Types Of Disinfectants Research Articles

The impact of iodinated X-ray contrast agents on formation and toxicity of disinfection by-products in drinking water

The presence of iodinated X-ray contrast media (ICM) in source waters is of high concern to public health because of their potential to generate highly toxic disinfection by-products (DBPs). The objective of this study was to determine the impact of ICM in source waters and the type of disinfectant on the overall toxicity of DBP mixtures and to determine which ICM and reaction conditions give rise to toxic by-products. Source waters collected from Akron, OH were treated with five different ICMs, including iopamidol, iopromide, iohexol, diatrizoate and iomeprol, with or without chlorine or chloramine disinfection. The reaction product mixtures were concentrated with XAD resins and the mammalian cell cytotoxicity and genotoxicity of the reaction mixture concentrates was measured. Water containing iopamidol generated an enhanced level of mammalian cell cytotoxicity and genotoxicity after disinfection. While chlorine disinfection with iopamidol resulted in the highest cytotoxicity overall, the relative iopamidol-mediated increase in toxicity was greater when chloramine was used as the disinfectant compared with chlorine. Four other ICMs (iopromide, iohexol, diatrizoate, and iomeprol) expressed some cytotoxicity over the control without any disinfection, and induced higher cytotoxicity when chlorinated. Only iohexol enhanced genotoxicity compared to the chlorinated source water.

Is There A Correlation Between Antibiotic Resistance and Decreased Susceptibility to Biocides in Different Genus of Bacterial Genera?

Results: With the antibiograms and MIC-dilutions for every bacteria and biocide, the bivariate analysis found that only 4.7% of the antibiotic-biocide pairs showed a significant correlation (p < 0.05%) between antibiotic resistance and decreased susceptibility to the disinfectant or antiseptic, 8.3% showed a significant inverse correlation, and the rest no correlation. Multivariate analysis of the above variables (controlling the effects of the type of microorganism and disinfectant or antiseptic used), showed that overall fit of the equation was very poor, since R 2 = 0.032. Conclusion: In a large sample of different bacteria genera there was no significant correlation between antibiotic resistance and decreased susceptibility to disinfectants and antiseptics, except in 4.7% of the antibiotic-biocide pairs. List of abbreviations: OPA: Ortho-phthalaldehyde; NFGNB: Non Fermentative Gram Negative Bacteria; ROC: Receiver Operating Characteristics; COR: Correlations with p < 0.05; Cor: Correlations with p between 0.05 and 0.1; SXT: Sulfamethoxazole trimethoprim; CPH: Cephalothin; LEVO: Levofloxacin; IPM: Imipenem; TOB: Tobramycin; CAZ: Ceftazidime; GM: Gentamicin; AN: Amikacin; FO: Phosphomycin; TZP: Tazobactam; ATM: Aztreonam; TEC: Teicoplanin

Diversity of DNA viruses in effluents of membrane bioreactors in Traverse City, MI (USA) and La Grande Motte (France)

This study assesses diversity of DNA viruses in the effluents of two membrane bioreactor (MBR) wastewater treatment plants (WWTPs): an MBR in the United States and an MBR in France. Viral diversity of these effluents is compared to that of a conventional activated sludge WWTP in the U.S. Diversity analysis indicates Herpesvirales to be the most abundant order of potentially pathogenic human DNA viruses in wastewater treated effluent in all utilities. Other potentially pathogenic human viruses detected include Adenoviridae, Parvoviridae, and Polyomaviridae. Bacteriophage order Caudovirales comprises the majority of DNA virus sequences in the effluent of all utilities. The choice of treatment process (MBR versus activated sludge reactor) utilized had no impact on effluent DNA viral diversity. In contrast, the type of disinfection applied had an impact on the viral diversity present in the effluent.

