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Perna viridis Linnaeus (1758) is a major foulant in the cooling water systems of electric power stations located on the East coast of India. Though chlorination is considered an effective fouling control measure, the strategy may fail in the case of bivalve mussels, due to the ability of the mussels to close their shells and still survive for extended periods of time. In a given power station, continuous low dose (exomotive) chlorination (0.2 ± 0.1 mg l−1) is practiced to control biofouling. Laboratory experiments were carried out to assess the mortality and valve movement response of Perna viridis exposed to chlorine, using a Mosselmonitor®. All size groups tested showed progressive reduction in valve opening upon chlorination. However, continuous dosing of chlorine concentration as high as 1.0 mg l−1 was required for sustained and complete valve closure response in this mussel. At lower concentration (0.7 mg l−1), the mussels were able to open their shells and feed. Sustained valve closure resulted in physiological stress to the mussels due to reduced feeding, subsequently leading to death. Time to 100% mortality was dependent on the size of the mussels. At 1.0 mg l−1 chlorine residual, smaller size group (30–50 mm) mussels showed 100% mortality in 79.3 h, while larger groups (50–70 mm and 70–90 mm) took 152 h and 243 h, respectively. Frequency of valve opening was high in smaller size group mussels (30–50 mm), compared with larger groups (70–90 mm). Even though the time taken for killing was size-dependent, frequency of valve opening and time period between successive openings were found to be characteristic of individual mussels. The observations provide new insight into the response of bivalve mussels to continuous chlorination in the context of biofouling control and point to the need to adopt pragmatic strategies to prevent mussel spat settlement rather than killing of adult mussels, thereby reducing environmental burden due to chlorine residuals. Usage of target-specific biocidal strategies (intermittent/pulse dosing) or alternative biocides (chlorine dioxide) may help mitigate green mussel fouling in tropical cooling water systems. [ABSTRACT FROM AUTHOR]

Background: Enteric fever is an endemic health problem and frequently associated with outbreaks. Objectives: Investigate sudden surge in gastroenteritis cases to confirm the outbreak, describe it in terms of time place and person, identify source of infection, modes of transmission and suggest remedial measures. Material & Methodology: Field visit was undertaken by the rapid response team (RRT) at Borsad town of Anand district in Gujarat for investigating suspected typhoid outbreak. This involved gathering information from local authorities, hospital admissions and home visits; collection of blood samples and water samples. Result: Of 30 suspected cases, 19 (63.3%) tested Widal positive. Common presenting symptoms were fever, vomiting followed by diarrhea and abdominal pain. Chlorine levels at source and end users were inadequate. 5 leakage points in water supply were identified in areas around the clustered cases. Conclusion and Recommendations: Leakage in piped water supply coupled with inadequate chlorination lead to contaminated drinking water and subsequent Typhoid epidemic. Corrective steps in form of rapid surveys to identify cases, household chlorination and appropriate engineering measures were recommended and implemented. [ABSTRACT FROM AUTHOR]

Apart from numerous other well-known drawbacks of chlorination, viz. on-site operational hazards and residual chlorine toxicity, trihalomethane (THM) formation is the major factor that came into limelight in the last 40 years, primarily in drinking water treatment industry. Treated effluent from wastewater treatment plants is also chlorinated and then discharged, indirectly coming in human contact, so there is need to consider THM as a potable as well as wastewater parameter. In this study, THMs were identified in seven sewage treatment plants (STPs) in North India. STPs were selected based on treatment technology employed, viz., up-flow anaerobic sludge blanket (UASB), activated sludge process (ASP), sequential batch reactor (SBR), and oxidation pond (OP). THM concentrations obtained at all the seven STPs were below BIS standards of drinking water (0-40 μg L). UASB plant shows considerably higher concentration of THM. UV followed by chlorination is suggested as an alternative to chlorination. Per million liter per day (MLD) capital and operation and maintenance (O&M) costs of UV disinfection were analyzed revealing decreasing per MLD capital cost of UV with increasing plant capacity. The comparative annual O&M cost analysis of chlorination, dechlorination, and UV disinfection shows that there is up to 63% reduction of the total annual O&M cost by UV in comparison to chlorination, whereas in the case of chlorination followed by dechlorination, total reduction is 71%. [ABSTRACT FROM AUTHOR]

