Dissolved organic matter (DOM) in water has adverse impacts on the water treatment process and is effectively removed by ion exchange (IEX). Some researchers have proposed the term biological ion exchange (BIEX) for the process of continuous DOM removal by ion exchange without the need for chemical regeneration that results in brine waste. Surface water with moderate dissolved organic carbon (DOC) concentrations (4–6 mg/L) and high sulfate concentrations (80 – 120 mg/L) was fed to two regenerated and two non-regenerated columns for 12,500 bed volumes (9 months) with the goal of investigating the effects of chemical and possibly biological regeneration on long-term IEX operation. Chemically regenerated columns achieved between 60 and 80% DOC removal for the entirety of the experiment, while non-regenerated columns achieved steady DOC removal of ~50%. Inorganic ion analysis showed that biological activity had minimal impact on DOC removal, and the main mechanism of removal was secondary IEX between sulfate (SO₄²⁻) and fractions of DOC with high affinities for ion exchange. Fluorescence and specific UV absorbance at 254 nm (SUVA 254) data showed that fractions of DOC with higher SUVA 254 values (terrestrial-like fractions) were better removed by secondary IEX than those with lower SUVA 254 values (aquatic/microbial-like fractions). Scanning electron microscopy showed that biofilms on non-regenerated resins covered 5–15% of the resin surface and are composed of numerous species of bacteria with varying functions, with some protozoa present.

水中溶解的有机物（DOM）对水处理过程有不利影响，并且可以通过离子交换（IEX）有效去除。一些研究人员提出了术语生物离子交换（BIEX），用于通过离子交换连续去除DOM的过程，而无需进行化学再生，而这会导致盐水浪费。将具有中等溶解有机碳（DOC）浓度（4–6 mg / L）和高硫酸盐浓度（80 – 120 mg / L）的地表水送入两个再生和两个非再生柱中，床量为12,500床（9个月）目的是研究化学再生和可能的生物再生对长期IEX操作的影响。在整个实验过程中，化学再生柱的DOC去除率在60％到80％之间，非再生柱的DOC稳定去除率约为50％。无机离子分析表明，生物活性对DOC的去除影响最小，而去除的主要机理是硫酸盐（SO₄ ²⁻）和具有高亲和力的DOC馏分，用于离子交换。254 nm的荧光和特定紫外线吸收率（SUVA 254）数据表明，具有较高SUVA 254值的DOC馏分（类似陆地的馏分）比具有较低SUVA 254值的DOC馏分（水样/微生物类）得到更好的分离。扫描电子显微镜显示，未再生树脂上的生物膜覆盖了树脂表面的5％至15％，并且由具有不同功能的多种细菌组成，并带有一些原生动物。