CP326b - Sustainable options for P&N removal
Many small UK sewage treatment works are now required to meet discharge consents that include limits on phosphorus and nitrogen concentrations. Technologies for phosphorus removal from wastewater are well established, but to achieve the lowest concentrations required in some discharge consents, addition of iron or aluminium salts is generally used to remove phosphorus in a robust and reliable manner. Concerns about the sustainability of using these methods have been linked to resource use, availability, transport, emissions and incorporation in sludges. Biological treatment for nutrient removal is practised at some large works, and there are other possible processes to enhance removal of nutrients.
A new project has recently been started by WRc as part of its Portfolio programme, with a small group of partners, to systematically assess sustainability of a range of processes that are currently or could possibly be used, with particular attention to requirements at small treatment works. Opportunities to improve sustainability and use of the main widely used processes of biological and chemical removal of nutrients will be examined and assessed. The assessments are being carried out and linked to the Sustainability Tool that was previously prepared by WRc. The partners are providing information on example small works for which the process options can be calculated and compared using quantitative and qualitative assessments. Other areas of nutrient recovery are also to be included, to provide a wide systematic assessment of options to reduce environmental and cost impacts of sewage treatment works.
By participating in this project the partners will improve their understanding of sustainability of their current and future options required to meet their obligations under discharge consents, and requirements for energy efficiency, and other environmental impacts reduction . The results will inform current and future works strategies and decisions on operations, process choices and investments.