Biomass-microorganism combination improves saline-alkalinity properties of bauxite residue

Abstract

The strongly saline-alkaline properties of bauxite residue hinder its ecological reclamation. To regulate the saline-alkalinity of bauxite residue, this study explored the effects of amendment application and ryegrass growth on the saline-alkalinity properties of bauxite residue. Results showed that the biomass-microorganism combination regulated the physicochemical properties (pH, EC, and ESP) and the exchangeable state contents of saline-alkaline ions (Na⁺, Ca²⁺, Mg²⁺, and K⁺) of bauxite residue, and promoted mineral transformation in bauxite residue. In addition, the enzyme activity and microorganism diversity of bauxite residue were improved after biomass-microorganism combination application. Correlation analysis suggested that the exchangeable Na⁺ content showed a negative correlation with enzyme activity, while the exchangeable Ca²⁺ content showed a positive correlation with enzyme activity in bauxite residue. The mechanism of saline-alkalinity regulation of bauxite residue can be ascribed to the synergistic effect of acid production by microorganisms, the secretion of organic acids by plant roots, and the buffering capacity provided by biomass decomposition. The findings in this study provide scientific evidence and practical reference for saline-alkalinity regulation and ecological reclamation of bauxite residue.

Keywords

bauxite residue / saline-alkalinity characteristics / ryegrass / biomass / microorganism

References

[1] Li Q, Geng C, Zhang H, et al.The large-scale sustainable utilization status of bauxite residue (red mud): Challenges and perspectives for China [J]. Environmental Reviews, 2025, 33: 1-16

[2] Wenzel M, Georget F, Matschei T. From bauxite residue mineralogy to reactivity and properties of blended cements [J]. Cement and Concrete Research, 2025, 192: 107854.

[3] Viana L, Araújo Seixas J A L, Dessureault P L, et al.Evaluation of the potential environmental impacts and benefits of producing alkali-activated concrete from bauxite residue [J]. Journal of Cleaner Production, 2026, 549: 147872.

[4] Deng B, Zhang J, Gong Y, et al.Formation behaviors of CaTiO₃ in bauxite residues under varied roasting conditions and development of an efficient extraction process [J]. Journal of Environmental Chemical Engineering, 2025, 13(6): 120127.

[5] Zhu X, Jin Q. Exploring the carbon neutrality pathway for China’s aluminium industry: An analysis from 1950 to 2060 [J]. Applied Energy, 2025, 393: 126090.

[6] Wu S, Wang F, Komárek M, et al.Ecological rehabilitation of mine tailings [J]. Plant and Soil, 2024, 497(1):1-5.

[7] Tang Y, Wan Z, Luo Y, et al.Metagenomic insight into microbial regulation of nutrient cycling in amended bauxite residue under various planting strategies: Implications for soil formation [J]. Applied Soil Ecology, 2025, 215: 106469.

[8] Tong Y, Jiang J, Xiang H, et al.Impacts of organic acids of varying molecular weights on alkaline transformation and cadmium immobilization in bauxite residue [J]. Journal of Environmental Sciences, 2026, 169: 194-204.

[9] Wu Y, Jiang Y, Jiang J, et al.Conversion of alkaline characteristics of bauxite residue by mechanical activated pretreatment: Implications for its dealkalization [J]. Journal of Environmental Management, 2022, 305: 114446.

[10] Guo Y, Ye Y, Zhu F, et al.Improvements on physical conditions of bauxite residue following application of organic materials [J]. Journal of Environmental Sciences, 2022, 116: 198-208.

[11] Wang G, Liu A, Wang Y, et al.Mechanism of biomass driving microbial community assembly in eco-engineering bauxite residues: Based on molecular traits of dissolved organic matter [J]. Bioresource Technology, 2026, 441: 133601.

[12] Zhu F, Zhong X, Zhang X, et al.Dynamics of dissolved organic carbon turnover and microbial communities reconstruction associated with giant reed during the soil-like formation in bauxite residue [J]. Journal of Environmental Management, 2025, 394: 127594.

[13] Xue S, Zhang Z, Qin X, et al.Alkalinity regulation of bauxite residue mediated by Penicillium oxalicum: Insights into carbon components dynamics [J]. Journal of Environmental Sciences, 2026, 164: 442-451.

