Severn Trent Water is testing a wastewater treatment unit that is claimed to consume less energy compared to other systems used by utilities.
The HYBACS (Hybrid Bacillus Activated Sludge) unit contains a newly designed rotating biological contactor (RBC) that is claimed to speed up the water treatment process too.
The RBC is a biological treatment tank that consists of closely spaced plastic plates mounted on a rotor, which is supported above the surface of the wastewater.
As the rotor revolves, the plates rise from the wastewater and dip back in. The surface of the plates are subjected alternately to wastewater and air — encouraging biomass to grow on their surface. The biomass contains bacteria and the enzymes that destroy or convert pollutants in the wastewater.
Garry Hoyland, technical director of London-based Bluewater Bio, said its new unit uses plates that are manufactured from a 50mm-thick plastic mesh instead of solid plastic material.
While biomass grows like a thin film on the solid plates, Hoyland added, Bluewater’s new design allows biomass to grow more thickly in the mesh so that greater amounts of bacteria can thrive and produce enzymes for de-polluting wastewater.
The mesh plates also drain water more easily when lifted in the air, allowing the biomass to be more efficiently oxygenated. Hoyland claimed HYBACS has an aeration efficiency that is three times better than conventional units, reducing the amount of energy required to oxygenate the wastewater.
Hoyland claimed HYBACS has an aeration efficiency that is three times better than conventional units, reducing the amount of energy required to oxygenate the wastewater.
He also said that the mesh structure reduces the amount of time to remove nitrogen and phosphorous compounds and ammonia from the water. This is because each mesh plate hosts a range of biological phenomena capable of carrying out different reactions such as nitrification and denitrification simultaneously. Hoyland said other units must complete these reactions through multiple cycles.
After going through enzyme treatments, the wastewater is filtered through two other stages of the HYBACS process before it is ready for release. Hoyland added that in the Middle East such effluent could be used for irrigation. In the UK, the HYBACS-treated wastewater meets standards for releasing it back into the environment.
‘The effluents treated by HYBACS have a very high quality and are very suitable for that type of discharge,’ said Hoyland. ‘It could bring about improvement of the receiving water of the river.’
The HYBACS process is currently being trialled by Severn Trent Water and Hoyland said early results are positive.
The energy efficiency of membrane bioreactor plants could be boosted thanks to work carried out at De Montfort University, Leicester.
Membrane bioreactors consist of a biological reactor containing selective bacterial micro-organisms that ‘digest’ organic contaminants generated from manufacturing processes. Wastewater is pumped through an ultra-filtration membrane to remove inorganic pollutants. It is then clean enough to be reused as a secondary supply of water.
Project coordinator Parneet Paul said: ‘If this wastewater can be fully recovered in an efficient manner it not only has cost implications for industry as a whole, but could also be a way for industry to meet emissions targets.’