Treatment and reuse of piggery wastewater by composting process of straw

Composting of piggery wastewater treated with three straws of corn, rice and wheat as carrier was investigated to probe the feasibility of treatment and reuse of piggery wastewater by composting process. Experiment result showed that 1 kg straw can absorb and utilize the amount of piggery wastewater ranging from 5.94 kg to 6.65 kg, and it also demonstrated that piggery wastewater can be effectively treated and reused by composting process with straw as carrier. As far as the composting temperature and duration above 50℃ or 55℃, the composts absorbing piggery wastewater were higher than those absorbing abaerobic effluent of piggery wastewater, and the composts with corn straw and rice straw as carrier were superior to those with wheat straw. The composts with corn straw and rice straw as carrier went through an acidification process with pH value down at first, then pH value up above 8.0, while composts with wheat straw as carrier almost were in acidification process. Nitrogen, phosphorus and kalium were found to increase constantly in the composting process. The kalium content of the compost with rice straw as carrier was obviously higher than that of the others. The contents of nitrogen, phosphorus and kalium for the composts with straw absorbing piggery wastewater were higher than those with straw absorbing abaerobic effluent. The composts of corn straw + piggery wastewater and rice straw+ piggery wastewater were more propitious to formation of humus, especially humic acid than composts with abaerobic effluent or wheat straw. The test results demonstrated that it was feasible to make use of composting process to treat and reuse piggery wastewater.