Investigation into the technical feasibility of biological treatment of precious metal refining wastewater
- Authors: Moore, Bronwyn Ann
- Date: 2013
- Subjects: Sewage -- Purification -- Biological treatment -- South Africa Sewage -- Purification -- Activated sludge process -- South Africa Water reuse -- South Africa Flotation -- South Africa Platinum mines and mining -- Waste disposal -- South Africa Platinum mines and mining -- Economic aspects -- South Africa Mine water -- Environmental aspects -- South Africa Platinum mines and mining -- Waste minimization -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3888 , http://hdl.handle.net/10962/d1002013
- Description: The hydrometallurgical refining of platinum group metals results in large volumes of liquid waste that requires suitable treatment before any disposal can be contemplated. The wastewater streams are characterized by extremes of pH, high inorganic ion content (such as chloride), significant residual metal loads and small amounts of entrained organic compounds. Historically these effluents were housed in evaporation reservoirs, however lack of space and growing water demands have led Anglo Platinum to consider treatment of these effluents. The aim of this study was to investigate whether biological wastewater treatment could produce water suitable for onsite reuse. Bench-scale activated sludge and anaerobic digestion for co-treatment of an acidic refinery waste stream with domestic wastewater were used to give preliminary data. Activated sludge showed better water treatment at lab scale in terms of removal efficiencies of ammonia (approximately 25%, cf. 20% in anaerobic digestion) and COD (70% cf. 43% in digestion) and greater robustness when biomass health was compared. Activated sludge was consequently selected for a pilot plant trial. The pilot plant was operated on-site and performed comparably with the bench-scale system, however challenges in the clarifier design led to losses of biomass and poor effluent quality (suspended solids washout). The pilot plant was unable to alter the pH of the feed, but a two week maturation period resulted in the pH increasing from 5.3 to 7.0. Tests on algal treatment as an alternative or follow-on unit operation to activated sludge showed it not to be a viable process. The activated sludge effluent was assessed for onsite reuse in flotation and it was found that there was no significant difference between its flotation performance and that of the process water currently used, indicating the effluent generated by the biological treatment system can be used successfully for flotation. Flotation is the method whereby minerals refining operations recover minerals of interest from ore through the addition of chemicals and aeration of the ore slurry. Target minerals adhere to the bubbles and can be removed from the process.
- Full Text:
- Date Issued: 2013
- Authors: Moore, Bronwyn Ann
- Date: 2013
- Subjects: Sewage -- Purification -- Biological treatment -- South Africa Sewage -- Purification -- Activated sludge process -- South Africa Water reuse -- South Africa Flotation -- South Africa Platinum mines and mining -- Waste disposal -- South Africa Platinum mines and mining -- Economic aspects -- South Africa Mine water -- Environmental aspects -- South Africa Platinum mines and mining -- Waste minimization -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3888 , http://hdl.handle.net/10962/d1002013
- Description: The hydrometallurgical refining of platinum group metals results in large volumes of liquid waste that requires suitable treatment before any disposal can be contemplated. The wastewater streams are characterized by extremes of pH, high inorganic ion content (such as chloride), significant residual metal loads and small amounts of entrained organic compounds. Historically these effluents were housed in evaporation reservoirs, however lack of space and growing water demands have led Anglo Platinum to consider treatment of these effluents. The aim of this study was to investigate whether biological wastewater treatment could produce water suitable for onsite reuse. Bench-scale activated sludge and anaerobic digestion for co-treatment of an acidic refinery waste stream with domestic wastewater were used to give preliminary data. Activated sludge showed better water treatment at lab scale in terms of removal efficiencies of ammonia (approximately 25%, cf. 20% in anaerobic digestion) and COD (70% cf. 43% in digestion) and greater robustness when biomass health was compared. Activated sludge was consequently selected for a pilot plant trial. The pilot plant was operated on-site and performed comparably with the bench-scale system, however challenges in the clarifier design led to losses of biomass and poor effluent quality (suspended solids washout). The pilot plant was unable to alter the pH of the feed, but a two week maturation period resulted in the pH increasing from 5.3 to 7.0. Tests on algal treatment as an alternative or follow-on unit operation to activated sludge showed it not to be a viable process. The activated sludge effluent was assessed for onsite reuse in flotation and it was found that there was no significant difference between its flotation performance and that of the process water currently used, indicating the effluent generated by the biological treatment system can be used successfully for flotation. Flotation is the method whereby minerals refining operations recover minerals of interest from ore through the addition of chemicals and aeration of the ore slurry. Target minerals adhere to the bubbles and can be removed from the process.
