Utilization of fly ash for treatment of coal mines wastewater: Solubility controls on major inorganic contaminants

Gitari, Wilson M.; Petrik, Leslie; Etchebers, O.; Key, David L.; Okujeni, C.

doi:10.1016/j.fuel.2008.03.018

Cited by 82 publications

(71 citation statements)

References 34 publications

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“…Due to the high costs associated with chemical treatment technologies and long residence time requirement for biological treatment, there has been a concerted effort towards developing a cost effective alternative technology for treatment of mine water . The treatment of mine water using coal fly ash (FA) has proved to be promising (Petrik et al, 2003;Gitari et al, 2006Gitari et al, , 2008Madzivire et al, 2010). Fly ash is an abundant waste material from coal power stations in South Africa.…”

Section: Introductionmentioning

confidence: 99%

Fate of sulphate removed during the treatment of circumneutral mine water and acid mine drainage with coal fly ash: Modelling and experimental approach

Madzivire

Gitari

Vadapalli

et al. 2011

Minerals Engineering

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Section: Introductionmentioning

confidence: 99%

Fate of sulphate removed during the treatment of circumneutral mine water and acid mine drainage with coal fly ash: Modelling and experimental approach

Madzivire

Gitari

Vadapalli

et al. 2011

Minerals Engineering

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“…However, the concentrations of Ca, Na, Mg and K increased. Gitari et al [28] found similar results when treating acid mine drainage with fly ash.…”

Section: Treatment Of Industrial Wastewatermentioning

confidence: 75%

“…For instance, Erol et al [46] investigated the capacity of fly ash to remove Cu 2+ and Pb 2+ finding it to be directly proportional to the CaO content, as the dissolution of oxides such CaO and MgO contribute to increasing in solution pH. Gitari et al [28] reported the importance of precipitation reactions in this process in elements such as Mn, Al, Zn and Cu. Bayat [24] found that fly ash with a high soluble calcium oxide content is more effective than fly ash with a low CaO content at equilibrium conditions for removing Ni 2+ , Cu 2+ and Zn 2+ metals due to the formation of Ca and Si complexes such as calcium silicates (2CaO·SiO 2 ).…”

Section: Effect Of Phmentioning

confidence: 99%

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A Case Study of Landfill Leachate Using Coal Bottom Ash for the Removal of Cd2+, Zn2+ and Ni2+

Ayala

Fernández

2016

Metals

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Abstract:The removal of Cd 2+ , Zn 2+ and Ni 2+ by coal bottom ash has been investigated. In single metal system, metal uptake was studied in batch adsorption experiments as a function of pH (2-3), contact time (5-180 min), initial metal concentration (50-400 mg/L), adsorbent concentration (5-40 g/L), particle size, and ionic strength (0-1 M NaCl). Removal percentages of metals ions increased with increasing pH and dosage. Removal efficiency at lower concentrations was greater than at higher values. The maximum amount of metal ion adsorbed in milligrams per gram was 35.4, 35.1 and 34.6 mg/g for Zn 2+ , Cd 2+ and Ni 2+ , respectively, starting out from an initial solution at pH 3. Simultaneous removal of Zn 2+ , Cd 2+ and Ni 2+ ions from ternary systems was also investigated and compared with that from single systems. Cd 2+ uptake was significantly affected by the presence of competing ions at pH 2. The results obtained in the tests with landfill leachate showed that bottom ash is effective in simultaneously removing several heavy metals such as Ni, Zn, Cd, As, Mn, Cu, Co, Se, Hg, Ag, and Pb.

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“…South African coal is sub-bituminous and generates fly ash that is characterized by low Fe content. The aqueous extracts of this fly ash are strongly alkaline (pH 12-12.5) due to the free lime content (Foner et al, 1999;Gitari et al, 2006;Gitari et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Partitioning of major and trace inorganic contaminants in fly ash acid mine drainage derived solid residues

Gitari

Petrik

Key

et al. 2010

Int. J. Environ. Sci. Technol.

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Acid mine drainage was reacted with coal fly ash over a 24 h reaction time and species removal trends evaluated. The evolving process water chemistry was modeled by the geochemical code PHREEQC using WATEQ4 database. Mineralogical analysis of the resulting solid residues was done by X-ray diffraction analysis. Selective sequential extraction was used to evaluate the transfer of species from both acid mine drainage and fly ash to less labile mineral phases that precipitated out. The quantity of fly ash, volume of acid mine drainage in the reaction mixture and reaction time dictated whether the final solution at a given contact time will have a dominant acidic or basic character. Inorganic species removal was dependent on the pH regime generated at a specific reaction time. Sulphate concentration was controlled by precipitation of gypsum, barite, celestite and adsorption on iron-oxy-hydroxides at pH > 5.5. Increase of pH in solution with contact time caused the removal of the metal ions mainly by precipitation, coprecipitation and adsorption. PHREEQC predicted precipitation of iron, aluminium, manganese-bearing phases at pH 5.53-9.12. An amorphous fraction was observed to be the most important in retention of the major and minor species at pH > 6.32. The carbonate fraction was observed to be an important retention pathway at pH 4-5 mainly due to initial local pockets of high alkalinity on surfaces of fly ash particles. Boron was observed to have a strong retention in the carbonate fraction.

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Utilization of fly ash for treatment of coal mines wastewater: Solubility controls on major inorganic contaminants

Cited by 82 publications

References 34 publications

Fate of sulphate removed during the treatment of circumneutral mine water and acid mine drainage with coal fly ash: Modelling and experimental approach

Fate of sulphate removed during the treatment of circumneutral mine water and acid mine drainage with coal fly ash: Modelling and experimental approach

A Case Study of Landfill Leachate Using Coal Bottom Ash for the Removal of Cd2+, Zn2+ and Ni2+

Partitioning of major and trace inorganic contaminants in fly ash acid mine drainage derived solid residues

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