Effect of Different Bulking Agents on Aerobic Composting of Swine Feces

Aerated static composting is one of the best choices to treat animal waste.Effect of different bulking agents on aerobic composting of swine feces was studied in a plastic greenhouse.Three kinds of organic composts were manufactured from pig feces with sawdust,rice hull and rice germ respectively.The change of temperature,pH,water content,the content of main nutrient element N and O_2 consumption were measured.The results showed that the highest temperature of the compost namely pig feces + rice germ was only 38℃,indicating that the rice germ was not fit for composting bulking agent;while,the temperature of the other two types of compost namely feces + sawdust and feces + rice hull were relatively high,the former being lower than the latter.Under environment temperature,the time of temperature decreasing in the compost feces + sawdust was much longer and the time maintaining above 55℃ was shorter than that of feces + rice hull compost.Since sawdust had good humidity absorption,the water loss of feces+sawdust was bigger.The changes of organic matter and TN in both composts were similar,but the feces+sawdust compost had more organic matter because the sawdust contained plenty of lignin that decomposed difficultly and increased more TN than the feces+rice hull compost at last,indicating that compost with rice hull was not good for conserving nutrient element N.TN and TP both increased,which suggested the promotion of composting maturity and quality.On the 9th day of composting,O_2 consumption reached maximum in both composts,being 0.87 mgO_2·L~(-1)·min~(-1) and 0.77 mgO_2·L~(-1)·min~(-1),respectively,much lower than that in summer composting,and feces+sawdust compost was higher than that of feces+rice hull compost.