Post Chlorination Research Articles

Assessment of Drinking Tap Water Quality in Wa Municipality, Ghana

Water quality analysis is an essential component of water supply globally. This study analyzed drinking water quality at the tap in the Wa Municipality of Ghana. Bacteriological, physicochemical, aesthetic, and some chemical parameters of raw, treated and tap water was analyzed. The analysis showed that drinking tap water has a good quality and was satisfactory according to the World Health Organization’s (WHO) guidelines for drinking water. However, an assessment of consumers’ perception of water consumption profiles revealed that 25 % of the respondents claimed that the water quality was bad and had some taste that may be attributable to the long period of water storage. Therefore, it is recommended that the post chlorination dose should be increased to ensure the disinfection requirements and avoid any post-treatment contamination.

Potential cancer risk estimates from trihalomethanes in peri-urban settings of Kawama East of Mufulira, Zambia.

In this study, we report the formation and cancer risk estimation of trihalomethanes (THMs) emanating from 'ex-situ' chlorination of shallow hand-dug well water obtained from a peri-urban area of Mufulira District, Zambia. The aim of the study was to evaluate the potential cancer risks for people in this area where chlorine water disinfection at the household level is commonly practiced. Water samples from 13 randomly selected hand-dug wells (4-8 m deep) were collected and analyzed for pH, turbidity, and dissolved organic carbon before chlorination. Then another set of water samples from the same 13 wells was chlorinated using the methods commonly practiced in this area, consistent with WHO recommended doses. The chlorination degradation products, THMs, trichloromethane, bromodichloromethane (CHCl2Br), dibromochloromethane (CHClBr2), and tribromomethane, were determined at three different times of 60, 180, and 300 min after chlorination, while residual chlorine was determined immediately after chlorination and at 60 and 1,440 min after chlorination. THMs were determined using gas chromatography (GC), while residual chlorine was determined colorimetrically. Then cancer risk estimation from ingestion, inhalation, and dermal routes was carried out. All water samples from the 13 wells showed elevated amounts of THMs, which also increased with increasing contact time. For instance, the concentrations of THMs at 60 min after chlorination ranged from 24.3 ± 2.0 to 61.3 ± 1.0 μg/L, while at 180 and 300 min, ranged between 85.6 ± 4.3-146.9 ± 2.5 μg/L and 188.1 ± 7.1-250.1 ± 7.1 μg/L, respectively. It was observed that tribromomethane was not detected at all in all samples, while CHCl2Br and CHClBr2 were only detected at 180 and 300 min post chlorination. The lifetime cancer risk estimation results showed negligible risk at 60 min post chlorination. However, at 180 and 300 min post chlorination, the results were far above negligible, but within the regulatory US EPA limits. The overall risk, however, could not be ignored, given a multiplicity of exposure to various other contaminants, raising concerns over additivity and synergistic interactive effects, particularly for non-cancer hazard indices.

Removal of trace organic pollutants and generation of halogenated disinfection by-products in membrane UV/chlorine combined process

In this study, the degradation kinetics and degradation mechanism of 23 trace organic pollutants (TrOCs) in the secondary effluent of sewage by the combined membrane-UV/chlorine process were investigated, and the halogenated disinfection by-products (X-DBPs) in the combined process were investigated and its generation potential (X-DBPsFP), and the cytotoxicity and genotoxicity of the treated water samples were also evaluated. The results showed that membrane pretreatment could effectively promote the degradation of TrOCs in UV/chlorine system, and nanofiltration (NF) was more effective than ultrafiltration (UF). Compared with UF, NF intercepts more dissolved organic matter (DOM), thus weakening the light shielding effect, chlorine consumption and radical quenching to a greater extent. It is found that the degradation mechanism of TrOCs can be divided into the following four categories: Ho˙ dominated, RHS dominated, chlorine and RHS jointly dominated and chlorine dominated. Membrane pretreatment can well reduce the formation of X-DBPs, among which UF and NF reduce the formation of haloacetamide (HAMs) and trihalomethanes (THMs) most significantly, while NF reduces the formation of X-DBPs and X-DBPsFP and the toxicity of water samples much stronger than UF. In addition, NF UV/chlorine can significantly remove the precursors of X-DBPs, so as to effectively control the enhancement of cytotoxicity and genotoxicity of water samples in the post chlorination process. The research results promote the development of advanced sewage treatment technology and provide theoretical guidance for related research.

