Posted on November 20, 2013

Sasol, the international integrated energy and chemical company and General Electric’s GE Power & Water have collaborated to develop a breakthrough technology that will clean waste water from Fischer-Tropsch plants used to produce synthetic fuels and chemicals, while also providing biogas as a by-product for power generation. The new Anaerobic Membrane Bioreactor Technology (AnMBR) will be further developed at a new demonstration plant at Sasol’s R&D Campus at its Sasol One Site in Sasolburg, South Africa.

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. Sasol currently uses aerobic microbes to treat GTL and coal-to-liquids (CTL) effluents in ORYX GTL plant at Qatar and Sasol Synfuels plant at South Africa, respectively.

One of the by-products from the Fischer-Tropsch (FT) process is an effluent stream rich in organic acids and alcohols. Traditional (aerobic) treatment technologies treat this effluent by converting the organics to carbon dioxide.

The anaerobes used in AnMBR break down the complex organics to simpler building blocks such as sugars that provide food to the micro-organisms. The waste produced is a methane-rich bio-gas which can then be used for power generation. This then results in an overall efficiency improvement in the GTL process.

The organics in waste water generated from our operations have proven to be the ideal food, or substrate, for anaerobic micro-organisms. We will now continue to explore and develop this technology further with the potential for commercial application to our future GTL facilities. Said Thulani Dlamini, Executive Manager Research and Development at Sasol Technology

By converting the effluents to a valuable product (power) there is a resulting improvement in the GTL value proposition. Another benefit of the AnMBR is that it produces almost 80% less waste biosolids than the previous generation process.

(L-R) Tim Schweikert - CEO GE South Africa, Flip de Wet - Managing Director of Sasol Technology, Henri Loubser - Managing Director Sasol New Energy at the official opening of the demonstration plant at Sasol's R&D facilities in Sasolburg, South Africa.

The treatment of GTL-derived effluents is complex and challenging. Sasol pioneered the treatment of effluents from the GTL process used at ORYX GTL in Ras Laffan, Qatar, where effluents are treated and recycled for use as irrigation water in the city of Ras Laffan.

Sasol’s second-generation offering, which is currently being designed for the US GTL facility, is the aerobic Membrane Bioreactor (MBR). The AnMBR helps maintain Sasol’s leadership position in this field by converting wastes into value-adding products.

Ernst Obersholster, Sasol Group Executive for International Energy, New Business Development and Technology, commented “This is another exciting technological innovation that will further entrench our position as a world-leader in gas-to-liquids (GTL) technology and synthetic fuels production. While sophisticated water treatment technologies are already employed at Sasol’s major operations, this particular development will enhance our efficiency even further.”

The partnership with GE is aimed at leveraging GE’s ecomagination qualified ZeeWeed 500 membrane and decades of membrane bioreactor experience with Sasol’s expertise in biological treatment of FT derived effluents.

Bench scale test work has been on-going for the past year with promising results and with the construction of a pilot plant at Sasol’s R&D facilities this improves the potential for commercialization of this technology.

Sasol anticipates that the technology will be commercially ready early in 2015. Sasol will have exclusive rights to apply this technology to FT-based plants whilst GE will have the right to market the technology for other industrial uses.