 Disinfection of... for disinfection to 30 days when request for such extension is received by him prior to the expiration...

9 CFR 51.8 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Disinfection of premises, conveyances... ANIMALS DESTROYED BECAUSE OF BRUCELLOSIS Indemnity for Cattle, Bison, and Swine § 51.8 Disinfection of... for disinfection to 30 days when request for such extension is received by him prior to the expiration...

HIGH-RATE DISINFECTION TECHNIQUES FOR COMBIND SEWER OVERFLOW

EPA Science Inventory

This paper presents high-rate disinfection technologies for combined sewer overflow (CSO). The high-rate disinfection technologies of interest are: chlorination/dechlorination, ultraviolet light irradiation (UV), chlorine dioxide (ClO2 ), ozone (O3), peracetic acid (CH3COOOH )...

Function analysis of 5'-UTR of the cellulosomal xyl-doc cluster in Clostridium papyrosolvens.

PubMed

Zou, Xia; Ren, Zhenxing; Wang, Na; Cheng, Yin; Jiang, Yuanyuan; Wang, Yan; Xu, Chenggang

2018-01-01

Anaerobic, mesophilic, and cellulolytic Clostridium papyrosolvens produces an efficient cellulolytic extracellular complex named cellulosome that hydrolyzes plant cell wall polysaccharides into simple sugars. Its genome harbors two long cellulosomal clusters: cip - cel operon encoding major cellulosome components (including scaffolding) and xyl - doc gene cluster encoding hemicellulases. Compared with works on cip - cel operon, there are much fewer studies on xyl - doc mainly due to its rare location in cellulolytic clostridia. Sequence analysis of xyl - doc revealed that it harbors a 5' untranslated region (5'-UTR) which potentially plays a role in the regulation of downstream gene expression. Here, we analyzed the function of 5'-UTR of xyl - doc cluster in C. papyrosolvens in vivo via transformation technology developed in this study. In this study, we firstly developed an electrotransformation method for C. papyrosolvens DSM 2782 before the analysis of 5'-UTR of xyl - doc cluster. In the optimized condition, a field with an intensity of 7.5-9.0 kV/cm was applied to a cuvette (0.2 cm gap) containing a mixture of plasmid and late cell suspended in exponential phase to form a 5 ms pulse in a sucrose-containing buffer. Afterwards, the putative promoter and the 5'-UTR of xyl - doc cluster were determined by sequence alignment. It is indicated that xyl - doc possesses a long conservative 5'-UTR with a complex secondary structure encompassing at least two perfect stem-loops which are potential candidates for controlling the transcriptional termination. In the last step, we employed an oxygen-independent flavin-based fluorescent protein (FbFP) as a quantitative reporter to analyze promoter activity and 5'-UTR function in vivo. It revealed that 5'-UTR significantly blocked transcription of downstream genes, but corn stover can relieve its suppression. In the present study, our results demonstrated that 5'-UTR of the cellulosomal xyl - doc cluster blocks the

9 CFR 53.7 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false Disinfection of premises, conveyances... LIVESTOCK OR POULTRY § 53.7 Disinfection of premises, conveyances, and materials. All premises, including... disinfection shall be shared according to the agreement reached under § 53.2 with the State in which the work...

9 CFR 53.7 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false Disinfection of premises, conveyances... LIVESTOCK OR POULTRY § 53.7 Disinfection of premises, conveyances, and materials. All premises, including... disinfection shall be shared according to the agreement reached under § 53.2 with the State in which the work...

9 CFR 53.7 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false Disinfection of premises, conveyances... LIVESTOCK OR POULTRY § 53.7 Disinfection of premises, conveyances, and materials. All premises, including... disinfection shall be shared according to the agreement reached under § 53.2 with the State in which the work...

9 CFR 53.7 - Disinfection of premises, conveyances, and materials.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false Disinfection of premises, conveyances... LIVESTOCK OR POULTRY § 53.7 Disinfection of premises, conveyances, and materials. All premises, including... disinfection shall be shared according to the agreement reached under § 53.2 with the State in which the work...

Simultaneous removal of dissolved organic matter and bromide from drinking water source by anion exchange resins for controlling disinfection by-products.

