Experimentation and Evaluation of Biodegradative Kinetic Parameters of Nitrate Removal from Drinking Water

Abstract

Nitrate (NO3−) contamination in drinking water is regulated by environmental agencies around the world since it causes health problems at higher concentrations. NO3−removal in drinking water has been a challenge for a long time. Microbial denitrification is one of the promising processes for remediation of NO3− from contaminated samples. In the present study, the effect of various carbon sources, temperatures, pH and inoculum concentrations on the removal of NO3− was first investigated using assimilatory NO3− reducing bacterial consortium (Pseudomonas sp. KW1 and Bacillus sp. YW4) in Mineral Salts Medium (MSM) containing 100 mg/Lof NO3−. Starch at 1%, temperature at 30oCand pH at 7 and 1% of inoculum concentration were found to be optimum. Monod and Haldane kinetic models were applied to evaluate the rate of nitrate removal by bacteria. Further, Friedman test was used to determine the role of each factor on degradation process. Second phase of experiments was studied in drinking water using a pilot scale treatment plant and the results showed that the consortium (KW1 and YW4), reduced nitrate to a level at 92% (100–8 mg/L) and verified with statistical test. Further, boiling, ultraviolet radiations, filtration by adsorption and chlorination methods were evident for consecutive elimination of microorganisms from the treated water.