[14] Liao J, Jiang J, Xue S, et al.A novel acid-producing fungus isolated from bauxite residue: The potential to reduce the alkalinity [J]. Geomicrobiology Journal, 2018, 35(10): 840-847.

[15] Chen Y, Luo Y, Wan Z, et al.Responses of microbial functional genes associated with carbon, nitrogen, and phosphorus cycling to pioneer vegetation in a bauxite residue disposal area [J]. Journal of Environmental Chemical Engineering, 2025, 13(5): 118818.

[16] Kong X, Li M, Xue S, et al.Acid transformation of bauxite residue: Conversion of its alkaline characteristics [J]. Journal of Hazardous Materials, 2017, 324: 382-390.

[17] Zeng L, Tian Z, Kang X, et al.Bacterial community drives soil organic carbon transformation in vanadium titanium magnetite tailings through remediation using Pongamia pinnata [J]. Journal of Environmental Management, 2024, 360: 121156.

[18] Miura Y S, Mulder J, Zivanovic V, et al.Enhancing chemical and physical properties of bauxite residue: A one-year assessment using Açaí Waste and Gypsum in in-situ rehabilitation [J]. Ecological Engineering, 2025, 212: 107500.

[19] Yao C, Bao D. Au nanocrystals modulate resistive switching and magnetic properties of spinel cobalt oxide-based memory devices [J]. ACS Applied Nano Materials, 2024, 7(1): 509-517.

[20] Yao C, Li J, Thatikonda S K, et al.Introducing a thin MnO₂ layer in Co₃O₄-based memory to enhance resistive switching and magnetization modulation behaviors [J]. Journal of Alloys and Compounds, 2020, 823: 153731.

[21] Nabi F, Kama R, Sajid S, et al.Synergistic effects of Mg and Fe-modified bimetallic biochar for immobilization of as and Cd in agricultural soils [J]. Environmental Chemistry and Ecotoxicology, 2025, 7: 1059-1071.

[22] Wu S, You F, Wu Z, et al.Molecular diversity of arbuscular mycorrhizal fungal communities across the gradient of alkaline Fe ore tailings, revegetated waste rock to natural soil sites [J]. Environmental Science and Pollution Research, 2020, 27(11): 11968-11979.

[23] Yang L, Wang W, Wronski T, et al.Community structure and environmental determinants of the bacterial and fungal gut microflora in Hainan Gibbons (Nomascus hainanus) [J]. Global Ecology and Conservation, 2022, 36: e02114.

[24] Gräfe M, Klauber C. Bauxite residue issues: IV. Old obstacles and new pathways for in situ residue bioremediation [J]. Hydrometallurgy, 2011, 108(1–2): 46-59.

[25] Wu C, Li C, Jiang J, et al.Revealing the alkaline characteristic evolution of bauxite residue under biomass fermentation [J]. Journal of Soils and Sediments, 2020, 20(8): 3083-3090.

[26] Tian T, Zhang C, Zhu F, et al.Effect of phosphogypsum on saline-alkalinity and aggregate stability of bauxite residue [J]. Transactions of Nonferrous Metals Society of China, 2021, 31(5): 1484-1495.

[27] Enríquez E, Fuertes V, Cabrera M J, et al.Study of the crystallization in fast sintered Na-rich plagioclase glass-ceramic [J]. Ceramics International, 2019, 45(7): 8899-8907.

[28] Yao C, Ismail M, Hao A, et al.Annealing atmosphere effect on the resistive switching and magnetic properties of spinel Co₃ O₄ thin films prepared by a sol–gel technique [J]. RSC Advances, 2019, 9(22): 12615-12625.

[29] He G, Baumann S, Liang F, et al.Phase stability and oxygen permeability of Fe-based BaFe_0.9Mg_0.05X_0.05O₃ (X = Zr, Ce, Ca) membranes for air separation [J]. Separation and Purification Technology, 2019, 220: 176-182.

[30] Xie W, Hu W, Zou L, et al.Tuning bipolar resistive switching by forming defect dipoles in A-site-deficient perovskite calcium titanate thin films [J]. Applied Physics Express, 2015, 8(4):045504.

Rights & permissions

Central South University