Evaluation of hollow fiber membrane bioreactor efficiency for municipal wastewater treatment

ABSTRACT

The membrane bioreactor technology has been proven to be a single step process in efficient treatment of wastewater, either directly or after pretreatment by reverse osmosis. In this study, a pilot scale experiment was studied to treat a synthetic municipal wastewater sample. The aerobic reactor with a submerged membrane used in this work was continuously aerated for organic matter oxidation, nitrification and phosphorous uptake as well as for fouling control. The mixed liquor was recycled from the aerated zone to the anoxic zone for denitrification. The membrane had a nominal pore size of 0.1 micro m and a filtration area of 4.0 m2. The performance of submerged membrane bioreactor was examined in order to determine the removal efficiency of organic compounds and nitrogen in different solid retention times [10, 20, 30, and 40 days] under a continuous inflow of the synthetic municipal wastewater. Results indicated that the submerged membrane bioreactor could efficiently remove the pollutants. Average removal rates of chemical oxygen demand, total Kejeldahl nitrogen removal, total nitrogen and phosphorous reached to as high as 99.3%, 98.1%, 85.5%, and 52%, respectively. Furthermore, concentrations of nitrate and nitrite in the last stage were well reduced and reached to 5.3 and 0.047 mg/L, respectively