Chlorinated Tap Water Research Articles

Time and Temperature Effects on the Viability and Infectivity of Cryptosporidium parvum Oocysts in Chlorinated Tap Water

The authors compared the viability and infectivity of Cryptosporidium parvum oocysts in chlorinated tap water at various storage durations (i.e., 2 wk, 4 wk, 6 wk, or 8 wk) and at 2 cool temperatures (i.e., 10 degrees C and 4 degrees C), using in vitro (excystation) and in vivo (suckling mouse) methods. After 8 wk, mean oocyst excystation decreased to 33.4% and 26.7% at 10 degrees C and 4 degrees C, respectively. Suckling mice infectivity was higher after storage at 10 degrees C than after storage at 4 degrees C. These data suggest that Cryptosporidium parvum oocysts can survive and remain infectious for 8 wk in cool chlorinated tap water.

Electrochemical Generation of Perchlorate Ions in Chlorinated Drinking Water

Abstract A scheduled, uncontrolled chemical monitoring program conducted by the Texas Rural Water Association during the spring of 2002 discovered perchlorate contamination in an elevated drinking water storage tank. The contaminated elevated storage tank (EST) was part of the Levelland, Texas municipal water distribution system. Subsequent investigations revealed that the most likely source of the perchlorate contamination was the impressed current corrosion protection system, which generated the perchlorate electrochemically in situ from the chlorinated drinking water stored in the tank. As a part of the authors' investigation into this phenomenon, batch scale laboratory experiments were designed and used to produce perchlorate ions in chlorinated tap water using an imposed electrical (direct current [DC]) current. This in situ generation process was found to follow an autocatalytic mechanism with respect to perchlorate ion concentration. Moreover, in parallel experiments, double-distilled water spiked ...

Effects of Water Source, Dilution, Storage, and Bacterial and Fecal Loads on the Efficacy of Electrolyzed Oxidizing Water for the Control of Escherichia coli O157:H7

To evaluate the potential of using electrolyzed oxidizing (EO) water for controlling Escherichia coli O157:H7 in water for livestock, the effects of water source, electrolyte concentration, dilution, storage conditions, and bacterial or fecal load on the oxidative reduction potential (ORP) and bactericidal activity of EO water were investigated. Anode and combined (7:3 anode:cathode, vol/vol) EO waters reduced the pH and increased the ORP of deionized water, whereas cathode EO water increased pH and lowered ORP. Minimum concentrations (vol/vol) of anode and combined EO waters required to kill 104 CFU/ml planktonic suspensions of E. coli O157:H7 strain H4420 were 0.5 and 2.0%, respectively. Cathode EO water did not inhibit H4420 at concentrations up to 16% (vol/vol). Higher concentrations of anode or combined EO water were required to elevate the ORP of irrigation or chlorinated tap water compared with that of deionized water. Addition of feces to EO water products (0.5% anode or 2.0% combined, vol/vol) significantly reduced (P < 0.001) their ORP values to <700 mV in all water types. A relationship between ORP and bactericidal activity of EO water was observed. The dilute EO waters retained the capacity to eliminate a 104 CFU/ml inoculation of E. coli O157:H7 H4420 for at least 70 h regardless of exposure to UV light or storage temperature (4 versus 24°C). At 95 h and beyond, UV exposure reduced ORP, significantly more so (P < 0.05) in open than in closed containers. Bactericidal activity of EO products (anode or combined) was lost in samples in which ORP value had fallen to ≤848 mV. When stored in the dark, the diluted EO waters retained an ORP of >848 mV and bactericidal efficacy for at least 125 h; with refrigeration (4°C), these conditions were retained for at least 180 h. Results suggest that EO water may be an effective means by which to control E. coli O157:H7 in livestock water with low organic matter content.