India faces high incidents of waterborne disease outbreaks owing to their limited access to safe drinking water. In many ways, the effort to improve the quality of drinking water is performed, and it has been keenly monitored. Among those, the disinfection of drinking water is considered a necessary and important step as it controls the microbial population. Chlorination is the most practiced (greater than 80%) disinfection process in India, and it is known to generate various disinfection byproducts (DBPs). Although the toxicity and trend of DBPs are regularly monitored and investigated in most countries, still in India, the research is at the toddler level. This review summarizes i) the status of drinking water disinfection in India, ii) types of disinfection processes in centralized water treatment plants, iii) concentrations and occurrence patterns of DBPs in a different region of India, iv) a literature survey on the toxicity of DBPs, and v) removal methodologies or alternative technologies to mitigate the DBPs formation. Overall, this review may act as a roadmap to understand the trend of disinfection practices in India and their impacts on securing the goal of safe drinking water for all. [Display omitted] • Chlorination is a widely used disinfection treatment in India. • Proper optimization of chlorine dosage is lacking in many water treatment plants (WTPs). • The governmental program acts as a forum to identify hotspots of microbial contamination. • In drinking water, trihalomethanes are the only regulated DBPs. • Halo acetic acids and nitrogen-based DBPs are emerging DBPs in Indian WTPs. [ABSTRACT FROM AUTHOR]

The present study was carried out for the treatment of effluent from the chlorination and extraction stages of a bleach plant at an Indian pulp and paper mill. The effluents were taken from an integrated paper mill employing OCEHH sequence for the bleaching of hardwood pulp. Effluent was treated via ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO). Thin film composite spiral-wound modules, having cross flow membranes composed of polysulfone and polyamide, were used in the study. Three initial inlet pressures were used for the UF and NF; 6.8, 10.3, and 13.7 bar. For RO initial inlet pressures of 10.3 bar, 13.7 bar and 17.2 bar, were taken in different trials. The retentate from each experiment was recycled back to the feed and retreated until the inlet pressure increased to the maximum cut-of pressure for each membrane. The UF permeate was fed to the NF, which was subsequently fed to the RO. Variations in the trans-membrane pressure and permeate flux were assessed. The removal of pollutants and fouling indices were obtained for each membrane at each initial inlet pressure. [ABSTRACT FROM AUTHOR]

We have investigated and determined the potentiality of different water sources, both for drinking and domestic purposes, in diarrheal disease transmission in diarrhea endemic foci of urban slums in Kolkata, India in a one and half year prospective study. Out of 517 water samples, collected from different sources, stored water (washing) showed higher prevalence of fecal coliforms (58%) (p < 0.0001) in comparison with stored (drinking) samples (28%) and tap/tubewell water (8%) respectively. Among different sources, stored water (washing) samples had the highest non-permissible range of physico-chemical parameters. Fecal coliform levels in household water containers (washing) were comparatively high and almost 2/3 of these samples failed to reach the satisfactory level of residual chlorine. Interestingly, 7% stored water (washing) samples were found to be harboring Vibrio cholerae Improper usage of stored water and unsafe/poor sanitation practices such as hand washing etc. are highlighted as contributory factors for sustained diarrheal episodes. Vulnerability of stored water for domestic usage, a hitherto unexplored source, at domiciliary level in an urban slum where enteric infections are endemic, is reported for the first time. This attempt highlights the impact of quality of stored water at domiciliary level for fecal-oral contamination vis-à-vis disease transmission. [ABSTRACT FROM AUTHOR]

