Nereda design capacity

  • 5000 m3/d
    Dry Weather Flow
  • 400 m3/h
    Peak Flow
  • 28182 PE
    PE (PE = 60 gBOD/d)

Project facts

  • Client
    Overstrand Municipality
  • Location
    Overstrand, South Africa
  • Period
  • Wastewater
  • Project type
  • Process configuration
    Pre-treatment + Nereda + Chlorination

About the Gansbaai Nereda WWTW

Gansbaai wastewater treatment plant (WWTP) is located in an environmentally sensitive area in the Western Cape, South Africa.

The challenge

The local municipality of Overstrand was planning to upgrade the Gansbaai plant from a 0.3 megalitres per day capacity to a five megalitres per day capacity. Because of the location of the plant, the size of any new development needed to be kept to a minimum and due to the climate, water conservation had to be prioritised.

South Africa - Gansbaai | Royal HaskoningDHV

Image: Overview of the Gansbaai WWTP

The solution

After comparing several different technologies, the Nereda process was selected as the most suitable solution. Nereda technology purifies wastewater through an aerobic granular biomass process, which produces high-quality final effluent, suitable for environmental discharge or irrigation. The system uses aerobic biological treatment methods that require fewer chemicals compared to conventional technologies. The Nereda process entails non-conventional bacteria consuming wastewater and producing compact granules. The special micro-organisms used in the treatment system do not develop in floc structures as with more traditional methods, but form concentrated compact granules. The granular biomass produced by these bacteria settles, making separation of the granules from treated water easier. The quick settlement means lower energy consumption and a more sustainable process.

The outcome

The effluent produced at Gansbaai is of such high quality that it can be re-used as irrigation water in the surrounding areas. Parkland and sports fields benefit from this recycling while some of the water is safely discharged into the Berg River. In addition to its environmental benefits, Nereda technology has proved to be thoroughly cost-effective, using fewer construction materials and requiring dramatically lower operating costs and energy consumption. It also has a 60% smaller footprint than a conventional plant.


  • High quality effluent residue

  • Smaller plant footprint

  • Benefits area via irrigation

  • Reduced environmental impact

  • Highly efficient process