Effect of Alfalfa Seed Washing on the Organic Carbon Concentration in Chlorinated and Ozonated Water

The bioassays assimilable organic carbon (AOC) and coliform growth response are better indexes than biological oxygen demand to determine water quality and water's ability to support the growth of bacteria. Ozonated (5 mg/liter) and chlorinated tap water were used to wash alfalfa seeds for 30 min. After washing in the ozonated tap water, the AOC concentration increased 25-fold, whereas the dissolved ozone decreased to undetectable levels. The AOC levels for the chlorinated water after washing the seeds also increased. These increases are due to ozone's strong oxidizing ability to break down refractory, large-molecular-weightcompounds, forming smaller ones, which are readily used as nutrient sources for microorganisms. This same phenomenon was observed when using ozone in the treatment of drinking water. The AOC value increased from 1,176 to 1,758 μgC-eq/liter after the reconditioned wastewater was ozonated. When the ozonated wastewater was inoculated with Salmonella serotypes, the cells survived and increased generation times were observed. The increased nutrients would now become more readily available to any pathogenic microorganisms located on alfalfa seed surface as seen with the increase in the inoculated levels of Salmonella in the ozonated wastewater. If the washing process using ozonated water is not followed by the recommended hypochlorite treatment or continually purged with ozone, pathogen growth is still possible.

Nosocomial pediatric bacteremia: the role of intravenous set contamination in developing countries.

To assess the rate of bacterial contamination of intravenous administration sets at their rubber injection ports and matching infusates. Cultures of injection ports and infusate during 26 visits to 4 hospitals. Four public general pediatric hospitals in Mexico City with substandard care practices. Hospitalized pediatric patients receiving intravenous solutions. Overall, 176 of 251 injection ports were contaminated (70.1%; 95% confidence interval [CI95], 64.5% to 75.8%), 35 (13.9%; CI95, 9.7% to 18.2%) with gram-negative rods, primarily of the tribe Klebsielleae. Cultures of infusates were positive in 17 cases (6.8%, CI95, 3.7% to 9.9%), 5 of which grew gram-negative rods (2%; CI95, 0.6% to 4.6%). In 3 cases (1.2%), the same species with gram-negative rods was found in the infusates and on the injection ports. During one visit, 8 clustered cases of injection port contamination with a clonal Enterobacter cloacae were found; this agent was also found in the blood culture, intravenous fluid, and parenteral nutrition of one patient. Inadequate chlorination of tap water, a potential risk factor, was recorded during 22 visits (84.6%). These data suggest that external contamination of the intravenous administration set could play a role in infusate contamination.

水道水残留塩素に侵されるＮＢＲの劣化メカニズム

In order to elucidate the degradation behavior of NBR caused by residual chlorine in tap water, NBR diaphragms used in chlorine-contained tap water for about 4 and 9 years at an ambient temperature in Yokohama City and the unused product were analyzed by means of FT-IR, EPMA and XPS. NBR usually leads to hardening and degradation with increase of crosslinking density by heat or UV. However, NBR used in tap water softened and chlorine atom invaded into surface layer of NBR diaphragm. The degradation process of the NBR in the tap water is considered as follows: (1) the α-H of the butadiene double-bond of the NBR is susceptible to substitution by chlorine; (2) the chlorinated NBR reacted with other NBR and subtraction of the α-H produced the radical; (3) the radical subsequently produced hydroperoxide at the α-position and an aldehyde was formed by decomposition similar to that in the oxidation degradation mechanism of polybutadiene; (4) vulcanized points were cleaved simultaneously. These processes are expected to lower the molecular weight of the NBR and lead to softening and degradation.

