Browsing by Author "Lee, Hyeyeon"

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    Increasing recovery opportunities of metal(loid)s from municipal solid waste via landfill leachate recirculation
    (Elsevier, 2023-01-17) Lee, Hyeyeon; Coulon, Frederic; Beriro, D. J.; Wagland, Stuart T.
    The recovery of 12 critical raw materials (CRM) from municipal solid wastes (MSW) via leachate recirculation was evaluated using a 4 L semi-pilot scale column percolation. The results showed that the recovery of the metal(loid)s was mainly influenced by order of importance: pH > organic content > type of metal(loid)s > age of the waste > redox potential. Among the CRM, Cd and Ni were the most mobile elements, while As and Cr were the least mobile. A comparison of leachate from the leachate recirculated columns before and after the initiation of recirculation indicates an increase in the concentrations of certain CRM and metalloids. The first recirculation cycle supported achieving 100 % recovery. CRM and metalloids in leachate can be recovered; however, the concentrations of CRM and metalloids are usually below 1 mg/L. In this regard, leachate recirculation may enhance the increasing concentration of CRM in landfill leachate. For example, after first recirculation cycle, Ni concentration increased from 0.05 mg/L to 0.11 mg/L. The results obtained from this study can develop further methodologies for the potential recovery of CRM and help foster further research into overcoming limitations for recovering CRM in landfill leachate.
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    The influence of humic acid on metal(loid)s leaching in landfill leachate for enhancing landfill mining
    (Elsevier, 2023-07-06) Lee, Hyeyeon; Coulon, Frederic; Wagland, Stuart
    The aim of this study was to investigate the effect of different concentrations of humic acid on the recovery rate of metal(loid)s in landfill leachate. The study focused on the release of 12 selected metal(loid)s, including critical raw materials (CRM) in landfills that were less than five years old and those that were more than ten years old. The experimental setup involved using different concentrations of humic acid (w/v) (0 %, 0.1 %, and 0.5 %) at pH 4 and 6. The results of the study showed that humic acid was effective in releasing Al, Cr, Co, Ni, Cu, Zn, As, Cd, and Pb. On the other hand, an increase in humic acid concentration led to a decrease in the release of Li, Mn, and Hg. The immobilization of Li, Mn, and Hg was due to the coordination and adsorption of humic acid. The presence of humic acid accelerated the release of metal(loid)s by carboxylic acidity compared to the recovery rate of metal(loid)s in landfill leachate without humic acid. However, a higher concentration of humic acid did not always result in a stronger recovery rate. The recovery rate of metal(loid)s was related to the solubility and concentration of humic acid. These findings can inform the development of more efficient and environmentally-friendly methods of recovering metal(loid)s using humic acid as a leaching agent.
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    Influence of pH, depth and humic acid on metal and metalloids recovery from municipal solid waste landfills
    (Elsevier, 2021-09-15) Lee, Hyeyeon; Coulon, Frederic; Wagland, Stuart
    The recovery of metal(loid)s from municipal solid waste (MSW) samples <10 years old and >10 years old was investigated using a series of pH-dependence leaching batch tests ranging between pH 2 and 10. Further to this, the influences of various parameters, including depth, and humic acid (HA) concentrations on the recovery of metal(loid)s including Li, Al, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Pb, and Hg were investigated. The Visual MINTEQ geochemical software was then used to model the metal(loid)s release in the presence of different HA concentrations ranging from 28 mg/L to 100 mg/L, which can be found in landfill sites and pH ranging from 2 to 10. The results showed that the release amount of Li, Al, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Pb, and Hg are in the range of 0.03–0.14 mg/L, 0.65–83.33 mg/L, 0.01–0.19 mg/L, 0.18–18.17 mg/L, 0.01–0.09 mg/L, 0.06–0.38 mg/L, 0.12–5.2 mg/L, 0.14–11.57 mg/L, 0.02–0.10 mg/L, 0.00–26.17 mg/L, 0.03–25.17 mg/L, and 0.00–0.01 mg/L with deionised water as leachant at different pH. The release amount of HA was relatively increased from 0 to 2% in 48–55 m compared to 3–9 m in the MSW landfill. HA can promote the leaching rate of metals with an appropriate amount. Base on the study results, the optimal condition of leaching metals was pH 2, and HA 28 mg/L at less than 10 m depth. The high concentration of metals in landfill leachate may be enhanced to effectively recover metals as the critical challenge of recovering metals from leachate is the low concentration of metals. Thus, the information can be useful for economically feasible in the recovery of metals.
