Decontamination Of Fermented Biogas Liquid In Piggery Coupling With Lipid Production Based On Chlorella Cultivation

With the rapid development of livestock and poultry raising industry scale,the scale of livestock and poultry breeding makes the anaerobic fermentation biogas liquid discharge very large,and a large amount of anaerobic fermentation waste liquid is produced,which brings great pressure to the surrounding environment.It is imminent to explore a kind of effective,simple and economic benefits of biogas liquid depth treatment technology.Using microalgae to treat pig biogas slurry,compared with traditional treatment methods,not only can clean biogas slurry,but also can get rich biomass resources.In this study,the anaerobic fermentation of pig farm was used to domesticate microalgae,which could not only purify the fermented marmos,but also accumulate oil and oil in microalgae cells.The results of the research are as follows:Cultivation of Chlorella of freshwater,Chlorella vulgaris and Chlorella pyrenoidosa by biogas slurry from pig farms.The growth and lipid accumulation characteristics of three Chlorella species in fermented biogas slurry were studied,and the purification effect of three Chlorella species on anaerobic fermentation was studied.The results showed that Chlorella of freshwater,Chlorella vulgaris and Chlorella pyrenoidosa can all use nutrients in anaerobic fermentation biogas slurry to grow.The removal rates of total nitrogen in anaerobic fermentation biogas slurry were 48%,61% and 73%,respectively.The removal rates of total phosphorus were 71%,93% and 89%,respectively.The removal efficiencies of COD from anaerobic fermentation biogas slurry by Chlorella of freshwater,Chlorella vulgaris and Chlorella pyrenoidosa were 75%,79% and 85%,respectively,and biomass dry weight were 2.27 g/L and 2.5 g/L and 2.8 g/L.The Lipid productivities and contents of Chlorella pyrenoidosa were the highest in the three Chlorella species,which were 28% and 51 mg/L/d,respectively.The main components of Chlamydomonas cholesta were C16:0 and C18:3,and Saturated fatty acids account for about 68.6% of the total.All the three Chlorella could use the nitrogen,phosphorus and organic carbon sources in biogas slurry to promote the continuous accumulation of biomass,neutral lipids and oils,but Chlorella pyrenoidosa had higher removal rate of pollutants in fermentation biogas slurry and can use more carbon sources to accumulate more and better quality oils.Culture of Chlorella pyrenoidosa using fermentation biogas slurry of different initial COD concentration.To study the growth and lipid accumulation characteristics of Chlorella pyrenoidosa in different concentrations of biogas slurry and its purification effect on biogas slurry,analysing the fatty acid composition contained in Chlorella pyrenoidosa.The results showed that Chlorella pyrenoidosa grew best in the biogas slurry with initial COD concentration of 250 mg/L.After 18 days of culture,the biomass reached 2.75 g/L.Chlorella pyrenoidosa was cultured in biogas slurry with initial COD concentrations of 50 mg/L,250 mg/L,and 450 mg/L,respectively.The total nitrogen removal efficiency was 92%,94%,and 71%,respectively.The removal rates of total phosphorus were 100%,91%,and 92%,respectively.The COD removal efficiency was 74%,77%,and 64%,respectively.In the anaerobic fermentation biogas slurry with initial COD concentrations of 50 mg/L,250 mg/L,and 450 mg/L,the oil content of Chlorella pyrenoidosa was 16%,29% and 22%.Under the appropriate COD culture conditions,Chlorella pyrenoidosa can use the residual nutrients of anaerobic fermentation biogas slurry to accumulate more oil.Different concentrations of anaerobic fermentation anaerobic fermentation biogas slurry cultured Chlorella pyrenoidosa contain different proportions of fatty acids.The ratio of total saturated fatty acids and unsaturated fatty acids in the anaerobic fermentation biogas slurry of the optimal initial COD(250 mg/L)was 42.6:57.4.The purification effects of Chlorella pyrenoidosa on the fermentation biogas slurry under different inoculation densities(0.11,0.54,1.2 g/L)were studied.The maximum dry weight of algal cell biomass obtained from the biogas slurry with a density of 0.54 g/L was 3.53 g/L.The initial inoculum density of 0.11,0.54,and 1.2 g/L Chlorella pyrenoidosa had little effect on the removal of total nitrogen after being cultured in the biogas slurry for 18 days.The removal rates were 69%,74% and 71%.The greater the initial inoculation density of Chlorella pyrenoidosa,the greater the removal rate of total phosphorus in the fermentation biogas slurry,and the removal rates were 80%,87% and 90%,respectively.The removal efficiency of COD in the biogas slurry with a density of 0.54 g/L was highest at 79%.The initial inoculum density of Chlorella pyrenoidosa was 0.54 g/L,and the growth of algal cells and the removal of contaminants were all better.The purification effect of Chlorella pyrenoidosa in the fermentation biogas slurry under different aeration rates(0.1,0.5,1 L/min)was studied.The results showed that the growth of Chlorella pyrenoidosa in the biogas slurry group with 0.5 L/min aeration volume for 18 days was the best.The maximum biomass dry weight of the obtained algal cells was 3.3 g/L.The removal efficiency of contaminants in fermented biogas slurry was best when the amount of aeration 0.5 L/min was in the biogas slurry group.After 18 days of culture,the removal rate of total nitrogen in biogas slurry was 90%.The total phosphorus removal rate was 96%,and the COD removal efficiency was 91%.When the amount of aeration was 0.5 L/min during the cultivation of Chlorella pyrenoidosa,the growth of algal cells and the removal of contaminants were all better.