What sets it apart?
The BIOCOS® activated sludge process is operated at a constant water level during the whole process cycle, and therefore represents a hybrid technology (Biological Combined System) comprising features of continuous flow and SBR systems.
How does it work?
BIOCOS, developed at the University of Innsbruck, Austria, is a cyclic activated sludge system with an aeration tank hydraulically connected to two alternating sludge recycling and settling tanks. The effluent valve of one of the settling compartments is open allowing the feed flow to the aeration tank to push out the supernatant water from the corresponding settler. No RAS pump-station or any electro-mechanical equipment for mixing or recycling is required – all phases of the operation cycle are exclusively driven by pressurized air from the same blower-source saving a lot of effort in operation and maintenance.
Sludge Recycle (RAS) Phase: Recycling of the thickened bottom layer of the settled sludge blanket from the ALT-tank to the selector zone of the AIR-reactor is provided by means of an air-lift. The transfer of the compressed sludge layer allows for a 50% higher MLSS in the aeration tank vs the settler compartments.
Mixing (MIX) Phase: The ALT-tanks are mixed by a roll current induced by coarse bubble aeration for a few minutes. High mixing intensity homogenizes and re-aerates the anoxic sludge blanket.
Sedimentation (SED) Phase: Settling sludge blanket creates formation of a floc-filter for fine particle removal and development of a dense bottom sludge layer.
Discharge (DIS) Phase: Intermittent aeration in the AIR-tank for nitrogen removal and continuous discharge of supernatant water from ALT-tank (no water level variation).