- Full Text:
- Date Issued: 2013
Metal bioaccumulation and precious metal refinery wastewater treatment by phoma glomerata
- Authors: Moore, Bronwyn Ann
- Date: 2008-03-18
- Subjects: Metals -- Bioaccumulation , Water purification -- South Africa , Metal ions , Water -- Purification -- Biological treatment -- South Africa , Water quality management -- South Africa , Factory and trade waste -- Purification -- South Africa , Metals -- Refining , Hyperaccumulator plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4097 , http://hdl.handle.net/10962/d1009441 , Metals -- Bioaccumulation , Water purification -- South Africa , Metal ions , Water -- Purification -- Biological treatment -- South Africa , Water quality management -- South Africa , Factory and trade waste -- Purification -- South Africa , Metals -- Refining , Hyperaccumulator plants
- Description: The biosorption of copper, nickel, gold and platinum from single metal aqueous solutions by the nickel hyperaccumulator Berkheya coddii plant biomass was investigated. Potentiometric titrations of the biomass and determination of optimal sorption pH for each metal showed that nickel ions were released from the biomass into solution. The presence of free nickel ions interfered with the uptake of the other three metals and further biosorption investigations were discontinued. Three fungal isolates found colonising metal solutions were cultured and screened for their ability to remove 50 mg.l⁻¹ of copper, nickel, gold and platinum from solution and to survive and grow in precious metal refinery wastewaters. One isolate was selected for further studies based on its superior metal uptake capabilities (35 and 39 mg.l⁻¹ of gold and platinum, respectively) and was identified as Phoma glomerata. Copper, nickel, gold and platinum uptake studies revealed that nickel and gold were the most toxic metal ions, however, toxicity was dependent on pH. At pH 6 more biomass growth was achieved than at lower pH values and metal uptake increased by 51 and 17 % for copper and nickel, respectively. In addition, the production of extracellular polymeric substances played a role in base metal interaction. Precious metals were observed to be preferentially removed from solution, complete removal of gold and platinum was observed at all initial pH values, 89 % of copper was bioaccumulated at an initial metal concentration of 55 mg.l⁻¹ (pH 6) and only 23 % of nickel was removed from solution under the same conditions. Metal bioaccumulation was confirmed through transmission electron microscopy and micro particle induced X-ray emission. The effect of P. glomerata immobilised in a packed bed reactor on precious metal refinery wastewaters was investigated. It was found that the fungal isolate was not able to remove the high salt and chemical oxygen demand concentrations found in the wastewaters, however due to its ability to survive and grow in undiluted wastewater and remove metal ions from solution it may be utilised as a metal detoxification step in the treatment process train. , PDFCreator Version 0.9.0 , AFPL Ghostscript 8.53
- Full Text:
- Authors: Moore, Bronwyn Ann
- Date: 2008-03-18
- Subjects: Metals -- Bioaccumulation , Water purification -- South Africa , Metal ions , Water -- Purification -- Biological treatment -- South Africa , Water quality management -- South Africa , Factory and trade waste -- Purification -- South Africa , Metals -- Refining , Hyperaccumulator plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4097 , http://hdl.handle.net/10962/d1009441 , Metals -- Bioaccumulation , Water purification -- South Africa , Metal ions , Water -- Purification -- Biological treatment -- South Africa , Water quality management -- South Africa , Factory and trade waste -- Purification -- South Africa , Metals -- Refining , Hyperaccumulator plants
- Description: The biosorption of copper, nickel, gold and platinum from single metal aqueous solutions by the nickel hyperaccumulator Berkheya coddii plant biomass was investigated. Potentiometric titrations of the biomass and determination of optimal sorption pH for each metal showed that nickel ions were released from the biomass into solution. The presence of free nickel ions interfered with the uptake of the other three metals and further biosorption investigations were discontinued. Three fungal isolates found colonising metal solutions were cultured and screened for their ability to remove 50 mg.l⁻¹ of copper, nickel, gold and platinum from solution and to survive and grow in precious metal refinery wastewaters. One isolate was selected for further studies based on its superior metal uptake capabilities (35 and 39 mg.l⁻¹ of gold and platinum, respectively) and was identified as Phoma glomerata. Copper, nickel, gold and platinum uptake studies revealed that nickel and gold were the most toxic metal ions, however, toxicity was dependent on pH. At pH 6 more biomass growth was achieved than at lower pH values and metal uptake increased by 51 and 17 % for copper and nickel, respectively. In addition, the production of extracellular polymeric substances played a role in base metal interaction. Precious metals were observed to be preferentially removed from solution, complete removal of gold and platinum was observed at all initial pH values, 89 % of copper was bioaccumulated at an initial metal concentration of 55 mg.l⁻¹ (pH 6) and only 23 % of nickel was removed from solution under the same conditions. Metal bioaccumulation was confirmed through transmission electron microscopy and micro particle induced X-ray emission. The effect of P. glomerata immobilised in a packed bed reactor on precious metal refinery wastewaters was investigated. It was found that the fungal isolate was not able to remove the high salt and chemical oxygen demand concentrations found in the wastewaters, however due to its ability to survive and grow in undiluted wastewater and remove metal ions from solution it may be utilised as a metal detoxification step in the treatment process train. , PDFCreator Version 0.9.0 , AFPL Ghostscript 8.53
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