Technology
Treatment Stages
First Treatment Stage
The first treatment stage comprises one or several reactors operating in parallel. Each reactor contains a rotating shaft along which lamellae are mounted perpendicular to the shaft. The lamellae provide support for the fixed biomass. As in conventional rotating biological contactors (RBCs), each part of the biomass is alternatively submerged and then exposed to air. However, whereas lamellae in conventional RBCs are generally constructed from solid plate, those used in the HYBACS’ Process are manufactured in the form of a three-dimensional reticulated structure, having a high voidage for supporting biomass.
The first stage reactors are called SMART units, denoting Shaft Mounted Advanced Reactor Technology. Currently, the units are commercially available in a range of standard sizes up to a population equivalent (PE) of 25 000. The dimensions of the largest unit are 4.9 m long, 4.8 m wide and 2.9 m high.
Concentrations of substrate, nutrients and dissolved oxygen in the biomass vary with depth from the biomass surface. Biochemical reactions are aerobic at the surface but anaerobic at depth. With such biochemical diversity, SMART units remove much of the nitrogen from the wastewater as well as carbonaceous matter. Further, owing to the three-dimensional structure of the lamellae the biochemical productivity is considerably higher than found in conventional RBCs.
SMART units consume little electrical energy since the aeration is derived from the rotation of the lamellae. When treating strong industrial wastewaters, the wastewater in the units may be aerated using diffused air but the electrical energy consumed by such aeration is comparatively small.
Second Treatment Stage
The second stage comprises biological reactors that are aerated using a fine-bubble diffused-air system as in conventional activated sludge processes. However the operating conditions are specific to the HYBACS Process.
