Treatment Of Rural Domestic Wastewater By The Novel Filtration Anaerobic Biofilm Reactor Enhanced By Packing Media

China's rural areas are widely distributed and dispersed,and the sewage discharge situation is relatively complex.There are some problems in environmental protection,such as insufficient funds,imperfect infrastructure,lack of technical management personnel and so on.When biofilm process is used to treat low concentration rural domestic sewage,it has the advantages of greater impact load resistance and less excess sludge.It can be used as a preferred choice for rural sewage treatment.However,there are still many problems in the treatment of wastewater in rural areas by conventional biofilm process,which is not suitable for large-scale use.It needs a new process with simpler equipment,more flexible management and better treatment effect to treat wastewater in rural areasThe new filter anaerobic biofilm reactor combines biofilm reactor and dynamic membrane technology.It has the advantages of short start-up time,small effluent resistance,small volume,low cost and low energy consumption.It can be used as an alternative process for wastewater treatment in rural areas.Because there is no activated sludge in the reactor,the removal efficiency of pollutants by a single biofilm is limited.In order to be more in line with the engineering application of the reactor,the filler strengthening of the reactor was studied.Comparing the hydrophilicity,mass transfer and bioadhesive ability of three kinds of fixed packings which are widely used at present,the packings are selected for reactor intensification(reactor B)and compared with the unreinforced reactor(reactor A).The reactor runs for 160 days.The main results are as follows:(1)Operation performance of the reactor:Reactor B with biological rope filler is more efficient than reactor A COD without biological rope filler.The COD removal efficiency of reactor A was higher during the stabilization period,with an average removal rate of 90.3%,which was higher than that of reactor A without filling 84.4%.The pH of the two reactors remained at normal level during operation,but the VFA content of reactor A was slightly higher than that of reactor B.(2)Filtration performance of the reactor:Packing enhancement did not have a significant impact on the turbidity of the reactor,but after adding padding,TMP of reactor B reached 4.8Kpa at the later stage of operation,which was higher than reactor A's 4.2Kpa.(3)Reactor morphology and physicochemical properties:Packing reinforcement has little effect on the morphology of biofilm,showing a loose surface and compact internal structure;After packing reinforcement,the average particle size of surface layer of reactor B biofilm is smaller than that of surface layer of reactor A biofilm,which does not affect the bottom PSD of the two reactors,nor does it change the organic composition of different layers of biofilm.The polysaccharide and protein content of reactor B with filler were higher than reactor A.(4)Biological community structure:The addition of biological rope filler changed the community structure of reactor B non-woven biofilm,and the increase of the expression activity of Proteobacteria and Bacteroidetes contributed to the improvement of the removal performance of reactor B.The addition of biological rope would optimize the archaeological community structure of reactor B non-woven biofilm and would make it possible to improve the removal performance of reactor B.Methanosaeta is dominant on the biofilm of reactor B.The increase of expression activity of methanogens is the reason for the improvement of the removal performance of reactor B.