Simple Organic Carbon Sources and High Diversity Inocula Enhance Microbial Bioneutralization of Alkaline Bauxite Residues

Bioneutralization of pH by microbial fermentation of added carbon substrates is a promising new method for remediation of the 1.7 GT/yr of alkaline mining tailings produced globally. Here, we present the first study to systematically compare and optimize the efficacy of microbial inocula of varying diversities, structures, and provenance and organic carbon substrates of varying complexities on the rate and extent of pH bioneutralization in alkaline bauxite residue tailings. Laboratory-scale bioreactors inoculated with soda lake sediments or with monosaccharide substrates added had a significantly lower minimum pH (0.02 μmol H+ day–1) and achieved these in significantly less time (Euryarchaeota and Bacteroidetes, rather than Acidobacteria and Actinobacteria), supporting higher acetate and formate-yielding fermentation pathways compared to other inocula. The strong performance of monosaccharides is attributed to widespread microbial capacity for efficient fermentation. Using either monosaccharide carbon substrates or soda lake sediments is recommended to maximize bioneutralization efficiency at the industrial scale.

通过添加碳底物的微生物发酵实现pH生物中和（bioneutralization），是治理全球每年产生的17亿吨碱性矿山尾矿的极具前景的新兴技术路径。本研究首次针对碱性铝土矿尾矿的pH生物中和速率与中和程度，系统对比并优化了不同多样性、群落结构及来源的微生物接种剂（microbial inocula），以及不同复杂程度的有机碳底物（organic carbon substrates）的应用效能。结果显示，接种苏打湖沉积物（soda lake sediments）或添加单糖底物（monosaccharide substrates）的实验室规模生物反应器，可达到显著更低的最终pH，其氢离子消耗速率达0.02 μmol H+·d⁻¹，且所需时间显著更短；该反应器的核心功能菌群为广古菌门（Euryarchaeota）与拟杆菌门（Bacteroidetes），而非酸杆菌门（Acidobacteria）和放线菌门（Actinobacteria），这对应了相较于其他接种剂更高效的乙酸（acetate）与甲酸（formate）生成型发酵通路。单糖底物与苏打湖沉积物展现出优异性能的原因，在于微生物普遍拥有高效发酵的代谢潜能。建议在工业规模化应用中选用单糖碳底物或苏打湖沉积物，以最大化pH生物中和的整体效率。