| Wastewater treatment plant VOC emissions are becoming more and more important,and the impact of carbon sources and carbon-to-nitrogen ratios on VOC emissions from wastewater plants is not yet clear.Through artificial water distribution and SBR plant operation with nitrogen and phosphorus removal,the effects of aeration stage on VOCs emissions were studied,and the relationship between organic compounds such as sodium acetate,glucose,methanol and emissions of VOCs under different carbon and nitrogen ratios were studied;and high-throughput sequencing technology was used.Comparing the changes of microbial communities under different operating conditions with different carbon sources and carbon-nitrogen ratios,the relationship between different carbon sources,carbon-nitrogen ratio microorganisms,and VOC emissions was obtained.Research indicates:(1)Under different carbon sources,the peak concentration of VOCs changed with time,the VOCs emission and the diversity of microbial communities were different during the aeration period.Among them,the VOCs emission from small to large in turn was:sodium acetate was 20.79 mg/(m3.d),glucose was 23.33 mg/(m3.d),methanol was 24.86 mg/(m3.d),and the peak concentration of sodium acetate is the smallest value of 1518 ?g/m3.Under different carbon-to-nitrogen ratios,the peak concentration of VOCs and the VOCs emissions during the aeration period increased with the increase of carbon-nitrogen ratio.When the carbon-nitrogen ratio was 2,4,6,and 8,VOCs The emissions were in turn 17.86 mg/(m3.d),20.24 mg/(m3.d),22.96 mg/(m3.d),and 25.60 mg/(m3.d).(2)When using methanol as a carbon source,the microbial compositional structure was relatively different when using sodium acetate and glucose as carbon sources.The microbial community diversity from high to low in activated sludge was glucose,sodium acetate and methanol.Different carbon and nitrogen ratios had different microbial compositional structures and different microbial community diversity.The microbial communities with high carbon to nitrogen ratios of 4 and 6 had high similarities,and the diversity of microbial communities in sludge varies from high to low.Carbon and nitrogen ratios are 2,8,4,6,respectively.(3)Proteobacteria was the optimal flora in SBR system,however,the proportions differed in different carbon sources and carbon to nitrogen ratios.Among them,when using sodium acetate as the carbon source,the ratio of the proteobacteria was 46.06%.When the ratio of carbon to nitrogen was less than 6,the ratio of the proteobacteria increased with the increase of the ratio of carbon to nitrogen,but when the ratio of carbon to nitrogen was 8,the proportion of Proteobacteria was reduced.Bacteroidetes was the dominant flora after Proteobacteria.Firmicutes had a preference for both carbon sources of glucose and methanol.Chloroflexi made it easier to use methanol,and when the carbon to nitrogen ratio was 8,the ratio was the largest.(4)From the perspective of emission reduction of VOCs and the quality of effluent,the best source of carbon was sodium acetate.Under the optimal carbon source conditions,the water quality achieved a good removal efficiency and the removal rates of COD,TP,and NH4-N were all above 90%,the removal rate of TN was also above 60%.Under this condition,the emission of VOCs was the least of the three carbon sources with the amount of 20.79 mg/(m3.d).The best C/N was 6.Under the optimal C/N condition,the water quality achieved a very good removal efficiency.The removal rates of COD,TP and NH4+-N were all above 90%,the removal rate of TN was over 60%,and the VOCs emission was 22.96mg./(m3.d),although emissions of VOCs were 5.lmg/(m3.d)and 2.72mg/(m3.d)more than the emissions of VOCs when C/N was 2,4,but when C/N was 2,4 When the water quality of the effluent was poor,the removal rates of TP and COD were all below 40%.(5)Functional organisms of organic matter mainly included ?-proteobacteria in the Proteobacteria,?-proteobacteria,Fusarium in Bacteroidetes,and acid in Acidobacteria.Pseudomonas and so on.In the sewage treatment process,the proportion of organic functional bacteria was appropriately changed to achieve emission reduction of VOCs... |
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