Secunda, South Africa - Sasol is piloting a project that will see it beneficiate sludge from its waste streams into environmentally friendly compost that has the potential to be used to rehabilitate old mine dumps, farmlands, and ash heaps.

Sasol's Secunda complex generates various sludge waste streams produced from its coal-to-liquids (CTL) process. Composting was identified as a sustainable solution to the management of these waste streams. This project will also enable Sasol to sustainably reduce its environmental footprint in line with the objectives of newly promulgated environmental legislations.

While composting of domestic sludges is practised world-wide, composting of industrial waste sludges is a unique concept.

"We are particularly excited about this project," said Dr Sarushen Pillay, Technology Manager: Environment, Group Technology, Sasol.

"We conducted our initial test work in April 2012 on a 30 ton batch of biosludge. This yielded such encouraging results that we decided to go ahead with further trials."

The composting these waste sludges is an intricate process.

Through ongoing research and development, Sola Fidei, which is a small business developed by Sasol's enterprise and supplier development division, has developed a novel method to activate specialised microbial populations (heavy metal composting bacteria) to target, assimilate and biochemically transform the potentially harmful trace elements found in industrial waste sludges into an immobilised and environmentally friendly form.

The process also uses a bulking agent. The compost produced as a result of the process is then used to grow more bulking agent to be used in subsequent batches, making the process a closed loop.

Working in partnership with Sola Fidei, Sasol's Research and Technology team has also established legal and governance processes to ensure compliance with all applicable legislation. Plans are also underway to have the compost legally classified as the quality of compost produced from the biosludges tested to date compares to that of commercial compost.

"Our results show us that we have succeeded in producing  compost that meets the stringent specifications of the Fertilisers, Farm Feeds, Agricultural Remedies and Stock Remedies Act," said Pillay.

"This is the legislation that regulates compost and fertiliser use in South Africa, and is important in laying the foundation for the success of this project."

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