Improved operational reliability and contaminant removal in water reuse through filter upgrades

AbstractA redesign, construction, and replacement of the filters used for water reuse at a 11 million gallon per day Florida municipal water reclamation facility provided a prime opportunity to evaluate the impact of the filtration technologies on water quality, trace organic contaminant (TOrC) removal, and removal of pathogens. This study was designed to capture operational data, pathogen removal (Cryptosporidium and Giardia), and TOrC removal before the replacement of the filters using the existing synthetic media filters (SMF) and traveling bridge filters (TBF) followed by an evaluation of the deep bed filters (DBF) after construction and commissioning. The new DBF units provided substantially improved control of turbidity and total suspended solids while also significantly improving the removal of Giardia cysts (increase of >2 log removal) as compared to removal across the older SMF and TBF units and minor improvements to Cryptosporidium oocyst removal. TOrC removal was not significantly changed when comparing removal across the SMF, TBF, and DBF units nor post chlorination (chloramination).Article Impact StatementThis manuscript will be of use to the community as it provides additional understanding of public health protection in water reuse.

Change of disinfection byproducts formation potential of natural organic matter after exposure to persulphate and bicarbonate

Activated persulphate (PS) oxidation is a promising in situ remediation technology for groundwater and soils. Application of this technology to contaminated zones may result in a large quantity of PS residue in the subsurface environment due to inefficient activation and repeated injection. In this study, we demonstrated that natural organic matter (NOM) molecules could be reconfigured due to exposure to unactivated PS and bicarbonate, resulting in reduced disinfection byproducts formation potential in post chlorination process. Fourier transformed inferred spectrometry (FTIR), size exclusive chromotraghy (SEC), and mass spectrometry (MS) analysis revealed that hydroxylation and carboxylation of NOM occurred, followed by inter-molecular coupling via ether bonds. The change of both the reactivity toward free chlorine and molecular structure of NOM during PS/bicarbonate treatment was well mimicked by 3,5-dihydroxylbenzoic acid, suggesting that phenolic moieties in NOM molecules were the main sites underwent transformation in the PS/bicarbonate system. We propose that peroxymonocarbonate (HCO4−) formed upon the reaction between PS and bicarbonate was the main reactive species responsible for the reconfiguration of NOM. It selectively attacked the phenolic moieties via single-electron abstracting mechanism, leading to phenoxy radical intermediates which couple to each other via C–O–C bonds. The findings of this study shed light on the environmental behaviors and impacts of PS in groundwater environment.

Development of a loop-mediated isothermal amplification assay targeting lmo0753 gene for detection of Listeria monocytogenes in wastewater.

Contaminated wastewater plays an important role in the transmission of Listeria monocytogenes in the environment. In this study, a loop-mediated isothermal amplification (LAMP) assay for sensitive detection of L.monocytogenes in wastewater from treatment plants was developed, validated and compared to conventional PCR. The lmo0753 gene which codes for a Crp/Fnr family transcription factor, was targeted to design four specific primers to detect L.monocytogenes in 60min at 63°C in a water bath. Amplification products were visualized by agarose gel electrophoresis. The detection limit of the LAMP assay was 65fgµl-1 of DNA and 38CFU per ml. Conventional PCR was 10 times less sensitive than LAMP assay with primers targeting the HlyA gene. A total of 70 crude wastewater samples collected at different treatment stages (aeration tank, pre chlorination and post chlorination), were tested directly by LAMP and PCR. Samples from aeration and pre-chlorination stages tested positive with LAMP and culture method but not with conventional PCR. LAMP assay was tolerant to inhibitors present in wastewater and circumvented the need for isolation of pure DNA for detection. Both LAMP assay and culture method failed to detect L.monocytogenes in post-chlorinated wastewater, confirming the efficiency of the treatment process in the removal of L.monocytogenes. SIGNIFICANCE AND IMPACT OF THE STUDY: Treated wastewater effluent contains Listeria monocytogenes which survives conventional wastewater treatment processes and can re-enter human food chain, thus it is imperative to detect L.monocytogenes using a rapid and an inexpensive method. To the best of our knowledge, this is the first report of a loop-mediated isothermal amplification (LAMP) assay, targeting the lmo0753 gene for detection of L.monocytogenes in wastewater from treatment plants. The LAMP assay detects L.monocytogenes in 60min at 63°C in a water bath. LAMP does not require isolation of pure genomic DNA hence it is a user friendly method for L.monocytogenes detection.

