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Query: UMLS:C0016382 (flushing)
 6,387 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A novel, colorimetric method using 2,3,5-triphenyltetrazolium chloride (TTC) in tandem with membrane filtration is described for the determination of death rates of Escherichia coli (E. coli) due to microbiocides. This method enables results to be obtained on the same day in contrast to the 18 h required by the accepted aerobic plate count method. The microbiocides investigated were the preservatives 2-bromo-2-nitro-1,3-propanediol (Bronopol), N-(hydroxymethyl)-N-(1,3-dihydroxymethyl-2,5- dioxo-4-imidazolidinyl)-N'-(hydroxymethyl)-urea (Germall II), phenethyl alcohol, and benzyl alcohol. D values (time required per log reduction of E coli) were determined by this method, and equations relating the D values to preservative concentrations were derived [i.e., eta values (the logarithmic values relating changes in rates of kill for specified changes in concentration) and A values (extrapolated D values at 1% concentration) were determined]. these equations are compared with those previously published using the accepted aerobic plate count method. The potential advantages of this method are that it has a broad range of application as TTC is reduced by a wide variety of microbes; the test is easily done; results can be achieved in one day; dead cells do not cause interference; test sensitivity can be increased by increasing the length of incubation time or by using membrane filtration in tandem with TTC reduction; and preservative inactivation may be achieved by filtration and flushing with an inactivator, or by adding neutralizers to the TTC broth.
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PMID:2,3,5-Triphenyltetrazolium chloride as a novel tool in germicide dynamics. 353 77

In an extensive, multiyear study of antibiotic resistance from wastewater oxidation ponds, five mobile home park wastewater oxidation ponds in Clarke and Oconee counties were shown to be discharging high numbers of antibiotic-resistant bacteria into the waterways of North Georgia. This effluent contributed to higher nitrogen, phosphorus, and fecal coliform levels in creeks downstream from the ponds. A survey of residents revealed that many people did not complete their antibiotic prescriptions, and the majority flushed leftover antibiotic medications down the toilet. In the pond discharges, resistance was found to eighteen antibiotics: amikacin, amoxicillin/clavulanic acid, ampicillin, apramycin, cefoxitin, ceftiofur, ceftriaxone, cephalothin, chloramphenicol, ciprofloxacin, gentamicin, imipenem, kanamycin, naladixic acid, streptomycin, sulphamethoxazole, trimethoprim/sulphamethoxazole, and tetracycline. The discharged bacteria contained both integrons and plasmids, the latter being transferable to a laboratory strain of Escherichia coil (E. coli). A turtle was found living at a pond discharge site with multiply-antibiotic-resistant bacteria in its feces. Last year, RNA fingerprinting conclusively documented the survival of three multiply-resistant important pathogenic bacteria. Ceftriaxone-resistant Stenotrophomonas maltophilia and Pseudomonas aerogenosa and a ciprofloxacin-resistant E. coli were traced through oxidation pond stages and into the discharge, thus documenting that the pathogens survived the treatment process. In addition, a potential pathogen, a serotype group D Salmonella spp., was found in the discharge. In this study, tetracycline-resistance genes C and G were detected in the first and second stages of the oxidation pond and the discharge went directly into the environment. These genes are generally found in intestinal bacteria, so it can be inferred that they are from a human source. Antimicrobial residue from the beta-lactam family of antibiotics was found in all oxidation pond stages and in the creek above the pond. Tetracycline residue was found in the first and second stages of the pond. In addition to the antibiotics, genes coding for antibiotic resistance and the antibiotics themselves were documented to survive oxidation pond treatment. Tetracycline-resistant genes were identified in the oxidation pond stages and in the discharge going into the environment. A model was also developed to study oxidation pond function in the laboratory. A biofilm was created using a highly antibiotic-resistant Salmonella typhimurium 3/97, and pond water was added. The biofilm was processed via a rotating disk bioreactor specifically designed to study biofilms in nature, but with conditions that were more favorable to bacterial inhibition than those in nature. Cultures revealed that, under these optimal conditions, S. typhimurium 3/97 was still present in this in vitro system. Thus, the competitive inhibition process that helps to remove bacteria in oxidation ponds did not effectively remove an important bacterium, S. typhimurium 3/97, in this mock oxidation pond. The bioreactor model developed in this study can be used to further investigate discharges from oxidation ponds. From this data, it is apparent that the problem is two-fold. A cost-effective technique must be developed that inactivates antibiotic-resistant bacteria in oxidation pond discharges and also removes the antibiotics. A public awareness campaign was initiated by the author to encourage proper use and disposal of antibiotics, as flushing them is a common practice in the United States.
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PMID:Antibiotic resistance from wastewater oxidation ponds. 1638 Nov 46

