Orthogonal Test Design Based Analysis of Factors Controlling Simultaneous Anaerobic Sulfide and Nitrate Removal Process

The present study deals with comprehensive analysis of the main factors like the effects of pH, influent substrate concentration and hydraulic retention time (HRT) driving simultaneous anaerobic sulfide and nitrate removal process. The analysis involved a multi-factorial orthogonal experiment. The results of range and variance analyses showed that decreasing influent substrate concentration might improve the effluent quality. Consequent to controlling the reaction pH at 7.0+-0.1, the effluent quality was the best keeping influent sulfide concentration of 220 mgL/sup -1/ and HRT of 10 h. Influent substrate concentration and HRT had significant bearing on the substrate removal rate, while pH had no significant effect. Decreasing HRT was a better option to increase substrate removal rate. Controlling the reaction pH around 7.0+-0.1, feeding influent sulfide concentration of 520 mgL/sup -1/ at HRT of 4h resulted in the optimum substrate removal rate. (author)