Activated Sludge

For wastewater treatment, why reinvent the wheel? Biomimicry offers simple solutions to complex problems already solved by nature.

At a fundamental level, the process of treating wastewater is relatively simple. Oxygen, bacteria and pollutants are mixed in order to degrade pollutants and yield clean water. This is the basis of the highly reliable activated sludge process which was discovered in 1914 by Ardern and Lockett. Similar processes are already present in nature; for example, river systems naturally replenish their oxygen rich environment to sustain aquatic life and good water quality, which is in many ways similar to the activated sludge process.

Aeration in a river is a natural process, derived from continuous high flow cascades delivering oxygen rich conditions to bacteria and protozoa which are responsible for breaking down organic matter and cycling nutrients. On the other hand, aeration in activated sludge treatment is an artificial process which drives oxygen into the water to activate bacterial metabolism. There is usually a large demand for oxygen necessitating significant levels of energy to overcome buoyancy to inject air deep into the bottom of a tank. The energy demand in this process is expressed as the amount of oxygen delivered per unit energy consumed, or kgO2/kWh.

VorTech’s Vortex Power Aeration (VPA) technology emulates the river environment in an activated sludge tank. Instead of relying on costly, high maintenance blowers to pump air, under 4 to 5 m of water pressure at the bottom of the tank, the VPA instead lifts water to the surface of the tank where it is mixed with air in a cyclone requiring low pressure and power. In this way, similar to river cascades, every molecule of water gets dosed with oxygen in the VPA and is dispersed efficiently back into the reactor to effect further mixing. This is how the VPA can maintain high oxygen transfer rates and aeration efficiencies.

Activated sludge treatment is a well understood, reliable and robust solution to treat industrial and municipal wastewater. The Vortex Power Aerator (VPA) is not trying to reinvent something that works effectively, but rather aspires to make one of the world’s most energy intensive processes more efficient.