Study On The Treatment Of Biogas Slurry From Pig Industry By Chlorella Vulgaris And Fungi/Bacteria-algae Symbiosis System

Since the21st century, meat products are increasingly appearing in people’s lives year by year, leading to the rapid development of large-scale pig-raising industry. This can greatly shorten the growth cycle, reduce raising costs, thereby increasing the economic benefits. But the large scale will result in large fecal sewage accumulation and rinse water increasing, which will cause serious environmental pollution and endanger the ecological security. The paper tried to use the biogas slurry from four facets The four facets are Chlorella vulgaris, Chlorella vulgaris and Ganoderma lucidum symbionts, Chlorella vulgaris under different ventilation conditions and the combination of activated sludge-Chlorella vulgaris The main results were as follows:1、Domesticated Chlorella vulgaris can grow fast in biogas slurry after short-term adaptation. After10days, the main nutrient indicators in biogas slurry:COD、Suspended solids、NH4+-N、TP are dropped to162.3mg/L、52mg/L、14.66mg/Land7.57mg/L correspondingly, and the removal rates are77.61%、91%、94.76%and80.03%. The experiment results show that:C.vulgaris is practicable to process pig industry biogas slurry.2、The experiment results get a stable bacteria-algae symbionts condition Experiment shows that the best carbon source for bacteria-algae ball is maltose, the best nitrogen source for the forming of bacteria-algae ball is yeast extract, the best initial pH for the forming of bacteria-algae ball is5.0. The experiments also make further investigation on the processing of pig industry biogas slurry by bacteria-algae ball. The experiment surveys the nutrient removal rate through putting the bacteria-algae ball into biogas slurry for10days. The results show that the co-processing of bacteria-algae ball and suspension algae is very effective in biogas slurry purification. After processing, TN、TP、NH4+-N、COD of biogas slurry are dropped to48mg/L、11.57mg/L、22.86mg/L and95mg/L, and the corresponding removal rates are88.84%、79.91%、90.86%、88.9%. The removal rate of COD is slightly higher than that of the processing only by C.vulgaris, and there is a little difference in the result of TP removal rate. The total biomass concentration of bacteria-algae ball is4.5462g/L, and daily average accumulation rate is0.4309g/L. These data suggest that processing the biogas slurry with bacteria-algae symbiosis can also reach the standard of sewage treatment, which also facilitates the later harvest.3、The experiment also compares the growth of C.vulgaris and the removal of various nutrients in three different ventilation conditions in biogas slurry. The results show that C.vulgaris grows best in biogas.slurry when the aeration rate is1.5L/min, and the OD68o is2.5346at8day while that of the other groups are1.8213and1.4527, which indicates that the C.vulgaris grows best when the aeration rate is1.5L/min. The experiment gets the same conclusion by comparing the removal of COD、TN、 TP and NH4+-N. The collecting of the algae biomass after treatment shows that when the aeration rate is1.5L/min the highest biomass mass concentration is4.3751g/L. Experiments show that biogas slurry through ventilation can be more effective removal of organic matters,1.5L/min is the best ventilation for C.vulgaris growth and nutrient removal of biogas slurry.4、The experiment makes further investigation on the removal of organic nutrients in the biogas slurry by the symbiont of C.vulgaris and activated sludge. By comparison, the symbiont of C.vulgaris and activated sludge system can remove organic nutrients in a more effective way. When using the symbiont of C.vulgaris and activated sludge system, the removal rates of COD、TN、 TP and NH4+-N are94.40%、91.80%、87.63%and95.28%, the daily removal rate are73.78mg.L-1.day-1、28.48mg.L-1.day-1、4.00mg.L-1.day-1and25.33mg.L-1.day-1.The treatment effect and daily clearance rate are significantly better than that of the treating only by C.vulgaris.