Development And Evaluation Of Static Composting Systems For Disposal Of Infectious Chicken Carcasses

This thesis focuses on building processing of chicken infected with low pathogenicity avian influenza biosafety static compost, and exploring animal carcasses and pathogen degradation efficiency to evaluate the safety and feasibility of this compost system. Replicate compost piles were built using chicken manure, chicken carcasses and wooden straw for40d static composting in2009while the larger replicate modified compost piles were built using caw manure, straw and chicken carcasses in2010. We examined temperature, pH value, moisture and carbon-nitrogen ratio to evaluate both systems. The pathogen degradation process was studied using natural occurring coliforms and inoculated Staphyloccocus aureus (S.aureus) as model microorganisms in compost2009. With the modification of compost material and scale of pile, by using chicken killed after injected with avian influenza virus (H9H1) as model, we detected the degradation of RNA of avian influenza virus by RRT-PCR. The decayed chicken tissues were collected at different intervals; the mass, the total and the specific DNA were quantified by molecular method. The decayed chicken tissues were collected at different intervals; the mass, the total and the specific DNA were quantified by molecular method. For composts in2009, temperatures at40cm depth exceeded45℃after9d, peaked at53.2℃on Day35, and averaged at44.7℃over the40d. For the modified composts, temperatures at the same depth exceeded50℃right after Id and lasted for7d, peaked at57.5℃. The natural occurring colifroms were inactivated rapidly, which was undetectable after2d of composting and maintained less than1.0log10CFU/g over Day2-40. The S. aureus was reduced gradually with2.4log10CFU/g detected on Day4but undetectable on Day40. Avian influenza virus RNA reduced to1/1000compared to Day0, and Day12totally blow the detection limit. During the forty-day composting period in2009, mass of chicken tissue reduced59±4.4%, total DNA reduced93%, dropped from19.43±2.8ng/μl to1.4±0.3ng/μl. Specific DNA degraded from7.59±0.14log copies/g to5.20±0.03log copies/g, with a degradation rate over99%. The degradation rates of mass and total DNA of the2nd composting system are153%(p<0.05) and93%(p<0.01) higher than those of the1st one respectively on day4, still, are62%(p<0.05) and17%higher than those of the former.Pathogens and virus are fully inactive and chicken carcasses are decomposing rapidly in both composting system. The modified composting piles shows higher efficience of disposal of chicken carcasses.