DBP alteration from NOM and model compounds after UV/persulfate treatment with post chlorination

The UV/persulfate process is an effective advanced oxidation process (AOP) for the abatement of a variety of micropollutants via producing sulfate radicals (SO4•-). However, when this technology is used to reduce target pollutants, the precursors of disinfection byproducts (DBPs), such as natural organic matter (NOM) and organic nitrogen compounds, can be altered. This study systematically investigated the DBP formation from NOM and five model compounds after UV/H2O2 and UV/persulfate treatments followed with 24 h chlorination. Compared to chlorination alone, the yields of trichloromethane (TCM) and dichloroacetonitrile (DCAN) from NOM decreased by 50% and 54%, respectively, after UV/persulfate treatment followed with chlorination, whereas those of chloral hydrate (CH), 1,1,1-trichloropropanone (1,1,1-TCP) and trichloronitromethane (TCNM) increased by 217%, 136%, and 153%, respectively. The effect of UV/H2O2 treatment on DBP formation shared a similar trend to that of UV/persulfate treatment, but the DBP formation was higher from the former. As the UV/persulfate treatment time prolonged or the persulfate dosage increased, the formation of TCM and DCAN continuously decreased, while that of CH, 1,1,1-TCP and TCNM presented an increasing and then decreasing pattern. SO4•- activated benzoic acid (BA) to form phenolic compounds that enhanced the formation of TCM and CH, while it deactivated resorcinol to decrease the formation of TCM. SO4•- reacted with aliphatic amines such as methylamine (MA) and dimethylamine (DMA) to form nitro groups, which significantly increased the formation of TCNM in post chlorination, and the rate was determined to be higher than that of HO•. This study illuminated the diverse impacts of the structures of the precursors on DBP formation after UV/persulfate treatment, and DBP alteration depended on the reactivity between SO4•- and specific precursor.

Electron donating capacity reduction of dissolved organic matter by solar irradiation reduces the cytotoxicity formation potential during wastewater chlorination

After treated wastewater is discharged into surface water for unplanned indirect potable reuse, solar irradiation transforms the dissolved organic matter (DOM), which would alter the formation of disinfection byproducts (DBPs) and change the cytotoxicity formation potential (CtFP) during post–chlorination in drinking water treatment plants. This study investigated the effects of solar irradiation on the CtFP and total organic halogen formation potential (TOXFP) of wastewater during post–chlorination. Exposure to natural sunlight decreased the formation potential of cytotoxicity to Chinese Hamster Ovary cells. Under 24 h simulated solar irradiation, CtFP and TOXFP decreased by more than 40%. X–ray photoelectron spectra and Fourier transformation infrared spectra suggested solar irradiation destroyed the key DBP precursors containing phenolic hydroxyl moieties (Ph–OH). The destruction of Ph–OH under solar irradiation was reflected by a decrease in the electron donating capacity (EDC) of DOM and the post–chlorination decreased the EDC further. Increasing the irradiation–consumed EDC abated the chlorine–consumed EDC, while the chlorine–consumed EDC was positively correlated to the CtFP and TOXFP by means of the electrophilic substitution–aromatic ring cleavage. Solar irradiation thus reduced the CtFP and TOXFP in wastewater during post–chlorination. This study revealed that solar irradiation decreased the risks of treated wastewater for unplanned indirect potable reuse and provided a strategy of controlling CtFP and TOXFP via reducing EDC of DOM in pretreatments.

