A Study On The Characteristic Of Using HSMBR To Treat Urban Domestic Wastewater

The study was mainly on the urban domestic wastewater treating characteristic using SMBR and HSMBR systems. And the effect of water temperature, pH value, HRT, SS and sludge load on the operation of the MBR system. Through longtime monitoring of the changes of trans-membrane pressure, the membrane fouling mechanism was discussed and the operational effects on the membrane fouling were studied. In the process of membrane cleaning, the efficiency of different chemical cleaning liquids was compared and analyzed. The main conclusions are as follows:Both SMBR and HSMBR have a stable and high removal rate of COD, NH₃-N, turbidity, TN and TR of which TN and TP removal efficiency becomes higher with a higher sludge concentration. Because of no sludge discharge, the spiecies of microbios in the reacter were massive and the SMBR had a strong adaptivity to temperature and pH value and the activity of sludge was mainly dominated by SS and sluge load. Because of no sludge discharge, the undegradable matters produced in the process of self dissolving and secretion accumulated, and the efficiency of bio-treatment was affected.In the study of membrane fouling, through the monitoring of periodic trans-membrane pressure change in the working and cleaning process, it was found that the increase of trans-membrane pressure was mainly caused by the concentration polarization and the settlement of particles of the feed water on the surface of membrane. Through hydrolic back washing, batch operation of membrane and aeration of the system, the concentration polarization and cake layer fouling could be controlled. The anti-fouling operations above did not affect the fouling caused by pore-narrowing. As time went on, the pore narrowing to a critical size, the criteria pressure reached and the gel layer formed. At the same time, the settlement layer had a structural change to closeness. So a chemical washing was in need.It was also found that as the increase of flowing, decrease of aeration, prolonging of outlet time in a period could speed up the membrane fouling. But the relation of fouling speed and trans-membrane pressure was not linear and seemed to be unclear in a certain scope. In the study of chemical washing, NaOH, HCl and NaClO were effective and each of them could not be replaced by another.