| Self-Forming Dynamic Membrane Bio-Reactor (SFDMBR) is a newwastewater treatment method based on traditional Membrane Bio-Reactor(MBR) and Dynamic Membrane (DM) technolog, which is instead ofexpensive microfiltration or ultrafiltration membrane. Relative largeaperture membrane is used to efect solid-liquid separation by the dynamicmembrane that is formed by the water head pressure. For its solution ofthe high cost and the membrane fouling, the DMBR has a high value toresearch and develop.Coarse pore-sized filtration material and the run mode ofself-forming dynamic membrane have a great influence of operation andtreatment effect, so the non-woven and the nylon mesh had a comparsionstudy. The results showed that considered the effect of oxygen transfercapacity and the inner loops, The system was determined0.25m3/h as theeconomy aeration. When the operation of the two coarse pore-sizedfiltration materials DMBR were stables, the turbidity of both systems were5NTU below, and removal efficiency of CODcr and NH3-N were alsovery well, The removal ratio of CODcr and NH3-N could be reachedabove85%and90%, but not significant on TN. After a long time run, thestrength of non-woven was greatly lower than nylon mesh, and thenon-woven membranes break easily during the experiment and changed anew one frequently. Therefore, in this study, choose the nylon net for thefurther study.Because of the low removal rate of TN and the membrane-fouling problem of the dynamic membrane bioreactor, this study aimed at to solvethis two problems by optimized the operation mode and anti-flushingtreatment and enhance removal efficiency of TN. The results showed thatthe reactor greatly improved the effect of TN removal, and comparaedwith original, the average removal rate increased from18.5%to53.1%;the continuous filter style accumulated75L water in a cycle of38h, whilethe intermittent style accumulated128L in a cycle of72h, both of thefilter volume and operation cycle were increase nearly one time comparingwith the continuous style, which could reduced membrane foulingeffectively and extended the continuous operation time, even reduced thecosts.This study was used DMBR to compare the formation and foulingbehaviors of normal sludge, bulking sludge and defocculated sludge. Thesludge properties was evaluated in terms of extracellular polymericsubstances (EPS), relative hydrophobicity (RH), sludge viscosity (μ) andcontact angle to specify the fouling mechanism. The results showed thatthe bulking sludge could cause severe cake fouling as a result ofadsorption and bridging of filamentous bacterias. The deflocculated sludgeresulted in dense cake layer, which resulted from the deposition ofcolloidal particles and soluble matter that plug some of the middle cakelayer channels. Comparatively, the normal sludge had a slight membranefouling tendency and thus the best performence. The EPS contentcomposition and the sludge morphology were two major factors affectingsludge properties and fouling behaviors of DMBR.The process was approved thugh the pilot scale experiment. TheDMBR used150and200mesh nylon as membrane material. It was foundthat150mesh nylon net DMBR run period of26d continuously, while200mesh nylon net DMBR period of18d, the reason might be the smaller diameter of200mesh retained more pollutants, so it would causemembrane fouling more easily. For30days stably running under theoptimized condition, two DMBR styme achieved good bio-chemicaleffects. The removal ratio of CODcr, NH3-N and TN was above85%,96%and48.8%. But the removal rate of TP was very low. The preliminarydesign of the DMBR was also discussed based on the result of this study. |
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