English

Assela, one of the developing towns in the south eastern central zone of Ethiopia, is located 175 km away from the Capital City of Addis Ababa. Anko River divides the town into two separate parts. In rural areas, water from Anko River is used for drinking and sanitation purposes. However, sewage from residential areas and Assela Hospital directly enters the river, affecting its quality. The objective was to determine Anko River water pollution status by the influence of wastewater discharge in Assela town. The cross sectional study design was conducted. The sampling techniques were wastewater samples taken from Assela Hospital waste water discharge site, upstream and downstream sites of Anko River for laboratory analysis in Addis Ababa. The average results of chemical and bacteriological parameters such as BOD5 from 11.8 to 131.9 mg/L; COD from 115.7 to 206.2 mg/L, ammonia from 8.4 to 42.4 mg/L, nitrate varied from 1.6 to 3 mg/L, nitrite from 0.1 to 0.2 mg/L, and phosphate values varied from 2.1 to 6.3 mg/L, faecal coliform counts/100 ml varied from 180 to 600 and total coliform beyond WHO recommended for wastewater discharge. The correlations among the bacteriological and chemical properties were observed in the studied sites. Ammonia with phosphate, BOD5 and COD had a significant positive correlation (r = 1.000, at P-value at 0.01, respectively). Nitrate had negative significant correlation with phosphate, BOD5, COD and FCF(r = - 1 and -0.820, P-value < 0.01) and phosphate correlated with BOD5, COD and FCF (r = 1 and 0.820, at P-value at 0.01, respectively). BOD5 correlated with COD and FCF (r=1 and 0.820 with P-value at 0.001 respectively). Water borne diseases may be transmitted due to waste pollution of Anko River. Therefore, Assela town health departments have to take intervention measures on proper Anko River water treatment. Also, to reduce the faecal and total coliform organisms applying waste water treatment system with sand filtration followed by post chlorination systems must be recommended by Assela Hospital and municipality. Key words: Water quality, indicator, water borne diseases, bacteriological and chemical water property.

The impact of a Wastewater Treatment Works in Southern Gauteng, South Africa on efavirenz and nevirapine discharges into the aquatic environment

Abstract There has been growing concern regarding the pollution of the aquatic environment with synthetic organic chemicals. Antiretroviral drugs, such as efavirenz and nevirapine, are pharmaceutical drugs and are referred to as emerging contaminants. Such drugs can be environmentally persistent and may be expected to pose potential risks to drinking water supplies. Sources of pharmaceutical drugs include effluents from Wastewater Treatment Works (WWTPs), hospital and pharmaceutical production facilities and the incorrect disposal of unused and expired medicines. Currently there are no monitoring programs and legislative guidelines for their regulations in South Africa. The aims of this study were firstly to develop a semi-quantitative method to extract and analyse efavirenz and nevirapine in the primary settling tank sludge. Secondly to use that method, and an existing method for liquid wastewater samples, to monitor the concentrations of efavirenz and nevirapine as the wastewater passes through the different stages of purification (anoxic; aerobic; pre and post chlorination) in the WWTP. This was repeated weekly over a period of 4 weeks. Thirdly, to determine if binding of efavirenz and nevirapine to the solids in the WWTP played a role in the removal of these compounds from the WWTP liquid phase. No references to the analysis of ARVDs in WWTP sludge were found in the literature. Grab samples of wastewater and sludge samples were collected from a WWTP (activated sludge treatment process) weekly for 4 weeks. Liquid samples were extracted solid phase extraction, solid samples were extracted using sonication followed by a QuEChERs clean-up. Sample extracts were then subjected to gas chromatography-time of flight mass spectrometry for analyte determination. Efavirenz concentrations entering the WWTP ranged between 5500 to almost 14 000 ng/L. The removal of efavirenz by the WWTP ranged between 27 and 71%. The largest removal occurred in the anoxic zone, smaller amounts were removed in the aerators. Slight increases in efavirenz concentrations were found after chlorination and the final effluent into the river post maturation ponds again were slightly lower. Solids were found to contain efavirenz at concentrations between 17 and 43 mg/kg dried primary settling tank sludge and it is proposed that this binding to the solids is the main mechanism of removal of efavirenz from the wastewater stream as it passes through the WWTP. Although an order of magnitude lower nevirapine concentrations displayed the opposite behaviour and gradually increased through the various stages of purification in the WWTP. Minor fluctuations occurred but the concentrations of nevirapine were higher at the effluent (between 92 and 473 ng/L) than those entering the WWTP. No nevirapine was detected in the PST sludge. The increase in nevirapine concentrations are likely to be the result of the de-conjugation of the hydroxylated metabolites of nevirapine in the WWTP, its resistance to degradation and the lack of binding of the nevirapine to the PST sludge.

