Evaluation of the Multistage Biological-Ecological Process for Removal of Organic Matter and Nutrient from the Rural Domestic Wastewater under Ambient Temperature

Abstract

The rural domestic wastewater system has been evaluated by using a pilot scale of a biological – ecological process which was built and monitored under operation for a long time. The system was operated for six months with an ambient temperature ranged of (5 – 22°C). The process used in this study was set up as a modified anaerobic/anoxic/oxic process followed by a constructed wetland. Stability and acclimatization of the anaerobic bacteria was achieved after 35 days by using glucose and trace nutrient. The system was then continuously operated with a real domestic wastewater. Hydraulic retention time and temperature are more important parameters of the biological-ecological process performance. Therefore, the system was operated with different HRT and temperature to evaluate the performance efficiency. The influent and effluent of the chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were analyzed. The anaerobic reactor showed that the optimal HRT was 4 days and the reactor demonstrated a removal efficiency rate of COD (55.5%). The average biogas production in the summer season was 6.8 l/d and in the winter was 1.24 l/d. The Biological– ecological process revealed good efficiency in the removal of the COD, total nitrogen and total phosphorous, where the maximum average removal was 85.5%, 79.8%, 74.9% respectively.