Distribution of Bromine/Chlorine-Containing Disinfection By-Products in Tap Water from Different Water Sources in the Hyogo Prefecture

An investigation was conducted to determine both the distribution and the concentration of 24 types of disinfection by-products (DBPs) formed by the chlorination of tap water during the water treatment process. The 24 DBPs consisted of 9 haloacetic acids (HAAs), 9 haloacetonitriles (HACNs), 4 trihalomethanes (THMs), chloral hydrate (CH) and formaldehyde (FA). The samples were collected from 8 different water sources in the Hyogo Prefecture. As a result of the field study, which was conducted 4 times in one year, 23 of the DBPs mentioned above [all except for tribromoacetonitrile (TBACN)] were detected in tap water. When the 24 DBPs are classified into their 5 main categories, it has previously been thought that THMs would form the highest concentration group. However, according to the results obtained in this study, the average values of the HAAs showed the highest at the various sampling points, followed by the THMs, HACNs, chloral hydrate and formaldehyde. The composition ratios of the bromine/chlorine-containing DBPs in tap water from different water sources were compared. The ratio of chlorine-containing DBPs in tap water derived from surface water was higher than that in tap water derived from ground water. On the other hand, the ratio of the bromine-containing DBPs in tap water extracted from ground water was higher than that of tap water extracted from surface water. This tendency was observed equally for HAAs, HACNs and THMs. This phenomena was also supported by numerical results obtained using the bromine incorporation factor [n(Br)]. It was newly revealed that n(Br) is applicable to HAAs and HACNs in addition to THMs.

Trace determination of peptides in water samples using packed capillary liquid chromatography with UV and MS detection and characterization of peptide oxidation products by MS.

A capillary liquid chromatographic column switching method has been developed for fast and sensitive determination of peptides in water samples. Sample volumes of 1 mL were loaded onto a (320 microm I.D. x30 mm) 10 microm Kromasil C(18) pre-column, providing on-line analyte enrichment, prior to back-flushed elution onto a (320 microm I.D. x150 mm) 3.5 microm Kromasil C(18) analytical column. Loading flow rates of 250 microL/min and a mobile phase composition of acetonitrile/water/trifluoroacetic acid (22/77.9/0.1, v/v) provided a total analysis time of less than 25 minutes for the test peptides angiotensin II, bombesin, bradykinin, corazonin, neurotensin and substance P, using temperature programmed elution. In addition, solvent gradient elution and combined solvent gradient elution and temperature programming were explored. Using on-capillary UV detection at 210 nm resulted in a concentration limit of detection (cLOD) of about 1 ng/mL. The method was validated over the concentration range 1-100 ng/mL, yielding a coefficient of correlation of 0.997 or better. The within-assay ( n=6) and between-assay ( n=6) precisions of peak areas were on average 6% RSD and 5% RSD, respectively. When the method was applied to spiked chlorinated tap water samples, it was found that peptides containing methionine, tryptophan and cystine were oxidized. Identification of the oxidation products of the peptides in hypochlorite-treated water was done with positive electrospray ionization time-of-flight mass spectrometric detection.

Degradation of isoxaflutole (balance) herbicide by hypochlorite in tap water.

Chlorine has been widely employed for the disinfection of drinking water. Additionally, it has the capacity to oxidize many organic compounds in water. Isoxaflutole (Balance; IXF) belongs to a new class of isoxazole herbicides. Isoxaflutole has a very short soil half-life and rapidly degrades to a stable and phytotoxic metabolite, diketonitrile (DKN). Further degradation of DKN produces a nonbiologically active benzoic acid (BA) metabolite. In experiments using high-performance liquid chromatography-UV spectroscopy (HPLC-UV) and HPLC tandem mass spectrometry (HPLC-MS/MS), DKN was found to rapidly react with hypochlorite in tap water, yielding the BA metabolite as the major end product. One milligram per liter (19 microM) of hypochlorite residue in tap water was able to completely oxidize up to 1600 microg/L (4.45 micromol/L) of DKN. In tap water, the disappearance of IXF was much more rapid than in DI water. As soon as the IXF is hydrolyzed to DKN, the DKN quickly reacts with the OCl(-) to form nonphytotoxic BA. As a result, the herbicide solutions prepared with tap water at 500 microg/L will no longer possess any herbicidal activity after 48 h of storage. However, in agronomic settings, highly concentrated tank solutions (600-800 mg/L) may be prepared with tap water since the conversion of IXF to BA would represent <5% of the herbicide; therefore, any impact on the herbicide efficacy would be negligible. Results of this study show that current chlorination disinfection protocols in municipal water systems would completely eliminate the phytotoxic form of this new herbicide, DKN, from drinking water supplies; yet, farmers can use chlorinated tap water without significant loss of efficacy.

