The Urban Wastewater Treatment Directive (UWWTD) has required flow monitoring for sites with Population Equivalent (PE) flows over 50m3/d (approx 250PE) to monitor flow into treatment. Often this must be combined with effective event logging when storm flows bypass full treatment following rainfall events. The monitoring of flow at WwTW’s is vital in demonstrating consent compliance through rainfall independent Dry Weather Flow (DWF). DWF measurements during AMP5 demonstrated consent exceedances at some sites which resulted in the tightening of sanitary determinant concentrations including those for Nitrogen and Phosphorus.

Effective quality monitoring is essential to the efficient operation and maintenance of WwTW’s. Quality monitoring technologies have evolved since AMP4 such that parameters including ammonia, phosphorus and even inferred values for BOD5 and COD can be reliably measured and logged throughout the wastewater treatment process.

Alone, the monitoring of effluent phosphorus demonstrates compliance with annual average consents and can be used to create models by which chemicals for P removal can be efficiently dosed. Combining flow monitoring, chemical and biological models with the effective measurement of sanitary parameters and dry solids provides an exciting opportunity to develop Real Time Control (RTC) strategies for aeration control, nutrient removal, sludge optimisation and sewer control, especially at those sites equipped with activated sludge plants. RTC provides opportunities to reduce energy Opex, improve and even potentially to increase the capacity of existing assets to treat increasing loads or meet new compliance targets in the future.