Natural polymer (biopolymer) treatment of engineered soil/waste is recognized as an environmentally-friendly sustainable method. This paper presents the findings in the improvement of strength characteristics of bauxite residue (red mud tailing) using two microbial biopolymers, xanthan (XG) and guar gum (GG), used individually and also together as a composite. A set of laboratory tests namely compaction test, sieve and hydrometer analysis, Atterberg limits, unconsolidated undrained triaxial (UU) test, unconfined compression (q_u) test, chemical analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM) have been performed on biopolymer stabilized specimens at varying biopolymer concentration and curing period. The results showed that q_u increases polynomially with the increase in biopolymer content (P) and curing period (t). Also, when compared with the conventional method, q_u at 0.5% XG was similar to 10% cement stabilized bauxite residue at 28 days curing period. The influence of a composite biopolymer on the strengthening behaviour of bauxite residue is also observed due to the additional ability to create a cross-linking network. XRD and SEM micrographs have also confirmed that bauxite residue particles are linked through the biopolymer, resulting in improved shear resistance. Finally, considering environmental perspectives, the economic feasibility of biopolymer treatment is also examined in comparison to cement and found that the biopolymer usage is an excellent substitute to the conventional engineered materials (cement) for soil/waste treatment.

工程土壤/废物的天然聚合物（生物聚合物）处理被认为是一种环境友好的可持续方法。本文介绍了使用两种微生物生物聚合物，分别是黄原胶（XG）和瓜尔豆胶（GG），也可以将它们组合使用来改善铝土矿渣（红泥尾矿）强度特性的发现。一组实验室测试，即压实测试，筛分和比重计分析，Atterberg极限，非固结不排水三轴（UU）测试，无侧限压缩（q _u）测试，化学分析，X射线衍射（XRD）和扫描电子显微镜（SEM）已经在生物聚合物稳定的标本上以不同的生物聚合物浓度和固化时间进行了测试。结果表明，q _ü随着生物聚合物含量（P）和固化时间（t）的增加，多项式增加。此外，当与常规方法相比，q _ùXG含量为0.5％时，在固化28天时与10％水泥稳定的铝土矿残渣相似。由于产生交联网络的附加能力，还观察到复合生物聚合物对铝土矿渣的强化行为的影响。XRD和SEM显微照片还证实，铝土矿残留物颗粒通过生物聚合物连接，从而提高了抗剪切性。最后，从环境角度考虑，与水泥相比还检查了生物聚合物处理的经济可行性，并发现生物聚合物的使用可以很好地替代用于土壤/废物处理的传统工程材料（水泥）。