Addressing the liquid waste ban

In anticipation of the changing legislation around the disposal of liquid waste at landfill, new innovations have sought to minimise the impacts of the disposal of wastes with a high moisture content.

Embracing the legislation promoting more sustainable and environmentally acceptable waste management practices, EnviroServ has taken steps to provide customers with legally compliant solutions.

The company recently unveiled its new micro encapsulation plant at its Holfontein Waste Management Facility in Gauteng. Similar to a cement batching plant, the plant’s end product is an immobile solid that easily complies with the norms and standards for landfill disposal.

“We knew the prohibition on disposal of highmoisture-content wastes to landfill was coming into effect in August 2019, so we started trialling various options to treat these problematic materials and turn them into immobile solids a few years ago,” says Terence Malan, national technical manager, EnviroServ.

“We have been working on various iterations, but it all came together last month [April 2020] with the latest upgrades to the plant being a shed to house the ash.”

Plant capabilities

The process starts with obtaining a waste sample from a customer, which is analysed in EnviroServ’s in-house laboratory. A recipe for treating the moisture content in the waste by converting the waste into an immobile solid that complies with legislation is then developed.

“Power station ash is a primary ingredient used in the blending process and this, together with other proprietary additives, absorbs the moisture, creating a stabilised and solidified waste material. We use front-end loaders to load the ash into feed bins.

“Conveyer belts control the rate at which the ash is added into the mix. The ash, together with other additives, is mixed with the high-moisture waste in the feed hopper. The combined mix drops down into the pugmill, which mixes the materials into a slurry,” explains Malan. Additives such as cement and lime, among others, are added into the mix to aid absorption and immobilisation of salts and moisture in the waste.

The pugmill discharges the stabilised waste into the bunker from where it is loaded on to trucks and transported to the landfill cell for disposal. The micro encapsulation plant is capable of treating approximately 1 000 m³ of waste per day.

“Any business that produces wastes of high moisture or salt content that are no longer suitable for traditional landfill disposal – including industries such as petrochemical, metallurgical and water treatment facilities – can potentially utilise the micro encapsulation plant, which can treat a multitude of problematic wastes,” says Malan.