| The pollution problems brought about by the livestock and poultry farming industry while providing products such as meat,milk and eggs cannot be underestimated.In order to explore the treatment of swine wastewater with high organic matter and high ammonia nitrogen and the solution to the problem of antibiotic pollution,this study took the simulated swine wastewater as the research object,and developed EGSB-two-stage A/O biofilm reactor.The start-up and operation test of the combined process were studied,and the influencing factors,film hanging test of different fillers and antibiotic test were discussed,and the characteristics of related sludge were explored and analyzed.Start the test by running the combined process continuously.The particle size of granular sludge in EGSB had increased to a certain extent,and it had successfully adapted to the organic load of the influent concentration of about 12195 mg/L.The maximum volume load can reach46.36 kg COD/(m~3·d),and the COD removal rate was about 85.33%.The removal effect of phosphorus was similar to other anaerobic processes,and there was no obvious removal effect except the assimilation of microorganisms.The suspended filler in the two-stage A/O process took 35 days to complete the film formation.The microorganisms in the reactor were retained,and the biomass increased significantly.The removal rates of COD and ammonia nitrogen were78% and 72.85% respectively.The combined process can meet the treatment requirements for this type of swine wastewater.By studying the operating parameters of the reactor and the effects of different fillers,the operating parameters such as HRT and reflux ratio of the EGSB reactor were discussed.When the hydraulic retention time were 8 hours and the reflux ratio was 8:1,the EGSB reactor had a better treatment effect.and operating efficiency,this operating condition can save operating costs and construction costs on the premise of meeting the pollutant emission standards of the livestock and poultry breeding industry.At the same time,the other two kinds of fillers were selected to explore the film hanging results and decontamination effects of different fillers.Filler A took 22 days to complete the film,the COD removal effect was about 84.38%,the effluent concentration was about 334.72 mg/L,the removal rate of ammonia nitrogen was about 91.86%,and the effluent concentration was about 16.38 mg/L.The film hanging of filler B took 21 days,the COD removal effect was about 85.82%,the effluent concentration was about 350.80 mg/L,the removal rate of ammonia nitrogen was about 87.37%,and the effluent concentration was37.62 mg/L.Comparatively speaking,the film-hanging effect of filler B was better,and the amount of sludge was more abundant.The change and operation effect of the system under high ammonia nitrogen concentration were studied experimentally.In the high ammonia nitrogen environment,the removal of organic pollutants by the EGSB reactor was affected to a certain extent.When the ammonia nitrogen concentration in the influent reached 800 mg/L,the removal effect of COD dropped to about70%.This indicated that the increase of ammonia nitrogen concentration enhanced the inhibition of the removal of organic matter.When the ammonia nitrogen concentration reached 750 mg/L,the removal rate of the two-stage A/O biofilm process following EGSB effluent continued to decline.Limited by conditions,environment and other factors,the ammonia nitrogen load exceeded the limit that the system can bear,and a large amount of free Ammonia produces toxic effects,and the ammonia nitrogen concentration in the effluent of the reactor cannot stably meet the relevant emission standards formulated.After adjusting the operating parameters such as dissolved oxygen and p H for the two-stage A/O process,the accumulation of nitrite nitrogen in the reactor and the decrease of nitrate nitrogen may exist in a certain short-range nitrification phenomenon.The experiment explored the changes and treatment effects of the system after adding sulfadimethoxine.After adding 1000 ?g/L SDM,the normal operation of the EGSB-two-stage A/O biofilm process was affected to different degrees.The treatment effect of the antibiotic in the EGSB reactor decreased to about 40.4%,and the effluent concentration was about 596 ?g/L.Under the influence of SDM,the removal effect of EGSB on COD decreased to 60.84%.The treatment effect of the two-stage A/O biofilm process on SDM also gradually showed a downward trend with the increase of time.The final removal effect was about 31.34%,and the effluent concentration was about 409.2 ?g/L.Under these conditions,the removal rates of COD and ammonia nitrogen were respectively were 60.62% and 59.95%.The effluent concentration of pollutants cannot stably meet the discharge standards required for pollutants in the livestock and poultry breeding industry,and advanced treatment technology should be considered in the follow-up.The experiment explored the relevant characteristics of granular sludge and biofilm sludge.Through scanning electron microscopy,it was observed that the granular sludge contained a large number of microbes such as coccidioides and brevis,which were stacked with each other to form a dense granular structure,and the voids facilitated the mass transfer of wastewater and the discharge of gas.The biofilm sludge contained filamentous bacteria,rod-shaped bacteria,etc.,which together formed a grid structure and adhered to form a biofilm tissue,and rod-shaped flora is the main flora for nitrification and denitrification.The richness and diversity of sludge microbial populations were explored by high-throughput sequencing.The Alpha diversity index showed that both the richness and diversity of microbial populations were affected by the addition of SDM,which led to a decrease in the removal efficiency of pollutants.The system included Proteobacteria,Synergistetes,Chloroflexi,Bacteroidetes,Firmicutes,Actinobacteria,Nitrospirae,etc.These microorganisms worked together to remove pollutants and cope with high organic loads.At the same time,it promoted sludge flocculation and maintained the spatial structure of granular sludge and biofilm sludge. |
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