Impacts posed by AMD from abandoned gold mines and assessment of reactive materials for remediation | |
| Author | Jeremia, Mathaba Machodi |
| Call Number | AIT Thesis no.ET-SUD-14-04 |
| Subject(s) | Gold mines and mining--South Africa Acid mine drainage--South Africa |
| Note | A thesis submitted in partial fulfilment of the requirements for the degree of Master of Engineering in Environmental Engineering and Management with area of Specialization in Environmental Technology for Sustainable Development at the Asian Institute of Technology and the degree of Master of Science at the UNESCO-IHE |
| Publisher | Asian Institute of Technology |
| Abstract | Streams affected by AMD are typically identifiable with very low pH and high metal concentration which poses a threat to aquatic life and stream quality. It is always desirable to avoid AMD generation but in most cases altogether is impossible and in such cases the wastewater must be treated before discharged into natural systems. The aim of this research was to evaluate ecotoxicity impacts of AMD in streams and to identify inorganic materials which could be used to develop a technology for remediation of affected water. It was found that streams which were receiving AMD were critically affected with high mortality rate of Daphnia Magna and slow survival rate increase was observed moving further away from AMD source. Adsorption batch experiments were carried out using fly ash, bottom ash, bentonite clay and activated charcoal to remove Al3+ and Mn2+ metal from solution. During the removal process, batch technique was used and the effects of adsorbent dosage, initial metal concentration and agitation time on adsorption efficiency were studied. The results showed increase in adsorption of metal ions with an increase in adsorbent dosage, initial metal concentration and agitation time up to when all adsorption surface sites are saturated. During single metal experiments, all the adsorbents had maximum removal efficiencies of ≥97% for Al3+ and Mn2+. Mixed metal adsorption had efficiencies of 89, 82 and 87 % for fly ash, bentonite clay and activated charcoal for Al3+ and 89, 96 and 86% for Mn2+. Generally, single metal adsorption data had linear fit to Langmuir isotherm and mixed metal to both Langmuir and Freundlich isotherms. Additionally, the theoretical amounts of heavy metal adsorbed per unit adsorbent mass which was too close to experimentally calculated one and Freundlich constant, n both had an indication of favourable adsorption. Activated charcoal had the highest maximum adsorption capacities of 4.396 and 21.186 mg/g for Al3+ and Mn2+ than fly ash and bentonite clay during single metal adsorption experiments while bentonite clay and activated charcoal had maximum Al3+ adsorption capacity of 37.88 mg/g and Mn2+ of 116.28 mg/g during mixed metal adsorption experiments. Kinetic studies showed that Al3+ and Mn2+ adsorption process followed pseudo-first-order and second-order kinetic models and the data fitted Elovich model indicating chemical sorption or chemisorption. It was deduced that identified adsorbents could be used to remove Al3+ and Mn2+ from solutions. |
| Year | 2014 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Annachhatre, Ajit P.;Steen, Peter Vander; |
| Examination Committee(s) | Visvanathan C.;Shipin, Oleg V.; |
| Scholarship Donor(s) | SKILL Programme; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2014; Thesis (M.Sc.) - Institute for Water Education Netherland, 2014 |