Study On Modeling Development Of Self-forming Dynamic Membrane Bioreactor

Self-forming Dynamic Membrane Bioreactor (SFDMBR) employs inexpensive mesh filter materials, such as non-woven fabric, replaces conventional microfiltration/ultrafiltration membranes as filtration modules. It uses formed Dynamic Membrane (SFDM) deposited on the mesh materials by active sludge in the initial separation process, to acquire approximately separate results of conventional membranes.The permeability performance and structure evolution of SFDM is very different with conventional MBR, even more complicated. As a result, the filtration mechanism at different stage was studied. The result shows that a completely different filtration mechanism happened at different run stage. From the initial filtration stage, standard blocking mechanism, standard blocking-complete blocking combined mechanism, complete blocking-cake filtration combined mechanism and cake filtration mechanism was successively dominated.The result of the force analysis on the activated sludge in SFDMBR showed that attachments was dominated by the drag force caused by trans-membrane pressure TMP, and detachment was dominated by the tangential force and lateral inertial lift force. Under the same operation condition, the smaller the particle size the easier the activated sludge attached to the inexpensive mesh filter materials. Therefore, at the stable stage, the fouling of the SFDM was mainly caused by the small particle size activated sludge (<1μm).Then the resistance respectively caused by standard blocking, complete blocking and cake filtration was further studied. The simulation result shows that the resistance respectively caused by standard blocking, complete blocking and cake filtration all increased rapidly initial and then increased slowly. The resistance caused by standard blocking was in accordance with the sludge particles concentration which can arrive to the material. The resistance caused by complete blocking was in accordance with filtration volume. The resistance caused by cake filtration was in accordance with the sludge particle mass which can attach to the material. The resistance respectively caused by standard blocking, complete blocking and cake filtration was dominated at the time initial20min,20-40min and after40min. Finally the resistance respectively caused by standard blocking, complete blocking and cake filtration was all stable.