Medical Waste Management Survey in Primary Health Care Centers, Saudi Arabia

Background & Aims: Primary healthcare services aim to promote health and prevent health problems. However, waste generated from primary healthcare centers (PHC) potentially harmful to public health and the environment. The aim of this study was to assess wastes management of these centers. Methods: The data of this observational – cross-sectional study were collected from the available primary healthcare centers in Al-Baha city, Saudi Arabia (N=15 PHC centers). Data collected using standardized questionnaire and observations. Results: Contaminated sharp and pharmaceuticals pressurized wastes were generated in all PHC centers. About 14 (93.3%) and 13 (86.7%) of the centers were generating wastes of live attenuated vaccines vials and articles contaminated with blood, respectively. Eight (53.6%) of the centers generated more than 3 kg per day of contaminated sharps, followed by; live and attenuated vaccines’ vials. Eleven (73.3%) and 7 (46.7%) of the PHC centers produces 1 to 3 kg of hazardous wastes per day of articles contaminated with blood and waste contaminated with excretion, respectively. All health centers except one were practicing waste segregation properly, and 2 (13.4%) of the centers lacked waste storage method. A total of 5 (33.5%) centers also did not practice any type of dis infection, 7 (46.7%) and 9 (60.0%) of these centers did not have medical waste plan, nor specification for the collection and handling procedures of their medical wastes, respectively. The most common methods used for medical waste packaging were bags (68.8%) and plastic containers (18.8%). Conclusion: Medical waste management practices were found to be deficient and their amendment highly recommended.

Evaluation of Surface Microhardness Following Chemical and Microwave Disinfection of Commercially Available Acrylic Resin Denture Teeth.

Denture disinfection is an indispensable procedure for preventing cross contamination and the maintenance of a healthy oral mucosa in patients rehabilitated with removable dental prosthesis. Nevertheless, they are known to cause changes in the physical and mechanical properties of denture base resins and acrylic resin denture teeth following immersion of a denture in a suitable chemical disinfectant solution or by undergoing microwave irradiation. One such mechanical property indicator for artificial tooth materials is hardness. To assess the surface hardness of acrylic resin teeth of three different commercial brands (Ivoclar, Newace, Acryrock) following chemical (2% glutaraldehyde, 1% sodium hypochlorite) and microwave disinfections. Ten specimens of each of the three commercial brands were made for control and each simulated disinfection type and stored in distilled water at room temperature for 24 hours. After water storage, specimens were immersed in 2% glutaraldehyde and 1% sodium hypochlorite (one and three cycles) at room temperature for 10 minutes. Irradiation with microwave (one and three cycles) was done in domestic microwave for three minutes with the specimens immersed in 150 ml of distilled water. The specimens were stored in distilled water at room temperature for seven days after each disinfection cycle. Vickers hardness measurements were made using a hardness indenter under a load of 50 g force for 10 seconds. Data was subjected to repeated measure two-way ANOVA test and Tukey's test. There were statistically significant differences for the variables disinfection, tooth, and cycle (p<0.05 for teeth & disinfectant interaction, p<0.05 cycle and disinfectant interaction). The mean surface hardness following one microwave disinfection cycle was lower than control, glutaraldehyde and sodium hypochlorite. Comparison among cycles revealed that microhardness was significantly decreased for three cycles of microwave disinfection. It was concluded that there was no significant difference in microhardness when the teeth were subjected to chemical disinfection but three cycles of microwave disinfection produced decrease in the microhardness of different types of artificial teeth.

Performance Evaluation of Alternative Disinfectants in Reducing Microbial Contamination of Vegetables Supplied from City of Kermanshah

