ASP - Efficiency without Compromise 

Case Study
Wastewater Treatment

United Utilities

Reduce energy without compromising quality

Payback within 15 months


The water industry accounts for almost 3% of the UK’s total energy bill. With tighter regulations and consent limits being put in place, higher quality has to be achieved, but as efficiently as possible.

United Utilities is the largest operator of clean and wastewater networks in the UK. They were the first water company to pledge carbon reduction in line with government targets.

Activated sludge plants are widely employed in the industry and require high levels of energy for aeration; optimal operation balances load, oxygen demand, and final discharge quality. Loss of sensor data can result in unnecessary over-aeration or loss of compliance.


A predictive control system, derived from actual operating data, able to minimise energy and minimise risk of compliance failure. Read more...


United Utilities’ Research & Development team have a track record of seeking innovative solutions from process industries – they are not afraid to ‘think outside the box’. Perceptive Engineering offered a potential solution to the dilemma of lowering energy costs without compromising on quality.

Using historical process data, Perceptive Engineering constructed a robust model able to predict plant behaviour and the impact of disturbances on performance. The model assesses the quality of signals taken from the plant, determining which are reliable and which should be discounted from future control decisions. The final control scheme is able to reconstruct missing or unreliable data, enabling optimal operation to be maintained even if some critical signals are lost.


This collaborative project was intended as a ‘proof of concept’ trial, but its success has meant full installation at the Lancaster Wastewater Treatment Works and beyond.  Average energy saving over 12 months has been 26% when compared with previous best performance, with continuing development offering significantly higher savings and fast return on investment.

United Utilities calculates an annual reduction in equivalent CO2 of more than 250 Tonnes, for this plant alone. Performance is more tightly controlled, with less operator intervention required to maintain optimal operation and ensure high quality treated water discharge.

“The project completed by Perceptive Engineering at Lancaster WWTP has successfully shown that significant reductions in electricity consumption can be achieved through the novel use of statistical monitoring and model based control.”

Dr Sarah Needham, Asset Standards and Innovation, United Utilities

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