7 November 2013
A new water technology that not only cleans waste water but produces biogas that can be used to generate power as a by-product is being piloted in South Africa.
This new technology, known as anaerobic membrane bioreactor technology (AnMBR), is being developed by South African petrochemicals company Sasol and US electrical services firm General Electric. While it has been applied to other waste water streams, Sasol will be the first to do so in a gas-to-liquids (GTL) environment.
The technology is being refined at a new demonstration plant at Sasol’s R&D Campus in Sasolburg in the Free State. Sasol is the world’s biggest producer of motor fuel from coal.
The companies said in a statement on Wednesday that they expect the technology to be commercially ready by early in 2015. Sasol will have exclusive rights to apply this technology to its Fischer-Tropsch plants, while GE will have the right to market the technology for other industrial uses.
As a chemicals company, Sasol is a water-intensive operation. This development will help it save water – as well as “limit the negative impact that South Africa’s water scarcity is having on the economy”, the companies said in a statement.
“While sophisticated water-treatment technologies are already employed at Sasol’s major operations, this particular development will enhance our efficiency even further,” said Ernst Obersholster, Sasol group executive for international energy, new business development and technology.
How does it work?
AnMBR involves anaerobic micro-organisms that are able to live in environments devoid of oxygen, such as sediment layers on floors of lakes, dams and the ocean. These organisms are found everywhere – from the human digestive system, to under the earth’s surface.
Sasol currently uses aerobic microbes to treat the effluents in many of its facilities as the Fischer-Tropsch process produces a stream rich in organic acids and alcohols. But while “traditional” aerobic-treatment technologies treat the effluent by converting the organic materials into carbon dioxide, the AnMBR technology converts them into a methane-rich biogas. This, in turn, can be used for power generation.
Another benefit of the AnMBR is that it produces almost 80% less waste bio-solids than the previous generation process.
“The organics in waste water generated from our operations have proven to be the ideal food, or substrate, for Anaerobic micro-organisms,” said Thulani Dlamini, executive manager for research and development at Sasol Technology. “We will now continue to explore and develop this technology further with the potential for commercial application to our future GTL facilities.”
While it has been developed in the petrochemical and refining environment, the AnMBR technology can also be used in other industries.