Reactive media in permeable reactive barrier for removal of metal ions from acid mine drainage | |
| Author | Varinporn Asokbunyarat |
| Call Number | AIT Diss. no.EV-15-05 |
| Subject(s) | Heavy metals--Environmental aspects Metal ions Acid mine drainage--Environmental aspects |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. EV-15-05 |
| Abstract | Investigations were undertaken to study the sorption of individual and multiple metal ions (Fe(II), Mn(II), Cu(II) and Zn(II)) from aqueous solution and acid mine drainage onto coal fly ash, coal bottom ash, bentonite clay, activated charcoal, limestone and iron filling through batch and column sorption tests. XRD analysis of coal fly ash indicated presence of quartz (SiO 2 ), magnetite (Fe 2+ Fe 3+ 2 O 4 ), mullite (Al 6 Si 2 O 13 ) and anhydrite (CaSO 4 ). XRD analysis of coal bottom ash indicated presence of quartz (SiO 2 ), feldspar (KAlSi 3 O 8 – NaAlSi 3 O 8 – CaAl 2 Si 2 O 8 ), magnetite (Fe 2+ Fe 3+ 2 O 4 ) and mullite (Al 6 Si 2 O 13 ). XRD analysis of bentonite clay indicated presence of montmorillonite ((Na,Ca) 0.3 (Al,Mg) 2 Si 4 O 10 (OH) 2 . nH 2 O) and calcite (CaCO 3 ). TCLP revealed that coal fly ash, coal bottom ash and bentonite clay contained heavy metals such as Fe(II), Fe(III), Mn(II), Cu(II), Zn(II), As(III), As(V), Pb(II) and Cd(II). Continuous column leaching test with the coal fly ash, coal bottom ash, bentonite clay, activated charcoal, limestone and iron filling showed negligible heavy metal ion leach-out at pH 6.0, although at pH 4.2 some heavy metal ion leaching, mainly of Mn(II), was observed. Batch sorption kinetic studies with six sorbents (coal fly ash, coal bottom ash, bentonite clay, activated charcoal, limestone and iron filling) and with individual heavy metal ions in aqueous solution and multiple heavy metal ions in acid mine drainage (Fe(II), Mn(II), Cu(II) and Zn(II)) revealed that the heavy metal ion sorption onto six sorbents could be described by pseudo-second order kinetics. Batch sorption isotherm studies with six sorbents and with individual heavy metal ions revealed that Langmuir isotherm adequately described the heavy metal ion sorption isotherm onto six sorbents with maximum sorption capacity (q m ) ranging from 19.8 to 73.5 mg/g (coal fly ash), 1.9 to 23.5 mg/g (coal bottom ash), 16.0 to 62.8 mg/g (bentonite clay), 3.6 to 13.8 mg/g (activated charcoal), 0.2 to 36.3 mg/g (limestone) and 0 to 95.2 mg/g (iron filling) for various heavy metal ions. Batch sorption isotherm studies with six sorbents and with multiple heavy metal ions in acid mine drainage also revealed that Langmuir isotherm adequately described the heavy metal ion sorption isotherm onto six sorbents with maximum sorption capacity (q m ) of 17.4 mg/g (coal fly ash), 11.8 mg/g (coal bottom ash), 28.5 mg/g (bentonite clay), 6.9 mg/g (activated charcoal), 6.8 mg/g (limestone) and 0 mg/g (iron filling) for Fe(II) ion.Column sorption tests with metal ion removal (Fe(II), Mn(II), Cu(II) and Zn(II)) from acid mine drainage using mixtures of fly ash (FA), bottom ash (BA), and bentonite clay (BC) in different proportions revealed that metal ion removal (87.5%) was the highest for the mixture ratio of 60% BA, 20% FA and 20% BC due to higher amount of fly ash and bentonite clay. However, hydraulic conductivity was the lowest for the mixture ratio of 60% BA, 20% FA and 20% BC due to clogged reactive media. Moreover, metal ion removal for the mixture ratio of 60% BA, 20% FA and 20% BC in horizontal-flow mode got breakthrough curve faster than in up-flow mode due to preferential flow or short circuit. Removal of heavy metal ions (Fe(II), Mn(II), Cu(II) and Zn(II)) by fly ash, bottom ash and bentonite clay is attributed to both sorption and precipitation of heavy metal hydroxides due to the presence of oxides of silicon (SiO 2 ), aluminum (Al 2 O 3 ), iron (Fe 2 O 3 ) and calcium (CaO) in fly ash, bottom ash and bentonite clay. For permeable reactive barrier (PRB) design, flow-through thickness of the barrier by mixture ratio of 60% BA, 20% FA and 20% BC is the smallest due to the highest of its metal removal For characteristics of effluent after achieving column breakthrough for acid mine drainage treatment, Mn concentration in effluent was the highest, while that of concentrations of Fe, Cu and Zn were low. Moreover, concentrations of other heavy metals such as As, Cr and Cd in effluent were low. For characteristics of used sorbent for acid mine drainage treatment, concentrations of Fe, Mn, Cu and Zn in TCLP leachate were high, while concentrations of other heavy metals such as As, Cr and Cd were low. Percentage of leaching of Mn, Cu and Zn (35.2-89.5%) were high, while percentage of leaching of Fe (0.1-0.2%) was low. Moreover, percentage of sorption of Cu and Zn (more than 90%) were the highest, followed by Mn (more than 50%) and Fe (less than 50%). In SEM-EDS, Fe, Mn, Cu and Zn in synthetic AMD were detected on surface of used sorbent. |
| Year | 2015 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. EV-15-05 |
| Type | Dissertation |
| 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 | Environmental Engineering and Management (EV) |
| Chairperson(s) | Annachhatre, Ajit P. |
| Examination Committee(s) | Visvanathan, Chettiyappan ;Pham Huy Giao |
| Scholarship Donor(s) | Asian Institute of Technology Fellowship |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2015 |