Abstract:

Sludge and its stabilized products are rich in functional organic matter, which can directly participate in the complexation process of heavy metals. By defining the binding properties of its products and heavy metals, hyper-thermophilic composting (HTC), a more advantageous sludge stabilization technique, might better assess the value of its land use. Adsorption experiments were used to investigate the binding capacities of Pb²⁺ to humic acids (HAs) derived from raw sludge (RS), thermophilic composting (TC) and HTC. The findings demonstrated that with composting time, the maximum adsorption values (q_m) of HAs derived from HTC and TC to Pb²⁺ steadily increased. During composting, the HTC-derived HAs content also increased significantly in comparison to TC-derived HAs, peaking on the 21st day. The adsorption capacity (on a dry basis) of HTC-derived HAs to Pb²⁺ (21d, 29.6mg/g) was 70.7% higher than HTC-derived HAs (21d, 17.3mg/g), indicating that HTC products had more benefits in the remediation of soil heavy metal contamination. The ¹³C NMR data showed that the phenolic and aromatic carbons of HTC-derived HAs increased more during composting, and the aromatic carbons of HTC-derived HAs grew more rapidly than TC in the early stage of composting (0—21d). Infrared spectroscopy, two-dimensional correlation spectroscopy and moving window analysis all indicated that the polysaccharides in HTC-derived HAs would initially combine with Pb²⁺. For the binding of Pb²⁺ to HTC-derived HAs, phenolic hydroxyl and aromatic groups were more important among them. Based on the previous insights, it was evident that HTC’s higher degree of humification and the rise in phenolic hydroxyl and aromatic groups were the main contributors to its stronger ability to bind, and HTC was helpful for the land use of sludge.

Key words: hyper-thermophilic compost, humic acids, lead, binding mechanism, land use

摘要：

污泥稳定化产物中含有丰富的功能有机物，能够直接参与重金属的络合过程。超高温堆肥作为一种更有优势的污泥稳定化手段，明晰其产物中的典型功能有机质与重金属结合特性，对于评估其土地利用的价值至关重要。本文采用吸附实验对比分析了超高温堆肥（HTC）、高温堆肥（TC）和生污泥（RS）样品中典型功能有机物胡敏酸（HAs）与Pb²⁺的吸附效果。结果表明，HTC和TC中HAs对Pb²⁺的理论最大吸附量（q_{\mathrm{m}}）会随着堆肥进行而逐渐增大。在堆肥过程中HTC的HAs含量相对TC也有明显增加，第21天即达到最高值。HTC堆肥（21天）衍生HAs对Pb²⁺的吸附量（29.6mg/g）比TC（17.3mg/g）高70.7%，这表明HTC产物在土壤重金属污染修复方面更具优势。¹³C NMR结果表明，在堆肥过程中HTC衍生HAs的酚基碳与芳香碳增加更多，堆肥前期（0~21天）HTC衍生HAs的芳香碳增加比TC更快速。进一步采用红外光谱，结合二维相关光谱和移动窗口技术解析，表明HTC堆肥衍生HAs的多糖类物质会最先与Pb²⁺进行结合。其中，HTC堆肥衍生HAs与Pb²⁺结合最重要的官能团是酚羟基和芳香族基团。基于上述认识，可知HTC的高腐殖化特性使酚羟基和芳香族基团等基团增加是HTC具有更强结合Pb²⁺能力的关键，HTC有利于污泥的高效土地利用。

关键词: 超高温堆肥, 胡敏酸, 铅, 结合机制, 土地利用