Abstract Large-scale discharge of bauxite residue, an alkaline, saline and nutrient-deficient waste material produced in the process of alumina production, has created extreme environments that are challenging to restore. Microbial pathways have been found to play a critical role in the rehabilitation of these residues. In this study, Penicillium oxalicum, an alkali-resistant acid-producing fungus screened from bauxite residue disposal sites, was used to examine its effectiveness for restoration of bauxite residue. By comparing different biomass pretreatment methods, steam explosion pretreatment biomass was added to the medium to enhance microbial metabolism. Following the optimal biomass pretreatment, the contents of organic acids secreted by P. oxalicum were oxalic acid 0.12 mg/mL, formic acid 0.31 mg/mL and acetic acid 0.51 mg/mL, respectively. Addition of pretreatment biomass and microbes significantly lowered bauxite residue pH from 10.9 to 7.2, whilst increasing the electrical conductivity and enzyme activity. Furthermore, the metabolic process of this fungus may promote the release of basic ions dominated by Na+ and increase soluble cations. The results suggest that the combined application of biomass and microorganism could reduce the alkalinity of bauxite residue effectively, which may provide theoretical basis and practical reference for bioremediation in the disposal areas.

中文翻译：

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草酸青霉产酸对铝土矿渣理化性质的影响

摘要 铝土矿渣是氧化铝生产过程中产生的一种碱性、盐分和营养不足的废物，大量排放造成了难以恢复的极端环境。已发现微生物途径在这些残留物的修复中发挥着关键作用。在本研究中，草酸青霉是一种从铝土矿渣处理场筛选出来的耐碱产酸真菌，用于检验其恢复铝土矿渣的有效性。通过比较不同生物质预处理方法，在培养基中加入汽爆预处理生物质，以增强微生物代谢。经过最优生物质预处理后，草酸假单胞菌分泌的有机酸含量分别为草酸0.12 mg/mL、甲酸0.31 mg/mL和乙酸0.51 mg/mL。添加预处理生物质和微生物后，铝土矿残留物的 pH 值从 10.9 显着降低到 7.2，同时提高了电导率和酶活性。此外，这种真菌的代谢过程可能会促进以 Na+ 为主的碱性离子的释放，并增加可溶性阳离子。结果表明，生物质与微生物联合应用可有效降低铝土矿渣的碱度，可为处置区生物修复提供理论依据和实践参考。