Optimizing the characteristics of granular activated carbon (GAC) can improve the performance of biologically activated carbon (BAC) filters, and iodine value has always been the principal index for GAC selection. However, in this study, among three types of GAC treating the same humic acid-contaminated water, one had an iodine value 35% lower than the other two, but the dissolved organic carbon removal efficiency of its BAC was less than 5% away from the others. Iodine value was found to influence the removal of different organic fractions instead of the total removal efficiency. Based on the removal and biological characteristics, two possible mechanisms of organic matter removal during steady-state were suggested. For GAC with poor micropore volume and iodine value, high molecular weight substances (3500–9000 Da) were removed mainly through degradation by microorganisms, and the biodegraded organics (soluble microbial by-products, < 3500 Da) were released because of the low adsorption capacity of activated carbon. For GAC with higher micropore volume and iodine value, organics with low molecular weight (< 3500 Da) were more easily removed, first being adsorbed by micropores and then biodegraded by the biofilm. The biomass was determined by the pore volume with pore diameters greater than 100 µm, but did not correspond to the removal efficiency. Nevertheless, the microbial community structure was coordinate with both the pore structure and the organic removal characteristics. The findings provide a theoretical basis for selecting GAC for the BAC process based on its pore structure.

优化颗粒状活性炭（GAC）的特性可以提高生物活性炭（BAC）过滤器的性能，碘值一直是选择GAC的主要指标。但是，在这项研究中，在处理相同腐殖酸污染水的三种类型的GAC中，一种的碘值比其他两种低35％，但其BAC的溶解有机碳去除率却低于5％。其他。发现碘值影响不同有机部分的去除而不是总去除效率。基于去除效果和生物学特性，提出了稳态过程中有机物去除的两种可能机理。对于微孔体积和碘值较差的GAC，高分子量物质（3500-9000 Da）主要通过微生物降解而去除，由于活性炭的吸附能力低，生物降解的有机物（可溶性微生物副产物，<3500 Da）被释放。对于具有较高微孔体积和碘值的GAC，低分子量（<3500 Da）的有机物更容易去除，首先被微孔吸附，然后被生物膜生物降解。通过孔径大于100μm的孔体积来确定生物量，但是其不对应于去除效率。然而，微生物群落结构与孔结构和有机去除特性都协调。该发现为基于BAC工艺的GAC孔结构选择GAC提供了理论依据。