Global Innovation Exchange Challenge: Accelerate the Concentration of Water Treatment Residue

Rand Water is actively looking for solutions which can rapidly and effectively remove water from Water Treatment Residue at their treatment facility.

Solutions are invited from, but not limited to, the following sectors:

• Agricultural sector
• Engineering and Design
• Chemical Sector
• Construction & Infrastructure
• Materials
• Mining

Rand Water, the largest water utility company in Africa, is based in South Africa and supplies drinking water to the Gauteng province and other areas of the country. They process and purify large volumes of water.

Rand Water Institute has focus areas for its innovation and R&D activities. One of these priorities is to utilize Circular economy thinking to encompass sludge beneficiation, waste beneficiation, water security and resiliency, and water reuse.

Disposal of Water Treatment Residue (WTR) is a universal problem with growing environmental awareness and subsequent legislative requirements. Rand Water’s situation is unique in that the nature of the raw water, the treatment process used and the significant volumes of water being processed results in the production of a very large mass of WTR.

The  WTR, created at Zuikerbosch and Vereeniging water treatment works is combined at Zuikerbosch and dried at the nearby facility of Panfontein. This is dried in stages, coming in at c. 1-2% solids, which is increased to 16-20% solids using gravity thickeners, and then sprayed into large earth beds where moisture both percolates and evaporates, leaving 75-100% dry matter. This ongoing process produces about 500-600 tonnes of residue per day (expressed as dry material). Due to the nature of the process (waste streams are combined from 2 different plants plus natural variations) this residue has variable compositions of primarily inorganic and lesser organic constituents.

The drying facilities are close to capacity and sustainable innovative solutions with minimal environmental impact for the dewatering process are needed. Rand Water is particularly interested in solutions which address circularity, water security and resilience, and water reuse.

Panfontein is permitted as a hazardous waste disposal site, with conditions of the permit that any disposal options are to be approved by relevant authorities. Previously, Rand Water’s WTR was approved for use as a ground improvement agent only. The vast bulk of WTR remains in the drying bed, and subsequent layers are added until the beds have reached capacity. The storage and logistical requirements of the facility require various logistical operations to be undertaken, e.g.: shifting to other locations if needed.

Panfontein is road accessible with mostly dirt roads within the site. There are 90 drying beds in total ranging in area from  2-3 hectares each with 1.5-4.0 m high sides.

Rand Water is looking for innovative solutions, which are sustainable and environmentally friendly, to accelerate the WTR drying process and preferably allow for recovery of water for reuse. These solutions may create an intervention at any stage of the treatment process prior to sedimentation, or at the Panfontein disposal site itself.

Rewards & Benefits