Feasibility Study Of Biogas Engineering Biogas Slurry Used For Efficient Cultivation Of Chlorella

The biogas slurry produced by large and medium-sized biogas projects under the"specialized energy utilization of manure"model promoted by the Ministry of Agriculture has the characteristics of high output,high concentration,complex and variable composition,poor biochemical properties,and unknown risks.The disposal of biogas slurry has become one of the bottleneck issues limiting the development of biogas technology and even the development of livestock and poultry breeding industry in China.This article aims to achieve high value utilization of biogas slurry resources,with biogas engineering biogas slurry as the research object,and Chlorella vulgaris NCU-7 selected by the research group as the test algae species,to explore the process methods that can be used for efficient cultivation of Chlorella vulgaris with biogas slurry.The main work and experimental results are as follows:Explored the feasibility of two pre-treatment methods for culturing Chlorella after pre-treatment of biogas slurry.It was found that the pre-treatment method of diluting biogas slurry after flocculation with hydrochloric acid（HCl）and cationic polyacrylamide（CPAM）,as well as the pre-treatment method of coagulating biogas slurry with polyaluminum chloride（PAC）and cationic polyacrylamide after high-temperature ammonia blowing,are feasible.The pre-treatment method of high-temperature ammonia stripping and flocculation,compared to the pre-treatment method of flocculation and dilution,not only reduces the use of a large amount of dilution water,but also shortens the cultivation time of Chlorella,making it a more suitable pre-treatment method.Based on the pre-treatment method of high-temperature ammonia stripping and flocculation,an experiment was conducted to optimize the cultivation conditions of Chlorella vulgaris.It was found that under sufficient N and P conditions,the growth of Chlorella was not affected by N:P;The inoculation amount of Chlorella will affect the growth cycle,with low inoculation amount,slow biomass growth,and long adjustment period;The N,P,Mg²⁺,and Ca²⁺in the biogas slurry are sufficient to support the growth of Chlorella;The biodegradability of organic matter in biogas slurry is low,and with the addition of organic carbon,Chlorella can undergo mixed nutrient growth and improve growth rate.Chlorella vulgaris has a certain tolerance range for NH4+-N concentration,and appropriate supplementation can improve the biomass production of Chlorella vulgaris.A new culture method for cultivating Chlorella vulgaris was established by simulating the utilization of ammonium sulfate（NH₄）₂SO₄ produced during the high-temperature ammonia stripping process.It was found that after adding 2.5 g L^-1 glucose,the phased addition of 50 mg L^-1NH₄⁺-N significantly improved the ability of Chlorella to produce biomass from biogas slurry.And comparing the functional groups and protein content of Chlorella cultured in Tap medium,it was found that there was no significant difference in functional groups of Chlorella,with a slight decrease in protein content,indicating that this method can be used for large-scale cultivation of Chlorella.