Aims: To study the microbial communities in three sites contaminated with chlorinated pesticides and evaluation of dehydrodechlorinase ( linA) gene variants involved in gamma-hexachlorocyclohexane (γ-HCH, lindane) degradation. Methods and Results: Using a culture-independent method, 16S rRNA genes were amplified from microbial communities occurring in contaminated soils. From 375 clone libraries analysed, 55 different restriction fragment length polymorphism phylotypes were obtained. Dehydrodechlorinase ( linA) gene, which initiates the γ-HCH degradation, was directly amplified by PCR from the DNA extracted from soils. Deduced amino acid sequences of eight variant genotypes of linA showed few amino acid changes. All the variants of linA had mutations of F151L and S154T, and one of the genotype carried 12 amino acid changes when compared to a linA of Sphingomonas sp. reported from the same soil. Conclusions: The microbial communities displayed complex and diverse groups similar to bacteria involved in biodegradation. The presence of biodegradative genes like linA indicates the presence of communities with capacity to biodegrade the persistent pesticide HCH. Significance and Impact of the Study: This study provides insights to evaluate the presence of catabolic genes and assessing the bioremediation potential of the industrial soils contaminated by chlorinated pesticides. [ABSTRACT FROM AUTHOR]

High rates of mortality and morbidity due to water-borne diseases are well known in India. Serious degradation of water quality in urban India has often been attributed to indiscriminate disposal of sewage and industrial effluents into surface water bodies. Although some degree of intervention in terms of chlorination and monitoring of water quality exists in major cities and towns, rural India, which constitutes the bulk (70%) of the population, is usually deprived of such interventions. The population in rural India is mainly dependent on the groundwater as a source of drinking water. As a quality concern the groundwater is often found to be contaminated with fluoride, arsenic, iron and salts. In recent years, fluorosis has emerged as major public health issue in rural India. At the technical level, some progress has been made in the development and use of field-level diagnostic kits. Decentralization of health-related monitoring at the villages needs to be institutionalized and this requires capacity development at all levels. This article discusses the various components that impact effective water quality management in rural India. Experience suggests that redesigning of data management programme at village, district and at national level, upgradation of district-level laboratories and addressing technical, legal and institutional components should become the first steps in achieving effective water-quality management and providing better health to millions of people living in rural India. [ABSTRACT FROM AUTHOR]

Abstract: This communication discusses a novel approach for the measurement of temperature in the mixing area of outflow water from Madras Atomic Power Station, located at a coastal site near Tamil Nadu, India. In addition, various environmental aspects such as chlorination, phytoplankton estimation and annual sea surface water temperature have also been addressed in this paper in the light of similar work published earlier from the same locality. [Copyright &y& Elsevier]

Chlorination is one of the most widely used techniques for controlling biofouling in power plant cooling water systems. It often leads to the formation of chlorination by-products (CBPs). Amongst these, trihalomethanes (THMs) are more predominant, relatively long-lived and have possible toxicity to organisms. Thus, THM levels in the coastal marine environment are of great concern. This communication discusses the concentration levels of THMs at various points in the cooling water system of a coastal nuclear power station located on the Bay of Bengal coast. The studies revealed the formation of bromoform in predominant quantities and dibromochloromethane in small quantities. The present values are comparable with those reported from other power stations elsewhere. [ABSTRACT FROM AUTHOR]

Results of investigations on desulphurisation of high-sulphur (2–8 wt%) coals of Meghalaya by radiation chlorinolysis, effected in different media of chlorination (CCl4, CCl4/H2O, and CCl4/CH3OH) via radiolysis of CCl4, for the removal of both the inorganic (pyritic and sulphate) and the organic forms of sulphur as well as mineral matter are reported. In general, maximum removal of total sulphur (up to 37%) and mineral matter (up to 10%) takes place in CCl4/CH3OH medium, which is attributed to the CH3OH acting as a better wetting agent for coal. It is found that while pyritic and sulphate sulphur are removed almost quantitatively, there is variation in the removal of organic sulphur from the coals. Furthermore, the coal matrix is not affected/degraded to any appreciable extent and the caking property of the coals is either improved or slightly degraded after desulphurisation. Mechanism of desulphurisation of coal via radiation chlorination is proposed. [Copyright &y& Elsevier]

