Driving WwTP efficiency delivers on energy costs

Driving WwTP efficiency delivers on energy costs

Wastewater treatment is one of the most energy-intensive processes for the water sector, and with electricity prices having increased by an average of 27% per year from 2021-2023, making sites run more efficiently is a major focus for utilities.

Water companies have dedicated teams working continually on wastewater treatment plant (WwTP) optimisation, and Xylem is supporting many in identifying where and how energy and emissions can be cut. 

The urgency of 2030 net zero targets in England is driving game-changing innovation, and companies intend to increase use of renewable power in the 2025-2030 asset management plans (AMP8), including more onsite biogas generation. This will bring many long-term benefits, but for companies wanting technology that can be implemented quickly for immediate results, many advanced products are widely available.

Upgrading legacy processes or equipment with the latest high-efficiency designs will have an instant impact on power consumption and energy costs, with potential payback of around two years. Up to 40% of a water company’s greenhouse gases comes from treating and managing wastewater, so optimisation is a win-win for time-stretched operational teams managing multiple priorities. 

Three energy-saving options that can deliver quick wins are smarter pumps, aeration upgrades and going digital.

Smarter pumps

The water sector is powered by pumps, and in terms of energy bills, the pumping of wastewater amounts to one of the biggest spends for water companies. The good news is that intelligent pump and mixer systems are now available that sense the operating conditions and adapt performance to changing flow rates in real-time. 

Integrated controls, clog detection and self-cleaning functions reduce the frequency of reactive callouts and maintenance visits, saving on operational expenditure (opex) and reducing numbers of vehicles on the road. 

Scottish Water partnered with Xylem to upgrade hundreds of pumping stations with sustainable technology, as part of its 2040 net zero commitment. In an initial trial, the Flygt Concertor pumping system reduced unplanned maintenance by 99.8% and cut energy use by up to 60 per cent.   

In a case study, Nathan Wield, wastewater operations west manager for Scottish Water, said, “After the successful trial of Concertor, and understanding the energy-saving that came with it, this led to more trials and then eventually wider adoption. Today we have about 300 Concertor pumps installed across Scotland, with many more to come.”

Aeration upgrades

Research has found aeration represents up to 75% of the total energy costs at a typical wastewater treatment works, mainly due to the electrical energy from air blowers.  

Many existing, older blowers are inefficient and maintenance intensive. Upgrading offers significant energy-saving opportunities. 

Options now available include high-speed air foil bearing turbo blowers, powered by variable frequency drives to control air flow. Intelligent controls can select the most efficient operating configuration of duty, assist and standby blowers to achieve necessary air volume. 

Also configuring higher density aeration diffuser layouts, which require smaller blowers and, coupled with high-efficiency blower systems and real-time control, can save up to 50% on energy costs compared to mechanical aerators.

Go digital 

Water companies are increasingly realising the benefits of digital technologies in making better use of the thousands of datasets they receive each day. Bringing data together on a single, smart platform provides a complete overview of operational performance and enables decision-making based on real-time insights. 

Such platforms will support the transition from a reactive to proactive network management model – a significant step-change for AMP8. Xylem’s digital offerings include Xylem Vue Powered by GoAigua, an integrated software and analytics platform that gives a complete picture of operational status and network efficiency, across water and wastewater.  

For wastewater teams tasked with making efficiencies, the system can provide optimisation of treatment processes, including pump and aeration performance, to support reductions in energy usage, carbon emissions and operating expenses. 

Primed for AMP8

There is no reason why UK utilities cannot have effective digital platforms up and running during AMP8. Companies planning to do so should be engaging now with stakeholders, including internal teams, the platform’s end-users and technology providers, to ensure a successful implementation. 

Now would also be a good time for utilities to undertake an audit of wastewater treatment processes, including visual and analytical inspections of equipment and instrumentation, to understand how much energy and chemical sites are consuming and which improvements should be prioritised to deliver most impact. 

With the water sector under ever-tightening budgetary constraints with higher expectations on operations and delivery, energy cost recovery is a win-win for water companies and their customers.

Written for and first published in Water Magazine June 2024

by Duncan Wildgoose, Head of Wastewater Business Development Manager, Xylem UK and Ireland