Treatment Of Municipal Wastewater Using A Contact Oxidation Filtration Separation Integrated Bioreactor

A new contact oxidation filtration separation integrated bioreactor (CFBR) was developed to decentralized wastewater treatment of low influent concentration and small-scale sewage. The idea relies on BAF (BAF is a submerged media wastewater treatment unit that combines aerobic biological treatment and biomass separation by depth filtration) prototype and principles of slow and cake filtration (A sticky mat of biological matter, called a "cake", forms on the media surface, where particles are trapped and organic matter is biologically degraded).The CFBR was packed with activated carbon and operated in a batch mode to treat a municipal wastewater. The CFBR combines the advantages of the biological contact oxidation process and the filtration bed in one system. Moreever, as the use of the CFBR, it can complete biological oxidation of sewage and filtration and separation of suspended solids in a reactor.In this study, the CFBR was operated in a batch mode to treat municipal wastewater. The objective of the paper was to evaluate the processing performance, explore degradation mechanism of pollutant and flow pattern, and establish kinetics model in the CFBR.The research indicated that it is efficient and feasible to treat decentralized wastewater by the CFBR.It can be proved as following:(1) The CFBR for decentralized wastewater treatment has some advantages such as lower effluent SS value, small land requirement, good power consumption, high degree of automation operation and stronger resistance to influent shock load.(2) The optimal operation parameters of the CFBR were determined as follows: Hydraulic loading of 3.% m3/(m3.d), DO of 2-3 mg/l in contact oxidation phase, and initial filtration velocity of 5m/h in filtration separation phase.Good performance of the CFBR was achieved under the optimal operation parameters. The total efficiencies of COD, NH4+,TN and turbidity removal in the CFBR were 94.8%,81.4%,64.6% and 97.5%(average value). The effluent concentration of COD,NH4+-N, TN and turbidity in the CFBR were 6～30mg/L,1.65-7.31 mg/L,4.95～12.62mg/L and 1～10ONTU. However, the CFBR showed that it seemed not to be effective in phosphorus removal.Maximal efficiency of TP removal was 63.0%.TP value of the CFBR effluent was 0.64～1.57mg/L.(3) The degradation mechanism of pollutant of the CFBR was explored.In contact oxidation phase, the organic substrate and DO goes into the attached growth biofilm. They are both utilized by the biofilm, and are degraded to CO2 and H2O in the end.The mass balance would show overall loss of nitrogen, which would logically be assumed to be simultaneous nitrification-denitrification (SND) in the CFBR.And partial TP removal is due to the normal absorption of microorganisms’growth.In filtration separation phase, a small amount of organic matter removal is attributed to granular filter media and attached growth biofilm. Through the interception and microbial metabolism, they achieved organic matter removal.And the removal of SS is mainly through two steps (Migration and adhesion).(4) The Flow pattern of the CFBR was completely mixed. But from organic matter degradation, the CFBR was plug-flow in terms of time.So, in essence, the CFBR was completely mixed batch reactor (CMB).(5) According to the operational characteristics of the CFBR and the degradation mechanism of organic pollutants, the kinetics model of the CFBR was established. The formula of kinetics model was The kinetics model was appropriate and feasible to describe the operational conditions of the CFBR system.