Reusing sludge: A circular solution to wastewater processing and construction in Ghana
With support from the Netherlands Enterprise Agency, a group of Dutch companies has found a way to reuse a waste product, making bricks from sludge. This solution should lead to more construction materials and improved waste processing in Ghana. "This is how we solve 2 issues at once," says Stefanie from Royal HaskoningDHV.
The WEIJA water treatment plant near Ghana's capital Accra produces 6,500 m3 of waste sludge daily. The plant discharges the sludge into the river, where fishermen earn their daily income catching fish. Also, Ghana needs more construction materials. Royal HaskoningDHV, NETICS B.V. and Allied Waters developed a new approach. The plant no longer discharges the sludge into the river. Instead, it is upcycled as a secondary raw material for building bricks. "Why throw away a waste product when you can use it to build with?" says Stefanie.
A good mix is a good starting point
Project manager Stefanie explains the details behind the innovation. "The process for making building bricks with this particular sludge is new. We make a product from this waste product, which we then add to the mix for building bricks alongside sand, water and cement. That way, you need less cement to produce the same number of bricks. "You do not get a strong brick just by adding sludge," explains Stefanie. "Developing a good mix requires research. The mix needs to be right; testing is essential to determine the correct ratios. The new mix must also meet quality requirements. You have to be able to split the bricks, but they also need to be strong enough to support each other."
From testing to building a factory
The collaborating companies are enthusiastic about the mix and have built a toilet block using the new bricks. "A local entrepreneur produces and sells the building bricks," explains Stefanie. "The next step is to build a factory to make the bricks using recycled waste. That is the only way to process 6,500 m3 of sludge a day. We are currently consulting with potential investors. The aim is for the factory to provide work for local people."
Innovating for developing countries
The Small Business Innovation Research (SBIR) in Developing Markets (DM) programme from the Netherlands Enterprise Agency (RVO) made this innovation possible. It was 1 of the 8 winners of the call for 'Circular innovations for fast-growing cities'. The SBIR in DM is an innovation competition for addressing challenges in developing countries. Competition winners receive financial support to research and develop a prototype for their innovation. The aim is to create a sustainable revenue model and local impact.
- Ministry of Foreign Affairs