Selected Information - Completed Research

Together with ‘in kind’ support from Severn Trent Water, the project will investigate an alternative design for the activated sludge process, in which the aeration and settlement stages are carried out within a single tank.

The process operates by restricting aeration to a re-circulating side stream rather than in the main tank, which is therefore considerably less turbulent than in the conventional process. This enables the demarcation within the main tank of a quiescent zone to separate the solids from the treated wastewater.

Microorganisms are not kept in suspension but settle to the bottom of the tank to be collected, via the re-circulating flow, for aeration and re-distribution at the surface of tank.

Benefits

The new process promises to provide:

• Significant cost reductions
• Levels of nitrogen removal significantly better than 50%, leading to superior effluent quality and additional energy savings.