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Application of metabolic division of labor in simultaneous removal of nitrogen and thiocyanate from wastewater

Pan, Jianxin, Ma, Jingde, Wu, Haizhen, Chen, Ben, He, Meiling, Liao, Chen, Wei, Chaohai
Water research 2019 v.150 pp. 216-224
ammonium, anaerobic ammonium oxidation, biological treatment, biomass, denitrification, ecosystems, industrial wastewater, mathematical models, metabolites, microbial communities, nitrifying bacteria, nitrogen, pollutants, pollution control, thiocyanates, total nitrogen, toxic substances, toxicity
Metabolic division of labor is a key ecological strategy in bacteria to allow concurrent execution of multiple tasks through functional differentiation and metabolite exchange. While it is prevalent in nature, a lot of novel interactions remain to be further explored for improved wastewater biological treatment. Here, we present a combined experimental and modeling study on the simultaneous removal of nitrogen and thiocyanate from wastewater by using a syntrophic microbial community. The syntrophic division of labor was achieved by coupling autotrophic denitrification (AD) and anaerobic ammonium oxidation (AN) through both cooperative and competitive interactions. We demonstrated that the syntrophic community can achieve almost complete removal of all pollutants under certain initial conditions. We then perturbed the initial condition by varying the concentration ratio between ammonium to thiocyanate as well as the biomass ratio between AD and AN. Our observations show that adding ammonium negatively impacts the thiocyanate removal efficiency and adding anammox bacteria have opposite effects on the removal efficiency of thiocyanate and ammonium. Using a mathematical model, we simultaneously varied these two initial conditions and identified the parameter regime where our syntrophic ecosystem can be most efficient in removing total nitrogen. By highlighting the utility of syntrophic pair of functional bacteria in removing pollutants, our study will facilitate the rational design of more complex microbial consortia for the removal of toxic and hazardous compounds from industrial wastewater.