Location: South Africa
The Water Research Commission is funding this project as part of the climate change and water-energy-food nexus programmes. The overall objective of the project is to assess the benefits (financial, social and environmental) of conducting energy audits and implementing energy efficiency practices at full scale wastewater treatment plants (WWTPs) and frame the incorporation of these practices into the national Drop Certification Programme.
To fulfil this objective we selected a few nitrification-denitrification enhanced biological phosphorus removal (ND-EBPR) activated sludge plants as case studies as they are representative of the majority of WWTPs in South Africa. We are conducting energy and GHG emission audits, identifying feasible energy efficiency measures, developing an energy efficiency focused climate change mitigation and adaptation framework, demonstrating potential operating cost savings, and framing the energy audits and efficiency practices for their incorporation into the Drop Certification Programme. The project involves data collection through site monitoring and application of mathematical modelling and simulation.
The project outcomes will provide guidance to Water Services Authorities on implementing energy efficiency and achieving Drop Certification. The outcomes will also contribute to the future national policy on climate change mitigation and adaptation strategies (planning, operational and capital/ infrastructure) in the wastewater sector.
Wastewater treatment plants consume large amounts of energy, estimated at between 1% and 3% of global energy output and are responsible for an estimated 3% of GHG emissions globally. Electricity consumption constitutes about 25% to 40% of a WWTP’s annual operating budget and makes up about 15% to 30% of a given municipality’s total energy bill. Aeration in activated sludge processes can account for upwards of 60% of the energy use in WWTPs. It has been estimated that off-site GHG emissions usually account for approximately 60% of the total emissions due to a considerable amount of energy consumed by plants and fuel consumption during transportation. Implementing energy efficiency not only saves energy and cost, but also reduces the carbon footprint of a WWTP.