鸟粪石负载硅藻土对土壤铅和金霉素的同步修复作用

使用镁盐改性硅藻土回收沼液中氮磷制得鸟粪石负载硅藻土 (Struvite-loaded diatomite，SD) ，将其用于土壤中铅 (Pb) 和金霉素 (CTC) 复合污染的原位修复。采用吸附-解吸实验评估SD对Pb和CTC迁移特性的影响，同时，通过测定土壤pH和酸缓冲能力、土壤Pb和CTC的有效态和形态、土壤速效磷和微生物群落结构变化等考察SD对土壤Pb和CTC的钝化能力，借助SEM、XRD、FT-IR等表征手段揭示其修复机理。结果表明，SD能有效降低Pb和CTC在土壤中的迁移特性；SD投加质量分数为3%，稳定49 d后，土壤酸中和能力提升1倍以上，土壤有效态Pb和CTC含量分别降低26%和56%，酸溶态Pb占比降低10%，残渣态Pb占比升高18%， CTC的水溶态和松散结合态占比分别降低5%和13%，紧密结合态CTC升高11%，一定程度上降低了Pb和CTC在土壤中的生物有效性；SD的投加可提升土壤速效磷含量，提高土壤微生物的相对丰度和多样性，尤其增加酸杆菌门 (Acidobacteria) 、绿弯菌门 (Chloroflexi) 和芽单胞菌门 (Gemmatimonadetes) 的相对丰度，降低放线菌门 (Actinobacteria) 和厚壁菌门 (Firmicutes) 的相对丰度；SD对土壤Pb和CTC的钝化机制主要为吸附和沉淀的协同作用。该研究可为污水氮磷资源化利用和重金属抗生素复合污染土壤原位修复提供参考。

Simultaneous remediation of lead and chlortetracycline in contaminated soil by addition of struvite-loaded diatomite

Struvite-loaded diatomite (SD), a product of nutrient recovery process from biogas slurry, has been applied as a soil amendment for soil multi-polluted with Pb and chlortetracycline (CTC). In this study, the effect of SD on the mobility characteristics of Pb and CTC in soil were evaluated by adsorption-desorption experiments. The passivation ability of SD on Pb and CTC were investigated through measuring soil pH, soil acid neutralization capacity, the bioavailable states and different binding states to soil of Pb and CTC, the bioavailable phosphorus and microbial community structure and so on. Also, the properties of the adsorbents were characterized by SEM, XRD, and FT-IR to reveal the the potential mechanisms during this process as well. The results showed that the immobilization ability of SD for Pb and CTC was much higher than that of soil, which can effectively reduce the migration properties of these two pollutants. Compared with the control group, the acid neutralization capacity of soil can be doubled by adding 3 wt% SD after stabilizing for 49 d. Meanwhile, the content of bioavailable Pb and CTC in soil was decreased by 26% and 56%, respectively. Specifically, the proportion of Pb in acid-soluble state has been cut down by 10%, and there was a 18% growth of Pb in residual state. The proportions of water-soluble state and loosely bound state of CTC reduced by 5% and 13%, and the proportion of its tightly bound state raised by 11%. Moreover, the usage of SD increased the content of bioavailable phosphorus and promoted the relative abundance and diversity of soil microorganisms, especially increasing the relative abundance of Acidobacteria, Chloroflexi and Gemmatimonadetes, accompanied by decreasing the relative abundance of Actinobacteria and Firmicutes. The passivation mechanisms of the SD to Pb and CTC were mainly adsorption and precipitation. The results of this study provide a useful guideline for the resource utilization of nitrogen and phosphorus in sewage and in-situ remediation of soil contaminated by heavy metals and antibiotics.