污水污泥和消化污泥热解过程中重金属迁移转化行为对比分析

摘要

Raw sludge (RS) and anaerobic digestion sludge (DS) were conducted to obtain the bio-char.Effects of anaerobic digestion on migration and transformation of heavy metals (Cu,Zn,Cr,Cd,Pb) from sewage sludge were explored during pyrolysis process.Results showed that the contents of steady-state Cd and Cr in DS bio-char were higher than RS bio-char at the same pyrolysis temperature.There was no significant difference in the form distributions of Pb between DS bio-char and RS bio-char.However,the content of unstable state Zn in DS bio-char were higher than that in RS bio-char at the same pyrolysis temperature.Further research results showed that migration and transformation ability of Cu、Zn、Cr and Pb in both RS and DS were significantly reduced at lowtemperature pyrolysis.Furthermore,the transformation of F1 and F2 fractions into F3 and F4 fractions were improved by the pyrolysis,indicating that environmental risk level of heavy metals in sludge was reduced by low-temperature pyrolysis.%以污水厂生污泥(RS)及其厌氧消化污泥(DS)为处理对象进行低温热解研究,对比分析了厌氧消化工艺对污水污泥热解炭中重金属(Cu、Zn、Cr、Cd、Pb)形态分布与迁变规律的影响.结果表明:消化污泥热解炭中稳态Cd、Cr、Cu含量均高于同等温度下生污泥热解炭,而两种热解炭中Pb形态无明显差异,但消化污泥热解炭中稳态Zn含量却小于同等温度下生污泥热解炭;低温热解能够有效地降低生污泥和消化污泥中Cu、Zn、Cr、Pb的潜在迁移转化能力,使重金属由F1态和F2态向稳定的F3态和F4态转变,降低重金属的环境风险水平.