Institute of Environmental Sciences and Engineering (IESE), School of Civil and Environmental Engineering (SCEE), National University of Sciences and Technology (NUST), Islamabad, 44000, Pakistan.
Sci Rep. 2020 Sep 25;10(1):15802. doi: 10.1038/s41598-020-72800-2.
Grasses have been used widely to remediate contaminants present in domestic wastewater, but leachate generated from municipal solid waste that usually contain some concentrations of heavy metals has never been reported to be treated with grasses, especially Rhodes grass. A series of experiments was performed to investigate the contaminant uptake from municipal solid waste leachate by Chloris gayana (Rhodes grass) grown in combination with two commonly available grass varieties namely Vetiveria zizanioides (Vetiver grass) and Pennisetum purpureum (Elephant grass). Leachate used for the experiments had high values for chemical oxygen demand (5 g/L), pH (8.5), electrical conductivity (9.0 mS/cm), nitrates (182.1 mg/L), phosphates 6.4 mg/L along with heavy metals i.e. copper, zinc and manganese. Different dilutions of leachate ranging from 0 to 100% were applied in batches and their result showed that collectively all the grasses reduced overall contaminant concentrations. These were reported for chemical oxygen demand, electrical conductivity, nitrates, and phosphates reduced up to 67, 94, 94, and 73%, respectively. Metals uptake by grasses also showed a significant decrease in applied dose i.e. zinc (97%), copper (89%), and manganese (89%). Plant analysis showed that all grasses showed preference to heavy metals uptake e.g. Rhodes grass favoured up taking zinc, Elephant grass for copper and Vetiver grass preferred manganese. Overall growth performance of Rhodes grass was better in dilute leachate, whereas in more concentrated leachate, Rhodes grass did not perform better and production of biomass decreased. In Vetiver grass, root and shoot lengths decreased with increasing leachate strength, but the biomass did not change significantly.
草广泛用于修复生活污水中的污染物，但从未有报道称用草处理通常含有一些重金属浓度的城市固体废物渗滤液，尤其是兰地狗尾草。进行了一系列实验，以研究在与两种常见草种即香根草（香根草）和象草（象草）组合生长的情况下，从城市固体废物渗滤液中摄取污染物。实验中使用的渗滤液具有高化学需氧量（5 g/L）、pH 值（8.5）、电导率（9.0 mS/cm）、硝酸盐（182.1 mg/L）、磷酸盐 6.4 mg/L 以及重金属铜、锌和锰。将渗滤液的不同稀释度从 0 到 100%分批应用，结果表明所有草类共同降低了整体污染物浓度。据报道，化学需氧量、电导率、硝酸盐和磷酸盐分别降低了 67%、94%、94%和 73%。草类对金属的吸收也表现出随着施用量的显著减少，即锌（97%）、铜（89%）和锰（89%）。植物分析表明，所有草类都表现出对重金属吸收的偏好，例如兰地狗尾草偏好吸收锌，象草偏好吸收铜，香根草偏好吸收锰。在稀渗滤液中，兰地狗尾草的整体生长性能更好，而在浓度较高的渗滤液中，兰地狗尾草的表现并不理想，生物量减少。在香根草中，根和茎的长度随渗滤液强度的增加而减小，但生物量没有明显变化。