Background: In recent decades, due to the scarcity of fresh water resources and high costs of wastewater treatment, cases of irrigation of cultivation of vegetables using raw sewage and polluted effluents or the use of human and animal faeces have been reported. Vegetables are important sources of exposure of human pathogenic pathogens such as fecal coliforms. The aim of this study was to evaluate the performance of three different disinfectant on several kinds of vegetables that would normally be released in Kermanshah. Methods: In this cross sectional study, 180 randomly selected vegetable samples were collected from mobile and fixed stores of vegetables in Kermanshah. Then, to evaluate the effectiveness of disinfectants in eliminating microbial samples, three types of disinfectants containing active ingredient Benzalconium chloride, were studied. Heterotrophic plate count (HPC) surface culture method, coliform count (VRBA) Violet Red Bile Agar purplate method and Yeast Glucose Chloramphemicole Agar (YGCA) surface culture method was used in order to count the microbial load. Results: The findings of this study suggest that the overall average performance of all three disinfectants was less than 75 and most disinfection efficiency was observed in two-fold concentrations of proposed by manufacturer. Based on the analysis of the resulting data, disinfectants examined in this study had an average efficiency of 76.13 for the removal of coliforms as an indicator of gram-negative bacteria and 100 for the removal of Streptococcus bacteria as indicators gram positive bacteria. Conclusion: Disinfection can not solely guarantees the maintaining the health of the consumer. We could have declared that recommended disinfection conditions and existing facilities can effectively reduce the microbial load of vegetables. However, preparing vegetables from safe and ensure proper burial are recommended. Moreover, consuming the raw vegetables in sensitive seasons and precarious conditions should be avoided.

Field study on evaluation of the efficacy and usability of two disinfectants for drinking water treatment at small cattle breeders and dairy cattle farms.

The hygienic quality of drinking water for cattle originated from different sources together with the efficacy and usability of two types of disinfectants against waterborne pathogens were assessed for small cattle breeders and dairy cattle farms. A total of 120 drinking water samples were collected from water troughs representing three different water sources commonly used for cattle drinking (tap, underground and surface water; n = 65, 25, and 30, respectively). Collected samples were cultured for isolation and identification of pathogenic bacteria using serological techniques and PCR. The bactericidal efficacy of the disinfectants, sodium dichloroisocyanurate (NaDCC) and hydrogen peroxide (H2O2) 50%, at different concentrations were evaluated by the determination of total viable and coliform counts of water prior and postwater treatment. In small cattle breeders, Escherichia coli was the most prevalent bacterial isolates from surface water (56.7%) followed by Staphylococcus aureus (36.7%), Salmonella spp. (26.7%), Streptococcus faecalis (23.3%), Shigella flexneri (16.7%), Proteus spp. (16.7%), and Klebsiella pneumonae (10.0 %) at X(2) = 9, P ≤ 0.01. Prior to the use of disinfectants, the averages of total bacterial and coliform counts were the highest in surface water (3.56 × 10(7), 240.0, and 38.0 CFU/100 ml, respectively). It has been found that hydrogen peroxide 50% at a concentration of 35 mg/l had a lethal effect (100 %) on indicator microorganisms compared with NaDCC at concentration of 2 mg/l. In conclusion, the higher bacterial contaminants in drinking water were found in surface water followed by tap water, particularly for small cattle breeders. Therefore, the usage of more hygienic water troughs with their regular treatment by hydrogen peroxide 50% at concentration of 35 mg/l is highly recommended to control waterborne bacteria and consequently improve and maintain the animal health.

Biological Stability of Drinking Water: Controlling Factors, Methods, and Challenges.

Biological stability of drinking water refers to the concept of providing consumers with drinking water of same microbial quality at the tap as produced at the water treatment facility. However, uncontrolled growth of bacteria can occur during distribution in water mains and premise plumbing, and can lead to hygienic (e.g., development of opportunistic pathogens), aesthetic (e.g., deterioration of taste, odor, color) or operational (e.g., fouling or biocorrosion of pipes) problems. Drinking water contains diverse microorganisms competing for limited available nutrients for growth. Bacterial growth and interactions are regulated by factors, such as (i) type and concentration of available organic and inorganic nutrients, (ii) type and concentration of residual disinfectant, (iii) presence of predators, such as protozoa and invertebrates, (iv) environmental conditions, such as water temperature, and (v) spatial location of microorganisms (bulk water, sediment, or biofilm). Water treatment and distribution conditions in water mains and premise plumbing affect each of these factors and shape bacterial community characteristics (abundance, composition, viability) in distribution systems. Improved understanding of bacterial interactions in distribution systems and of environmental conditions impact is needed for better control of bacterial communities during drinking water production and distribution. This article reviews (i) existing knowledge on biological stability controlling factors and (ii) how these factors are affected by drinking water production and distribution conditions. In addition, (iii) the concept of biological stability is discussed in light of experience with well-established and new analytical methods, enabling high throughput analysis and in-depth characterization of bacterial communities in drinking water. We discussed, how knowledge gained from novel techniques will improve design and monitoring of water treatment and distribution systems in order to maintain good drinking water microbial quality up to consumer’s tap. A new definition and methodological approach for biological stability is proposed.

