Optimization Of Photosynthetic Bacteria Medium And Treatment Of Ammonia Nitrogen Wastewater

Ammonia wastewater has the characteristics of wide sources,difficult to treat,variable water quality,and strong pollution to the environment.These reasons make the treatment of ammonia wastewater become a difficulty in the field of environmental protection.Biodegradation of wastewater has the advantages of good treatment effect on target pollutants,simple operation,strong pertinency and small economic investment,so it is widely used in the treatment of ammonia nitrogen wastewater.Among them,photosynthetic bacteria can achieve self-growth and reproduction while degrading water pollutants,and the bacteria has the advantages of strong tolerance,non-toxic effect and no surplus sludge.Therefore,it is efficient and feasible to use photosynthetic bacteria to treat ammonia nitrogen wastewater.In this experiment,photosynthetic bacteria with high efficiency degradation of pollutants in water were selected through cultivation and acclimation,and the medium was optimized and improved.Then,the influence of four single factors,temperature,light,initial p H and inoculum amount of bacterial solution,on COD and NH₄⁺degradation by photosynthetic bacteria was studied.The treatment effect of photosynthetic bacteria on ammonia nitrogen wastewater was studied on the basis of optimizing factors by response surface method.Finally,high-throughput sequencing was used to study the changes of microbial community structure in ammonia nitrogen wastewater after the addition of photosynthetic bacteria,and then the reasons for the degradation of pollutants in water were analyzed at the microbial level.The main research conclusions are as follows:（1）Photosynthetic bacteria capable of efficiently degrading ammonia nitrogen wastewater pollutants under light and anaerobic conditions were screened out after enrichment and acclimation culture.The absorption peak scanning of living cell characteristics of the strains showed that the acclimated strains contained carotenoids and bacterial chlorophyll a.（2）Optimize and improve photosynthetic bacteria medium through single factor experiment,orthogonal experiment and range analysis,and determine the improved medium formula as follows:Sodium acetate 1.5g/L,NH₄Cl 0.5g/L,yeast paste 1.4g/L,K₂HPO₄ 0.8g/L,Na Cl 1g/L,Mg SO₄ 1g/L,Ca Cl₂0.05g/L.At the same time,the optimized and improved medium was used to culture the bacteria solution,and the OD660 value of the bacteria solution was 1.794 after 48h,which was 15.07%higher than that of the traditional medium.（3）Single factor and response surface experiments were used to optimize the influencing factors of COD and NH₄⁺degradation in simulated ammonia nitrogen wastewater by photosynthetic bacteria.The optimization experiment shows that under the condition of light anaerobic,temperature is 31.9℃,initial p H is 7.9 and inoculation amount is 24.2%,the best NH₄⁺removal rate is 62.85%.The removal rates of COD,NH₄⁺and TP are 69.88%,55.18%and 82.72%,respectively,in the treatment of livestock and poultry wastewater under light anaerobic condition.（4）High-throughput sequencing technology was used to analyze the microbial community structure in four experimental groups:raw bacterial solution（unacclimated）（group A）,simulated ammonia nitrogen wastewater with acclimated photosynthetic bacteria（group B）,livestock and poultry breeding wastewater with acclimated photosynthetic bacteria（group C）,and livestock and poultry breeding wastewater with unacclimated bacteria（group D）.The causes of COD,nitrogen and phosphorus degradation in wastewater by photosynthetic bacteria were analyzed from the microbial level.The results showed that the community structure and relative abundance of acclimated photosynthetic bacteria were changed when they were added into simulated ammonia nitrogen wastewater and livestock and poultry wastewater.The dominant bacteria in group B are:Proteobacteria（44.53%）,Firmicutes（18.86%）,Bacteroidetes（13.54%）,Epsilonbacteraeota（9.26%）and thermotobacter Thermotogae（7.32%）,and the dominant bacteria in Group C were:Proteobacteria（47.51%）,Firmicutes（19.54%）,Epsilonbacteraeota（11.25%）,Bacteroidetes（8.95%）and thermotobacter Door（Thermotogae）（5.34%）,In experimental group B and C,under the combined action of functional bacteria Rhodopseudomona,Ectothiorhodospira,Lentimicrobium,Acinetobacter,Exiguobacterium and other dominant bacteria,It can remove COD,nitrogen and phosphorus in wastewater effectively.The addition of photosynthetic bacteria improved the community structure in the water and enhanced the removal efficiency of pollutants in the water,indicating the high efficiency and feasibility of using photosynthetic bacteria to treat ammonia nitrogen wastewater.