Effect of Microbial Agents on Composting of Sludge Collected in Fuqing

Addition of microbial agents to the sludge collected in the city of Fuqing for composting was investigated. Changes on the surface and center temperatures, contents of moisture, humus acid, organic matters, total nitrogen, total phosphorus and total potassium, as well as the seed germination rate index (GI) of the compost during the fermentation process were monitored as the sewage sludge was mixed with plant ash, chicken manure, Bacillus subtilis (Agent A, Treatment T1) and/or BFA humus acid (Agents B, Treatment T2). The results showed that (a) T1 and T2 rendered the compost to reach a higher maximin temperature faster and maintain it longer than CK did; (b) the moisture content in compost decreased as the fermentation progressed, with the greatest reduction by T2 at 22.9%, followed by T1 at 19.6% and CK at 16.9%; (c) after 40 d composting, the humus acids, organic matters, total nitrogen and total potassium contents in the composts were higher with T1 or T2 than CK; and (d) the 40 d fermentation resulted in GIs by all treatments greater than 50%, and that of T2 beyond 80% achievinga maximal degree of composting effect.