PubMed

Phetrak, Athit; Lohwacharin, Jenyuk; Sakai, Hiroshi; Murakami, Michio; Oguma, Kumiko; Takizawa, Satoshi

2014-06-01

Anion exchange resins (AERs) with different properties were evaluated for their ability to remove dissolved organic matter (DOM) and bromide, and to reduce disinfection by-product (DBP) formation potentials of water collected from a eutrophic surface water source in Japan. DOM and bromide were simultaneously removed by all selected AERs in batch adsorption experiments. A polyacrylic magnetic ion exchange resin (MIEX®) showed faster dissolved organic carbon (DOC) removal than other AERs because it had the smallest resin bead size. Aromatic DOM fractions with molecular weight larger than 1600 Da and fluorescent organic fractions of fulvic acid- and humic acid-like compounds were efficiently removed by all AERs. Polystyrene AERs were more effective in bromide removal than polyacrylic AERs. This result implied that the properties of AERs, i.e. material and resin size, influenced not only DOM removal but also bromide removal efficiency. MIEX® showed significant chlorinated DBP removal because it had the highest DOC removal within 30 min, whereas polystyrene AERs efficiently removed brominated DBPs, especially brominated trihalomethane species. The results suggested that, depending on source water DOM and bromide concentration, selecting a suitable AER is a key factor in effective control of chlorinated and brominated DBPs in drinking water. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

In-Use Evaluation of Peracetic Acid for High-Level Disinfection of Endoscopes.

PubMed

Chenjiao, Wu; Hongyan, Zhang; Qing, Gu; Xiaoqi, Zhong; Liying, Gu; Ying, Fang

2016-01-01

Many high-level disinfectants have been used for disinfection of endoscopes such as 2% glutaraldehyde (GA), 0.55% ortho-phthalaldehyde (OPA), and peracetic acid (PAA). Both GA and OPA are widely used in disinfection of endoscopes and have been previously discussed, but there is little research on the practical use of PAA as an endoscope disinfectant. An experimental model of a flexible gastrointestinal endoscope being contaminated with 9 strains of microorganism was designed. After the cleaning and disinfecting procedure was completed, we evaluated the biocidal activity (850 ppm PAA, 2% GA, and 0.55% OPA) on our flexible gastrointestinal endoscope model. We also evaluated sterilization effectiveness of PAA on other bacteria, including some antibiotic-resistant bacteria (methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and Clostridium difficile). The residual bacterial colony count number of the PAA-disinfected endoscope was significantly lower than that of the GA- and OPA-disinfected endoscopes. The biocidal effect and efficiency of the endoscope disinfection by PAA appeared to be better than either the GA- or OPA-disinfected endoscope. PAA has demonstrated a good sterilization effect on other bacterial species; of particular note are common antibiotic-resistant bacteria such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and Clostridium difficile. The results of this study demonstrate that PAA is a fast and effective high-level disinfectant for use in the reprocessing of flexible endoscopes.

Sewage disinfection towards protection of drinking water resources.

PubMed

Kolch, A

2000-01-01

Wastewater applied in agriculture for irrigation could replace the use of natural drinking-water resources. With respect to high concentrations of human pathogens wastewater has to be disinfected prior to use. This paper introduces disinfection methods with emphasis on UV irradiation.

Algorithm Development and Validation for Satellite-Derived Distributions of DOC and CDOM in the US Middle Atlantic Bight

NASA Technical Reports Server (NTRS)

Mannino, Antonio; Russ, Mary E.; Hooker, Stanford B.

2007-01-01

In coastal ocean waters, distributions of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) vary seasonally and interannually due to multiple source inputs and removal processes. We conducted several oceanographic cruises within the continental margin of the U.S. Middle Atlantic Bight (MAB) to collect field measurements in order to develop algorithms to retrieve CDOM and DOC from NASA's MODIS-Aqua and SeaWiFS satellite sensors. In order to develop empirical algorithms for CDOM and DOC, we correlated the CDOM absorption coefficient (a(sub cdom)) with in situ radiometry (remote sensing reflectance, Rrs, band ratios) and then correlated DOC to Rrs band ratios through the CDOM to DOC relationships. Our validation analyses demonstrate successful retrieval of DOC and CDOM from coastal ocean waters using the MODIS-Aqua and SeaWiFS satellite sensors with mean absolute percent differences from field measurements of < 9 %for DOC, 20% for a(sub cdom)(355)1,6 % for a(sub cdom)(443), and 12% for the CDOM spectral slope. To our knowledge, the algorithms presented here represent the first validated algorithms for satellite retrieval of a(sub cdom) DOC, and CDOM spectral slope in the coastal ocean. The satellite-derived DOC and a(sub cdom) products demonstrate the seasonal net ecosystem production of DOC and photooxidation of CDOM from spring to fall. With accurate satellite retrievals of CDOM and DOC, we will be able to apply satellite observations to investigate interannual and decadal-scale variability in surface CDOM and DOC within continental margins and monitor impacts of climate change and anthropogenic activities on coastal ecosystems.

Disinfection of Needleless Connector Hubs: Clinical Evidence Systematic Review

PubMed Central

Moureau, Nancy L.

