Alemu Tadesse, Mekonnen Andualem, Leta Seyoum
Biology Department, College of Natural Science, Assosa University, Assosa, Ethiopia; Center for Environmental Sciences, College of Natural and computational sciences, Addis Ababa University, Addis Ababa, Ethiopia E-mail:
Center for Environmental Sciences, College of Natural and computational sciences, Addis Ababa University, Addis Ababa, Ethiopia E-mail:
Water Sci Technol. 2018 Feb;77(3-4):988-998. doi: 10.2166/wst.2017.613.
In the present study, a pilot scale horizontal subsurface flow constructed wetland (CW) system planted with Phragmites karka; longitudinal profile was studied. The wetland was fed with tannery wastewater, pretreated in a two-stage anaerobic digester followed by a sequence batch reactor. Samples from each CW were taken and analyzed using standard methods. The removal efficiency of the CW system in terms of biological oxygen demand (BOD), chemical oxygen demand (COD), Cr and total coliforms were 91.3%, 90%, 97.3% and 99%, respectively. The removal efficiency for TN, NO and NH-N were 77.7%, 66.3% and 67.7%, respectively. Similarly, the removal efficiency of SO, S and total suspended solids (TSS) were 71.8%, 88.7% and 81.2%, respectively. The concentration of COD, BOD, TN, NON, NH-N, SO and S in the final treated effluent were 113.2 ± 52, 56 ± 18, 49.3 ± 13, 22.75 ± 20, 17.1 ± 6.75, 88 ± 120 and 0.4 ± 0.44 mg/L, respectively. Pollutants removal was decreased in the first 12 m and increased along the CW cells. P. karka development in the first cell of CW was poor, small in size and experiencing chlorosis, but clogging was higher in this area due to high organic matter settling, causing a partial surface flow. The performance of the pilot CW as a tertiary treatment showed that the effluent meets the permissible discharge standards.
在本研究中，对一个中试规模的水平潜流人工湿地（CW）系统进行了研究，该系统种植了卡开芦；研究了其纵向剖面。该湿地采用制革废水进水，废水先在两级厌氧消化池中进行预处理，然后进入序批式反应器。从每个CW系统采集样本并使用标准方法进行分析。该CW系统对生物需氧量（BOD）、化学需氧量（COD）、铬和总大肠菌群的去除效率分别为91.3%、90%、97.3%和99%。对总氮（TN）、硝酸盐氮（NO）和氨氮（NH-N）的去除效率分别为77.7%、66.3%和67.7%。同样，对硫酸根（SO）、硫化物（S）和总悬浮固体（TSS）的去除效率分别为71.8%、88.7%和81.2%。最终处理后的出水的COD、BOD、TN、NON、NH-N、SO和S的浓度分别为113.2±52、56±18、49.3±13、22.75±20、17.1±6.75、88±120和0.4±0.44mg/L。在前12米内污染物去除率下降，沿CW单元增加。CW第一个单元中卡开芦生长不良，植株矮小且出现黄化现象，但由于高有机物沉降，该区域堵塞程度较高，导致部分表面流。作为三级处理的中试CW系统的性能表明，出水符合允许排放标准。
