High-strength wastewater defined by elevated levels of hazardous pollutants measured in BOD, heavy metals, nutrients and other toxic substances. This kind of wastewater discharged to water body without treatment from different industrial sectors that adversely affects aquatic environment and downstream water consumers. The general objective of this study is to investigate efficient substrate with selected plant type for constructed wetland to remove hazardous pollutants from tannery wastewater. This study was conducted at Modjo town, Modjo tannery PLC. Plug flow experimental study design was carried out. The substrate (Pumice) was collected around the study area and chemical characteristics were determined. Chrysopogon zizanioides was planted and grown for 5 months before running tannery wastewater for the treatment. The composite wastewater was introduced to the constructed wetland from Modjo leather industry, Ethiopia. The physicochemical analysis of the sample wastewater was done before and after treatment at four different hydraulic retention time. Characterization of the untreated tannery wastewater revealed that the mean concentration of BOD5, COD, TSS, PO4-P, TP, NO3-N, TN and total chromium were 1641 ± 373.6, 6953.33 ± 339.4, 1868 ± 863.1, 88.06 ± 40.8, 144.53 ± 20.8, 116.66 ± 26.6, 650.33 ± 93.6 and 18.33 ± 6.7 mg/l respectively beyond the permissible limits. The maximum removal efficiency of the constructed wetland in pumice bed revealed that BOD5 at HRT 7and 9 days (96.42%, 96.30%), COD at HRT 5 and 7 days (96.76%, 96.91%), NO3-N at HRT 5 and 7 days (99.99%, 99.68%), TN (98.67%, 99.00%), PO4-P HRT 7and 9 days (96.97%,100%), TP at HRT 5 and 7 days (94.79%, 96.17%) and total Chromium at HRT 5 and 7 days (98.36%, 98.91%) respectively. Whereas, the removal efficiency of constructed wetland bed with gravel substrate used as a control subject with similar condition to pumice showed lower performance. The result between pumice and gravel bed was tested for their significance difference using two sample t-test statistics. Based on the test statistics, the pumice substrate perform better than the gravel significantly at 95% confidence interval, p-value = 0.01. Pumice substrate and Chrysopogon zizanioides have a potential ability to remove hazardous pollutants from tannery wastewater in horizontal subsurface constructed wetlands.

中文翻译：

---

开发利用浮石和金缕梅处理制革废水的水平潜流人工湿地

高浓度废水定义为 BOD、重金属、营养素和其他有毒物质中有害污染物含量升高。这类废水未经不同工业部门的处理直接排入水体，对水环境和下游用水户产生不利影响。本研究的总体目标是研究人工湿地选择植物类型的有效基质，以去除制革废水中的有害污染物。本研究是在 Modjo 制革厂 PLC 的 Modjo 镇进行的。进行了活塞流实验研究设计。在研究区域周围收集底物（浮石）并确定化学特性。Chrysopogon zizanioides 种植并生长了 5 个月，然后再运行制革厂废水进行处理。复合废水从埃塞俄比亚莫乔皮革工业引入人工湿地。在四种不同水力停留时间处理前后对样品废水进行理化分析。未经处理的制革废水表征表明，BOD5、COD、TSS、PO4-P、TP、NO3-N、TN 和总铬的平均浓度分别为 1641±373.6、6953.33±339.4、1868±863.1、84.04.3±16 ± 20.8、116.66 ± 26.6、650.33 ± 93.6 和 18.33 ± 6.7 mg/l 分别超出允许限值。人工湿地浮石床最大去除效率显示，HRT 7、9天BOD5（96.42%、96.30%）、HRT 5、7天COD（96.76%、96.91%）、HRT 5、7天NO3-N天 (99.99%, 99.68%), TN (98.67%, 99.00%), PO4-P HRT 7and 9 days (96.97%,100%), HRT 5 天和 7 天的 TP（94.79%、96.17%）和 HRT 5 天和 7 天的总铬（98.36%、98.91%）。而以砾石基质为对照的人工湿地床的去除效率与浮石相似，条件相似。使用两个样本 t 检验统计量测试了浮石和砾石层之间的结果的显着性差异。根据测试统计，在 95% 的置信区间，浮石基材的性能显着优于砾石，p 值 = 0.01。浮石基质和 Chrysopogon zizanioides 具有去除水平地下人工湿地制革废水中有害污染物的潜在能力。以砾石基质为对照的人工湿地床的去除效率与浮石相似，表现出较低的性能。使用两个样本 t 检验统计量测试了浮石和砾石层之间的结果的显着性差异。根据测试统计，在 95% 的置信区间，浮石基材的性能显着优于砾石，p 值 = 0.01。浮石基质和 Chrysopogon zizanioides 具有去除水平地下人工湿地制革废水中有害污染物的潜在能力。以砾石基质为对照的人工湿地床的去除效率与浮石相似，表现出较低的性能。使用两个样本 t 检验统计量测试了浮石和砾石层之间的结果的显着性差异。根据测试统计，在 95% 的置信区间，浮石基材的性能显着优于砾石，p 值 = 0.01。浮石基质和 Chrysopogon zizanioides 具有去除水平地下人工湿地制革废水中有害污染物的潜在能力。在 95% 的置信区间，浮石基材的性能显着优于砾石，p 值 = 0.01。浮石基质和 Chrysopogon zizanioides 具有去除水平地下人工湿地制革废水中有害污染物的潜在能力。在 95% 的置信区间，浮石基材的性能显着优于砾石，p 值 = 0.01。浮石基质和 Chrysopogon zizanioides 具有去除水平地下人工湿地制革废水中有害污染物的潜在能力。