Welsh wastewater plant gets high-speed biological treatment

March 1, 2001—A long-term multi-stage solution to eliminate sewage pollution from outfalls on the west side of the Severn Estuary in Cardiff, Wales is making huge strides with the construction of a major new sewage treatment works that will serve the City of Cardiff and the valleys to the north.

The plant will use a Sequencing Batch Reactor, a new level of technology to treat sewage with the state-of-the-art and high-speed biological processes.

The plant is due to be commissioned in 2002 and will be the largest in Europe built as a Sequencing Batch Reactor (SBR). The SBR introduces a new level of technology to treat sewage with the state-of-the-art and high-speed biological processes (See Box). At the core of the SBR process is technology from ITT Industries' ABJ(tm) and SANITAIRE(r) product brands, including sophisticated control software from ABJ, over 87,000 SANITAIRE fine bubble membrane diffusers and 64 ABJ stainless steel decanters.

The SBR system performs all its water treatment functions in a wastewater single basin in a four-hour cycle. This leads to a series of simple basins rather than a combination of separate storm tanks, primary settlement tanks, aeration lanes and final settlement tanks.

Providing secondary treatment (after the removal of inorganic solids), SBR technology is one of the most cost effective wastewater treatment methods for those plants required to be built as small footprint plants and to meet tight effluent standards.

The plant equipped with an SBR system typically produces a 25% reduction in capital costs and a 10% reduction in running cost over conventional activated sludge processes. The decanted liquid effluent from the basins will typically require no tertiary treatment and will be discharged directly to the estuary via a new long sea outfall.

With the new sewage treatment works designed to serve a population of almost 900,000, Mike Brooker, Managing Director of Welsh Water said that, "This represents a major step forward in Welsh Water's capital investment program which aims to improve Wales' coastal environment, winning 50 European Blue Flags and creating one of the cleanest coastlines in Europe."

Brooker continued, "We are putting in place a network of wastewater treatment centers which will be unique in the UK and the envy of many European countries. Over the next 5 years, the pace of this investment will quicken with the impact felt across Wales."