Depending on the wastewater flow and characteristics, a Nereda plant comprises multiple modular reactors (often 3) or a combination of a feed buffer tank plus one or two reactors. 

Retrofit CAS or SBR 

Since the detailed configuration of Nereda is quite flexible, the technology can often be used to convert existing conventional CAS or SBR plants into a Nereda. Often the technology enables the use of approximately a two times higher biomass concentration, with outstanding biomass settling characteristics. As a result of a retrofit to Nereda, the biological and/or hydraulic capacity of existing plants will be significantly increased and/or the effluent quality will be considerably improved. 

Hybrid Capacity Extension 

In a hybrid application, a new Nereda plant is fed with only part of the plants raw wastewater while the remaining part is treated by the existing conventional treatment system. An important additional advantage of such a hybrid extension is that by feeding of granular surplus sludge from the Nereda into the conventional activated sludge reactors will augment the activated sludge. By this inoculation process, the sludge characteristics and settling performance of the activated sludge will improve, resulting in improved sludge settling characteristics, increased capacity and enhanced biological nutrient removal.