Southern Water has 12 Total Nitrogen (TN) consent sites with imposed limits ranges from 8.4 mg/l to 15 mg/l. The TN consents are implemented under Urban Waste Water Treatment Regulations (UWWTR) and/or Water Resources Act (WRA). The Population Equivalent (PE) of these sites equates to about 24% of total PE served by Southern Water.
Optimisation measures have been taken on sites to reduce CAPEX and OPEX, and improve site resilience to comply with TN consent limits. These measures includes for example changing the carbon source, changing control system, installing anoxic SAF to reduce carbon dosing and converting conventional moving bed sand filters into denitrifying sand filters.
This paper will review the performance, optimisation measures and operational experience of TN sites in Southern Water.