Acid mine drainage (AMD) from Grootvlei Mine in Springs is no longer neutralised in a biological process, using partially treated sewage. A patented co-treatment process was applied to Grootvlei effluent, charged for by Ekurhuleni based East Rand Water Care Company, Erwat, in a test phase from 1998, and on a large scale from 2003 to May 2009.
An effluent co-treatment five year contract ran out and was not renewed by Grootvlei's new owners, Aurora Empowerment Systems.
Before the Rhodes Biosure process was applied, in 1996, the Blesbokspruit was on the Montreux Record in terms of Article 3.2 of the Ramsar Convention, due to mine water pollution. Grootvlei is treating its effluent, but faces funding, organisational and maintenance problems.
Erwat is one of the few sewage water treatment works that have not collapsed, and maintains effluent at a certified 'Green Drop' quality, tested by Ekurhuleni as well as Department of Water Affairs. But Erwat is no longer contributing to removing AMD from Grootvlei effluent.
BIOSURE DESIGNER COMMENTS
Biosure originator, Prof Peter Rose of Rhodes University, commented to Miner's Choice about renewed focus on AMD. "It was clear from numbers crunched in early 1990s that we were heading for disaster.
"Scott's study on the East Rand basin, about 1995, was the main study on this issue. Studies implied we would need sustainable treatment over the long term, or very long term. A biological approach linked to sewage treatment seemed a useful way to go, since electron donor source could be guaranteed as long as people were impacted by AMD."
Other organic donors could work as well, but would probably be more expensive.
Could there be some benefit in incidental mixing of AMD and partially treated, or untreated sewage in streams? "I do not think so, since sulphur would have to be removed at some point to prevent subsequent sulphate cycling," said Prof Rose.
Incidental commingling of the two waste streams are "commonly observed in polluted river systems. You see two differently coloured waters blending, and a white sulphate precipitate appearing immediately downstream."
POLICY FOCUS
Do state authorities acknowledge AMD and sewage problems? "There have been repeated conferences on the topic and DWE regulations do cover the issues," said Prof Rose.
No water authorities have approached Prof Rose, Rhodes University, or Erwat. The Water Research Commission had funded relevant research for several years.
Need, capacity and scope for applying the Rhodes Biosure process exists everywhere anywhere raw sewage and AMD occur relatively close together.
WATER TREATMENT RESEARCH
Licensing costs of the Biosure process is ruled by Erwat, but there have been no applications. Barriers to applying the process include policy, cost, equipment, communication, and awareness. Prof Rose laments "drying up of R&D funding, as the technology moved from experimental to full scale demonstration stage.
COAL AND GOLD WASTE TREATMENT
The process is relevant to coal as well as gold mining effluent, and any mine or industry with sulphidic waste effluent.
Health and environmental risks to water supply services like Rand Water, and the public, if AMD discharge continued at current levels, are high. "Alternative technologies will cost a bomb, and would have to be sustained indefinitely," explained Prof Rose.
Sewage discharge is a less expensive problems, since "effective technology is in place to deal with that problem."
Prof Rose called on industry and policy makers to note the valuable, low cost, sustainable and demonstrated solution, which was "inadequately supported during technology scale up and transfer phases".
SLUDGE VERSUS AMD
The Rhodes Biosure process uses sewage sludge, Instead of expensive carbon and electron donor sources. Sludge is a by-product from Erwat's Ancor water works. The two waste products reacted to improve water quality before discharge into streams, leaving safe and stable bio solids behind.
The technology is "not over complicated to operate, but the application usually has to be tailor made, and is site specific due to local circumstances at different treatment works", Erwat said in response to queries from Miner's Choice.
Erwat's Ancor plant was used to 'polish' effluent water in line with requirements set by Water Affairs.
Sump 740m below surface
Grootvlei, one of the last remaining gold mines in the East Rand basin, has been pumping groundwater from 740 metres below surface for many years, treating this effluent in a high density sludge plant, which mainly removes dissolved irons, and releasing treated water into the Blesbokspruit that runs from Springs, via Nigel.
The mine sump water contains high levels of dissolved salts. Grootvlei had to seek methods to improve its effluent quality. The mine's former owners and Erwat chose the Rhodes Biosure process in the late 1990s.
A two megalitre pilot scale plant was built to test feasibility of specific desalination of Grootvlei's water, and a 10 megalitre full scale plant was started in 1998. The process has since been registered as a patent. Erwat declined to disclose the chemical formulae and process determinants involved.
TWO REACTORS AND CONNECTIONS
The Erwat sewage treatment site used gravity flow between a recycling sludge bed reactor, R1, and a baffle reactor, R2. A neutralised AMD stream from Grootvlei Mine's high density sludge plant was connected to a fresh water supply, using electrical power.
"Test results showed an almost 90% sulphate removal efficiency from AMD water", Erwat told Miner's Choice. "The process was a step towards treating the volume of water discharged, and towards restoring ecology of the stream."
