Electrical Power & Protection


Optimising power consumption in wastewater treatment plants

Technews Industry Guide: Sustainable Manufacturing 2023 Electrical Power & Protection

There are many opportunities in the wastewater industry to respond to climate change challenges. This includes improving energy efficiency, reducing greenhouse gases, and generating own energy. In an advanced wastewater treatment plant, the energy cost is around 25 to 40% of the operations and maintenance budget (Water Research Commission, 2021). The National Green Drop Report of 2022 indicates that very few water services authorities (WSAs) conducted a baseline energy audit, or can account for their wastewater treatment plant CO2 footprint. In addition there are limited energy efficiency initiatives in place, except for some municipalities in Gauteng, KwaZulu-Natal and Western Cape.

The first step towards improving a wastewater treatment plant’s efficiency, including energy efficiency, is to capacitate operations and maintenance staff, and managers, with adequate training relevant to plant and process efficiency. The second is to measure, capture and monitor data in real time. Using this data will present the WSA with the opportunity to reduce costs through process optimisation and improved energy efficiency, through the beneficial use of sludge and other energy resources.

Route to improved energy efficiency

One of the important ways of making energy usage more transparent is by calculating key performance indicators (KPIs). These highlight overall energy consumption, and help operators to identify energy-saving potential. Analysing the performance and energy consumption of a wastewater treatment plant helps to:

• Detect savings potential through constant monitoring of energy-relevant areas of the treatment plant.

• Benchmark efficiency of treatment plants with similar plants to create transparency and define further activities.

• Track energy usage, and determine the cost of wastewater treatment.

• Evaluate equipment, system, and control performance to find the ideal point of operation, avoid downtimes and ensure plant safety.

• Quantify benefits of system modifications and improvements.

• Verify predicted performance.

• Improve KPA in Green Drop audits.

Aeration performance

Depending on the type of aeration in the bioreactors, the power consumption of the aerators or blowers can be up to 50% of the plant’s power consumption. Typical causes for inefficiencies of blowers relate to pressure loss through leaks in piping, blockages in air piping, or blocked aeration elements. This will increase the power consumption of the blowers. Through monitoring pressure, air flow and power consumption measurements, it will indicate where the optimum operational point of the blowers is and when maintenance is required on the aeration elements.

To calculate this KPI, it is required to measure and monitor the blower air flow, air pressure, COD value, inflow into aeration basin and blower power consumption.

By using in-line dissolved oxygen and ammonia measurements we can determine the optimum air required for nitrification to take place, which supports energy efficiency gains within the process.

Electricity generation

Increase of electricity production is often easier to achieve and less expensive than electricity-saving measures. Key process parameters such as gas to chemical oxygen demand ratio or electrical and thermal efficiency of combined heat and power (CHP) plants are essential parameters for optimisation and verification of electricity production or quantifying effects of co-fermentation. Here it is necessary to focus not only on single processes but to monitor the complete system to discover related effects of interactions between processes. For a CHP plant to produce heat and electricity optimally, the CHP efficiency and sludge gas production efficiency must be analysed and optimised. The following measurements would be required to optimise CHP and sludge gas production efficiency: sludge flow into digesters; COD value; biogas volume flow; biogas pressure; biogas temperature; power production; and total power consumption.

Pump performance monitoring

Key performance area benchmarking based on power consumption, flow and pressure are useful to discover weak performance and maintain pumps in time. For example, centrifugal pumps require regular impeller adjustment to avoid significant efficiency loss.

In some of the more advanced wastewater treatment plants, most of these process measurement points might already exist, which decreases the capital cost for this investment. Endress+Hauser can assess existing instrumentation and analyse what additional measurement points are required to achieve efficiency goals and gains to improve the plant’s Green Drop rating. A simple solution could be to centralise KPA calculations on an RSG45 data manager, or create a dedicated consumption monitoring solution hosted in Endress+Hauser’s Netilion ecosystem. Endress+Hauser understands the importance of efficiency and sustainability in the sub-Equatorial African wastewater industry, and remains committed to supporting you in achieving these KPAs.


Credit(s)



Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Power portfolio with enhanced static transfer switch for critical applications
Electrical Power & Protection
Vertiv has launched the Vertiv PowerSwitch 7000, a next-generation static transfer switch that strengthens the company’s position as a complete power solutions provider.

Read more...
Why utilities must prioritise maintenance of SA’s remote data
Schneider Electric South Africa Electrical Power & Protection
The story of power generation is more than meets the eye. Beyond energy distribution and the infrastructure are invisible, point of presence data centres located the remotest parts of our country that play a fundamental role in keeping systems running

Read more...
The house that revolutionises substations
WEG Africa Electrical Power & Protection
Traditional substations have major drawbacks in terms of their construction and resilience. One solution is the E-house, a prefabricated, customised and transportable steel structure designed to house a range of electrical and automation equipment.

Read more...
Localised inverter-integrated transformer
Electrical Power & Protection
ACTOM, South Africa’s largest manufacturer, repairer and distributor of electromechanical equipment, is launching a breakthrough in renewable energy integration with its localised inverter-integrated transform

Read more...
Steinmüller Africa integrates advanced technologies at Mondi’s boiler project
Electrical Power & Protection
Steinmüller Africa is leading a boiler project at Mondi’s Richards Bay mill. The 18-month undertaking showcases the company’s blend of engineering excellence and cutting-edge technology.

Read more...
ABB innovation for energy efficiency and sustainability
Electrical Power & Protection
The application of sensor technology to reduce the operational and standby power losses of traditional current and voltage transformers can lead to energy savings of 181 MWh over a 30-year period, the lifetime of a typical switchboard in the African environment.

Read more...
UPS systems are key to keeping SA’s automotive industry up and running
Schneider Electric South Africa Electrical Power & Protection
During loadshedding, PLCs and OT systems often fail, not because they are directly tied to the factory’s core manufacturing process, but because they are now an integral part of IT infrastructure. When an IT system shuts down, the impact is far more complex than simply restarting machinery.

Read more...
ACTOM advances energy infrastructure
Electrical Power & Protection
At this critical juncture where South Africa is poised to modernise its power infrastructure, ACTOM’s Engineering Projects and Contracts (EPC) Division showcased its capabilities for the first time at Enlit Africa 2025.

Read more...
Advanced contactor solution to revolutionise motor management
Schneider Electric South Africa Electrical Power & Protection
Schneider Electric South Africa has launched the TeSys Deca Advanced, an advanced contactor solution designed to revolutionise motor management with unparalleled efficiency, reliability, simplicity and sustainability.

Read more...
Steaming ahead with boiler skills development
Electrical Power & Protection
As an expert in steam and boiler operations and maintenance, AES is very focused on safety, quality, technology advancement and the development of human capital. The company invests heavily in training and the promotion of talented people on an equal opportunity basis into the industrial operations environment.

Read more...









While every effort has been made to ensure the accuracy of the information contained herein, the publisher and its agents cannot be held responsible for any errors contained, or any loss incurred as a result. Articles published do not necessarily reflect the views of the publishers. The editor reserves the right to alter or cut copy. Articles submitted are deemed to have been cleared for publication. Advertisements and company contact details are published as provided by the advertiser. Technews Publishing (Pty) Ltd cannot be held responsible for the accuracy or veracity of supplied material.




© Technews Publishing (Pty) Ltd | All Rights Reserved