Proceedings

Global warming is now an issue that has to be taken seriously by everyone. The Water Industry needs
to look to the future and assess the carbon footprint of its activities. The carbon footprint of a process
is associated with energy which has a cost and thus generally by reducing the carbon footprint of a
process the cost will be reduced.

This paper looks at the different sewage treatment methods available to achieve the same final
effluent nitrogen and phosphorus standards, assessing the most advanced membrane bioreactor
(MBR) to the most traditional biological filters and including the activated sludge process. The paper
also considers the future of sewage treatment and analyses the latest development work on
anaerobic treatment of sewage and in particular the anaerobic MBR. The paper analyses the cost of
construction, the cost of operation, the physical footprint and the carbon footprint. Each of the four
methods of assessment can be used to determine the most appropriate process for treatment for a
particular scheme. The process with the smallest physical footprint will not necessarily have the
lowest carbon footprint but where land availability is a major issue, physical footprint may become
the deciding factor in the choice of process.

Key Words
Carbon footprint, Anaerobic MBR, sewage treatment, cost.