Detection of Genome Content of Pseudomonas Aeruginosa Biofilm Formation and Resistance to Some Disinfectants and Antibiotics

This study have been includedfortyisolates ofthe bacteriumPseudomonas aeruginosaisolatedfrom Department ofbiology /College of Science /University of Mustansiriya from different clinical specimens itwas diagnosisbased on themethodsof microscopic,culturalandbiochemicalandfinal diagnosisusingVitek 2system . The ability of the isolates to produce biofilmwas tested usingCongo Red Agar Method (CRA).The resultshowed that(12)isolated (30%) are biofilm producer. Antibiotic sensitivity test have been done multiple drug resistance therevealed showed thatisolates had moreoverallclinical isolates ofP. aeruginosa 100%) )were resistantto Piperacillin, Amoxicillin / Clavulanic acid, Cephalexin, Ceftriaxone and Ceftazidime and while the isolates gradually were resisttoother antibiotics untilshowedlessresistantto theImipenem.( 16.7%)In addition, the minimum inhibitory concentration (MICs) for P. aeruginosa isolateswere determinedto five antibiotics included ( Amikacin, Ciprofloxacin Ceftriaxone, Ceftazidime and Imipenem) and three types of disinfectants (Povidin - Iodine, Chloroxylenol, Formalin) . Bacterial isolates under this study were showed high resistance to both Ceftriaxone and Amikacin. The rang of (MICs) Values was between (16-512) µg / mL. the results showed Values of the (MICs) of disinfectant formalin was low compared otherdisinfectants in this study. Since rang values(MICs) between (512-2000) µg / mL, (512-3500) µg / mL for Dettol and (1024-4000) µg / mL for Iodine solution. The study also showed that sensitivity percentage increased with increasing of disinfectant concentration. All isolates showed negative results for of Metallo-β-lactamase by EDTA method and PCR showed negative results for both of blaSHVand blaTEM genotype , While isolates showed positive results for blaCTX-M .

Impact of Water Chemistry, Pipe Material and Stagnation on the Building Plumbing Microbiome.

A unique microbiome establishes in the portion of the potable water distribution system within homes and other buildings (i.e., building plumbing). To examine its composition and the factors that shape it, standardized cold water plumbing rigs were deployed at the treatment plant and in the distribution system of five water utilities across the U.S. Three pipe materials (copper with lead solder, CPVC with brass fittings or copper/lead combined pipe) were compared, with 8 hour flush cycles of 10 minutes to simulate typical daily use patterns. High throughput Illumina sequencing of 16S rRNA gene amplicons was employed to profile and compare the resident bulk water bacteria and archaea. The utility, location of the pipe rig, pipe material and stagnation all had a significant influence on the plumbing microbiome composition, but the utility source water and treatment practices were dominant factors. Examination of 21 water chemistry parameters suggested that the total chlorine concentration, pH, P, SO4 2- and Mg were associated with the most of the variation in bulk water microbiome composition. Disinfectant type exerted a notably low-magnitude impact on microbiome composition. At two utilities using the same source water, slight differences in treatment approaches were associated with differences in rare taxa in samples. For genera containing opportunistic pathogens, Utility C samples (highest pH of 9–10) had the highest frequency of detection for Legionella spp. and lowest relative abundance of Mycobacterium spp. Data were examined across utilities to identify a true universal core, special core, and peripheral organisms to deepen insight into the physical and chemical factors that shape the building plumbing microbiome.

