Energy Efficiency of Wastewater Treatment Plants

IWES, University of Queensland, WaterAid Energty Efficiency

Target Audience

This course is designed for water industry professionals, engineers, managers, urban planners, environmental consultants, and regulators who are interested in improving energy efficiency at wastewater treatment plants.


Improving energy efficiency represents an opportunity to both lower operational costs and carbon footprint. This course covers the state-of-the-art in energy efficient wastewater treatment, with emphasis on the approaches to:
(i) Minimise the contribution of process units to energy use on wastewater treatment plants (including aeration, pumping, mixing, solids treatment, solids handling, disinfection and other forms of tertiary treatment); and
(ii) Recover energy from the waste itself.

At the end of the course participants will have detailed knowledge of the major energy inputs and the potential for energy recovery at typical wastewater treatment facilities; be conversant with other professionals regarding the water-energy nexus as it relates to wastewater in the urban system; and ultimately be able to identify the opportunities for energy savings at wastewater treatment plants. They will examine typical electricity tariff structures, and be introduced to energy efficiency benchmarking studies both overseas and in Australia. Additionally, they will understand the relationship between energy input and process performance (in terms of carbon and nutrient removal), appreciate why they are not necessarily directly proportional and why there are economies of scale.

This highly interactive course uses a number of workshop-based exercises to explore energy input and recovery at wastewater treatment plants. The course will use spreadsheets as a tool for understanding energy use and calculating energy balances, so participants are encouraged to bring a laptop computer (with Microsoft Excel installed).

Learning Objectives

Day 1

Wastewater treatment and energy use in the urban water cycle
Energy efficiency benchmarking
Breakdown of energy use on typical wastewater treatment plants
State-of-the-art in energy efficient wastewater treatment
Wastewater composition
Energy sinks in wastewater treatment
The energy balance concept
Spreadsheets as a tool to conduct energy balances for at wastewater treatment plants
Virtual Tour of a wastewater treatment plant highlighting energy use and energy recovery.

Day 2

Motors – the basics of motor types and efficiency, apparent vs. true power, and the power factor
Pumping – how flow, head, systems design, and viscosity affect energy inputs
Aeration – how wastewater characteristics, type of aeration system, reactor depth, diffuser characteristics and blower choices affect energy inputs
Mixing – what are the opportunities to save energy?
Electricity supply tariff considerations
Solids processes – energy input for stabilising, mixing, dewatering/ drying and transport biosolids. How do solids process selections influence treatment (e.g. recycles and nutrient removal)?

Day 3

Energy recovery from anaerobic digestion of organics – what’s the energy input and what are the benefits? To what extent do different types of sludge and biogas pre-treatment influence energy recovery?
Energy considerations around solids incineration and drying
Energy use for tertiary treatment, including disinfection and water recycling
New directions in wastewater treatment, energy and resource recovery
Relationships between plant performance (carbon and nutrient removal) and energy input
Workshop on energy management and plans.