Post-Chlorination Process Control based on Flow Prediction by Time Series Neural Network in Water Treatment Plant

It is very important to maintain a constant chlorine concentration in the post chlorination process, which is the final step in the water treatment process (hereafter WTP) before servicing water to citizens. Even though a flow meter between the filtration basin and clear well must be installed for the post chlorination process, it is not easy to install owing to poor installation conditions. In such a case, a raw water flow meter has been used as an alternative and has led to dosage errors due to detention time. Therefore, the inlet flow to the clear well is estimated by a time series neural network for the plant without a measurement value, a new residual chlorine meter is installed in the inlet of the clear well to decrease the control period, and the proposed modeling and controller to analyze the chlorine concentration change in the well is a neuro fuzzy algorithm and cascade method. The proposed algorithm led to post chlorination and chlorination improvements of 1.75 times and 1.96 times respectively when it was applied to an operating WTP. As a result, a hygienically safer drinking water is supplied with preemptive response for the time delay and inherent characteristics of the disinfection process.

Removal of phages and viral pathogens in a full-scale MBR: Implications for wastewater reuse and potable water

The aim of this study was to demonstrate how seasonal variability in the removal efficacy of enteric viral pathogens from an MBR-based water recycling system might affect risks to human health if the treated product were to be used for the augmentation of potable water supplies. Samples were taken over a twelve month period (March 2014–February 2015), from nine locations throughout a water recycling plant situated in East London and tested for faecal indicator bacteria (thermotolerant coliforms, intestinal enterococci n = 108), phages (somatic coliphage, F-specific RNA phage and Bacteroides phage (GB-124) n = 108), pathogenic viruses (adenovirus, hepatitis A, norovirus GI/GII n = 48) and a range of physico-chemical parameters (suspended solids, DO, BOD, COD). Thermotolerant coliforms and intestinal enterococci were removed effectively by the water recycling plant throughout the study period. Significant mean log reductions of 3.9–5.6 were also observed for all three phage groups monitored. Concentrations of bacteria and phages did not vary significantly according to season (P < 0.05; Kruskal-Wallis), though recorded levels of norovirus (GI) were significantly higher during autumn/winter months (P = 0.027; Kruskal-Wallis). Log reduction values for norovirus and adenovirus following MBR treatment were 2.3 and 4.4, respectively. However, both adenovirus and norovirus were detected at low levels (2000 and 3240 gene copies/L, respectively) post chlorination in single samples. Whilst phage concentrations did correlate with viral pathogens, the results of this study suggest that phages may not be suitable surrogates, as viral pathogen concentrations varied to a greater degree seasonally than did the phage indicators and were detected on a number of occasions on which phages were not detected (false negative sample results).

The formation of aldehydes and ketones ozonation by-products and their variation through general water treatment plant in Hamadan, Iran

&lt;div&gt; &lt;p&gt;The effect of pre-ozonation on the formation of four aldehydes (i.e. formaldehyde, acetaldehyde, glyoxal, methyl glyoxal) and two ketones (i.e. pyruvic acid and glioxalic acid) at the Beheshti water treatment plant in Hamadan, Iran were studied. Water samples were taken from the treatment plant at different points of the treatment train during September-January, 2013. The variation of formaldehyde, acetaldehyde, glyoxal, methyl glyoxal, pyruvic acid, and acid glioxalic concentration within treatment process were monitored in September and January. The results indicated that formaldehyde and acetaldehyde were the most abundant aldehyde species in the raw water. After pre-ozonation all of the aldehydes and ketones reached the maximum concentration. On the contrary, results show that the coagulation-filtration process was beneficial to the removal of aldehydes and ketones. Also, the results indicated that the level of aldehydes was increased after post chlorination. The percent increase was 52.3, 34.6, 12.1, 26.8 and 38% for formaldehyde, acetaldehyde, glyoxal, methyl glyoxal and glyoxalic acid, respectively, in September. Therefore, final chlorination led to increase in the formation of aldehydes in the pre-ozonated water. Ketones were not detected in the post-chlorinated water. Moreover, there was no correlation between total organic carbon (TOC) and total aldehyde and total ketone in water samples.&amp;nbsp;&lt;/p&gt; &lt;/div&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Degradation of chlortoluron during UV irradiation and UV/chlorine processes and formation of disinfection by-products in sequential chlorination

