城市污泥强制通风堆肥过程中的生物学和化学变化特征

采用间竭式强制通风堆肥法进行的肥堆体积约4m3,堆肥时间为53d的污泥堆肥试验表明,堆肥的第2天即达高温阶段(≥55℃)并能保持8d,平均最高温度达68℃,局部温度达74℃.粪大肠杆菌由开始时的1.41×105个·g-1降至试验结束时的2.32×101个·g-1.污泥堆肥过程中挥发性固体,总有机C、水溶性有机C、固体有机 C/N比和水溶性有机 C/有机 N比下降明显,而 N、P及重金属含量有所升高.随着堆肥的进程,在前1周堆肥过程中产生的氨氮大幅下降,硝酸盐含量随之升高.相应地,pH在第1周内升高,随后降低.堆肥40d左右,水芹(Lepidiumsativum L.)种子发芽指数即可达 80%.综合堆肥过程中堆温和化学与生物学变化特点,表明污泥堆肥在40d左右基本上接近腐熟,50d后达到完全腐熟.产品外观呈黑褐色,蓬松,无明显异味.

Changes of chemical and biological properties during compost ing sewage sludge by using forced aerated static pilemodel

Municipal sewage sludge was composted for 53 days with Chinese medical herb residues as bulking agent through forced aerated static pile model. The temperature of the pile could quickly rise to more than 55 degrees C after the second day after composting. Furthermore, the temperature of more than 55 degrees C maintained as long as 8 days, which was helpful in inactivation of pathogens in compost. The cress seed germination index (GI) and the ratio of water-soluble organic carbon to organic nitrogen (soluble C/N-organic), used as indicators of phytotoxicity and maturation of compost, exhibited that the sludge compost was almost stabilized and matured near the 40th day of composting, when 80% of GI and 6.4 of soluble C/N-organic were obtained. The content of total N, P, Cu, Zn and Cd in compost increased as the composting time elapsed, while volatile solids, solid and water soluble organic carbons, pH, and NH4(+)-N decreased. F. coli, as a common indicator of pathogens in sludge, was reduced greatly from 1.41 x 10(5) to 2.32 x 10(1) in the final examination of the compost.