Study On The Treatment Of Livestock And Poultry Wastewater By Sequencing Batch Activated Sludge Process System

The sources of livestock wastewater are scattered,the water quality is complex,and the concentrations of organic matter,nitrogen and phosphorus are relatively high.In this study,the anaerobic aerobic alternating sequencing batch reactor（SBR）was constructed in the laboratory to treat simulated livestock wastewater.The difference of pollutant removal performance and the change rule of functional microorganism activity and composition under different influent load conditions in the start-up and formal operation stages of SBR were studied.The main conclusions are as follows（1）By inoculating the sludge into the SBR reactor,the acclimation of activated sludge can be completed in the SBR reactor.The reactor has a better removal effect on pollutants such as soluble chemical oxygen demand（sCOD）,positive phosphorus(PO₄^3--P),total nitrogen（TN）.Under different influent loads,the removal rate of sCOD in SBR reactor is above 80.0%.With the influent sCOD concentration increasing from 400 mg/L to 1000 mg/L,the average PO₄^3--P concentration of effluent decreased from 1.88 mg/L to 0.73 mg/L,and the average removal rate increased from 76.7%to 95.4%.The increase of influent PO₄^3--P concentration has little effect on the stability of phosphorus removal effect.Under the conditions of stage Ⅰ and Ⅱ,the influent ammonia nitrogen（NH₄⁺-N）can be completely removed,but under the conditions of stage Ⅲ,the removal rate is reduced.Combined with the treatment effect and wastewater discharge standard,the optimal operation condition of SBR is stage Ⅱ.（2）The results of typical cycle experiment and sequencing batch experiment with different carbon sources（sodium acetate/sodium propionate）showed that the absorption and utilization rate of organic matter and phosphorus release rate of microorganisms in SBR reactor were higher in the first 60 min of typical cycle anaerobic stage.With the increase of influent load,the activity of functional microorganisms related to phosphorus accumulation and absorption in the reactants increased,the amount of biological phosphorus absorption/release also increased,and the concentration of PO₄^3--P in the effluent decreased.Compared with sodium acetate,sodium propionate as carbon source was more favorable to the release/absorption of phosphorus.With the increase of influent load,the contents of protein,polysaccharide and humic acid in EPS increased.（3）The effects of different influent loads on microbial diversity and community structure of SBR reactor were studied.The results showed that the microbial community structure of SBR reactor was similar in stage Ⅱ and stage Ⅲ,and most different from that of inoculated sludge.With the increase of influent load,the relative abundance of phosphorus removal microorganisms increased,while the relative abundance of nitrogen removal microorganisms decreased,which may be one of the reasons for the change of nitrogen and phosphorus removal performance.Tetrasphaera is always the dominant phosphorus accumulating bacteria in SBR,which plays an important role in promoting the phosphorus removal performance of SBR.Under the condition of high substrate concentration,there was no obvious competitive relationship between phosphorus accumulating bacteria and glycan accumulating bacteria in SBR reactor.