The degradation kinetics and pathways of chlortoluron during UV irradiation and UV/chlorine process as well as the formation of disinfection by-products (DBPs) after post-chlorination were investigated in this study. The quantum yield of chlortoluron was calculated as 0.0258moleinstein−1 and the effect of solution pH was negligible during UV irradiation. On the other hand, the degradation rate of chlortoluron during UV/chlorine process was significantly promoted at acidic conditions as well as high chlorine doses and UV intensity. UV irradiation and UV/chlorination of chlortoluron both followed the pseudo-first order reaction kinetics, but UV/chlorine process is more efficient than UV irradiation with the reaction rate constant between chlortoluron and OH radicals determined as (2.18±0.83)×109M−1s−1. The mineralization of chlortoluron was considerably increased with increasing chlorine dose and decreasing pH during UV/chlorine process. The degradation pathways of chlortoluron during UV irradiation and UV/chlorine processes were proposed according to the identified intermediates. The formation of carbonaceous DBPs (C-DBPs) and nitrogenous DBPs (N-DBPs) during direct chlorination and post chlorination of UV irradiation and UV/chlorine processes were investigated as well. More DBP precursors were formed during UV/chlorine process compared to direct chlorination and UV irradiation, which deserves extensive concerns in drinking water treatment processes.

Impact of UV/persulfate pretreatment on the formation of disinfection byproducts during subsequent chlorination of natural organic matter

Ultraviolet/persulfate (UV/PS) has been widely used to generate sulfate radicals (SO4−) in degrading organic pollutants. However, its impact on chlorinated disinfection byproducts (DBPs) is unclear. Impact of UV/PS pretreatment on the formation of DBPs during subsequent chlorination of natural organic matter was evaluated in this study. For the samples pretreated by UV/PS, the formation of some carbonaceous disinfection byproducts (C-DBPs) such as chloroform and haloacetic acids only increased a little, but the formation of nitrogenous disinfection byproducts (N-DBPs) including haloacetonitriles and trichloronitromethane decreased slightly. UV/H2O2 pretreatment increased the formation of both C-DBPs and N-DBPs significantly with the initial dosage of H2O2 being 30μM. Chloral hydrate and haloketones followed an increasing and then decreasing pattern, but dichloroacetonitrile and trichloronitromethane followed an opposite pattern with increasing UV/PS pretreatment time. Most of the C-DBPs rose monotonically with increasing dosages of PS, but N-DBPs declined at the dosage of PS being 10μM by UV/PS pretreatment. Preoxidation pH and the presence of nitrate played little role in DBP formation. In the presence of 2.5mg/L ammonia, UV/PS pretreatment increased most of the DBPs except for trichloroacetonitrile and trichloronitromethane. Bromine incorporation factors for trihalomethanes, haloacetic acids and dihaloacetonitriles were affected by UV/PS preoxidation insignificantly. It is suggested that the combination of UV/PS and post chlorination was expected to be a good choice in controlling the formation of DBPs.

Diarrheal Epidemic Grips Ghallour Sub-centre, Jawalamukhi Block, Kangra District, Himachal Pradesh, India

Background: On 31st August, 2014, eighty cases of the gastroenteritis were reported in Ghallour sub-centre area. We investigated the outbreak to identify the source, propose control and preventive measures. Materials and methods: We defined a case as occurrence of three or more watery stools with or without vomiting, w.e.f 27 January, till 2nd Feb2014 in residents of Ghallour sub-centre area of Jawalamukhi Block. We hypothesized it as a water borne outbreak. We determined age and sex specific attack rate. We collected information about personal history on age, sex, residence, and date of onset of symptom from case patient and established line list. We collected 9 stool samples/rectal swabs from the cases; 3 pre and 4 post chlorination water samples and sent them for microbiological testing. We mapped water supply pipelines of the area and reviewed water chlorination record. Results: We identified 390 cases. The overall attack rate was 8% with range of 1.3% to 36%. The cases patients were reported from all age groups and both the genders with the youngest student; 1 year old to the oldest one as 88 years. Two thirds of the cases reported vomiting with some complaining of pain abdomen. Villages like Jathman, Khattni, Rajol Patta, Kohara has 100% case patients of loose motions while villages like Dhroli, (100%), Sasan (63%) and Ghallour (50%) etc have combined symptoms of loose motions and vomiting. No fatality was reported. Escherichia coli was detected in the samples from water samples. Records of chlorination were not properly maintained. Conclusion/recommendation: The outbreak was caused due to contamination of water at the source in Jolly Khad. Regular treatment of the water needs to be done right at the source before being lifted.

