Study Of Membrane Bioreactor (MBR) In Small Town Sewage Treatment

The small towns in our country are developed rapidly, the quantity of the urban sewage and the degree of polluting are all increasing constantly, therefore, we must strengthen the treatment of the sewage in the small towns. Membrane bioreactor (MBR) is a new-type and high-efficient techonolgy for sewage disposal and reuse, which combines biodegradation and high-efficent membrane separation. It has much advantage than the conventional sewage biochemistry, and there is a wide application prospect in the sewage disposal of small town. The main research contents of this study is the feasibility, stability and practicability of integrative type hollow biber membrane bioreactor in the sewage treatment in small town .This test has a initial search for the craft parameter, operation terms and the quality of outlet water. The result shows that the removal rate of MBR for COD is 96.0%, for NH3-N is 98.6%, and for TN is 63%, which is a better result. Through investigation during the experiment we can find that MBR has stronger shock load, and when the COD of inlet water is kept between 130mg/L and 780mg/L, it has better removal rate. The change of removal rate has no relativity with the load of sludge and volume of COD, which shows the stability and dependability of the system.The membrane flux is a important index to evaluate the performance of MBR. The test has studied the membrane resistance through the cause of the decline of membrane flux. We can conclude that, the membrane resistance is caused by biofilm jam in the membrane hole when it is running .If we want to decrease this resistance, the fundamental countermeasure is to improve membrane quality, increase the membrane fiber's intensity, adjust the turbulence intensity for both air and water and avoid forming biofilm in the membrane hole. The test has studied the MBR system inwhich PAC was casted in .The result shows that casting PAC can decrease the resistance of filter cake from 51.3% of the total membrane resistance to 11.6%. The measure can improve the structure of the sludge floc and the filtration character, decrease membrane pollution and jamming ,furthermore, it can also enhance and maintain higher membrane flux in a long time. Through the study of various factors which can affect the membrane flux, it is shows that, the biophase in the sludge can affect the filtration character in the mix liquid. When the sludge is mature, the filtration character is better. However when the COD concentration is high, it will cause negative effect.MBR is a activated sludge method , The quality of the outlet water is good and steady, and the outlet water can be used for various reuse water source.