2015-01-01

Background. Needleless connectors (NC) are used on virtually all intravascular devices, providing an easy access point for infusion connection. Colonization of NC is considered the cause of 50% of postinsertion catheter-related infections. Breaks in aseptic technique, from failure to disinfect, result in contamination and subsequent biofilm formation within NC and catheters increasing the potential for infection of central and peripheral catheters. Methods. This systematic review evaluated 140 studies and 34 abstracts on NC disinfection practices, the impact of hub contamination on infection, and measures of education and compliance. Results. The greatest risk for contamination of the catheter after insertion is the NC with 33–45% contaminated, and compliance with disinfection as low as 10%. The optimal technique or disinfection time has not been identified, although scrubbing with 70% alcohol for 5–60 seconds is recommended. Studies have reported statistically significant results in infection reduction when passive alcohol disinfection caps are used (48–86% reduction). Clinical Implications. It is critical for healthcare facilities and clinicians to take responsibility for compliance with basic principles of asepsis compliance, to involve frontline staff in strategies, to facilitate education that promotes understanding of the consequences of failure, and to comply with the standard of care for hub disinfection. PMID:26075093

Wettability changes in polyether impression materials subjected to immersion disinfection.

PubMed

Shetty, Shweta; Kamat, Giridhar; Shetty, Rajesh

2013-07-01

Disinfection of impression materials prevents cross-contamination; however, the disinfectants may alter the wettability property. The purpose of this investigation was to evaluate the wettability changes of polyether impression material after immersing in four different chemical disinfectant solutions for a period of 10 min and 30 min, respectively. A total of 45 samples of polyether dental impression material (Impregum soft, 3MESPE, St. Paul, MN, USA) were randomly divided into nine groups with five specimens each. Each specimen was disc shaped, flat of 32 mm diameter and 3 mm thickness. The samples were immersed in four disinfectant solutions: 2% Glutaraldehyde, 5% sodium hypochlorite, 0.05% iodophor, and 5.25% phenol for 10 min and 30 min, respectively. The control was without disinfection. Wettability of the samples was assessed by measuring the contact angle by using the Telescopic Goniometer. Data were subjected to analysis of variance (Fisher's test) and Tukey's post hoc test for multiple comparisons at 5% level of significance. The contact angle of 20.21° ± 0.22° were recorded in the control samples. After 10 min, the samples that were immersed in 5% sodium hypochlorite and 5.25% phenol showed significant statistical increase in the contact angle as compared to the control (P < 0.001). After 30 min of disinfection, only the samples immersed in 0.05% iodophor showed there were no significant changes in the contact angle, whereas the other disinfectants significantly increased the contact angle and decreased the wettability of the polyether material. Within the limitations of the study, 2% glutaraldehyde proved safe for 10 min of immersion disinfection while 0.05% iodophor holds promise as an effective disinfectant without affecting the wettability of the material.

Wettability changes in polyether impression materials subjected to immersion disinfection

PubMed Central

Shetty, Shweta; Kamat, Giridhar; Shetty, Rajesh

2013-01-01

Background: Disinfection of impression materials prevents cross-contamination; however, the disinfectants may alter the wettability property. The purpose of this investigation was to evaluate the wettability changes of polyether impression material after immersing in four different chemical disinfectant solutions for a period of 10 min and 30 min, respectively. Materials and Methods: A total of 45 samples of polyether dental impression material (Impregum soft, 3MESPE, St. Paul, MN, USA) were randomly divided into nine groups with five specimens each. Each specimen was disc shaped, flat of 32 mm diameter and 3 mm thickness. The samples were immersed in four disinfectant solutions: 2% Glutaraldehyde, 5% sodium hypochlorite, 0.05% iodophor, and 5.25% phenol for 10 min and 30 min, respectively. The control was without disinfection. Wettability of the samples was assessed by measuring the contact angle by using the Telescopic Goniometer. Data were subjected to analysis of variance (Fisher's test) and Tukey's post hoc test for multiple comparisons at 5% level of significance. Results: The contact angle of 20.21° ± 0.22° were recorded in the control samples. After 10 min, the samples that were immersed in 5% sodium hypochlorite and 5.25% phenol showed significant statistical increase in the contact angle as compared to the control (P < 0.001). After 30 min of disinfection, only the samples immersed in 0.05% iodophor showed there were no significant changes in the contact angle, whereas the other disinfectants significantly increased the contact angle and decreased the wettability of the polyether material. Conclusion: Within the limitations of the study, 2% glutaraldehyde proved safe for 10 min of immersion disinfection while 0.05% iodophor holds promise as an effective disinfectant without affecting the wettability of the material. PMID:24130593

Disinfection of Vegetative Cells of Bacillus anthracis

DTIC Science & Technology

2016-03-01

1. INTRODUCTION Disinfection of Bacillus anthracis spores in drinking water is well documented in peer-reviewed literature (Adcock et al., 2004... Disinfection kinetics of vegetative cells of Bacillus anthracis in water with free available chlorine ([FAC] 2 mg/L) and monochloramine ([MC] 2 mg/L) were...anthracis. Bacillus anthracis cells Drinking water Chlorine demand-free (CDF

Determination of several common disinfection by-products in frozen foods.