Nitrogenous disinfection byproducts in English drinking water supply systems: Occurrence, bromine substitution and correlation analysis

Despite the recent focus on nitrogenous disinfection byproducts in drinking water, there is limited occurrence data available for many species. This paper analyses the occurrence of seven haloacetonitriles, three haloacetamides, eight halonitromethanes and cyanogen chloride in 20 English drinking water supply systems. It is the first survey of its type to compare bromine substitution factors (BSFs) between the haloacetamides and haloacetonitriles. Concentrations of the dihalogenated haloacetonitriles and haloacetamides were well correlated. Although median concentrations of these two groups were lower in chloraminated than chlorinated surface waters, median BSFs for both in chloraminated samples were approximately double those in chlorinated samples, which is significant because of the higher reported toxicity of the brominated species. Furthermore, median BSFs were moderately higher for the dihalogenated haloacetamides than for the haloacetonitriles. This indicates that, while the dihalogenated haloacetamides were primarily generated from hydrolysis of the corresponding haloacetonitriles, secondary formation pathways also contributed. Median halonitromethane concentrations were remarkably unchanging for the different types of disinfectants and source waters: 0.1 μg·mgTOC−1 in all cases. Cyanogen chloride only occurred in a limited number of samples, yet when present its concentrations were higher than the other N-DBPs. Concentrations of cyanogen chloride and the sum of the halonitromethanes were not correlated with any other DBPs.

Improved (and Singular) Disinfectant Protocol for Indirectly Assessing Organic Precursor Concentrations of Trihalomethanes and Dihaloacetonitriles.

Measurements of disinfection byproduct (DBP) organic precursor concentrations (OPCs) are crucial to assess and improve DBP control processes. Typically, formation potential tests - specified in Standard Methods (SM) 5710-B/D - are used to measure OPCs. Here, we highlight several limitations of this protocol for dihaloacetonitriles and trihalomethanes and validate a novel Alternative Method (AM). The effects of pH, disinfectant type (free chlorine and monochloramine), and chlor(am)ine residual (CR) were examined on DBP formation in a suite of waters. Using the SM, DHAN decreased 43-47% as the CR increased from 3 to 5 mg L(-1) as Cl2, compromising OPC assessments. In contrast, a high monochloramine dose (250 mg L(-1) as Cl2) at pH 7.0 (the AM) accurately reflected OPCs. The two methods were compared for assessing DBP precursor removal through three granular activated carbon (GAC) columns in series. Breakthrough profiles assessed using the AM only showed DBP precursor sorption occurred in each column that decreased over time (p = 0.0001). Similarly, the AM facilitated ranking of three types of GAC compared in parallel columns, whereas the SM produced ambiguous results. Fluorescence intensity of a humic-like fluorophore (i.e., I345/425) correlated strongly to precursor removal in the GAC columns. The practical implications of the results are discussed.

Factors affecting lead release in sodium silicate-treated partial lead service line replacements