Analysis of aldehydes in water by solid-phase microextraction with on-fiber derivatization

The solid-phase microextraction (SPME) technique with on-fiber derivatization was evaluated for the analysis of aldehydes in water. The poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB) fiber was used and O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) were first loaded onto the fiber. The aldehydes in water sample were agitated into headspace and extracted by SPME with on-fiber derivatization. Gas chromatography/mass spectrometry (GC/MS) was used for the analysis of oximes formed and the adsorption-time profiles were examined. The precision, recovery and method detection limits (MDLs) were evaluated with spiked bidistilled water, chlorinated tap water as well as well water. The relative standard deviations from different spiked water sample were all less than 10% and the recoveries were 100±15%. With 2 ml of water sample, MDLs were in the range of 0.12–0.34 μg/l. Compared with other techniques, the study shown here provided a simple, fast and reliable method for the analysis of aldehydes in water.

Design and Operation of Point-of-Use Treatment System for Arsenic Removal

A point-of-use ~POU! system was designed and constructed using commercially available activated alumina to remove arsenic from drinking water. Testing with City of Albuquerque chlorinated tap water containing an average of 23 ug/L arsenic found that 1 L of adsorbent would provide water for direct consumption by a family of four for 435 days. It was estimated that the POU system constructed for this study could be sold for $162, and the arsenic adsorption columns were estimated to cost $4. A monthly cost to the customer of $10/month was estimated to purchase, install, and operate this POU system, assuming annual replacement of adsorption media cartridges. The implications of relying upon POU systems to comply with a new drinking water standard for arsenic are discussed.

Flow-injection investigation of the chemiluminescent reaction of bis(2,4,6-(trichlorophenyl)oxalate) with free chlorine

This work investigated the chemiluminescent reaction of free chlorine with bis(2,4,6-(trichlorophenyl)oxalate) (TCPO) in the presence of 9,10-diphenylanthracene in acetonitrile/water medium, with analytical application for free chlorine in tap water. In the absence of free chlorine, the background signal increased with the pH and the chemiluminescence emission showed strong dependence with the sample acidity. A flow injection analysis system, for free chlorine determination, was developed. The linear range for free chlorine was (0.2–3.0)×10 −5 mol l −1. Chloramine 1.0×10 −5 mol l −1 and chlorite 1.0×10 −6 mol l −1 also enhanced the chemiluminescence intensity.

Behavior oｆ Residual Free Chlorine in Tap Water Treated by the Advanced Water Treatment and the Management in Municipal Water Distribution System

Behavior oｆ Residual Free Chlorine in Tap Water Treated by the Advanced Water Treatment and the Management in Municipal Water Distribution System

Simple miniaturized amperometric flow cell for monitoring residual chlorine in tap water.

Simple miniaturized amperometric flow cell for monitoring residual chlorine in tap water.

Assessment of airborne exposure to trihalomethanes from tap water in residential showers and baths.

