Brijesh Kumar Mishra

Multi-exposure cancer and non-cancer risk assessment of trihalomethanes in drinking water supplies – A case study of Eastern region of India

The lifetime cancer risk and the hazard index of trihalomethanes (THMs) through oral ingestion, dermal absorption, and inhalation exposure from supply water of five WTPs were analysed. THMs concentration varied from plant to plant and was found to be in the range of 274-511µg/l, which is much higher than the prescribed USEPA standards of 80µg/l. Chloroform was the most dominant THM followed by bromodichloromethane (BDCM), and dibromochloromethane (DBCM). Cancer risk analysis through multi-pathways exposure reveals that residents had a higher cancer risk through oral ingestion than other two routes of exposure. The lifetime cancer risks of THMs from supply water were 100 times higher than prescribed USEPA guidelines. The higher cancer risk found for Indian context than those reported for other countries like USA, UK, Japan, Australia, is mainly due to the higher concentration level of THMs, water intake and average body weight. The study also revealed that amongst different THMs, chloroform is the major THMs causing cancer risk through both oral and dermal route of exposure whereas in case of inhalation it was mainly because of BDCM. Average lifetime cancer risk analysis indicated that females are more prone to cancer risk than males. Oral ingestion is a major route indicating the potential impact of non-cancer risk while it was insignificant through dermal exposure. Sensitivity analysis of THMs revealed that chloroform is the predominant parameter followed by body weight and exposure duration influencing cancer risk.

A novel strategy for simultaneous removal of nitrogen and organic matter using anaerobic granular sludge in anammox hybrid reactor

The coexistence of organic matter (OM) and nitrogen in industrial effluent is the major bottleneck in field-scale application of anammox process. The present study emphasized on investigating the role of seeding anaerobic granular sludge towards simultaneous removal of ammonium and OM in anammox hybrid reactor (AHR). The study delineated simultaneous reduction of both OM (94.8%) and nitrogen (96.8%) at optimal COD/N ratio (0.54). Pearson correlation matrix showed positive and strong correlation of ARE (ammonium removal efficiency) and CRE (COD removal efficiency) with NRE (nitrogen removal efficiency). The negative correlation of OLR and COD/TN ratio with NRE indicated that increase in organic loadings may suppress anammox activity. The process inhibition was evaluated using Haldane model considering free ammonia, OM and nitrite as inhibitors. The strategy of using anaerobic granular sludge not only augmented endurance of bacterial communities against OM inhibition but also facilitated simultaneous removal of OM and nitrogen.

Metal pollution in water environment and the associated human health risk from drinking water: A case study of Sukinda chromite mine, India

ABSTRACT Sukinda is one of the most polluted regions of the globe due to chromium pollution. The study sheds light into the heavy metal pollution around the mining area and its effect on the health of the resident populace. The Cr(VI) was in the range of 0.027–2.48 mg/L in surface water and BDL–1.35 mg/L in the groundwater. Multivariate analysis revealed that mining activity was the main source of TCr, Cr(VI), and Zn in the surface water that warrants attention. Heavy metal evaluation index showed high levels of Fe, Mn, and Cr in groundwater that can pose serious threat to the exposed population. Cancer and non-cancer risk of Cr(VI) was higher than other metals in groundwater. The results revealed that the total cancer risk was 1.21E-03 and 1.05E-03 in adults and children, respectively, which exceeded the USEPA acceptable cancer health risk. High health risk was observed through oral intake of water, while both cancer and non-cancer risks were negligible through dermal contact. This study strongly advocates proper periodic assessment of drinking as well as surface water in the area and regulation to restrict the use of contaminated water for daily use.

Modified amylopectin based flocculant for the treatment of synthetic effluent and industrial wastewaters

Herein, we report the application of an efficient polymeric flocculant based on amylopectin grafted with poly (acrylic acid) (g-AP) for the treatment of synthetic effluent as well as various industrial wastewaters. The flocculation characteristics of g-AP have been explored in different pH conditions using silica suspension by measurement of residual turbidity as well as floc size. Results suggest that in acidic pH, patching mechanism is predominating while at neutral and alkaline pH, bridging is the main mechanism. In addition, aggregation of particles and particle collision models confirm that bridging mechanism is the key mechanism at alkaline condition. Further, g-AP demonstrates excellent potential as flocculant for the treatment of paper effluent, textile wastewater and shows better flocculation performance than that of commercially available flocculant. Besides, the pilot scale study of mine processwater suggests excellent efficacy of g-AP as flocculant.

