The Treatment Of Sewage By Rotating Dynamic Membrane Bioreactor

As a new biological treatment technology, dynamic membrane bioreactor has showed its great advantage on the treatment of sewage. The diversification of membrane structure is one of the hot research topics. This research designs a new rotating dynamic membrane bioreactor. We observed the treatment effect of ammonia in the condition of optimum technological parameters, which is obtained by experiment. The main work and conclusions are as follows:1、Analyzing the structure of current filter discs and taking reference of a patent that biological rotating disc with filter cavity, we designed a new dynamic membrane bioreactor, effluent flow to central axis and driven by rotating discs. The result of small scale experiment with gravity outflow showed that the appropriate parameters of he polyurethane sponge film substrate were:aperture 20PPI, thickness of 20mm, the best water head is 300mm, stable flux 40L·m-2· h-12、Carrying out the process, structure, operation after the basic parameters of the film substrate are obtained. Based on the theoretical calculations about the activated sludge process and the frame size of the membrane,the desired sponge’s area is 0.36m2. It was designed to accurately calculate the size of the center plate, vertical plate, side plate, mechanical seal seat, mechanical seal ring limit, rotary dynamic membrane bioreactor side cover, side panels, the reactor shell and other component parts. Subsequently, the experimental running design of the reactor is studied.3、The biofilm was cultivated in the condition of continuous feeding and the effluent reflux into the reactor without any additional nutrients. During star-up, COD of influent is 200～800mg/L, respectively. The speed and immersion rate of rotating discs were 4r/min and 75%. gas-water ratio was 3:1. After three days, the SS of effluent was blow 10mg/L, COD removal rate gradually increased to 85%, which means that biofilm has cultivated successfully.4、Comparative study the treatment effect of COD when the rotary dynamic membrane bioreactor is in different rotary speed (4,6,8,10r/min), different gas-water ratio (2:1,3:1,4:1,5:1), various immersion percentage (65%,80% 90%).The best process parameters are got:speed (6r/min), gas-water ratio (3:1), immersion (80%). The result of the optimal process parameters showed that ammonia removal effect is not ideal, the reactor average removal rate of ammonia was 76.1%, the removal rate and the influent ammonia loading are closely linked.