Study on Intermittent Aerobic and Earthworm Assisted Two-stage Composting Treatment of Pig Manure

In order to realize the efficient resource utilization of pig manure, a two-stage composting process comprised of intermittent aerobic and earthworm assisted composting was proposed and applied to the composting treatment of pig manure, garden leaves and sawdust mixture (5∶1∶0.2, mass ratio). The change rules of pH, TOC, TN and TP of the compost materials in the process of natural composting and earthworm-assisted composting were compared by analyzing the temperature changes of the compost in the process of intermittent aerobic composting. The experimental results showed that the composting temperature entered the high-temperature stage (> 50℃) from the 3 rd day to the 12 th day, with the highest temperature of 55℃. At the end of composting, the pH values of the compost materials in the natural composting and earthworm assisted composting were 6.75 and 6.77, respectively. The total organic carbon content decreased to 25.4% and 21.08%, respectively; The TN content decreased to 1.84% and 1.58%, respectively; The TP content increased to 9.88% and 10.13%, respectively. At the end of composting, the maximum increase in the weight of earthworms before and after breeding was 0.22 g, and the minimum increase was 0.13 g. This indicated that the two-stage composting process comprised of intermittent aerobic composting and earthworm assisted natural composting could not only improve the stability of pig manure but also cultivate the earthworms, thereby improving the economic efficiency of the composting process.