Proceedings

The water industry uses 3% of UK electricity and is rapidly becoming aware of its contribution to global
warming, through its consumption of energy and other consumables.
Waste water and sludge treatment is an area that has the potential to use a significant quantity of energy
but also the potential to generate renewable energy.

This paper examines the operational carbon footprint of several waste water and sludge treatment plants
based on typical process selections for a given set of site constraints. It compares carbon footprints for sludge drying, anaerobic digestion, BAFFs and ASPs. It demonstrates the
significant effect process selection has upon carbon footprint. The most energy efficient process had a
carbon footprint 1.6 times less than the process selected to meet the most stringent site space
constraints.

The paper also quantifies the important role of anaerobic digestion in recovering energy from waste
water. In doing this it shows the need to optimise sludge harvesting from secondary treatment.

Keywords
Waste Water Treatment; carbon footprint; sludge treatment; GHG emissions; renewable energy; sludge
harvesting.