| In order to achieve effective control on rural domestic water,and curb the trend of eutrophication of water environment,it is imminent to treat rural domestic sewage.Moving bed biofilm reactor(MBBR)and subsurface wastewater infiltration system(SWIS)are the ideal technique for regions and towns with out-dated economy,less environmental professionals and no perfect sewerage reticulation system.In this study,by studying the start-up,operation and regulation of the process in the system which use rural domestic sewage as the treat object,obtain the following findings:(1)Under normal conditions,detecting content of pollutants in inlet/outlet and appropriate nature of the activated sludge by treating simulated rural rural domestic water with moving bed biofilm reactor.The research shows that viscous bulking of activated sludge had a great impact on biofilm in the start-up period.When start-up was done,MBBR stable run with the conditions that pH was about 7,DO was in the range of 2-4 mg/L,HRT was 3h,the removal rate of COD,NH4+-N,TN and TP were 85%,85%,60%,70%as the influent COD,NH4+-N,TP concentrations were 400 mg/L,35mg/L and 7mg/L.MBBR has a good effect on treating simulation rural non-point source sewage,it can be to treat the source wastewater in the towns and areas where do not have improved sewer systems.(2)Modifying peat soil(A)as the main soil in subsurface wastewater infiltration system with slag,iron tailings and zeolite then detecting the content of NH4+-N in effluent.When subsurface wastewater infiltration system run with the conditions that rate of arid/wet was 1:3,substrate with best ability to deal with pollutants was 35%A+2.5%B2+ 2.5%D + 2.5%C+50%A,2.5%B2,2.5%C and 2.5%D(B2 is the slag which the particle size is 1～2mm,D is iron tailings,C is zeolite which the particle size is 1～2mm)completely mixed,the removal rate of NH4+-N was 98.36%as the influent COD,NH4+-N,TP concentrations were 60 mg/L,8mg/L and 2mg/L.(3)It took 40 days to successfully start of coupling process of moving bed biofilm reactor and subsurface wastewater infiltration system by using simulated rural rural domestic water as the processed objects with the conditions that pH was about 7,DO was in the range of 2-4 mg/L,HRT was 3h,rate of arid/wet was 1:3,the removal rate of COD,NH4+-N,TN and TP were 95%,100%,71%,99%as the influent COD,NH4+-N,TP concentrations were 400 mg/L,35mg/L and 7mg/L.It took another 40days that the effluent of moving bed biofilm reactor is full access to subsurface wastewater infiltration system,the removal rate of COD,NH4+-N,TN and TP were 95%,100%,60%,100%with the condition that rate of arid/wet was 1:1.Operation for 100 days,using Baita river water as the processed objects with the condition that rate of arid/wet was 1:1,the removal rate of COD,NH4+-N and TN of the effluent in coupling process of moving bed biofilm reactor and subsurface wastewater infiltration system decreased to 70%,75%,-23%due to the C/N ratio was only 7:1 in Baita river,after adjusting the C/N ratio of 11:1,the removal of all pollutants increased to 85%,98%,30%.No matter how the the C/N ratio changed,TP was not detected in the effluent.(4)16S rDNA high-throughput sequencing results showed that the major dominant species in SWIS were heterotrophic nitrogen removal like Pseudolabry sand Nitrosomonadaceae,organic degradation such as Gaiellales,and phosphorous removal like Rhizomicrobium;Anaerolineaceae is dominant microflora in anoxic soil after the set-up period of SWIS.Coupling process of moving bed biofilm reactor and subsurface wastewater infiltration system running 147 days,the removal rate of COD,NH4+-N,TN,TP reached 83%,100%,35%and 100%. |
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