The BIOCOS® main focus is to improve the conventional activated sludge system by combining the benefits of the Conventional Activated Sludge process and the Sequenced Batch Reactor process in a continuous process that has two alternating sludge recycling and settling tanks without the need for any electro-mechanical equipment. The main differences between the BIOCOS and conventional systems is the sludge-water-separation and the sludge recycling.

The BIOCOS process represents a cyclic activated sludge system that has been developed at the University of Innsbruck (Prof. Ingerle) throughout the last 15 years. The aeration tank is hydraulically connected to two alternating sludge recycling and settling tanks. A RAS pump-station or any electro-mechanical equipment for stirring or cycling are NOT required – all phases of the operation cycle are exclusively driven by pressurized air.

The development strategy of BIOCOS was based on the intention to avoid disadvantages of the secondary clarification and the sludge recycle to allow the development of a system with the highest possible:


Download PDF

• Efficiency
• Highest purification performance, by reduction of volume and space
• Operational safety
• Less mechanical equipment, less parts that wear out
• Purifying performance
• Nitrification and endogenous denitrification
• Biological phosphorus removal
• Additional reduction of COD
• Development of a floc filter ensuring very low TSS effluent quality
• Sustainability
• Emission value compliant with environmental law for biologically purified sewage
• Ability to use the odorless, fully biological purified outflow for irrigations

With low:
• Construction costs
• Only simple rectangular reactors w/flat bottom
• Savings of volume up to ~ 20%
• Savings of space up to ~ 50%
• Machinery
• No electrical devices under the water surface
• Only fine bubble aerators for a high oxygen input and
• Hydro- air- syphones for water and sludge movements
• Energy costs
• Savings of energy costs up to ~ 50%
• Maintenance requirements
• Savings of spare parts, personnel and time