Sasol – bioremediation of industrial sludge

Sasol’s industrial sludge bioremediation project will move into full commercial scale over the next two years and will have the capacity to treat its 200 000 t/y of industrial sludge. The projects makes use of aerobic composting to convert sludges from Sasol’s Bioworks water treatment plant in Secunda into fertilisers, which would be used for the growing sugar graze. The process was designed to be labour intensive and the full scale project would provide employment for 150 people in the community.

Sludges were previously disposed of either by incineration or it was sent to a hazardous waste site, in compliance with the Air Quality Act and the National Waste Act. Dr Sarushen Pillay – Environmental Manager at Sasol Technology, explained that since the development of the bioremediation process the Secunda plant is a zero-effluent plant. The bioremediation process was developed as a means to reduce energy consumption for the incineration process and the cost of waste disposal.

Pillay said: “This bioremediation process, which will use 200 000 t/y of sugar graze to convert 200 000 t/y of sludges into 80 000 t/y of fertiliser, will reduce our energy consumption and costs for waste disposal.”

“We have designed and tested this process over two years. Our sugar graze growing lands were monitored prior to and after being dosed with the fertilisers, and our results show an improvement in soil conditions.”

“Sasol will use 2 000 ha of land, dosed with this bioremediated fertiliser, around its Secunda plant to grow the sugar graze. The land is not currently under cultivation.”

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