Water borne epidemic of gastroenteritis in Ghallour sub-centre of Jawalamukhi block, Kangra District, Himachal Pradesh, India

Background: On August 31, 2014, eighty cases of the gastroenteritis were reported in Ghallour sub-center area. We investigated the outbreak to identify the source, propose control, and preventive measures. Materials and Methods: We defined a case as occurrence of three or more watery stools with or without vomiting, w.e.f January 27, till February 2, 2014 in residents of Ghallour sub-center area of Jawalamukhi block. We hypothesized it as a water borne outbreak. We determined age and sex specific attack rate. We collected information about personal history on age, sex, residence, and date of onset of symptom from case patient and established line list. We collected nine stool samples/rectal swabs from the cases; three pre and four post chlorination water samples and sent them for microbiological testing. We mapped water supply pipelines of the area and reviewed the water chlorination record. Results: We identified 390 cases in 16 villages under the sub center. The overall attack rate was 8% with a range of 1.3% to 36%. The cases patients were reported from all age groups and both the genders with the youngest student; 1-year old to the oldest one as 88 years. Two-third of the cases reported vomiting with some complaining of pain abdomen. Villages like Jathman, Khattni, Rajol Patta, Kohara has 100% case patients of loose motions while villages like Dhroli, (100%), Sasan (63%) and Ghallour (50%), etc., have combined symptoms of loose motions and vomiting. No fatality was reported. Escherichia coli was detected in the samples from water samples. Records of chlorination were not properly maintained. Conclusion / Recommendation: The outbreak was associated due to contamination of water at the source in Jolly Khad. Regular treatment of the water needs to be done right at the source before being lifted.

서울시 정수장의 THMs 생성과 관련된 한강 원수의 주요 수질 특성 조사

In a study on THMs formation at the distribution facilities in Seoul water supply for past 3 years from 2007 to 2009, THMs production was increased from inlet to outlet during the process in water treatment plant. However, such increased THMs amount was very small compared to THMs production formed after pre-chlorination and post chlorination. Accordingly, this study is aimed to investigate the characteristics of water quality parameters of Han River related to THMs formation in 6 water treatment plants in Seoul. The results showed that THMs and other factors such as temperature (r = 0.539~0.846) and turbidity (r = 0.421~ 0.863) had positive correlation while THMs had negative correlation with pH (r = -0.613~-0.800) and algae (r = -0.582~-0.901). There is no correlation between THMs and NH3-N. According to the factor analysis, generally metabolite and organic matter factor X1 (pH, BOD, algae), and seasonal and natural factor X2 (temperature, turbidity) played an important role in the formation of THMs. Multiple regression analysis for THMs formation showed significance of regression appeared in most water systems.

Simultaneous reduction of by-products of chlorine dioxide and chlorine using Fe(II)–Al(III) coagulant mixture

Ferrous iron has been considered very useful for removal of chlorite, a by-product of chlorine dioxide. However, a serious problem can occur associated with high residual iron concentrations in water after Fe(II) treatment, especially at weak acidic condition (pH 6), having a higher capacity of chlorite reduction. Simultaneous removal of chlorite, dissolved iron, and humic acids was achieved with a Fe(II) –Al(III) (1:5) coagulant mixture. Moreover, a significant reduction of chlorine by-products formed after subsequent post chlorination was observed. The by-products of chlorine dioxide and chlorine could be dramatically reduced by the simple addition of the coagulant mixture without the additional problem of dissolved iron.

Evaluation of Potable Water Quality of AL-Diwaniyah Water Treatment Plants

The selection of proper treatment is of prime importance in the providing of drinking water. In this study tow WTPs in Diwaniyah were selected to evaluate their water quality in producing potable water according to the Iraqi standards. The two plants had high removal efficiency in turbidity which reached to ( 90 – 95) % and the turbidity of the treated water did not exceed 5 NTU.As for the natural constituents in raw water Ca, Mg and Na, their concentrations decreased in the treated water, but were within the desirable standards. Concentration of Al appeared also, as alum is added in the coagulation process. The final effluent had concentrations of Al ranging 0.01 - 0.02 mg/l. Fe with concentrations of 0.01 -0.2 mg/l appeared also, but Fe salts were not added for treatment. Must therefore follow-up tests of water on an on going basis to determine the cause. The two plants are efficient in bacterial removal as pre and post chlorination is applied. The residual chlorine in the effluent fr0m the plants ranged 2.0 - 2.5 mg/l, which was enough to leave 0.5 mg/l in the distribution system.