| At present,in northern China's villages and townships and other areas,the sewage treatment process is unable to meet the standard emission due to the impact of low temperature in winter,and China currently lacks a highly efficient and low-consumption sewage treatment process suitable for rural areas.The development of related technologies has become The important research direction in the field of sewage treatment.The aeration biological filter process is a preferred process for sewage treatment in villages and towns due to its high quality and small area.However,the conventional aeration biological filter process has a low nitrogen and phosphorus removal efficiency and cannot meet the discharge standards.In this experiment,a composite biological aerated filter was used to improve the process using iron-rich fillers and manganese sand at low temperatures,so as to improve the removal efficiency of the process at low temperatures,and at the same time,from the microbiological perspective Optimization and theoretical research provide data support.The experiment first examined the start-up process of aeration biological filter composed of ceramsite and zeolite filler at normal temperature,and analyzed the influence of iron-rich filler and manganese sand on the removal of pollutants at low temperature,and then studied the inside of the reactor.The variation of pollutants and microbiological characteristics along the height of the filler layer,and finally the analysis of changes in the microbial community diversity under the influence of low temperature and manganese ions in the reactor.When the reactor was started under normal temperature conditions for 43 days,the COD removal rate was stable at more than 70%,and the NH4+-N removal rate was stable at more than 60%.The membrane formation process was basically completed.The reflux ratio of the nitrification solution under the action of the iron-rich filler has an important influence on the treatment efficiency of the reactor,at a temperature of 15°C,a hydraulic load of 0.50 m3/(m2·h),a reflux ratio of 100%,and a gas to water ratio of 10:1.The removal rates of COD,NH4+-N,TN,TP,and SS by the reactor reached 81.01%,92.10%,53.51%,87.81%,and 84.59%,respectively,of which COD,NH4+-N,TP,and SS all can meet the first-grade A standard emission requirements.When the manganese ion concentration was 4.0mg/L,the removal effect of pollutants was better in the reactor.However,due to the absence of chemical phosphorus removal,the TP removal in the reactor effluent was lower than that in the iron-rich filler.When the temperature decreased from 15°C to 11°C,the COD concentration of the effluent of the BAF-1 reactor remained below 50 mg/L,and the removal rates of NH4+-N,TN,TP,and SS decreased by 9.87%,6.19%,and 4.51,respectively.The removal efficiency of COD and TN in the BAF reactor increased by 3.72% and 4% under the synergistic effect of Fe3+ and Mn2+,respectively.The removal rate of TP from the reactor increased by 50.61% due to the presence of Fe3+.In different working conditions of manganese sand,the treatment efficiency of BAF is not significantly improved.When the filler height of manganese sand is 30 cm,the TN removal rate of BAF reactor is 5.7% higher than that of the control group,and the TP removal rate is increased by 8%.With the decrease of temperature,the NO2--N accumulation degree of the effluent of the two sets of reactors showed an upward trend,and at the same time,the NO3--N concentration of the effluent gradually decreased due to the deterioration of the nitrification effect.The results of biofilm activity tests at different low temperatures show that low temperature has a certain degree of inhibitory effect on the biofilm activity,and the biofilm content gradually increases with decreasing temperature.From the statistical results of denitrifying bacteria in the BAF reactor,the RA15,RA11,and MA415 included 83,78,and 82 denitrifying bacterial communities at the species classification level,and three samples at the species level.The order of species richness from high to low was as follows: RA15>MA415>RA11;among them,Gliocladium,Ideonella,Taurella,Azotobacter,Dechloromonas,and Sulfuritalea hydrogenivorans were the abundances of bacteria on the taxonomic level.Higher predominant strains;lower temperature and manganese ion respectively reduced the number of strains by 5 and 1 species.The abundance of Sulfuritalea genus and Dechloromonas genus are increased under the temperature increase and the synergy of manganese ions.The proportion of Azotobacter spp.was increased,but the proportion of manganese ions in the denitrifying bacteria population was greater than that in the abundance of dominant bacteria.RA15,RA11 and The genus contained in MA415 produced a total of 3 association networks.Among them,the core species Sulfuricella and Dinoroseobacter,Bacillus,Sulfolobus,and Acidophilus in denitrifying bacteria showed as Correlated with the Alicycliphilus genus,rose Bacillus,Flavobacterium and Azospirillum showed a negative correlation.The results of bacterial community diversity in the middle of aerobic filter column of BAF reactor under different low temperature and different concentrations of manganese ions showed that the abundance of Nitrospira decreased by 10% after the temperature dropped from 15°C to 11°C.The low temperature had a significant inhibitory effect on the genus;the abundances of the green beetles,the hydrogen genus and the Terrimonas increased to varying degrees,and the low temperature mainly inhibited the nitrification-associated bacterial population.Bacterial populations with the ability to degrade organisms showed a promoting effect;at the temperature of 15°C,at the species classification level,the effect of manganese ions increased the bacterial population in the BAF reactor,compared with the control group,2.0mg/L.And 4.0mg/L concentration of manganese ions increased the number of bacterial flora by 19 species and 5 species respectively.That is,as the concentration of manganese ions increased,the bacterial population showed a trend of increasing first and then decreasing;at a higher temperature and manganese ions Under synergistic effect,the number of bacterial populations in the BAF reactor increased by 18 species,among which the abundance of elevated genus bacteria mainly included Flavobacterium,Acidobacter,Denitratisoma,and Azohydromonas.The abundance of Nitrospira was significantly reduced;under the synergistic effect of iron and manganese ions,the abundance of Nitrospira increased by 19%,and the abundance of Streptomyces rose by 6%,Xanthomonas spp.The abundances of Rhizobium,Rhodobacter,and Sphaerotheca spp.increased by 2%.The abundances of the fungi decreased,including Azohydromonas and Nitrospira,and the abundances were reduced by 3% and 2%,the abundance of the rest of the genus is basically below 1%.The individual effect of manganese ions compared with the synergy of iron and manganese ions,there is also a clear difference in bacterial population abundance,mainly reflected in: the abundance of Nitrospira increased from 34% to 54%,and the abundance increased by 20%,the effect of iron ions has a significant effect on the abundance of Nitrospira in the reactor,and the abundance of reduced bacteria is mainly composed of genus Myxococcus,acid bacterium,and genus Capella,and their abundance decreases.5%,4% and 2%.The results of association network analysis among bacteria groups showed that the synergistic or competitive relationship among the bacterial species in the bacterial samples is relatively clear,and they together constitute a microbial community structure with certain stability. |
PDF Full Text Request