Study On The Municipal Sewage Treatment With An Innovative Dynamic Membrane Bioreactor

High cost and membrane fouling are two main blocks which restrict the wide application of the membrane bioreactors(MBR) in wastewater treatment.Nowadays, the dynamic membrane bioreactor(DMBR),with some advantages such as excellent anti-pollution,relatively higher flux and lower cost of membrane modul,has been the hot research area of the membrane technology.Studies on the municipal sewage treatment with an innovative process,named BBF-DMBR,are described in this research.BBF-DMBR was coupled by the dynamic membrane modul and the biomass biofilm reactor(BBF) filled with Luffa cylindrical sponge(LS) media.The process performances of BBF-DMBR are comprehensively studied,and the BBF-DMBR technology would be optimized and improved based on analyzing its fouling control and cleaning technique.The results indicate that the system of BBF-DMBR is more efficient in biofilm forming as well as pollution disposing and has a better capacity of anti-impact.It is an efficient way of separating water from mixed liquid,reducing the loss of microorganisms and ensuring the quantity of biofilms on LS fibers.During the stable operation period,the removal of COD,NH₄⁺-N,TN and TP are respectively 79.41%,96.22%,55.93%and 43.77%in the BBF-DMBR sewage treatment.All these parameters of the discharge but TP achieves the first-level A standard of Discharge standard of pollutants for municipal wastewater treatment plant,China (GB18918-2002).As the concentension of TP in the discharge just reaches the second-level of the Standard GB18918-2002,the capacity of TP disposal is going to be improved in further study.Also,during the operation period,LS fibers degraded slowly,which shortened the service life,affected the stability and increased the cost of BBF-DMBR system.Experiments on membrane fouling control indicate that a certain intensity of aeration could extremely reduce membrane fouling.When the aeration intensity is 20m³Â·m^-2·h^-1,the stable operating period of dynamic membrane could be as long as 45 days with a comparatively steady membrane flux under the same pressure-difference.The data shows that when the pressure-difference is 100mm,the average membrane flux will be 67.42L/(m²h).The fouled membrane is cleaned by back blowing with air for 10min at first,then with water for 15min,and by washing with acid for 1h at last.After cleaning,the dynamic membrane modul,with good performance in reproducing and reusing,renew its permeate flux up to 95%of its clean water flux. The experimental study shows that optimization and improvement of BBF-DMBR could enhance its efficiency of sewage treatment.By way of graft copolymerizing,the anti-biodegrading period and service life of LS will be extended respectively to 122.2%and 2.2 times of its original ones.Precoating the dynamic membrane with RM provides the BBF-DMBR system with better absorption and more chemical function,and as a result enhances its TP removal.As the data shows, when the influent TP is 1-2mg/L,the effluent TP was 0.2mg/L,which achieves the first-level A standard of Discharge standard of pollutants for municipal wastewater treatment plant.