For long time water disinfection is being done to inactivate or control bacteria populations in the treated water and simple chlorination is the most common method to disinfect the water. Almost certainly for over a decade chlorination is being effectively utilized for controlling of water borne contamination. An assortment of disinfection by-products (DBPs) are formed like trihalomethanes (THMs), haloacetic acids (HAAs) and halogenated acetonitriles (HANs) etc., when the naturally occurring natural organic matters (NOMs) present in raw water reacts with chlorine that may have adverse health impacts on humans. These compounds fall apart the water quality and there are epidemiological confirmations of close connection between its emergence and unfavourable results especially the malignant growths of fundamental organs in individuals. Concerns related with the prospective health hazards of DBPs provoked a few industrialized nations to build up various guidelines. Due to lack of data more research is required to understand its adverse health effects on human beings which are being restrained by funds required for researches. DPBs dermal and inhalation exposure routes have greater risk as compared to ingestion route. The DBPs can be controlled by methods like coagulation with polymer, alum, lime or iron, sulphates, adsorption on activated carbons, ion exchange or membrane process and to more effectively reduce the precursor i.e. NOMs. In this paper we have discussed about the formation of disinfection by-products in treated municipal water during chlorination and how these DBPs were discovered. Moreover, we briefly compared the present status of their guidelines value or regulations in India with other regulating bodies and what are the category of cancer groups under which the different DBPs are categorized by WHO. A portion of the basic science related to DBPs formation is explained and the different exposure routes of DBPs in a human body are discussed. Fifty-two studies were reviewed about DBPs toxicity and epidemiology to understand the greatness of hazards caused by exposure of DBPs as shown by various researchers. Many innovations and methodologies can be used for controlling or removal of the DBPs. • Chlorine is the principal disinfectant used worldwide with more benefit when compared with the other disinfectants present. • Disinfection by-products are carcinogenic but can be removed by various techniques. • Microbial risk is of greater magnitude, then the risk presented by disinfection byproducts. [ABSTRACT FROM AUTHOR]

Formation potential and speciation characteristics of two important groups of disinfection byproducts (DBPs), namely, trihalomethanes (THMs) and haloacetic acids (HAA S ), during Cl 2 and ClO 2 treatment of water samples collected from three different sources, namely, sea, river, and reservoir, were investigated with reference to key controlling parameters. Formation of inorganic DBPs such as chlorate and chlorite was evaluated. Dissolved organic carbon (DOC) and UV absorbance (UV 254 ) of the sea, river, and reservoir samples were 3.35 ± 0.05, 3.12 ± 0.05, and 3.23 ± 0.05 mg/L and 0.062 ± 0.01, 0.074 ± 0.01, and 0.055 ± 0.01 cm -1 , respectively. For Cl 2 and ClO 2 treatments, the respective formation potential of THMs and HAAs from the three water sources studied exhibited unidentical trend suggesting that higher THM formation was not necessarily associated with higher HAA formation. On chlorination, the concentrations of total HAAs formed were 9.8 μg/L (sea), 12.8 μg/L (river), and 20.6 μg/L (reservoir) and total THM yields were 38.3 μg/L (sea), 18.8 μg/L (river), and 21.5 μg/L (reservoir) for a Cl 2 dose of 1 mg/L and 30 min reaction time. The trend of formation of THMs and HAAs for Cl 2 treatment was similar to that for ClO 2 treatment. However, the amount of HAAs (3.5 μg/L (sea), 1.8 μg/L (river), and 1.9 μg/L (reservoir)) and THMs (not detected) formed was much lower than that formed during chlorination. Regardless of source water type, di-HAAs were the most favored HAAs, followed by tri-HAAs with a small amount of mono-HAAs formed for both Cl 2 and ClO 2 treatment. Chlorination yielded more THMs than HAAs, whereas it was reverse for chlorine dioxide treatment. Irrespective of treatment with ClO 2 or Cl 2 , seawater samples showed the highest bromine incorporation percentage (BIP) in both THMs and HAAs followed by that for river and reservoir water samples. HAAs were found to be always associated with lower amount of BIP than THMs., (Copyright © 2018 Elsevier Ltd. All rights reserved.)