Proceedings

An Anaerobic Baffled Reactor is a simple compartmentalised reactor, designed for retrofit inside an existing primary clarifier. The novel design approach can significantly reduce sludge production by encouraging in situ anaerobic biological degradation of the primary sludge. The key to the successful operation of the Anaerobic Baffled Reactor (ABR) is to separate the solids retention time (days) from the hydraulic retention time (hours).

Atkins has been involved in the development of the ABR technology since 2000. A consortium of UK water companies, and Orange County Sanitation District (OCSD) in the US funded the original work. However, conditions for operation are different in Southern California to the UK so it became necessary to operate an ABR under OCSDspecific conditions. A large scale pilot plant ran from March 2003 to July 2004. A detailed mass balance confirmed that 30% of the sludge was being destroyed. With increasing demand on existing facilities at OCSD, the advantages of ABR could potentially offset future capital investment.

KEY WORDS Anaerobic baffled reactor, ABR, primary treatment, sludge minimisation