Treatment of Chinese traditional medicine wastewater in a submerged membrane bioreactor

A pilot scale test was conducted in a submerged membrane bioreactor SMBR with capacity of 10.0 m3/d for 120 days to treat high-strength Chinese traditional medicine wastewater. Performance of the SMBR was investigated with a sludge retention time ( TSR ) of 50 days, a hydraulic retention time ( THR ) of 8. 0 h, membrane flux of 8. 0 L/( m2 · h) and dissolved oxygen (DO) concentration of 2.0 - 3.0 mg/L, respectively. It was observed that the SMBR had high capacity of COD and suspended solid (SS) removal. The influent COD concentration was fluctuated between 1 000 and 5 000 mg/L, while the averaged effluent COD concentration was only 44.6 mg/L. The influent SS concentration was fluctuated between 1 000 and 1 600 mg/L, while little effluent SS was detected. It was found that the COD remove rate increased with mixed liquor suspended solids (MLSS) and organic loading rate (ROL). In order to obtain good-quality effluent, the operational conditions of the SMBR were suggested as follows: the temperature was controlled above 10 ℃, MLSS about 7000 mg/L, ROL under 24. 76 kg/( m3 · d) , low vacuum value and constant water flux.