Primary study of the membrane bioreactor to treat restaurant wastewater

Membrane bioreactor treating restaurant wastewater was studied. The operating conditions including operating pressure, velocity at membrane surface and mixed liquid suspended sludge (MLSS) were studied. Results revealed that the suitable operating pressure is 0.2 MPa, the velocity is 6.5 m/s-7.5 m/s. The membrane flux is proportional to the pressure when the pressure is low, and the flux is unrelated to pressure when the pressure is high. The flux increases proportionally with the increase of temperature, and the flux is in linear relationship with mixed liquid suspended sludge. To observe the membrane fouling, the scanning electron microscopy (SEM) of membrane were taken. The cleaning method for fouling membrane was decided. It was washed by tap water and then submerged by 0.2% NaClO for 0.5 h and by 1% HAc for 0.5 h. The flux recovered little after tap water washing, recovered to 62% of its original after alkaline washing, and recovered to 84% of its original after acid washing.