The good work has now come to naught, since co-treatment was stopped.
REDUCING SULPHATES
One of the aims was to remove the Blesbokspruit wetland from the Montreux Record. In terms of Article 3.2 of the Ramsar Convention, the Blesbokspruit Ramsar site in eastern Ekurhuleni was placed on the Montreux Record in 1996, since the ecological character of the wetland was threatened by mine water pollution.
The pioneering, locally developed biological process for treating AMD, was found to be cost effective at reducing sulphates in acid rich mine water, without addition of chemicals.
The co-treatment process removes heavy metals and sulphates, breaks down aromatic pollutants, destroys pathogens, offers an unusually robust biotechnological solution, and renders a waste of safe humus compost.
ALTERNATIVE AMD TREATMENTS
In South Africa, several technologies have been implemented by various university and institutional research groups and private companies, to treat or remediate acid mine drainage.
The major challenge in South Africa is implementation of these technologies at a national level, said Erwat.
"There should be a collaborative network between scientific researchers at various universities, and government policy makers."
Research groups are normally challenged with insufficient funding to take their research from pilot scale studies, to full scale implementation.
Several local technologies have been developed for treating acid mine drainage;
" Reverse osmosis and electrodialysis for sulphate removal
" Lime neutralisation
" Lime stone neutralisation
" Biological metal removal
" Ferrite process for heavy metal removal
" Treatment of acid mine drainage with fly ash
" Biological sulphate removal.
SULPHATE REACTION CHAIN
Acid mine drainage is a multifactor pollutant since heavy metals in the effluent are environmental toxins, threatening biota. Acidic pH disturbs ecological systems in the receiving water streams.
If left untreated, acidic and metallic water could enter groundwater systems, with devastating effects on terrestrial and aquatic ecosystems.
Acid mine drainage is caused by chemical and microbiological factors. The product is a leachate resulting from oxidation of sulphide containing minerals, when exposed to water, air and bacteria.
Sulphate is an important component of acid mine drainage, causing formation of sulphuric acid in receiving water. A chain of chemical reactions lead to formation of sulphuric acid, but the reactions could be interrupted by removing sulphate.
The biological waste driven process to remove sulphate from acid rich mine water was developed by Rhodes University's Environmental Biotechnology Research Unit, with support from Erwat, Water Research Commission, and Biopad.
Sewage co-treatment neutralises acid mine drainage
Acid mine drainage (AMD) from Grootvlei Mine in Springs is no longer neutralised in a biological process, using partially treated sewage. A patented co-treatment process was applied to Grootvlei effluent, charged for by Ekurhuleni based East Rand Water Care
Company, Erwat, in a test phase from 1998, and on a large scale from 2003 to May 2009.
An effluent co-treatment five year contract ran out and was not renewed by Grootvlei's new owners, Aurora Empowerment Systems.
Before the Rhodes Biosure process was applied, in 1996, the Blesbokspruit was on the Montreux Record in terms of Article 3.2 of the Ramsar Convention, due to mine water pollution. Grootvlei is treating its effluent, but faces funding, organisational and maintenance problems.
Erwat is one of the few sewage water treatment works that have not collapsed, and maintains effluent at a certified 'Green Drop' quality, tested by Ekurhuleni as well as Department of Water Affairs. But Erwat is no longer contributing to removing AMD from Grootvlei effluent.
BIOSURE DESIGNER COMMENTS
Biosure originator, Prof Peter Rose of Rhodes University, commented to Miner's Choice about renewed focus on AMD. "It was clear from numbers crunched in early 1990s that we were heading for disaster.
"Scott's study on the East Rand basin, about 1995, was the main study on this issue. Studies implied we would need sustainable treatment over the long term, or very long term. A biological approach linked to sewage treatment seemed a useful way to go, since electron donor source could be guaranteed as long as people were impacted by AMD."
Other organic donors could work as well, but would probably be more expensive.
Could there be some benefit in incidental mixing of AMD and partially treated, or untreated sewage in streams? "I do not think so, since sulphur would have to be removed at some point to prevent subsequent sulphate cycling," said Prof Rose.
Incidental commingling of the two waste streams are "commonly observed in polluted river systems. You see two differently coloured waters blending, and a white sulphate precipitate appearing immediately downstream."
POLICY FOCUS
Do state authorities acknowledge AMD and sewage problems? "There have been repeated conferences on the topic and DWE regulations do cover the issues," said Prof Rose.
No water authorities have approached Prof Rose, Rhodes University, or Erwat. The Water Research Commission had funded relevant research for several years.
Need, capacity and scope for applying the Rhodes Biosure process exists everywhere anywhere raw sewage and AMD occur relatively close together.