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    Metal(loid)s concentration with humic acid in <1 and >10 year old landfills
    (Cranfield University, 2023-03-21 08:43) Wagland, Stuart; Lee, Hyeyeon; Coulon, Frederic
    Metal(loid)s mobilised from landfill samples at differing pH and humic acid concentrations. The datasets provide metal(loid) concentrations for samples 10 years old.
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    Occurrence and distribution of organic compounds in landfill leachate and their influence on metal mobility and recovery.
    (Cranfield University, 2021-09) Lee, Hyeyeon; Wagland, Stuart; Coulon, Frederic
    Resource security has attracted increasing attention globally due to the growing demand for use in a wide range of products. Municipal solid waste landfills and leachate are significant untapped resources that can contribute to a sustainable and secure supply of raw materials. Recent studies reported heavy metals (HM) and rare earth elements within the waste mass buried in landfills that can theoretically be recovered and reintroduced within the material loop of the circular economy framework. However, metal recovery only cannot be visible economically due to its low concentration. Therefore, research is required to understand how metals can be effectively mobilised. This research is carried out to develop a methodology to demonstrate the metals in landfill leachate as a potential secondary source. The batch and column percolation tests are performed to establish the relationship between metals recovery rate and other parameters. This PhD project investigates the influence of factors to increase metal mobility. Firstly, pH value and depth effect on metal release were analysed. The pH value plays a critical role to increase metal recovery rate; however, no significant correlation between depth and metal release was observed. As the analysis shows that metal release is highly increased in acidic conditions, column percolation was conducted at the optimise pH values with leachate recirculation. Leachate recirculation accelerates the degradation of organic waste, consequently enhancing the hydrolysis rate that may reduce the pH value. Lastly, different humic concentration on the metal(loid)s release from landfill leachate was investigated. This thesis presents a high potential to help evaluate the environmental impact to control the pollution and recover metal(loid)s.
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    Recent developments and prospects of sustainable remediation treatments for major contaminants in soil: A review
    (Elsevier, 2024-02-20) Lee, Hyeyeon; Sam, Kabari Simeon; Coulon, Frederic; De Gisi, Sabino; Notarnicola, Michele; Labianca, Claudia
    Rapid industrialisation and urbanisation are contributing to the entry of emerging contaminants into the environment, posing a significant threat to soil health and quality. Therefore, several remediation technologies have been investigated and tested at a field scale to address the issue. However, these remediation technologies face challenges related to cost-effectiveness, environmental concerns, secondary pollution due to the generation of by-products, long-term pollution leaching risks, and social acceptance. Overcoming these constraints necessitates the implementation of sustainable remediation methodologies that prioritise approaches with minimal environmental ramifications and the most substantial net social and economic advantages. Hence, this review delves into diverse contaminants that threaten soil health and quality. Moreover, it outlines the research imperatives for advancing innovative remediation techniques and effective management strategies to tackle this concern. The review discusses a remediation treatment train approach that encourages resource recovery, strengthens the circular economy, and employs a Life Cycle Assessment (LCA) framework to assess the environmental impacts of different remediation strategies. Additionally, the study explores mechanisms to integrate sustainability principles into soil remediation practices. It underscores the necessity for a comprehensive and systematic approach that takes into account the economic, social, and environmental consequences of remediation methodologies in the development of sustainable solutions.
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    Recovering metal(loids) and rare earth elements from closed landfill sites without excavation: leachate recirculation opportunities and challenges
    (Elsevier, 2021-12-27) Lee, Hyeyeon; Coulon, Frederic; Beriro, D. J.; Wagland, Stuart
    Metal (loids) and Rare Earth Elements (REE) (‘metals’) are used in a wide range of products, and therefore, the improvement of expectations for everyday comforts with demand continues to grow. Metal-bearing wastes are a secondary source of raw material that can meet this demand by providing a previously unconsidered low impact supply source. Total annual leachate production is 1,056,716 m3. Therefore, landfill leachate emerges as a significant potential resource as it contains high concentrations of metals. However, realising a profitable return on investment for leachate processing is a challenge due to relatively low recovery rates of approximately 0.02% of total heavy metals in a landfill being leached out in 30 years. Variation within the multi-element value and the effect of other chemicals in these complex mixtures. There is a need to better understand the mechanisms and potential applicability of extraction methods for optimising metals recovery from leachate. This paper addresses this need by providing a systematic review of the critical factors and environmental conditions that influence the behaviour of metals within the landfilled waste. The paper provides a synthesis of how the factors and conditions may affect leachate recirculation efficiency for recovery in the context of a range of opportunities and challenges facing circular economy practitioners. To approach feasibility metal recovery economically from landfill leachate without energy-intensive and environmentally destructive, future research actions need to be initiated in lab-based and later on semi-pilot to pilot studies, which the review can help achieve the challenges.