Eker Serkan, Kargi Fikret
Department of Environmental Engineering, Dokuz Eylul University, Buca, Izmir, Turkey.
Water Environ Res. 2006 Jul;78(7):686-90. doi: 10.2175/106143006x101656.
Wastewaters containing chlorophenol compounds are difficult to treat by biological means because of the toxic effects of those compounds on microorganisms. To investigate the adverse effects of chlorophenols on microorganisms, synthetic wastewater containing 2,4 dichlorophenol (DCP) was biologically treated in an activated sludge unit at different hydraulic residence times (HRTs) between 5 and 40 hours, whereas the feed chemical oxygen demand (COD), DCP concentrations, and sludge age were kept constant at 2500 +/- 50 mg/L, 150 mg/L, and 20 days, respectively. The resazurin method based on dehydrogenase activity was used for assessment of the feed and effluent wastewater toxicity. Percent COD, DCP, and toxicity removals increased, and the effluent COD, DCP, and toxicity levels decreased with increasing HRT. Biomass concentration in the aeration tank increased with increasing HRT because of low levels of DCP at high HRT levels, resulting in high COD, DCP, and toxicity removals. The sludge volume index decreased with increasing HRT, yielding well-settling organisms as a result of low levels of toxicity and high concentrations of active cells. Percent DCP and COD removals decreased with increasing specific DCP loading rate. The rates of DCP and COD removals showed a maximum at a low DCP concentration of 6 mg/L in the aeration tank, corresponding to a 25-hour HRT.
由于含氯酚化合物对微生物具有毒性作用，含有此类化合物的废水很难通过生物方法进行处理。为了研究氯酚对微生物的不利影响，在活性污泥装置中对含有2,4 -二氯酚（DCP）的合成废水进行生物处理，水力停留时间（HRT）在5至40小时之间变化，而进水化学需氧量（COD）、DCP浓度和污泥龄分别保持在2500±50mg/L、150mg/L和20天不变。基于脱氢酶活性的刃天青法用于评估进水和出水的废水毒性。随着HRT的增加，COD、DCP的去除率百分比以及毒性去除率均上升，而出水的COD、DCP和毒性水平则下降。由于在高HRT水平下DCP含量较低，曝气池中的生物量浓度随着HRT的增加而增加，从而实现了较高的COD、DCP和毒性去除率。污泥体积指数随着HRT的增加而降低，由于毒性水平较低且活性细胞浓度较高，产生了沉降性能良好的微生物。随着特定DCP负荷率的增加，DCP和COD的去除率百分比下降。在曝气池中DCP浓度为6mg/L的低浓度水平下（对应25小时的HRT），DCP和COD的去除率达到最高。
