Chromium (Cr) is a major heavy metal pollutant that has been found in many groundwater-polluted sites. The effectiveness of hexavalent chromium [Cr(VI)] plume containment and remediation via the bioreduction and adsorption mechanisms were evaluated in this study using the developed green slow-releasing denaturing-colloidal substrates (G-SDS). The major components of G-SDS were gelatin, agar, and cane molasses (optional), and weight ratios for gelatin and agar were 3 and 0.5%, respectively. Gelatin was used for slow carbon release and Cr(VI) adsorption, cane molasses was applied for rapid carbon release, and agar was used as the solidifying agent to form G-SDS. Environmental scanning electron microscope analyses indicate that the G-SDS had a rigid and stable 3-D structure with irregular and rippled surface and staged sheets, which created significant surface areas for Cr(VI) adsorption. Results from the column study show that more than 98% of Cr(VI) was removed with increased Cr(III) concentrations in column effluents. The G-SDS could form a permeable and reticulated fiber biobarrier after its injection for Cr(VI) adsorption. The released carbon substrate from G-SDS could subsequently enhance Cr(VI) bioreduction mechanisms. The released amine from gelatin could react with water and produce ammonia, which could neutralize the acidified water due to the produced organic acids from G-SDS fermentation. The microbial communities in column soils were characterized by the next-generation sequencing technology. G-SDS supplement caused the variations in microbial diversities and predominant bacteria. The released carbon from G-SDS resulted in the formation of anaerobic conditions, and thus, the growth of the Cr(VI) reducer was enhanced. G-SDS could serve as a source of primary substrate for Cr(VI) bioreduction. The dominant groups of bacterial communities include Acinetobacter, Bacillus sp., Clostridium, Desulfovibrio, and Geobacter. Both G-SDS and column soils contained significant amounts of Cr(III) after the column experiment indicating that the adsorbed Cr(VI) within G-SDS was bioreduced to Cr(III). Moreover, Cr(OH)₃ was formed and precipitated in soils after Cr(VI) bioreduction. Results indicate that the passive biobarrier system containing G-SDS can be used as an economically and practically acceptable remedial system to contain the Cr(VI) plume and reduce the environmental risks caused by Cr(VI).

铬 (Cr) 是一种主要的重金属污染物，已在许多地下水污染场地中发现。本研究使用开发的绿色缓释变性胶体底物 (G-SDS) 评估了通过生物还原和吸附机制抑制和修复六价铬 [Cr(VI)] 羽流的有效性。G-SDS 的主要成分是明胶、琼脂和甘蔗糖蜜（可选），明胶和琼脂的重量比分别为 3% 和 0.5%。明胶用于缓慢碳释放和Cr(VI)吸附，甘蔗糖蜜用于快速碳释放，琼脂作为固化剂形成G-SDS。环境扫描电子显微镜分析表明，G-SDS 具有刚性和稳定的 3-D 结构，具有不规则和波纹表面和阶梯状的片层，这为 Cr(VI) 吸附创造了显着的表面积。色谱柱研究结果表明，随着色谱柱流出物中 Cr(III) 浓度的增加，超过 98% 的 Cr(VI) 被去除。G-SDS注入后可形成可渗透的网状纤维生物屏障以吸附Cr(VI)。G-SDS 释放的碳底物随后可以增强 Cr(VI) 的生物还原机制。明胶释放的胺能与水反应生成氨，氨能中和由于G-SDS发酵产生的有机酸而被酸化的水。微生物群落通过下一代测序技术对柱状土壤进行了表征。G-SDS 补充剂引起微生物多样性和优势细菌的变化。G-SDS 释放的碳导致厌氧条件的形成，从而促进了 Cr(VI) 还原剂的生长。G-SDS 可作为 Cr(VI) 生物还原的主要底物来源。细菌群落的主要群体包括不动杆菌属、芽孢杆菌属、梭菌属、脱硫弧菌属和地杆菌。在柱实验后，G-SDS 和柱状土壤都含有大量的 Cr(III)，这表明 G-SDS 中吸附的 Cr(VI) 被生物还原为 Cr(III)。此外，Cr(OH)₃在 Cr(VI) 生物还原后在土壤中形成并沉淀。结果表明，含有 G-SDS 的被动生物屏障系统可以作为一种经济实用的补救系统来遏制 Cr(VI) 羽流并降低 Cr(VI) 造成的环境风险。