Simultaneous sequestration of nitrate and phosphate from wastewater using a tailor-made bacterial consortium in biofilm bioreactor

BACKGROUNDMunicipal wastewater usually contains nitrate and phosphate as major contaminants, and if discharged untreated affects the health of the environment and human population. Currently available treatment technologies to treat municipal wastewater lose the essential growth nutrients P' and N' during treatment. This paper presents a strategy of simultaneous sequestration of nitrate and phosphate in biomass, by using a tailor-made consortium in a biofilm reactor. RESULTSThe consortium comprising of three novel Bacillus strains in a fixed bed biofilm bioreactor maintained at ambient temperature showed reduction up to 94% of nitrate, 68% of phosphate, 93% of chemical oxygen demand, 97% of biochemical oxygen demand, 73% in total organic carbon while maintaining an effluent pH of 6.8 0.02. Response surface methodology revealed maximum reduction at a flow rate of 1.97 L h(-1) with 306.04 mg L-1 and 19.62 mg L-1 of initial nitrate and phosphate concentrations respectively. The system was scaled up from 4.5 L to 220 L with the same retention time of 2 h and operated with consistent performance for over 212 days. CONCLUSIONThe treated wastewater met the criterion for reuse as non-potable water for applications like irrigation and aquaculture, hence making it the fastest microbial process for simultaneous nitrate and phosphate removal from wastewater. (c) 2017 Society of Chemical Industry