Background and Objectives:
Nitrogen is a potential pollutant of water resources. They penetrate in water resources through insufficiently treated wastewater that is rich in nitrogen. The present study aimed at evaluating the efficiency of an anoxic/aerobic cycling reactor (AACR) with continuous flow in removing nitrogen and organic matter from wastewater.
Methods:
Experiments were performed using a reactor with continuous intermittent influent and effluent. In this reactor, 4 phases with aeration and mixing cycles were designed and efficiency of each phase in removing nitrogen compounds was evaluated at 600 mg/L chemical oxygen demand (COD) concentration, 40 mg/L ammonia concentration, and 18- to 30-hour hydraulic retention times (HRT).
Results:
Results demonstrated that all cycles had great performance in removal of COD. Average COD removal efficiencies in phases 1, 2, 3, and 4 were 93%, 96.3%, 96%, and 94%, respectively. In phase 2, removal efficiency of 98.7% was obtained at hydraulic retention time of 24 hours, COD concentration of 600 mg/L, and ammonia concentration of 40 mg/L.
Conclusions:
Phase 2 showed great efficiency in removal of nitrogen compounds. Combination of anoxic aeration stages and short cycles in anoxic/aerobic cycling reactor resulted in great performance of this reactor in removing nitrogen from wastewater. As a result, continuous influent and effluent flow, and not needing external carbon resulted in AACR good performance in removing nitrogen compounds and organic materials.
Keywords:Nitrogen Compounds,Wastewater,Organic Matter,Anoxic/Aerobic