WATER TREATMENT RESEARCH
Licensing costs of the Biosure process is ruled by Erwat, but there have been no applications. Barriers to applying the process include policy, cost, equipment, communication, and awareness. Prof Rose laments "drying up of R&D funding, as the technology moved from experimental to full scale demonstration stage.
COAL AND GOLD WASTE TREATMENT
The process is relevant to coal as well as gold mining effluent, and any mine or industry with sulphidic waste effluent.
Health and environmental risks to water supply services like Rand Water, and the public, if AMD discharge continued at current levels, are high. "Alternative technologies will cost a bomb, and would have to be sustained indefinitely," explained Prof Rose.
Sewage discharge is a less expensive problems, since "effective technology is in place to deal with that problem."
Prof Rose called on industry and policy makers to note the valuable, low cost, sustainable and demonstrated solution, which was "inadequately supported during technology scale up and transfer phases".
SLUDGE VERSUS AMD
The Rhodes Biosure process uses sewage sludge, Instead of expensive carbon and electron donor sources. Sludge is a by-product from Erwat's Ancor water works. The two waste products reacted to improve water quality before discharge into streams, leaving safe and stable bio solids behind.
The technology is "not over complicated to operate, but the application usually has to be tailor made, and is site specific due to local circumstances at different treatment works", Erwat said in response to queries from Miner's Choice.
Erwat's Ancor plant was used to 'polish' effluent water in line with requirements set by Water Affairs.
Sump 740m below surface
Grootvlei, one of the last remaining gold mines in the East Rand basin, has been pumping groundwater from 740 metres below surface for many years, treating this effluent in a high density sludge plant, which mainly removes dissolved irons, and releasing treated water into the Blesbokspruit that runs from Springs, via Nigel.
The mine sump water contains high levels of dissolved salts. Grootvlei had to seek methods to improve its effluent quality. The mine's former owners and Erwat chose the Rhodes Biosure process in the late 1990s.
A two megalitre pilot scale plant was built to test feasibility of specific desalination of Grootvlei's water, and a 10 megalitre full scale plant was started in 1998. The process has since been registered as a patent. Erwat declined to disclose the chemical formulae and process determinants involved.
TWO REACTORS AND CONNECTIONS
The Erwat sewage treatment site used gravity flow between a recycling sludge bed reactor, R1, and a baffle reactor, R2. A neutralised AMD stream from Grootvlei Mine's high density sludge plant was connected to a fresh water supply, using electrical power.
"Test results showed an almost 90% sulphate removal efficiency from AMD water", Erwat told Miner's Choice. "The process was a step towards treating the volume of water discharged, and towards restoring ecology of the stream."
The good work has now come to naught, since co-treatment was stopped.
REDUCING SULPHATES
One of the aims was to remove the Blesbokspruit wetland from the Montreux Record. In terms of Article 3.2 of the Ramsar Convention, the Blesbokspruit Ramsar site in eastern Ekurhuleni was placed on the Montreux Record in 1996, since the ecological character of the wetland was threatened by mine water pollution.
The pioneering, locally developed biological process for treating AMD, was found to be cost effective at reducing sulphates in acid rich mine water, without addition of chemicals.
The co-treatment process removes heavy metals and sulphates, breaks down aromatic pollutants, destroys pathogens, offers an unusually robust biotechnological solution, and renders a waste of safe humus compost.
ALTERNATIVE AMD TREATMENTS
In South Africa, several technologies have been implemented by various university and institutional research groups and private companies, to treat or remediate acid mine drainage.
The major challenge in South Africa is implementation of these technologies at a national level, said Erwat.
"There should be a collaborative network between scientific researchers at various universities, and government policy makers."
Research groups are normally challenged with insufficient funding to take their research from pilot scale studies, to full scale implementation.
Several local technologies have been developed for treating acid mine drainage;
" Reverse osmosis and electrodialysis for sulphate removal
" Lime neutralisation
" Lime stone neutralisation
" Biological metal removal
" Ferrite process for heavy metal removal
" Treatment of acid mine drainage with fly ash
" Biological sulphate removal.
SULPHATE REACTION CHAIN
Acid mine drainage is a multifactor pollutant since heavy metals in the effluent are environmental toxins, threatening biota. Acidic pH disturbs ecological systems in the receiving water streams.
If left untreated, acidic and metallic water could enter groundwater systems, with devastating effects on terrestrial and aquatic ecosystems.
Acid mine drainage is caused by chemical and microbiological factors. The product is a leachate resulting from oxidation of sulphide containing minerals, when exposed to water, air and bacteria.
Sulphate is an important component of acid mine drainage, causing formation of sulphuric acid in receiving water. A chain of chemical reactions lead to formation of sulphuric acid, but the reactions could be interrupted by removing sulphate.
The biological waste driven process to remove sulphate from acid rich mine water was developed by Rhodes University's Environmental Biotechnology Research Unit, with support from Erwat, Water Research Commission, and Biopad.
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