中国大中型城市的城市污泥热值分析

Investigation on Calorific Value of Sewage Sludges in Large and Middle Cities of China

对我国大中型城市的37座污水处理厂的脱水污泥进行取样调查,结果表明,污泥干基热值范围为5844～19303kJ/kg,均值为11850kJ/kg,比欧美等发达国家的低22.4%～37.7%,比畜禽粪便、秸秆和锯末等常见可燃废弃物的低17.8%～34.2%。污泥的有机质含量越高,其干基热值也越高,两者呈显著正相关。对于含水率为80%的脱水污泥,若使其焚烧所放热量与脱水能耗达到平衡,要求其干基热值≥14680kJ/kg。从能量平衡角度考虑,若采用焚烧方式处理脱水污泥,目前我国80%以上的城市污泥都存在能量亏损问题。

Dewatered sewage sludge samples were collected from 37 sewage treatment plants in large and middle cities of China, and their calorific values were investigated. The results show that they are in the range of 5 844 to 19 303 kJ/kg and the average is 11 850 kJ/kg, which is 22.4% to 37.7% lower than that in developed countries and 17.8% to 34.2% lower than those of livestock manure, straw, saw dust and other common combustible wastes. There is a significant positive correlation between the organic matter content and calorific value of sewage sludge： a higher calorific value on dry weight is consistent with a higher organic matter content. However, for sludge with a high water content of 80%, the energy acquired from incineration can not compensate for the evaporation energy consumption until the calorific value on dry weight basis is more than or equal to 14 680 kJ/kg. In view of energy balance, the energy deficit problems exist in more than 80% sewage sludges in China if treating dewatered sludge by incineration method.