This study evaluates airborne concentrations of common trihalomethane (THM) compounds in bathrooms during showering and bathing in homes supplied with chlorinated tap water. Three homes in an urban area were selected, each having three bedrooms, a full bath, and approximately 1,000 square feet of living area. THMs were concurrently measured in tap water and air in the shower/bath enclosure and the bathroom vanity area using Summa canisters. Chloroform (TCM), bromodichloromethane (BDCM), and chlorodibromomethane (CDBM) were quantified using U.S. Environmental Protection Agency (EPA) Method TO-14. Air samples were collected prior to, during, and after the water-use event for 16 shower and 7 bath events. Flow rate and temperature were measured, but not controlled. The increase in average airborne concentration (+/- standard error) during showers (expressed as microg/m3 in shower enclosure or bathroom air per microg/L in water) was 3.3+/-0.4 for TCM, 1.8+/-0.3 for BDCM, and 0.5+/-0.1 for CDBM (n = 12), and during baths was 1.2+/-0.4 for TCM, 0.59+/-0.21 for BDCM, and 0.15+/-0.05 for CDBM (n = 4). The relative contribution of each chemical to the airborne concentrations was consistent for all shower and bath events, with apparent release of TCM > BDCM > CDBM. The results are therefore consistent with their relative concentration in tap water and their vapor pressures. When the shower findings for TCM are normalized for water concentration, flow rate, shower volume, and duration, the average exposure concentrations in these urban residences are about 30% lower than those reported by other investigators using EPA analytical methods. This difference is likely attributable primarily to greater air exchange rates in residential shower/bath stalls compared to more "airtight" laboratory shower chambers. This appears to be the first field study to thoroughly evaluate THM exposures from residential showers and baths, and can be used to validate previously published models of tap water volatile chemical transfer to indoor air.

Aeromonas hydrophila and its relation with drinking water indicators of microbiological quality in Argentine.

In Argentine, water municipal supplies disinfection is carried out by chlorine. We have isolated Aeromonas hydrophila from a chlorinated water supply in Buenos Aires that fulfilled Argentinean microbiological quality standards. It is an aquatic organism that could produce cytotoxins and enterotoxins associated with acute gastroenteritis and wound infections in human and hemorrhagic septicaemia of fish, reptiles and amphibians. The isolated strain produced protein bands at isoelectric point in the range of 4.6-5.3 lightly labile at 56 degrees C and heat labile at 100 degrees C non cholera antitoxin reactive in electrofocusing assay (IEF) and showed hemolytic activity thermolabile at 56 degrees C and 100 degrees C in 5% rabbit erythrocytes in phosphate buffered saline. A cytotoxic effect thermolabile at 56 degrees C and 100 degrees C and a cytotonic activity were demonstrated in Vero cell cultures. Survival assay of A. hydrophila and indicator organisms would show no correlation between their contamination sources. Biofilms production could explain the persistence of this gram negative pathogen organism in chlorinated tap water. A water system supply maintenance program and pasteurisation may be performed in spite of water chlorination.

Ascorbic acid reduction of residual active chlorine in potable water prior to halocarboxylate determination.

In studies on the formation of disinfection byproducts (DBPs), it is necessary to scavenge residual active (oxidizing) chlorine in order to fix the chlorination byproducts (such as haloethanoates) at a point in time. Such research projects often have distinct needs from requirements for regulatory compliance monitoring. Thus, methods designed for compliance monitoring are not always directly applicable, but must be adapted. This research describes an adaptation of EPA Method 552 in which ascorbic acid treatment is shown to be a satisfactory means for reducing residual oxidizing chlorine, i.e., HOCl, ClO-, and Cl2, prior to determining concentrations of halocarboxylates. Ascorbic acid rapidly reduces oxidizing chlorine compounds, and it has the advantage of producing inorganic halides and dehydroascorbic acid as opposed to halogenated organic molecules as byproducts. In deionized water and a sample of chlorinated tap water, systematic biases relative to strict adherence to Method 552 were precise and could be corrected for using similarly treated standards and analyte-fortified (spiked) samples. This was demonstrated for the quantitation of chloroethanoate, bromoethanoate, 2,2-dichloropropanoate (dalapon), trichloroethanoate, bromochloroethanoate, and bromodichlorocthanoate when extracted, as the acids, into tert-butyl methyl ether (MTBE) and esterified with diazomethane prior to gas chromatography with electron capture detection (GC-ECD). Recoveries for chloroethanoate, bromoethanoate, dalapon, dichloroethanoate, trichloroethanoate, bromochloroethanoate, bromodichloroethanoate, dibromoethanoate, and 2-bromopropanoate at concentrations near the lower limit of detection were acceptable. Ascorbic acid reduction appears to be the best option presently available when there is a need to quench residual oxidants fast in a DBP formation study without generating other halospecies but must be implemented cautiously to ensure no untoward interactions in the matrix.

