Inorganic media selection for permeable reactive barrier in treating heavy metals from acid mine drainage contaminated groundwater | |
| Author | Orakwue, Emelda Obianuju |
| Call Number | AIT Thesis no.ET-SUD-14-01 |
| Subject(s) | Acid mine drainage--Nigeria Acid mine drainage Thailand |
| Note | A thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Environmental Engineering and Management at the Asian Institute of Technology with specialization in Environmental Technology for Sustainable Development (ETSUD)and degree of Master of Science at the UNESCO-IHE |
| Publisher | Asian Institute of Technology |
| Abstract | Acid mine drainage (AMD) is a persisting environmental problem and a grievous nuisance in the mining sector. Both active and passive treatment methods have proven to be effective for AMD treatment; however, there is still need for further research in this field in order to provide energy-efficient and ecologically stable performance of different treatment technologies. In this study, digestion, toxicity characteristics leaching procedure (TCLP), batch and column tests were performed to study copper, iron, zinc and manganese removal from AMD (Banpuu coal mine, Thailand and Enugu-Okpara coal mine, Nigeria) contaminated groundwater by using bottom ash (BA), bentonite clay (BC) and fly ash (FA) as adsorbents. The leaching capacities of the heavy metals were found to be less than their composite concentrations from digestion tests. In order to understand the mechanism of adsorption between the sorbent and sorbate, the following batch tests were conducted to ascertain Fe removal; (i) effect of adsorbent dose on Fe removal, final pH and qe, (ii) effect of Fe initial concentrations on Fe removal and qe, (iii) fitting the adsorption data to well-known isotherm models (Langmuir, Freundlich, Dubinin-Radushkevich and Temkin), and (iv) analysis of adsorption kinetics (pseudo first and second order and Elovich's kinetic models), respectively. The results from batch tests showed that the optimum adsorbent dosages for BA, BC and FA were found to be3g, 4g and 4gper 100ml, respectively. The optimum initial Fe concentration selected for BA, BC and FA was 1308mg/l. Concerning model fitting, Langmuir, Freundlich, Dubinin-Radushkevich and Temkin showed chi-square values of 24, 18, 32 and 9,respectively. Based on the R2and chi-square values, it was concluded that the Temkin adsorption isotherm model fitted the experimental data well for Fe removal. The results from kinetic analysis showed that, the Fe removal efficiency increased with an increase in the contact time and then remained almost constant after 50 min for all the three tested adsorbents. Column tests were performed in continuous mode for ~3 months to ascertain the removal of synthetic metal-laden wastewater containing Cu, Fe, Zn and Mn, respectively. The adsorbent dose used in individual columns were: CNC-1 (100% BA), CNC-2 (BA: BC: FA = 80:10:10) and CNC-3 (BA: BC: FA = 60:20:20), respectively. However, when BA, BC and FA were mixed at ratios of 60: 20: 20, the removal of Cu, Fe, Zn and Mn from Banpuu coal mine(Thailand)AMD was found to be >99.7%. Finally, it is recommended that BA, BC and FA be activated with dilute acids (HNO3, H2SO4or HCL) prior to usage for the improvement of the adsorbent surface areas. Also, chemical characterization of the raw, pre-treated and used adsorbents should be necessary. It is crucially recommendable that PRB be operated until adsorbent breakthrough is ascertained. |
| 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.; |
| Examination Committee(s) | Lens, Piet N. L.;Ren, Eldon R.;Nguyen, Thi Kim Oanh;Thammarat Koottatep; |
| Scholarship Donor(s) | Netherlands Fellowship Programme (NFP); |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology - UNESCO-IHE, 2014 |