Leading water and wastewater experts Veolia Water Solutions and Technologies South Africa, a subsidiary of Veolia Water Solutions & Technologies, partnered with KV3 Civil Engineers in a R100 million project to make the Tubatse Ferrochrome smelter in Steelpoort a zero effluent plant aimed at conserving the water in the Steelpoort River by assisting the reuse of wastewater without the risk of salinating process water. This was accomplished through the use of novel process designs and equipment supplied by Veolia Water Solutions & Technologies South Africa.
The plant treats all water outflow on the smelter's site, including industrial storm water, contaminated groundwater, treated sewage water and industrial effluent containing a high concentration of dissolved salts.
According to Frank Rosslee, Engineering Manager, Tubatse Ferrochrome, the true value of this plant lies in the fact that by treating the contaminated groundwater and other wastewater sources, a large volume of water is re-used, without releasing anything harmful into the surrounding environment. "The added environmental gain from the project is that the volume of water that the smelter needs to extract from the Steelpoort River is reduced, which translates into more fresh water for the residents in the fast developing rural areas downstream," he says."The plant is evidence of Samancor Chrome's unfailing commitment to environmental conservation and the future well-being of its surrounding communities."
Rosslee notes that the added advantage to the smelter is that its process water quality has improved considerably, which assists in enhancing the life expectancy of all its major process equipment. "Most components in the smelting process have to be water cooled and harsh water can cause damage due to corrosion, embrittlement, stress corrosion cracking, chemical deposition, fouling, organic growth and other negative effects of dirty and saline process water."
Gunter Rencken, Managing Director, Veolia Water Solutions & Technologies South Africa, says that the plant, modelled on the successful ZLD plant designed and constructed by the company for ArcelorMittal in 2006, has the capacity to treat 5 000 cubic metres of water per day."The basic processes that the wastewater and groundwater are subjected to include adding ferrous chloride, removing silt and oil residue, clarification, ultra-filtration, reverse osmosis and a combination of thermal and solar evaporation."
The plant captures all industrial storm water on site and channels it via a silt-trap to an HDPE lined storm water dam capable of holding 35 000 cubic metres of storm water with a spill frequency of less than 1 percent.The storm water, considered contaminated due to having fallen within the industrial area, is stored and treated for use by the plant as process water.It is fed to the water treatment plant at a rate of 1 000 cubic metres per day and assists in reducing river water extraction during the rainy season.
The plant process-effluent water is routed from the plant via an automated self-cleaning silt trap to the water treatment plant balancing dam, while the sewage water is piped to the plant's own licensed sewage treatment works from where the treated effluent flows to the water treatment plant balancing dam. The contaminated groundwater is evenly extracted from eight boreholes situated over the spread of the aquifer, and is pumped directly into the water treatment plant balancing dam.
The four sources of water are fed from a balancing dam into Veolia Water Solutions & Technologies' patented high rate package plant Actiflo® clarifiers, which are configured to remove all suspended solids and some precipitated salts.
A portion of the clarified water flows to the clean water dam for reuse by the smelter, while the remainder of the water flows to the desalination section of the plant.
The desalination stream is first filtered through MyCelx® bag-type oil filters, from US-based company MyCelx, to remove oil slick before passing through a process of ultra-filtration, where all the ultra-fine suspended solids and most of the fouling potential in the water are removed for protection of the reverse osmosis membranes in the next process step.
Thereafter, the water is filtered through cartridge-type MyCelx® filters to remove any remaining traces of oil. The water is then desalinated through cellulose acetate reverse osmosis membranes.The high concentration brine remains in the plant, while the desalinated water flows to the clean water dam for re-use as process water in the smelter.The reverse osmosis equipment was locally manufactured by Veolia Water Solutions & Technologies South Africa at their manufacturing facilities in the Western Cape.
Two mechanical vapour compression (MVR) evaporators, supplied by Veolia Water Solutions & Technologies South Africa, are used to concentrate the brine in order to reduce the volume of brine waste water and therefore the surface area of the final evaporation ponds, where the brine is stored. The MVR LED evaporators are standard modular package type plants manufactured by VWS in Italy.
The plant has high quality process water as product and generates three waste streams. The first waste stream is harmless silt from the silt traps that is stored on the smelter's registered waste dumps. The second stream of waste is the sludge from the clarifier units, which is pressed to a stackable cake by two belt filter presses.This sludge contains no harmful chemical compounds and is also stored on the smelter's registered waste dumps.
The third stream of waste is the hyper-concentrated brine that retains 1.5 tons of salt per day. The brine is stored in triple skin HDPE lined dams with double leak detection where it is allowed to solidify through natural evaporation.None of the salts is poisonous and can be harvested as cattle-lick or raw material feed for other industries.
Rencken concludes that the Tubatse Ferrochrome water treatment plant will assist the client in minimising its impact on the environment, while still operating efficiently and cost-effectively, something that forms the core of Veolia Water Solutions & Technologies South Africa's business philosophy.
The plant was commissioned in November 2010.
Veolia Water Solutions & Technologies South Africa is a Veolia Water Solutions & Technologies entity. Veolia Water Solutions & Technologies(VWS), subsidiary of Veolia Water, is a leading design & build company and a specialized provider of technological solutions in water treatment. With over 9,500 employees in 57 countries, Veolia Water Solutions & Technologies recorded revenue of €2.5 billion Euros in 2009. Veolia Water, the water division of Veolia Environnement, is the world leader in water and wastewater services. Specialized in outsourcing services for municipal authorities, as well as industrial and service companies, Veolia Water provides water service to 95 million people and wastewater service to 66 million. With 95,789 employees in 66 countries, its 2009 revenue amounted to €12.5 billion.
Veolia Water Solutions & Technologies South Africa is a Veolia Water Solutions & Technologies entity.
Veolia Water Solutions & Technologies(VWS), subsidiary of Veolia Water, is a leading design & build company and a specialized provider of technological solutions in water treatment. With over 9,500 employees in 57 countries, Veolia Water Solutions & Technologies recorded revenue of €2.5 billion Euros in 2009.
Veolia Water, the water division of Veolia Environnement, is the world leader in water and wastewater services. Specialized in outsourcing services for municipal authorities, as well as industrial and service companies, Veolia Water provides water service to 95 million people and wastewater service to 66 million. With 95,789 employees in 66 countries, its 2009 revenue amounted to €12.5 billion.
For more information, please contact us:
Veolia Water Solutions & Technologies South Africa (Pty) Ltd
Tel: +27 11 663 3600
Fax: +27 11 608 4772