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Environmental Impacts of Acid Rock Drainage Remediation in a Coal Waste Pile: An Experimental and Hydro-Geochemical Modeling Approach

Year: 2018
Type: article
Abstract: The mining-related acid rock drainage (ARD) constitutes a serious type of pollution that causes widespread degradation of water resources in regions with mining activity. Despite of a large number of research activities carried out on this topic, studies about ARD passive remediation have shown various existing issues that require further investigation. For instance, what long-term impacts will the remediation techniques have? Is there an optimal content of the reactive material that should be applied in the field? What impacts will the hydrological processes have on the ARD remediation techniques at the watershed scale? To investigate these issues, a comprehensive and systematic approach is developed through this dissertation research work in which laboratory experiments (> 3 years), complemented with field measurements (> 5 years), and hydro-geochemical modeling have been combined to explore the effectiveness and long-term impacts of a remediation technique -- alkaline clay (AC), an industrial waste, used as the remediation material in coal refuse (CR) waste piles. Our study yielded the following main findings: 1) AC is an effective and environmentally sustainable material for passive ARD remediation, maintaining a neutral pH and immobilizing metals/metalloids; 2) There is a range for the mixing ratio between the amount of AC and CR to achieve an optimal or close to optimal remediation effectiveness; 3) The appropriate depth for the amended layer was determined and it was found to be mostly constrained by the root zone depth; 4) Complementary strategies such as a vegetated cover and a saturated sand layer are highly beneficial; 5) The utilization of a sophisticated hydro-geochemical model allowed to investigate the remediation effectiveness and its long-term performance at a watershed scale, making possible the assessment inside and outside the coal waste pile ; and 6) Both the laboratory experiments and modeling results show that the proposed remediation design can lead to the total alkalinity in the system exceeding the total acidity over a long time period. In summary, this study provides valuable new insights through three defined stages (i.e., laboratory experiments, field measurements and modeling) to demonstrate the effectiveness and sustainability of the proposed remediation approach.
Language: English
Open Access status: green
OpenAlex ID: W2906146005
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Cites: 113
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Related to: 10