In many coastal cities around the world, marine outfalls are used for disposal of partially treated wastewater effluent. The combined use of land-based treatment and marine discharge can be a cost-effective and environmentally acceptable sewage strategy. Before 2001, screened sewage was discharged into Victoria Harbour through many small outfalls. After 2001, the Hong Kong Harbour Area Treatment Scheme (HATS) was implemented to improve the water quality in Victoria Harbour and surrounding waters. Stage I of HATS involved the construction of a 24 km long deep tunnel sewerage system to collect sewage from the densely populated urban areas of Hong Kong to a centralized sewage treatment plant at Stonecutters Island. A sewage flow of 1.4 million m3 d(-1) receives Chemically Enhanced Primary Treatment (CEPT) followed by discharge via a 1.2 km long outfall 2 km west of the harbor. The ecosystem recovery in Victoria Harbour and the environmental response to sewage abatement after the implementation of HATS was studied using a 21-year data set from long term monthly water quality monitoring. Overall, the pollution control scheme has achieved the intended objectives. The sewage abatement has resulted in improved water quality in terms of a significant reduction in nutrients and an increase in bottom DO levels. Furthermore, due to the efficient tidal mixing and flushing, the impact of the HATS discharge on water quality in the vicinity of the outfall location is relatively limited. However, Chl a concentrations have not been reduced in Victoria Harbour where algal growth is limited by hydrodynamic mixing and water clarity rather than nutrient concentrations. Phosphorus removal in the summer is suggested to reduce the risk of algal blooms in the more weakly-flushed and stratified southern waters, while nutrient removal is less important in other seasons due to the pronounced role played by hydrodynamic mixing. The need for disinfection of the effluent to reduce bacterial (E. coli) concentrations to acceptable levels is also confirmed and has recently been implemented.
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PMID:Environmental response to sewage treatment strategies: Hong Kong's experience in long term water quality monitoring. 2187 38

The aim of this article is to introduce the methodology of disease burden (DB) to quantify the health impact of microbial regrowth during wastewater reuse, using the case study of a decentralized water reuse system in Xi'an Si-yuan University, located in Xi'an, China. Based on field investigation findings, Escherichia coli (E. coli), Salmonella and rotavirus were selected as typical regrowth pathogens causing potential health hazards during the reuse of reclaimed water. Subsequently, major exposure routes including sprinkler irrigation, landscape fountains and toilet flushing were identified. Mathematical models were established to build the relationship between exposure dose and disease burden by calculating the disability adjusted life year (DALY). Results of disease burden for this case study show that DALYs attributed to E. coli were significantly greater than those caused by other pathogens, and DALYs associated with sprinkler irrigation were higher than those originating from other routes. A correlation between exposure dose and disease was obtained by introducing a modified calculation of morbidity, which can extend the assessment endpoint of health risk to disease burden from the conventional infection rate.
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PMID:Application of disease burden to quantitative assessment of health hazards for a decentralized water reuse system. 2687 64

A Water Exclosure Treatment System (WETS) is developed and installed to minimize the occurrence of beach closures due to algae and Escherchia coli (E. coli) in an inland lake. WETS consists of an "exclosure" sub-system with a five-sided polypropylene, barrier that excludes offshore lake contaminated water from the swimming area. Inside the exclosure, water is pumped to a portable filtration-ultraviolet treatment sub-system with three components. First, heavy debris like aquatic plants are removed through a strainer. Second, fine particles are removed through a sand filter and backwashing is automated through a program logic controller triggered by pressure sensor readings. Third, pathogens, algae, bacteria, and viruses are inactivated through ultraviolet (UV) disinfection. To determine sizing of sand filters and evaluation of efficiency of UV disinfection and aid in the design of the inlet and outlet locations for the pump system, computational fluid dynamics modeling with a Lagrangian particle-tracking method are employed. Flushing time is determined to range from 0.67 to 1.89days. Residence time maps reveal inlet and outlet locations play an important role in depicting the duration of particles within the swimming area. Comprehensive water quality sampling is conducted and analyzed with ANOVA testing reveal that water quality parameters inside the exclosure are significantly different than those outside. There have been no beach closures issued since deployment of WETS. Overall, WETS, an innovative Water Exclosure Treatment System, provides safe, clean water inside the exclosure for minimizing beach closure.
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PMID:Water Exclosure Treatment System (WETS): An innovative device for minimizing beach closures. 2930 69