Impacts on N and P conservation during swine manure composting with different modified metal-salts addition
不同改性金属盐对猪粪堆肥过程氮磷保存的影响

Batch experiments were carried out by using mixed-level uniform design method U6(62×3) to investigate the effect of the addition of different metal-salts at 20%, 40% and 60% of NTN respectively, including modified red-mud (MR) at pH 5.0±0.2 and 7.0±0.2, respectively, modified forsterite (MF) at pH 7.0±0.2, and MgSO4 on nitrogen and phosphorus conservation during swine manure composting. The results showed that the optimum effect of N saved occurred at No.5 experiment (20%, MF, day 17) and No.3 experiment (40%, MgSO4, day 10). Meanwhile, the P conservation of experiments with metal salts addition was better than that of the control, and the No.6 experiment (20%, MR with pH=5, day 21) was the highest on TP conservation, with the lowest ratio of PO3-4-P/TP.