Compressed Air as a Source of Inhaled Oxidants in Intensive Care Units

Exhaled gas from mechanically ventilated preterm infants was found to have similar oxidant concentrations, regardless of lung disease, leading to the hypothesis that wall outlet gases were an oxidant source. Oxidants in compressed room air and oxygen from wall outlets were assessed in three hospitals. Samples were collected by flowing wall outlet gas through a heated humidifier and an ice-packed condenser. Nitric oxide (NO) was measured in intensive care room air and in compressed air with and without a charcoal filter using a Sievers NOA280 nitric oxide analyzer (Boulder, CO). Oxidants were measured by spectrophotometry and expressed as nMol equivalents of H2O2/mL. The quantity of oxidant was also expressed as amount of Vitamin C (nMol/mL) added until the oxidant was nondetectable. This quantity of Vitamin C was also expressed in Trolox Equivalent Antioxidant Capacity (TEAC) units (mMol/L). Free and total chlorine were measured with a Chlorine Photometer. Oxidants were not found in compressed oxygen and were only found in compressed air when the compression method used tap water. At a compressed room air gas flow of 1.5 L/min, the total volume of condensate was 20.2 +/- 1 mL/hr. The oxidant concentration was 1.52 +/- 0.09 nMol/mL equivalents of H2O2/mL of sample and 30.8 +/- 1.2 nMol/hr; 17.9% of that found in tap water. Oxidant reduction required 2.05 +/-0.12 nMol/mL vitamin C, (1.78 +/- 0.1 x 10(-3) TEAC units). Free and total chlorine in tap water were 0.3 +/- 0.02 mg/mL and 2.9 +/- 0.002 mg/mL, respectively. Outlet gas contained 0.4 +/- 0.06 mg/mL and 0.07 + 0.01 mg/mL total and free chlorine, respectively; both 14% of tap water. When a charcoal filter was installed in the hospital with oxidants in compressed air, oxidants were completely removed. Nursery room air contained 12.4 +/- 0.5 ppb NO; compressed wall air without a charcoal filter, 8.1 +/- 0.1 ppb and compressed air with a charcoal filter 12.5 +/- 0.5 ppb. A charcoal filter does not remove NO. (Table 3) We recommend that all compressed air methods using tap water have charcoal filters at the compression site and the gases be assessed periodically for oxidants.

Lemon Puts Different Twist on Taste Issue

This article discusses adding lemon juice to tap water to improve its taste. Tests were done using lemon doses from 0.2 to 0.5 percent by volume. Acceptance and preference testing were done by a flavor profile analysis panel with results indicating that the more noticeable the lemon taste became, the less acceptable the drinking water became. Lemon treatments were found to reduce the water's chloramine residual by about 0.8 mg/L over five hours at room temperature. The panel's final conclusion was that a 0.1 percent solution of lemon in chlorinated tap water (three drops from a freshly squeezed lemon in an 8 oz. glass) would be the optimal amount to add.

Flow injection analysis for residual chlorine using Pb(II) ion-selective electrode detector

A simple flow injection analysis (FIA) system for residual chlorine in tap water has been developed by using a Pb(II) ion-selective electrode (ISE) detector. The method is based on a specific response of the Pb(II)-ISE to residual chlorine. The FIA system consists of a millivolt meter, a peristaltic pump, a Pb(II)-ISE detector and a recorder. A linear working curve between peak height and concentration of residual chlorine was obtained from 0.1 to 1 mg l −1 for the developed FIA system. The relative standard deviation for repeated injections of a 0.2 mg l −1 residual chlorine sample was 2%. The regression line and its correlation factor between the conventional o-tolidine colorimetric method and the present method were Y=0.75 X+0.17 and 0.967, respectively, for this determination.