Four sewage sludge (SS) feedstocks with distinct properties were converted into biochars by pyrolysis at 300–700 °C, in order to clarify the effects of the composition difference of SS feedstocks. The yields of biochars present a positive correlation with the contents of ash in SS. Notedly, the contents of organic matter (OM) in SS largely determine the quality of biochars. SS feedstocks with high content of OM are more likely to form stable biochars with higher aromaticity/carbonization degree, and the formed biochars possess higher calorific values. The contents of residual OM in biochars derived from SS feedstocks with low content of OM likely fail to meet the needs of soil improvement (10 wt.%). Most of heavy metals (HMs) existing in raw SS are remained in biochars after pyrolysis. The biochar produced from SS feedstocks with high content of HMs usually contains higher contents of HMs. Surprisingly, the leachability of HMs in biochars is all weakened to some extent compared to raw SS. In addition, the biochars show higher thermal stability and pH values, and P/K nutrients are enriched in biochars. The biochars prepared from four SS feedstocks exhibit different adsorption ability of methylene blue, especially at low dosage of biochar.

为了阐明SS原料组成差异的影响，将四种具有不同特性的污水污泥（SS）原料通过在300–700°C下的热解转化为生物炭。生物炭的产量与SS中的灰分含量呈正相关。值得注意的是，SS中有机物（OM）的含量在很大程度上决定了生物炭的质量。具有较高OM含量的SS原料更可能形成具有较高芳族度/碳化度的稳定生物炭，并且所形成的生物炭具有较高的热值。来自OM含量低的SS原料的生物炭中的残余OM含量可能无法满足土壤改良的需求（10重量％）。原始SS中存在的大多数重金属（HMs）在热解后仍保留在生物炭中。由具有高含量HM的SS原料生产的生物炭通常包含较高含量的HM。令人惊讶的是，与生SS相比，HMs在生物炭中的浸出性都在一定程度上减弱了。另外，生物炭显示出更高的热稳定性和pH值，并且P / K营养物富含生物炭。由四种SS原料制得的生物炭表现出不同的亚甲基蓝吸附能力，尤其是在低生物炭剂量下。