What makes the Nereda process so special is the aerobic granules (biomass). In the usual treatment process, flocs of sludge are suspended in the water. It takes time for these flocs to settle in the treated wastewater, so the water has to go to a special secondary settling tank or clarifier. Nereda granules settle much faster, and can do so in the same tank in which the treatment process takes place.
- Aerobic granular sludge
- Heterotrophic growth
- P-removal/anoxic growth
- Oxygen gradient in granule enables simultaneous COD, P and N-removal.
Owing to their composition, the granules have an outside shell that is rich in oxygen and a core that is low in oxygen. This means that we can find different treatment conditions in one granule. In a normal treatment plant, the high-oxygen and low-oxygen processes take place in different parts of the overall process.
- Fill / draw
In a normal wastewater treatment plant, the various steps in the treatment process take place at different locations in the system. This means that the wastewater has to be pumped through the entire plant.
In the Nereda process, the dirty wastewater flows into the tank with the granular sludge. The sludge and water are then aerated and mixed and the bacteria begin to do their work. As soon as the granular sludge has settled following aeration, the clean effluent can be pumped out of the tank.