Water quality parameters affecting sodium silicate performance in partial lead service line replacements were examined using a fractional factorial experimental design and static pipe systems. An external copper wire was used to create a galvanic connection between a former lead service line and a new copper pipe. The pipe systems were filled with lab prepared water made to mimic real water quality. Water was changed on a three times per week basis. A 24−1 fractional factorial design was used to evaluate the impact of alkalinity (15 mg L−1 or 250 mg L−1 as CaCO3), nitrate (1 mg L−1 or 7 mg L−1 as N), natural organic matter (1 mg L−1 or 7 mg L−1 as dissolved organic carbon), and disinfectant type (1 mg L−1 chlorine or 3 mg L−1 monochloramine), resulting in eight treatment conditions. Fractional factorial analysis revealed that alkalinity, natural organic matter and monochloramine had a significant positive effect on galvanic current. Natural organic matter and monochloramine also had a significant positive effect with respect to both total and dissolved lead release. For the treatment conditions examined, 67–98% of the lead released through galvanic currents was stored as corrosion scales and predominantly comprised of particulate lead (96.1–99.9%) for all eight treatments. The use of monochloramine and the presence of natural organic matter (7 mg L−1) were not favourable for corrosion control in sodium silicate-treated partial lead service line replacements, although further studies would be required to characterize optimal water quality parameters for specific water quality types. For utilities operating with sodium silicate as a corrosion inhibitor, this work offers further evidence regarding the consideration of chlorine as a secondary disinfectant instead of monochloramine, as well as the value of controlling natural organic matter in distributed water.

Distribution System Water Quality Affects Responses of Opportunistic Pathogen Gene Markers in Household Water Heaters

Illustrative distribution system operation and management practices shaped the occurrence and persistence of Legionella spp., nontuberculous mycobacteria (NTM), Pseudomonas aeruginosa, and two amoebae host (Acanthamoeba spp., Vermamoeba vermiformis) gene markers in the effluent of standardized simulated household water heaters (SWHs). The interplay between disinfectant type (chlorine or chloramine), water age (2.3-5.7 days) and materials (polyvinyl chloride (PVC), cement or iron) in upstream simulated distribution systems (SDSs) profoundly influenced levels of pathogen gene markers in corresponding SWH bulk waters. For example, Legionella spp. were 3-4 log higher in SWHs receiving water from chloraminated vs chlorinated SDSs, because of disinfectant decay from nitrification. By contrast, SWHs fed with chlorinated PVC SDS water not only harbored the lowest levels of all pathogen markers, but effluent from the chlorinated SWHs were even lower than influent levels in several instances (e.g., 2 log less Legionella spp. and NTM for PVC and 3-5 log less P. aeruginosa for cement). However, pathogen gene marker influent levels correlated positively to effluent levels in the SWHs (P < 0.05). Likewise, microbial community structures were similar between SWHs and the corresponding SDS feed waters. This study highlights the importance and challenges of distribution system management/operation to help control opportunistic pathogens.

Eradication of Pseudomonas biofilm by disinfectants and some plants extracts

In the present study three isolates belonging to Pseudomonas sp and one reference strain of P. aeruginosa ATCC 27853 were tested for biofilm formation on two types of support (glass and polystyrene), using two cultures medium Tryptone Soy Broth (TSB) and Modified Biofilm Broth (MBB). The results showed that the quantity of biofilm formed depends on the nature of culture medium, where the rate of the adherent bacteria was more significant in TSB medium. Polystyrene was more favorable to bacteria for adherence compared to glass. We examined the effectiveness of three types of disinfectants, sodium hypochlorite, hydrogen peroxide and temperature on a biofim formed by the studied bacteria. Sodium hypochlorite reached good levels of biofilm eradication using all isolates adhered on the two types of support. Hydrogen peroxide exerted less significant effect compared to sodium hypochlorite, eliminating approximately 56% from the biofilm adhered on polystyrene at concentration of 3%. The elimination of biofilm temperature (80°C) was rather weak compared with the two chemical disinfectants. Our study included the testing of extracts of three plants: Allium sativum, Aloe vera and Lawsonia inermis on biofilm eradication formed by P. aeruginosa ATCC 27853. The effect of these plant extracts on planktonic cells was also studied. The results showed that Allium sativum and Lawsonia inermis inhibit both bacterial growth and biofilm formation and no activity was detected for Aloe vera extract.