Performance evaluation of the anammox hybrid reactor seeded with mixed inoculum sludge

ABSTRACT Long startup and poor granulation are the major bottlenecks in field-scale application of the anammox (ANaerobic AMMonium OXidation) process. In the present study, the anammox process was investigated in a modified anammox hybrid reactor (AHR) inoculated with mixed seed culture (anoxic and activated sludge). The startup study delineated four distinct phases, i.e. cell lysis, lag phase, activity elevation and stationary phase. Use of mixed seed culture at influent ratio (1:1) and hydraulic retention time (HRT) of 1 d led to early startup of the anammox process. The removal efficiencies of and during acclimation were found to be 94.3% and 96.4%, respectively, at nitrogen loading rate (NLR) of 0.35 kg N/m3 d. Pearson correlation analysis dictated strong and positive correlation of HRT and sludge retention time (SRT) with nitrogen removal efficiency (NRE) while NLR and sludge loading rate (SLR) were negatively correlated. Attached growth system (AGS) in AHR contributed an additional 11% ammonium removal and reduced the sludge washout rate by 29%. Mass balance of nitrogen revealed that the major fraction (74.1%) of input nitrogen was converted into N2 gas indicating higher substrate conversion efficiency of anammox biomass. Scanning electron microscope (SEM) study of biomass indicated the presence of heterogeneous population of cocci and rod-shaped bacteria of average diameter varying from 1.2 to 1.5 mm. Owing to the features of early start-up, ability to retain high biomass and consistently higher NRE, hybrid reactor configuration seeded with mixed culture offers noble strategy for cultivation of well-compacted anammox granules for field-scale installation. GRAPHICAL ABSTRACT

Investigation and mapping of fluoride-endemic areas and associated health risk—A case study of Agra, Uttar Pradesh, India

ABSTRACT The present study aimed at identifying the fluoride-endemic areas in five different blocks in Agra district, Uttar Pradesh, India. A total of 365 groundwater samples from 73 villages were analyzed for establishing the concentration range of fluoride in drinking water. The fluoride level in the study area varied from 0.14 to 4.88 mg/L. Out of 73, the fluoride levels in 45 villages did not meet the permissible Word Health Organization standards. The Baroli Ahir block was found the highly fluoride-endemic area followed by Saiyan, Bichpuri, Achnera and Etmadpur. Chronic daily intake of fluoride in adults was 1.25 and 1.5 times higher than those in children and infants, respectively. The probability of dental fluorosis in infants was higher (42%) while adults were more prone to bone and skeletal fluorosis (60%). The hazard quotient analysis revealed that children were found to be at maximum risk followed by infants and adults. Sensitivity analysis revealed that the fluoride concentration is the major influencing parameter responsible for different types of fluorosis in various age groups.

Performance evaluation of the electro-coagulation treatment process for the removal of total suspended solids and metals from water

Globalization, industrialization, mining, and uncontrolled population growth have fostered a shortage of potable water. Thus, it has become imperative to understand an effective and reasonable water purification technique. A renewed interest in electrocoagulation has been spurred by the search for reliable water-treatment processes. This paper has elucidated a technical approach for getting rid of heavy metals and total suspended solids from water using an aluminum electrode. The effect of operational parameters, i.e. current density, inter-electrode distance, operating time, and pH, were studied and evaluated for maximum efficiency. The study corroborates the correlation between current density and removal efficiency. Neutral pH and a low electrode gap have been found to aid the efficacy of the electrocoagulation. The results shows a maximum TSS removal efficiency of 76.6 % at a current density of 5.3 mA/cm2 and contact time of 30 minutes. In the heavy metal remediation, 30 min of process time has exhibited extreme reduction rates of 99 %, 59.2%, and 45.8%, for Cu, Cr, and Zn, respectively. During the experiments, electrical conductivity and dissolved solids were found to fluctuate by 5-6 % of the original value. Moreover, kinetic study has also demonstrated for pollutants removal follows first and second order model.