Innovative Solutions to Beneficiation of Water Treatment Residue

This Innovation Exchange challenge, delivered by Innovate UK KTN through the Global Alliance Africa project, is supporting Rand Water to identify innovative solutions for the utilisation of water treatment residue. The residue consists of suspended material and compounds formed when coagulants are added during the treatment process. The chemical compounds within WTR have potential market value without modification, or via separation or combination with additional materials. An innovative beneficiation solution will lead to waste being transformed into products and services with commercial value.


Challenge opens


Challenge closes



Successful applicants will be given the opportunity to pitch their solution to Rand Water. The winning applicant, as selected by Rand Water, will get the opportunity to collaborate with them on a trial project. Up to GBP 25,000 seed funding is available to the successful finalist/s for this collaboration.

The Challenge

Rand Water is looking for solutions which can transform large volumes of dry/semi-dry/wet water treatment residue at their treatment facility into products or services with commercial value. 

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.

Panfontein is permitted as a hazardous waste disposal site, with conditions of the permit such that any disposal options are to be approved by relevant authorities. The vast bulk of WTR remains in the bed, and subsequent layers are added till the beds have reached capacity. The storage and logistical requirements of the facility require various logistical operations to be undertaken, eg: 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 utilise this dry water treatment residue. The process of recovering value is known as  Beneficiation and the process of generating new value is Valorisation. Both of these concepts are applicable to this challenge. Previous uses considered for WTR have been for soil beneficiation (expired approval) and brick making (previous thermal process investigation).

This challenge has both technical and commercial aspects. Primary drivers for this pilot project include: 

  • Generation of new products and solutions
  • Revenue generation and extracting commercial value
  • Job creation and skills transfer

Further to the pilot project, additional process drivers ensuring long-term viability will include:

  • Management and disposal of WTR
  • Environmental compliance
  • Cost-effective and economically viable solution

There is a pilot project for accelerating the concentration of WTR running concurrently. This aims to lessen the drying times required to improve operational efficiencies. Success with this beneficiation challenge may also support the concentration project. 

Technical Information:

Panfontein Water Treatment Residue Process Stages


Water Treatment Residue Production


Composition of Rand Water’s WTR

Rand Water’s WTR (sludge from the potable water treatment process) is primarily composed of aluminosilicate (clay) material which makes up the bulk of the suspended matter in the source water. The moisture content of WTR in the drying beds will be 80-84% initially to 0-25% when dried. On average 500-600 tonnes dry WTR is accumulated per day. It’s overall composition includes:

  • Clay and fine particulates
  • Organic matter
  • Inorganic particulates
  • Algae, bacteria and other biological organisms
  • Added chemical treatments

Samples are available to iX challenge applicants upon request (to request please contact

Macro Chemical Composition of WTR


* The loss on ignition component typically includes residual water, carbonates, synthetic coagulation chemicals and natural organic matter present in the source water.


Some elements in the WTR may be considered harmful or undesirable for certain applications. Maximum and average concentrations of selected elements are provided in the table below.


Potentially Harmful Elements in WTR

*Manganese is also present and its values are included in the macro-chemical chart above

Beneficiation of WTR

2018 government guidelines allow for a waste stream or portion to be excluded from the definition of waste if it can be demonstrated that it can be used beneficially. This would be a highly desirable outcome. However there are some challenges with such beneficiation/valorisation initiatives. These include the high water content within WTR that requires removal, and the large volume of dry solids to deal with (of about 500-600 tons/day). Upstream solutions would require the additional processing of significantly larger volumes of liquids.

Previous research studies have considered the possibilities of producing material such as: soil ameliorant, cement making, pressed building blocks, ceramic blocks, extruded bricks, road construction, neutralisation agent for acid mine water and precipitated calcium carbonate.

These initiatives have not progressed due to possible limitations such as: variability of WTR, high transport costs* of WTR or products in relation to their value and lack of enabling commercial mechanisms. However, Rand Water will be happy to explore any of these ideas further if there are technically and commercially viable means of execution. For example, there have been improvements to regional infrastructure resulting in more efficient, and cheaper, transport options now available.

*Some general transport cost estimations may be found here.

Rewards & Benefits

  • Up to GBP 25,000 seed funding (Subject to T&C)
  • Opportunity to pitch your solution to Rand Water
  • Collaboration/partnership with Rand Water
  • Access to Rand Water facilities (specific sites require prior security approvals) 
  • Technical support and Mentorship from Rand Water team
  • Mentorship programme with Startup Discovery School (facilitated by KTN)
  • Access to materials, e.g.: Water Treatment Residue (Rand Water to provide relevant samples)
  • Sector expertise from KTN
  • Support in the development of a prototype or pilot 
  • Invitation to attend or present at KTN events
  • Investor introductions (if investment is required)
  • Application support for any Innovate UK or similar competitions that are relevant.

