| At present,the livestock and poultry breeding industry in various regions is becoming more and more large-scale and intensive,and the environmental pollution problems brought by it are also becoming more and more serious.Large-scale aquaculture wastewater has the characteristics of large production,concentrated concentration,high organic concentration and close proximity to cities.These characteristics lead to serious pollution of the environment caused by improper treatment of dairy farming wastewater.At present,large-scale dairy farms mainly use anaerobic treatment,aerobic treatment,anaerobic-aerobic combined treatment and other traditional treatment methods to treat dairy farming wastewater.These traditional treatment methods can only remove some of the pollutants in the wastewater,and the removal effect on COD,N,and P is poor,and it is difficult to meet the national emission standards.Therefore,finding an energy-efficient and efficient treatment method is a top priority.The use of microalgae to treat sewage can effectively remove nitrogen and phosphorus pollutants from sewage and convert it into biomass energy,which can turn waste into treasure.In this paper,anaerobic digestion of dairy cattle was used as the research object.Chlorella and compound bacteria were used as experimental materials.In order to achieve the main goal of efficiently removing total nitrogen and COD from dairy culture digestive juice,the domestication and high efficiency of chlorella were carried out.The construction of algal symbiosis system and the optimization of immobilization conditions.It provides ideas for purifying anaerobic digestion of dairy cows through the algal symbiosis system,and provides theoretical and technical support for production practice.The main results are as follows:1.Domesticated chlorella(HC-2)was domesticated,and domesticated algae were more suitable for growth in anaerobic digestion;a certain proportion of compound bacteria was added to domesticated chlorella.It was found that its biomass and specific growth rate were significantly improved,and the total nitrogen removal rate and COD removal rate of dairy farm anaerobic digestion liquid were also significantly improved.Therefore,it is considered to construct an algal symbiosis system with chlorella and composite bacteria.2.The total nitrogen removal rate and COD removal rate were used to optimize the culture conditions of the algae symbiotic system of chlorella and compound bacteria by the design and analysis of the corresponding surface experiments,in order to further improve the total nitrogen and COD removal rate.The optimal conditions for the final optimization are:temperature 23 ℃~ 26℃,algal bacteria ratio between 3:2 and 1:1,the light cycle is controlled at 12:12 ~ 16:8.Under the optimal optimization conditions,the total nitrogen removal rate of the algae symbiosis system for dairy cattle digestive juice treatment was 69.93%,and the COD removal rate was 51.34%.3.Using sodium alginate and calcium chloride as carriers of immobilized chlorella and compound bacteria,the total nitrogen removal rate and COD removal rate were reference indexes,and the best experimental scheme for immobilized rubber balls was determined by orthogonal experimental analysis..The optimal optimization conditions were as follows: the optimum immobilization conditions were determined by the total nitrogen removal rate as 2%sodium alginate,3% calcium chloride,and 6 hours.Based on the COD removal rate,the optimal immobilization conditions were determined to be 3% sodium alginate,4% calcium chloride,and 12 hours cross-linking time. |
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