Assessment of the Efficiency for some Disinfectants Against the Microorganisms Isolated From the Wards of Newborn and Premature Babies in Baghdad Teaching Hospital

Objective : To assess the efficiency for some disinfectants against the microorganisms isolated fromthe wards of newborn and premature babies in Educational Baghdad Hospital .Methodology :This study had done from 1\8\2014 untile 1\9\2014, we had selected three types ofdisinfectants ( Incidine , Bleach and Microbac Forte )which were used for disinfection in the wards ofnewborn babies at Educational Baghdad Hospital to assess their effect against the microorganismsisolated from these wards and study the mixed affect of these disinfectants againt samemicroorganisms .Results : The results of the present study showed that there is affect of the different concentrations ofthe used disinfectants against the microorganisms isolated from the wards of the newborn andpremature babies , also there is a synergism affect of microbac forte with sodium hypochlorite andincidine , as well as , there is an antagonism affect of sodium hypochlorite with incidine a comparisionif they used alone .Recommendation : The present study had been suggested to use the highly concentrations ofMicrobac forte , Incidine and sodium hypochlorite to sterilize the wards of newborn and prematurebabies , also the study had been suggested to use the mixed solutions of microbac forte with incidineand sodium hypochlorite to disinfect the same wards .

Impact of disinfection on drinking water biofilm bacterial community

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.

Development of cost functions for water supply and sanitation technologies: case study of Bahir Dar and Arba Minch, Ethiopia

Sustainable and improved water supply and sanitation service provision for communities who are lacking it is the forefront issue of the Millennium Development Goals (MDGs). To assist the achievement of the MDGs, it is essential to overcome the traditional approach to planning water supply and sanitation (WS&amp;S) systems. This study developed user and/or service provider cost functions for available WS&amp;S technologies in the vicinity of Bahir Dar and Arba Minch townships. The cost functions help to estimate the life cycle cost of WS&amp;S systems. Eight water supply and eleven sanitation technologies' design documents and cost data were collected and analysed. Results revealed that the maximum daily water demand and person equivalent were the responsive variables for the initial investment and/or recurrent costs of almost all WS&amp;S technologies, respectively. In addition, disinfectant types, pump head, pipe length and diameter, tower height, well depth, conveyance distance and composting volume were identified as important parameters for the corresponding WS&amp;S technologies. However, the cost of shallow well equipped with hand pump was influenced merely by the well depth. The obtained cost functions contribute to overcoming the common practice of WS&amp;S systems comparison in the study area, which largely focus on their initial investment costs.

Chlorate Challenges for Water Systems

Chlorate, currently included in the US Environmental Protection Agency's monitoring of unregulated contaminants and on the contaminant candidate list, could potentially receive a regulatory determination in the near future. This article, using available literature along with past and current monitoring data, assesses the presence of chlorate in drinking water and the potential impact of its regulation. The article gives specific attention to the variety of threshold concentrations that appear most often in the literature—210, 700, and 840 μg/L—and evaluates the effect a regulatory requirement at each of these values would have on utilities. The research indicated that potential regulatory thresholds &gt; 700 μg/L would be violated by only &lt; 10% of utilities. The effects of regional conditions and type of disinfection used depend greatly on the adopted thresholds. Utilities in the southern region of the United States and those using chloramination are most at risk if a low maximum contaminant level is adopted.

Efficacy of Five Commonly Used Disinfectants Against Turkey Arthritis Reovirus.

Since late 2009, an unusual problem of reovirus-related lameness has been seen in market-age tom turkeys in the upper Midwest area of the United States. In this study, we determined the efficacy of five commonly used disinfectants (Virocid, Keno X5, Synergize, One Stroke, and Tek Trol) against turkey arthritis reoviruses (TARVs). For comparison, turkey enteric reovirus (TERV) and chicken arthritis reovirus (CARV) were also included. At their recommended concentrations, all five disinfectants were found to be effective virucidals, inactivating 99.99% of all viruses within 10 min. However, oxidizing agents and quaternary ammonium compounds + aldehyde types of disinfectants were more effective, killing the viruses in a shorter time (2-5 min) than the other types of disinfectants. These results indicate that these disinfectants can be an effective tool in the control of these viruses.