Characterization of odor emissions and microbial community structure during degradation of pig carcasses using the soil burial-composting method.

A soil burial-composting method was proposed as a hybrid disposal method for infected carcasses. This is a modified soil burial technique that involves covering carcasses with compost to achieve a final compost bed of 1.0-1.2 m during the soil burial process. To evaluate the feasibility and applicability of the soil burial-composting method, a pilot-scale system was constructed to dispose of pig carcasses and monitored its performance for 346 days. Temperature around the pig carcasses in the compost bed increased gradually, and was in the range of 35-45 °C after 200 days. Mesophilic (Sporosarcina and Steroidobacter) and thermophilic (Truepera) bacteria were dominant in the compost bed. Based on odor gas profiling and the morphological properties of the carcasses excavated after 346 days, it was estimated that an advanced decay stage was reached after 243 days. Considering the results of previous studies, the carcass degradation rate achieved by soil burial-composting was faster than that of soil burial, but slower than that of the composting method. Sum of odor quotient (SOQ) in the upper soil bed was lower than the SOQ in the compost bed where the carcasses were buried. This result demonstrated that the upper soil bed functioned as a biofilter to mitigate odor gases emitted during degradation of the carcasses. The soil burial-composting disposal method is preferred over soil burial because the degradation of carcasses is faster, and over composting because odor complaints and compost usage can be minimized.