Functional Requirements

  • Solutions must be able to process large volumes of the WTR
  • Complete or near complete removal of WTR
  • Compliance with regulations for Type 3 Waste*
  • Cost effectiveness and economic viability of the solution
  • Potential for generating new value/ revenue
  • Potential reuse of WTR constituents
  • Generation of clean energy
  • Environmental friendliness
  • Ideally improve, but at least meet minimum regulatory and statutory requirements, as well as consumer perceptions pertaining to environmental sustainability
  • Technological maturity: preference for late stage solutions (TRL 7+) that have passed proof of concept stage, are in pilot, ready to commercialize or commercialized. However lower TRL ideas will also be considered.

*Classification of waste and associated disposal requirements as specified in regulations R.635 and R.636 of the South African National Environmental Management: Waste Act, 2008 (Act No.59 of 2008)

  • R.635 National Norms and Standards for the Assessment of Waste for Landfill Disposal
  • R.636 National Norms and Standards for the Disposal of Waste to Landfill

Link to the consolidated regulations on an open archive site and not an official government site.

Technical Requirements

  • Solution may be integrated with Rand Water’s existing system or may be a separate system alongside it.
  • Please detail any new infrastructure requirements for this solution
  • Solution must be applicable in modular format, so it may be scaled progressively
  • Solution should be viable for large volume usage (500-600 tonnes/day as dry solids)
  • Solution should be able to accommodate significant WTR composition fluctuations
  • Solutions should estimate Iife cycle costing with a 20-year planning horizon

Operating Conditions

  • Solution must be easily transportable by road
  • Solution must be robust and stable under normal temperatures
  • Solution must be viable for internal and external environments
  • Solution must be able to operate in all seasons
  • Solution must be non-polluting 
  • A minimal liquid discharge solution shall be preferable 

Deployment Timescale

  • 16 Nov 2022 - Competition Launch 
  • 30 Nov 2022 – Information session/Q&A
  • 17 Feb 2023 - Deadline for applications
  • Mar 2023 - Selection and notification of finalists
  • Apr 2023 - Pitch day
  • Apr 2023 – Selection of Winner
  • May 2023 – Collaboration Discussions
  • Jun 2023 – Pilot programme activated

Cost Requirement & Market Opportunity

  • The solution process must be cost-effective in terms of ROI (or at least cost-neutral)
  • There is 500-600t/day of feedstock available daily (available at no cost) to be monetised
  • Winning solution providers will become long-term partners, gaining access to all WTR stocks available

Out of Scope

Various ideas have been developed and/or tested previously. Proposed solutions will not be viable if they cannot deal with the common limitations expected including:

  • Solutions unable to deal with WTR composition variability and its primarily inorganic nature
  • Solutions with excessive transport costs of WTR or product
  • Solutions lacking enabling commercial mechanisms

Eligibility & Assessment Criteria

Entrants to this competition must be:

  • Established businesses, start-ups, SMEs or individual entrepreneurs
  • Africa-based entrants, UK-based entrants and those from RoW are invited to apply.

Due Diligence requirements for seed funding:

  • Applicants must ensure that receiving the £25k seed funding will not exceed the £315,000* state aid threshold under UK Minimal Financial Assistance regulations over the current and last 2 fiscal years [or *200,000 euros for applicants affected by EC de minimis regulations]
  • Further information will be required later relating to company policies, financial history and recent grant funding received.

Applications will be assessed on:

  • Relevance to the topic
  • Innovative nature of the subject
  • Coherence of the proposed business model
  • Feasibility/ economic viability
  • Development potential
  • Maturity of project/solution
  • Ability to launch project quickly/Ease of implementation
  • Price/quality ratio
  • Suitability for the South African Market

*Please ensure that you explain your idea clearly and concisely and add any useful attachments to support your application (eg: images, diagrams, prototypes, process, case studies, etc.) 

IP & Potential Commercial Route

  • Existing background IP associated with a potential solution will remain with Solution Provider(s). Where any new IP generation is envisaged, it will be subject to the mutual IP agreement of the Solution Provider(s) and Innovation Challenger.
  • Any commercial deployment of a transferred solution or newly developed solution, through licensing, joint venture, partnership or direct investment, will be subject to the commercial agreement between the Solution Provider(s) and Innovation Challenger.
  • Where necessary, a non-disclosure agreement (NDA) may be signed to uphold confidentiality in the engagement between the Solution Provider(s) and Innovation Challenger. (This would be expected to be after company selection, it is suggested that details of IP be not disclosed initially; focus on the outcomes of the technology proposed).
  • KTN do not take any share of IP ownership or enter into commercial ventures through the iX programme.