G. R. Abhijith

Bio: G. R. Abhijith is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Computer science & Water quality. The author has an hindex of 3, co-authored 7 publications receiving 16 citations.

Modeling Bacterial Regrowth and Trihalomethane Formation in Water Distribution Systems

Abstract: The formation of bacterial regrowth and disinfection by-products is ubiquitous in chlorinated water distribution systems (WDSs) operated with organic loads. A generic, easy-to-use mechanistic model describing the fundamental processes governing the interrelationship between chlorine, total organic carbon (TOC), and bacteria to analyze the spatiotemporal water quality variations in WDSs was developed using EPANET-MSX. The representation of multispecies reactions was simplified to minimize the interdependent model parameters. The physicochemical/biological processes that cannot be experimentally determined were neglected. The effects of source water characteristics and water residence time on controlling bacterial regrowth and Trihalomethane (THM) formation in two well-tested systems under chlorinated and non-chlorinated conditions were analyzed by applying the model. The results established that a 100% increase in the free chlorine concentration and a 50% reduction in the TOC at the source effectuated a 5.87 log scale decrement in the bacteriological activity at the expense of a 60% increase in THM formation. The sensitivity study showed the impact of the operating conditions and the network characteristics in determining parameter sensitivities to model outputs. The maximum specific growth rate constant for bulk phase bacteria was found to be the most sensitive parameter to the predicted bacterial regrowth.

Random Walk Particle Tracking Embedded Cellular Automata Model for Predicting Temporospatial Variations of Chlorine in Water Distribution Systems

Abstract: Cellular Automata (CA) is an evolutionary computing technique that makes discrete idealizations of differential equations and represents the physical system at the mesoscopic scale. A novel CA approach for predicting the temporal and spatial variations of chlorine in Water Distribution Systems (WDSs) is presented in this paper. Random Walk Particle Tracking (RWPT), a stochastic Lagrangian technique, is used to represent the advection and dispersion processes. A one-dimensional CA-based reactive-transport model for chlorine, named as RWPT_CA model, incorporating advective-dispersive transport mechanism is developed and demonstrated. The significance of the cell dimension in the model algorithm is ascertained, and a deterministic approach is formulated for its selection. An indirect numerical solution technique is developed to improve the computational efficiency of the CA algorithm and to minimize the restrictions in the process of discretization of mass into equivalent particles. The numerical accuracy of the proposed RWPT_CA model is verified by applying it on to a benchmark problem. The RWPT_CA model provided excellent representations of the chlorine concentration profiles for low to medium range dispersion in WDSs. The model testing on a benchmark problem from the literature, well tested by researchers, revealed its effectiveness to derive the chlorine concentration patterns under dynamic hydraulic conditions. The dispersion mechanism was found significant in controlling the temporospatial distribution of chlorine at the nodes farther from the source nodes. The models which consider only advective transport mechanism were found over-predicting the chlorine concentrations, and thereby, establishing untrue representations of the quality of the delivered water.

Cellular Automata-Based Mechanistic Model for Analyzing Microbial Regrowth and Trihalomethanes Formation in Water Distribution Systems

Abstract: This paper describes a novel cellular automata-based mesoscale multispecies reactive-transport (CA-MSRT) model for predicting microbial regrowth and trihalomethanes (THMs) formation in wate...

Hydraulic Analysis of Intermittent Water-Distribution Networks Considering Partial-Flow Regimes

Abstract: Modeling intermittent water distribution networks (WDNs) requires effective incorporation of the transient flow conditions, including the transitions from pressurized to partial flow regime...

Water Resources Systems Planning And Management

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Modeling Bacterial Regrowth and Trihalomethane Formation in Water Distribution Systems

Abstract: The formation of bacterial regrowth and disinfection by-products is ubiquitous in chlorinated water distribution systems (WDSs) operated with organic loads. A generic, easy-to-use mechanistic model describing the fundamental processes governing the interrelationship between chlorine, total organic carbon (TOC), and bacteria to analyze the spatiotemporal water quality variations in WDSs was developed using EPANET-MSX. The representation of multispecies reactions was simplified to minimize the interdependent model parameters. The physicochemical/biological processes that cannot be experimentally determined were neglected. The effects of source water characteristics and water residence time on controlling bacterial regrowth and Trihalomethane (THM) formation in two well-tested systems under chlorinated and non-chlorinated conditions were analyzed by applying the model. The results established that a 100% increase in the free chlorine concentration and a 50% reduction in the TOC at the source effectuated a 5.87 log scale decrement in the bacteriological activity at the expense of a 60% increase in THM formation. The sensitivity study showed the impact of the operating conditions and the network characteristics in determining parameter sensitivities to model outputs. The maximum specific growth rate constant for bulk phase bacteria was found to be the most sensitive parameter to the predicted bacterial regrowth.

Drivers for Intermittent Water Supply in India: Critical Review and Perspectives

Abstract: Intermittent Water Supply (IWS) is prevalent in most developing countries. Specifically, in India, IWS is existent throughout the country. Many studies focus on documenting the effects of IWS, and rarely the drivers of the IWS regime are studied. In this study, a systematic literature review was conducted on IWS studies around the globe. The various causes for IWS were documented. Then, by studying India’s typical water supply system (WSS) configuration, the vicious cycle of IWS in India is discussed. Further, the drivers of IWS were identified and elaborated with the causing mechanisms. This knowledge will help devise strategies and solutions for improving the IWS in India and other developing countries with similar socio-economic conditions.

Modeling the Response of Nonchlorinated, Chlorinated, and Chloraminated Water Distribution Systems toward Arsenic Contamination

Abstract: A mechanistic simulation model predicting the response of water distribution systems (WDSs) operated with or without disinfectant residual toward accidental arsenic contamination is develop...