Study On Biodegradating Technology For Aerobic Composting Of Pig Carcass

Aerobic fermentation composting is an important way of harmless disposal of animal carcasses.This method is simple,practical,economical and environmental friendly,but it also have some disadvatages,for example,long time for fermentation and low qulity.In order to improve the quality of compost products,shorten the composting time,we should screen the highly effective microorganisms and make into a compound microbial inoculum to investigate the effects of microbial inoculum on porcine carcass composting system.The main results as follows:(1)Isolated 24 strains of bacteria,9 strains of fungi and 2 strains of actinomycetes had been from the samples.(2)Four strains bacterium with higher lipase activity,protease activity and amylase activity had been screened.They had been identified as Bacillus licheniformis,Bacillus subtilis,Bacillus methylotrophicus and Bacillus amyloliquefaciens by physiological and biochemical and 16 S r DNA.(3)The effect of different strains on the microbial proliferation in mixed fermented broth were studied by orthogonal experiment of L9(34).The results showed that the addition of Bacillus licheniformis was the most important factor.The best combination was 0.75% for Bacillus licheniformis,0.5% for Bacillus methylotrophicus,0.25% for Bacillus amyloliquefaciens,0.75% for Bacillus subtilis.Its effective bacteria number was 6.89 × 109 cfu / m L,which was required for the subsequent composting experiment.(4)The maximum temperature of aerobic composting of porcine carcasses with compound microbial inoculum was 58?,above 50? lasted 15 days.But the maximum temperature of the control group was 52?,above 50? lasted 10 days.The changed of water content of the microbial inoculum group was the same as that of the control group,which decreased from 55% to 33%.The total nitrogen content of the microbial inoculum group and the control group were 1.9% and 2.7%,respectively.The germination index of the microbial inoculum group reached 97.3% at the end of composting,which was only 40.5% of the control group at the end of composting.(5)The structure and dynamic changed of microbial community in pig carcass composting system had been analyzed by 16 S rRNA high throughput sequencing technology.In the first month of the microbial inoculum group,the index of chao1 and Shannon were 1059 and 7.06,which was 682 and 5.96 of the control group.The results showed that the microbial inoculum group could increase the abundance and diversity index of composting microorganisms.The diversity of bacteria in the two groups of dead pig compost were similar.The main dominant flora were Proteobacteria,Firmicutes and Actinobacteria,but at different times their composition was different.(6)The CCA results showed that the temperature(p=0.002),pH(p=0.004),humidity(p=0.020),total nitrogen(p=0.064)were the most important factors in the composting environment parameters and bacterial community.The temperature were positively correlated with S1,Paenibacillus.GI were positively correlated with S6,Pseudomonas Total nitrogen were closely correlated with D6,Alcanivorax.Adding Paenibacillus,Pseudomonas,and Alcanivorax in porcine carcass compost,may improve the temperature,accelerate the degradation of organic matter,increase the nitrogen content and improve the maturity rate.