Application of A²/O bio-reactor & constructed wetlands for removing organic and nutrient concentrations from rural domestic sewage

This paper examined the efficiency of integrated bio-reactor processes (A²/O) combining anaerobic, anoxic, waterfall aeration contact oxidation (oxic) and constructed wetlands for removing organic and nutrient concentrations from rural domestic sewage. The study was carried from June 2012 to November 2012. Chemical oxygen demand (COD), total phosphorus (TP) and total nitrogen (TN) in the effluent from this process was stably below 50 mg/l, 0.6 mg/l and 13.2 mg/l respectively. The results of the system denoted that this integrated process was efficient in organics and nutrients removal from rural domestic sewage. COD was mainlyy removed in anaerobic, anoxic and in waterfall aeration contact oxidation (oxic) columns. Nitrogen was typically reduced by nitrification in contact oxidation unit and denitrification in anaerobic and anoxic column. Constructed wetland played an imperative role in phosphorus removal by filter interception, plant adsorption and microbial transformation. Scraped plaster added in the constructed wetland reacted with orthophosphate and relieved the influence of temperature on phosphorus removal in cold days. Overall, this integrated process was efficient and in rural domestic sewage treatment.