Study On The Characteristics Of Mechanical Scraping Type Membrane Bioreactor

Water pollution problems causing by wastewater that is not discharge have become increasingly prominent, new and efficient wastewater treatment technology has become the widespread hotspot in the water pollution control. MBR is favored by its stable effluent quality, high biochemical efficiency, small footprint, etc. and high performance membrane materials and membrane fouling control become the major problems.This article takes the mechanical scraping membrane bioreactor which made by homemade PVA membrane modules, test the performance of PVA microfiltration membrane, study the Anti-fouling properties and operating characteristics of the reactor, then get the best conditions of membrane pollution control and best operating conditions. We get the treatment effect of COD, ammonia, turbidity in Synthetic wastewater by comparing the test, and we get the following conclusions:1. The results of testing PVA microfiltration membrane performance show that:(1) Compared to the traditional membrane module, homemade PVA microfiltration membrane has high flux, soft membrane material, easy to scraping, lower operating pressure.(2) We can clean the contamination layer in surface of the membrane through physical scraping, and let the membrane flux and pressure restore the initial level within a certain time frame.2. The results of mechanical scraping membrane bioreactor anti-fouling properties test show that:(1) Mechanical scraping is able to effectively restore the membrane flux within a certain range of running time, and scraping has the best time interval. Membrane flux has the smallest change in the test of scraping at intervals of120min, and membrane flux recover best, membrane fouling control effect is also the best.(2) With the increasing particle size investment and added to membrane bioreactor, the diversification of membrane flux is smaller, and that is better for membrane bioreactor to run. When the particle size is increased to a certain extent, the particle cannot play an important role in effective collision with membrane, and erosion effect of mud pie on the membrane surface is not obvious. The membrane pollution prevention effect is the best when reactor adds the size of1.5cm x1.5cm x1.5cm particles.(3) Dosing particles can effectively prevent the membrane flux decreasing into mechanical scraping membrane bioreactor, and dosing square particles is better than round particle.(4) Adding more particles is conducive to the control of membrane fouling, when the dosage is to a certain extent, the influence of erosion effect of mud pie on the membrane surface is not big and control of membrane fouling is not increased significantly though it increased particle collision frequency on the membrane. The best dosage is30in the test.(5) It is more effectively prevent the membrane flux decreasing for dosing dry particles than the elastic particles into mechanical scraping membrane bioreactor within a certain range of running time.(6) The aeration rate of mechanical scraping membrane bioreactor is greater, the amount of membrane flux reducing is smaller, and the effect of membrane pollution prevention is better. Membrane pollution prevention is the best when aeration rate is0.5m3/h.3. Experimental study on the running of mechanical scraping membrane bioreactor shows that:(1) We take operating conditions as the research object, we get operating conditions:suction time is10min, pause time is2min, aeration rate is0.4m3/h, and the amount of pumping out the water is40L/h by controlling suction time, pause time, aeration rate, and the amount of pumping out the water obtained by orthogonal experiment.(2) Dosing particles can increase the velocity of turbulent flow in the reactor, and at the same time the air bubbles become smaller and disperse uniformly, the mass transfer rate of the oxygen increases, the transport rate of incoming organic and outing metabolites in microbial improves, thereby the COD removal rate increases.(3) Dosing particles is conducive to growth of nitrifying bacteria and Asian nitrifying bacteria. NH3-N is converted to nitrite in the role of Asian nitrifying bacteria, and nitrite is converted to nitrate in the role of nitrifying bacteria, thereby the COD removal rate increases.(4) The scouring action of the particles can destroy the sludge floe, and the size of the sludge become smaller. The removal rate of turbidity is mainly rely on the interception of membrane, when the size of sludge floc is smaller than the size of membrane pore, the interception reduces, the removal rate of turbidity decreases.