| Author: | Chan, Kin Yee Kinny |
| Title: | Combination of soil washing with biodegradable chelant and phytoremediation for brownfield |
| Advisors: | Li, X. D. (CEE) |
| Degree: | M.Sc. |
| Year: | 2017 |
| Subject: | Hong Kong Polytechnic University -- Dissertations Soils -- Heavy metal content Soil pollution Bioremediation |
| Department: | Faculty of Construction and Environment |
| Pages: | 60 pages : illustrations |
| Language: | English |
| Abstract: | Considering the land shortage problem in Hong Kong, the reuse of brownfield becomes a hot issue. Heavy metals are usually found in contaminated soils due to the previous land usage, which makes the reuse of the land become difficult. Cleaning up heavy metal-contaminated soils is a necessary step to minimize their toxic impacts to human health and ecosystem. Brownfield soil was collected for remediation in laboratory experiment. Concentrations of Cu and Zn in soils were 723 mg/kg and 6530 mg/kg, exceeding the class B limit by 21 % and 335 %, respectively, according to soil environmental quality evaluation standard limits from China. Contents of Pb and As in soils were 376 mg/kg and 33.9 mg/kg, which were higher than the urban residential limit by 0.46 and 0.53 times, respectively, according to the risk-based remediation goals (RBRGs) for soil & soil saturation limit from Hong Kong. In order to achieve a successful soil remediation in a short period of time, combination of soil washing and phytoremediation was investigated. During initial soil washing, citric acids (0.625 M, pH 2) was efficient to extract Zn as high as 30% of total Zn from contaminated soils after reaction for 8 h. For subsequent phytoremediation, ryegrass was able to absorb and primarily store Cu, Zn, and As in roots. The leachability of Cu, Zn, and As increased in the washed soils, and planting of ryegrass reduced the leachability of As, Cu, and Zn by 41%, 62% and 66%, respectively. Amendment of goethite with planting further decreased leachable As by 100%, and calcium carbonate further decreased leachable Zn by 58%. |
| Rights: | All rights reserved |
| Access: | restricted access |
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|---|---|---|---|---|
| 991022142755903411.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 592.62 kB | Adobe PDF | View/Open |
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