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城市污泥中重金属含量及其生物有效性是限制污泥农用的主要因素之一,研究污泥堆肥过程中重金属形态及其生物迁移规律具有重要意义。用BCR顺序提取法浸提堆体中各种形态重金属,研究堆肥过程中不同形态重金属的变化规律以及主要影响因素。结果表明:除Zn、Cd外,城市污泥中Cu、Ni、Cr、Pb主要以可氧化态及残渣态存在,生物有效性较低;堆肥处理改变了重金属的形态分布,使污泥中的酸溶态及可还原态的重金属向更稳定的可氧化态及残渣态转变,显著降低了重金属的生物有效性;堆肥结束时Cu、Zn、Ni、Cd、Cr、Pb六种重金属残渣态含量比堆肥初始均有所增加,增幅分别达6.3%、6.7%、22.0%、15.2%、11.0%、40.5%;不同形态重金属含量与DOC含量相关性显著,而与OM相关性不强;pH主要影响可还原态及生物有效态重金属的分布,与其他形态相关性不强。
The heavy metal content in urban sludge and its bioavailability are one of the main factors that limit the agricultural use of sludge. It is of great significance to study the morphology and biotransformation of heavy metals in sludge composting process. The BCR sequential extraction method was used to extract various forms of heavy metals in the pile body to study the variation rules of heavy metals in the composting process and the main influencing factors. The results showed that in addition to Zn and Cd, Cu, Ni, Cr and Pb in urban sludge mainly existed in oxidizable and residual forms and their bioavailability was low. Composting treatment changed the distribution of heavy metals, The changes of acid soluble and reducible heavy metals to more stable oxidizable and residual states significantly reduced the bioavailability of heavy metals. At the end of composting, the contents of six heavy metal residuals (Cu, Zn, Ni, Cd, Cr and Pb) Compared with the initial composting, increased by 6.3%, 6.7%, 22.0%, 15.2%, 11.0% and 40.5% respectively. Significant correlations were found between the contents of DOC and DOC, but not with OM Affect the distribution of reducible and bioavailable heavy metals, which is not correlated with other forms.