经济、有效、易获得的生物质和地质材料（及二者的废弃物）可用来取代传统的活性炭或离子交换树脂用于去除废水中的重金属。已经公开发表的低成本吸附剂主要可分为两类：（1）生物质（包括林业和农业的废弃物）:树皮/富含丹宁酸的物质，木质素，几丁质/甲壳质，死的生物体，苔藓，海草/海藻/褐藻酸，废弃的茶叶，稻壳，羊毛，棉花等;（ 2）地质材料（包括矿物利用后的工业废弃物）:沸石，粘土，泥炭,有铁氧化物包壳的砂，粉煤灰等。其中，对于重金属具有强吸附能力的吸附剂有甲壳质、沸石和木质素，例如，它们对一些重金属的最大吸附能力分别为：甲壳质对Cd，Hg，Pb分别为558，1 123，796 mg/g，沸石对Pb为155.4 mg/g，木质素对Pb为1 587 mg/g。地质材料的环境利用值得引起地学界和环境工程界更广泛的重视。基于地质材料和水岩相互作用机理的环境污染控制技术有望成为21世纪重要的环保替代技术。由于缺少连续的可比性强的成本信息，要比较不同的生物质和地质材料的成本和吸附性能仍较困难。尽管已对低成本吸附剂领域进行了很多研究，但要更好地了解低成本吸附剂的作用机理及其实用性，仍需要做大量的室内和现场工作。%Cost-effective and easily available biomass and geomaterial can be alternatives for conventional activated carbon or ion exchange resins to remove heavy metals from wastewaters. Reported low cost sorbents can be classified into two groups: (1) biomass including wastes of timbering industry and agriculture: tree bark/ tannin-rich materials, lignin, chitin/chitosan, dead biomass, moss, seaweed/algae/alginate, waste tea, rice hulls, wool and cotton; and (2) geomaterial including industrial wastes of mineral processing/utilization: zeolite, clay, peat, iron oxide-coated sand, and fly ash. Among the sorbents, chitosan, zeolite and lignin are of the greatest sorption capacities. For instance，the greatest sorption capacities of them for some heavy metals are as follows: chitosan for Cd,Hg and Pb—558,1 123 and 796 mg/g，zeolite for Pb—155.4 mg/g，and lignin for Pb—1 587 mg/g. The application of geomaterials to environmental protection should gain greater attention of geologists and environmental engineers. Environmental control technology based on geomaterial and water-rock interaction studies will probably become alternative technology for environmental protection in the 21st century. It is still difficult to compare the cost and sorption capacity between different biomass and geomaterial due to shortage in information about costs of the materials. Although a lot of research has been done on low cost sorbents, more detailed laboratory and in-situ work is needed to better understand the sorption process and applicability.
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