Removal of High C and N Contents in Synthetic Wastewater Using Internal Circulation of Anaerobic and Anoxic/Oxic Activated Sludge Processes

School of Environmental Engineering, Institute of Engineering, Suranaree University of Technology

Abstract

Internal circulation (IC) of activated sludge anaerobic and anoxic/oxic processes was used to treat high carbon (C) and nitrogen (N) synthetic wastewater in order to achieve an effluent standard. The 1^st & 2^nd internal circulation anoxic (ICA) has shown a great advantage. Because under anoxic conditions heterotrophs utilize organic matter (OM). OM and NO₃⁻-N are an electron donor and an electron donor, respectively. As a result, under conditions high carbon and NO₃⁻-N, N₂ production can generate higher than with 1^st ICA BNR system only. Aerobic IC to anoxic, 1^st ICA, and effluent IC to anoxic, 2^nd ICA, could remove 100% of COD, 99.60% of TKN, and 99.90% of NH₄⁺-N. The organic loading rate and NH₄⁺-N loading rate are 68.38 kg-COD m⁻³ d⁻¹ and 9.86 kg NH₄⁺-N m⁻³ d⁻¹, respectively in synthetic wastewater. Performance of these ICA activated sludge treatment was achieved the discharge standard with effluent COD less than 0 mg L⁻¹,effluent NH₄⁺-N less than 4 mg NH₄⁺-N L⁻¹, effluent NO₂⁻-N less than 0.1 mg NO₂⁻-N L⁻¹, and NO₃⁻-N less than 0.02 mg NO₃⁻-N L⁻¹.