Experimental and numerical results of a single submerged attached growth bioreactor for simultaneous oxidation of organics and nitrogen removal

Two primary advantages of a submerged attached growth bioreactor (SAGB) are the small volume requirement and the elimination of downstream clarification. While different configurations of SAGBs have been developed for various applications, the use of a single SAGB for achieving the combined removal of organics and nitrogen has not been extensively studied. This research studied the microbial kinetics of a multispecies biofilm within a single-unit, single-zone SAGB designed to achieve the combined removal of both carbonaceous organics and nitrogen. A pilot-scale SAGB plant was developed and operated to treat a municipal wastewater to an effluent BOD₅≤30 mg/l, TSS≤30 mg/l, and total nitrogen≤10 mg/l. At a total organic loading of 4.0 kg/m³-day adequate nitrogen removal, resulting in an effluent total nitrogen of 8.5 mg/l, was achieved. The numerical simulation of reactor performance using AQUASIM showed good agreement in overall trends. This research demonstrated an expanded and improved application of a multispecies biofilm process for wastewater nutrient removal.