Increased focus on water technology and conservation

Owing to energy and chemicals company Sasol’s water-conservation partnership with the Emfuleni municipality, 4.76-million cubic metres of water, valued at about R26-million, has been saved in the past year.

Speaking during the company’s financial results announcement last month at Sasol’s head office in Rosebank, Johannesburg, Sasol president and CEO David Constable highlighted that multiple leaks had been repaired at 114 000 households and 94 schools over the past two years.

He noted that repairing these leaks had resulted in water conservation improvements equating to the water use of 16 000 households during a year, or 22% of Sasol’s Sasolburg facility’s yearly raw-water needs.

Constable pointed out that the company had also been advancing in terms of energy efficiency.

“In this financial year, we intensified efforts to improve energy efficiency management and operating practices. As a result, the utility energy intensity index for Sasol South Africa improved by a further 3%, up from the 6% improvement achieved in the previous financial year,” he added.

These improvements allowed for the curbing of Sasol’s overall South African process operations’ energy cost increases to below the energy inflation rate.

Constable said the company’s greenhouse-gas emissions decreased to 70.5- million tons in this financial year, with plans in place to reduce this amount by a further one- million tons by 2020.

Anaerobic Membrane Bioreactor Technology
Sasol and power generation and water technologies provider General Electric Power & Water (GE) have developed the new anaerobic membrane bioreactor (AnMBR) water technology, which will clean wastewater while providing biogas as a by-product for power generation.

The technology will be further developed at a new demonstration plant at Sasol’s research and development campus at its Sasol One site, in Sasolburg.

“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 employed at Sasol’s major operations, this particular development will enhance our efficiency even further,” says Sasol new business development and technology executive Ernst Oberholster.

GE South Africa president and CEO Tim Schweikert says: “GE is excited to be partnering with Sasol on this initiative, which further outlines our commitment to supporting the sustainable development of South Africa with advanced infrastructure technologies, services and solutions.”

He adds that this partnership demonstrates what the private sector can achieve by working together to grow the economy and make it competitive.

AnMBR technology involves anaerobic microorganisms that can live in environments devoid of oxygen, such as the sediment layers on floors of lakes, dams and the ocean. These organisms are ubiquitous, as they are also found in the human digestive system, under the earth’s surface, in deserts and on mountain peaks, to name a few.

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

AnMBR technology is beneficial because the microorganisms convert these organisms into a methane-rich biogas, which can be used for power generation.

This results in an overall efficiency improvement in the GTL process. By converting the effluents into a valuable product – power – there is a resulting improvement in the GTL value proposition. Another benefit of the technology is that it produces almost 80% less waste in terms of biosolids than the previous generation process.

Sasol pioneered the treatment of effluents from the GTL process in Ras Laffan, Qatar, where effluents are treated and recycled for use as irrigation water.

The first-generation AnMBR helps maintain Sasol’s leadership position in this field by converting waste into value-adding products.

“The organisms in wastewater generated from our operations have proven to be the ideal food, or substrate, for anaerobic microorganisms,” says Sasol Technology research and development executive manager Thulani Dlamini.

“We will continue to explore and develop this technology further, with the potential for commercial application to our future GTL facilities,” he adds.

Sasol has been developing the AnMBR technology for several years with promising results. The partnership with GE aims to leverage GE’s ZeeWeed 500 membrane and decades of membrane bioreactor experience, as well as Sasol’s expertise in biological treatment of FT-derived effluents.

“The AnMBR technology is one of the many solutions that can be developed in the petrochemicals and refining environment to benefit all other industries,” says GE account executive Daniele Scenarelli.

He adds that this strategic partnership, which was signed in 2010, symbolises “a new way of doing business between customers and suppliers”.

Scenarelli notes that the partnership is a collaborative approach and a mutual commitment to technology development and innovation to accelerate the commercialisation of the new technology.

It is expected that the AnMBR technology will be commercially ready in early 2015.

Sasol will have exclusive rights to apply this technology to FT-based plants, while GE will have the right to market the technology for other industrial uses.