The textile industry discharges large amounts of polluted wastewater containing synthetic dyes. A down-flow hanging sponge (DHS) reactor is a novel aerobic wastewater treatment process that utilizes a sponge as a biomass-retaining carrier. This sponge carrier has both aerobic and anaerobic zones owing to different dissolved oxygen concentrations. In this study, the process performance of a DHS reactor treating actual textile wastewater obtained from a factory in Japan was evaluated. The effects of hydraulic retention time (HRT) and effluent recirculation (recirculation ratio = 1) on the DHS process performance were investigated. The DHS reactor showed good organic (up to 93 ± 13% of BOD) and nitrogen removal (56 ± 14% of TN) abilities during the entire experimental period. The color removal efficiencies of the DHS reactor were 55 ± 15%, 53 ± 26%, 72 ± 34%, and 35 ± 22% with HRTs of 4 h, 4 h + effluent recirculation (R = 1), 8 h + effluent recirculation (R = 1), and 8 h, respectively. Microbial community structure analysis of the DHS retained sludge showed that genus Acinetobacter was detected predominantly and reported as an azo dye-degrading bacterium. Effluent recirculation was also observed to increase the presence of aromatic-degrading bacteria and protists in the DHS reactor. These results suggest that the DHS reactor is suitable for textile wastewater treatment. Furthermore, the effluent recirculation is effective for enhancing decolorization performance.

纺织工业排放大量含有合成染料的污染废水。下流式悬挂式海绵（DHS）反应器是一种新型的好氧废水处理工艺，该工艺利用海绵作为生物质保持载体。由于不同的溶解氧浓度，该海绵载体具有需氧区和厌氧区。在这项研究中，评估了DHS反应器处理从日本一家工厂获得的实际纺织废水的过程性能。研究了水力停留时间（HRT）和废水再循环（再循环比= 1）对DHS工艺性能的影响。在整个实验期间，DHS反应器均显示出良好的有机能力（最高BOD的93±13％）和脱氮能力（TN的56±14％）。DHS反应器的脱色效率为55±15％，53±26％，HRT分别为4小时，4小时+废水再循环（R = 1），8小时+废水再循环（R = 1）和8小时的HRT分别为72±34％和35±22％。DHS保留污泥的微生物群落结构分析表明，该属主要检测到不动杆菌，并报道其为偶氮染料降解细菌。还观察到废水再循环增加了DHS反应器中芳香分解细菌和原生生物的存在。这些结果表明，DHS反应器适用于纺织废水处理。此外，废水再循环对于增强脱色性能是有效的。