Denitrification of nitrate-contaminated groundwater in an anoxic rotating biological contactor: a case study

In this study, denitrification of Tehran (Iran) oil refinery groundwater in an anoxic rotating biological contactor (ARBC) was investigated. Influence of different parameters such as hydraulic retention time (HRT), Carbon/Nitrogen ratio, and nitrate loading in the influent, on the nitrate, nitrite, ammonium, alkalinity, and chemical oxygen demand concentration of effluent were evaluated. Acetate was used as a carbon source in a heterotrophic process. Nitrate concentration of treated water in all experiments was far below the standard limitation and nitrate removal efficiency reached over 97% in optimum value of Carbon/Nitrogen = 1.25 and HRT = 8 h. Nitrite accumulation wasn’t observed up to nitrate loading of 105 mg/L. Based on the results of this experiment, ARBC reactor could be an adequate and convenient method in denitrification of groundwater.