Nutrients Removal from Domestic Wastewater in Basrah City (Southern Iraq) using Combined A2/O Bio Contact Oxidation Technology

Abstract

The nutrients removal from domestic wastewater in Basrah City (Southern Iraq) by using the technology of up flow A2-O Bio Contact Oxidation with bypass flow was studied in this research. The treatment system was designed in order to treating 100 L/day of domestic wastewater by using a laboratory scale Anaerobic-Anoxic-Aerobic Moving Bed Biofilm Reactors (MBBRS) in series form with effective volume equal to 15 L, 15 L, and 30 L respectively. Kaldnes polyethylene media (K1) was used in this study in order to achieve attached biofilm process with filling ratio equal to 30% for both anaerobic anoxic MBBRS. and with filling ratio 50% for aerobic MBBR. After the biofilm was developed in the carriers the system was operated under internal recycle ratio equal to 100%. bypass ratio equal to 40%. and under 3 different external recycle ratio (25%, 50%, and 100%). The experimental results showed that the optimal value of the external recycle ratio was equal to 50 %, which the average values of removal efficiencies of COD, NH4+-N, TN and TP were equal to 98.15 %, 97.16%, 82.12%, and 93.39 % respectively. Under the condition of the optimum value of external recycle ratio the average concentration of the dissolved oxygen in both anoxic and aerobic reactors were equal to 0.151 mg/L, and 3.57 mg/L respectively, and the temperature of water wras controlled in the range of 35° C in the anaerobic reactor and in the range of 30°C in both anoxic and aerobic reactors by used temperature controlled.