吴启堂教授团队：一种不用担心重金属污染的污泥农用技术
华南农业大学资源环境学院吴启堂教授团队使用独特的间接利用方式农用市政污泥，经过9年的追踪实验表明，通过该技术利用污泥养分，能够大幅度减少污泥重金属的污染。相关成果以“Indirect application of sludge for recycling in agriculture to minimize heavy metal contamination of soil”为题发表在资源环境领域的权威期刊Resources, Conservation and Recycling（IF=8.086）。
市政污泥（MSS）农业利用的主要限制因素是其含有过量的重金属。市政污泥中的重金属容易在土壤中积聚，除了被农作物吸收，也可以进入地表水和地下水，所以将市政污泥进行农业利用一直存在争议。在这项研究中，采用了间接利用方式，并且经过9年的追踪试验，验证了该技术的安全性与可靠性。该技术使用透水网袋装填污泥，堆放在在香蕉、木瓜和玉米等作物旁边，通过降雨或者浇水将污泥中的养分淋出，间接为作物供肥，而污泥网袋处理（SSN）将污泥固体以及绝大部分重金属留在网袋内。试验另外设置化肥对照（MF）和污泥直接施用处理（SS）进行对比，连续监测了土壤、农作物和污泥残渣中的Cd、Pb、Cu、Zn变化情况。污泥网袋施肥9年后，土壤中四种重金属含量均未超过土壤标准（GB15618-2018）规定的筛选值，而直接施用处理土壤中的Cd和Cu则分别在第3年和第4年超过了该标准。SSN处理的农作物的产量和重金属含量与化肥对照无显著差异，并且农作物果实中的重金属含量均达到了相应的食品标准（GB 2762-2017）。通过SSN处理，超过90%的重金属保留在干化的污泥中，而且主要以残渣态存在，回收后作后续处置。综上所述，使用间接利用的方式农用污泥可安全为作物提供养分，解决了市政污泥农用会造成土壤重金属污染的问题。
Indirect application of sewage sludge using net bags (SSN) investigated.
9-year field experiments showed that SSN protects soil from heavy metal pollution.
Heavy metal contents in crops within food standard limits when SSN treatment used.
Yields of crops using SSN and chemical fertilizers were not significantly different.
Net bags retained most of the heavy metals, prolonging the safe application period.
In this study, an indirect application method was developed for safe recycling of nutrients from municipal sewage sludge (MSS) for use in agriculture. Permeable net bags were filled with MSS to prepare sewage-sludge net bags (SSN). The SSN were stacked next to banana, papaya, and corn crops. Cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) levels in the soil, crops, and MSS were monitored. After application of the SSN for 9 years, the levels of the four heavy metals did not exceed soil standard limits. By comparison, direct application of MSS resulted in soil Cd and Cu levels that exceeded China's soil standards in the 3rd and 4th years. The crop yields obtained with the SSN were not significantly different to those obtained using mineral fertilizer, and the heavy metal concentrations in the crops met the required food standards. With the SSN, more than 94% of the heavy metals were retained in the MSS, and these were mainly present in the residual fraction. In conclusion, indirect application of MSS could considerably reduce heavy metal pollution of soil and safely supply nutrients for crops.
论文链接：
https://www.sciencedirect.com/science/article/pii/S092134492030673X