Energy Audits and Efficiency for Climate Change Mitigation
Country: South Africa
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.
Funding for project is part of 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.
Start/End Date: 2022/2024
Project Title: Piloting Energy Audits and Energy Efficiency as a Climate Change Mitigation and Adaptation Strategy for the South African Wastewater Sector and Framing its Use in the Drop Certification Programme.
Transitioning to a Circular Economy: The Role of Technology
Country: South Africa
This project investigated the role of emerging wastewater sludge processing technologies in accelerating the transition to a circular economy (CE) in the wastewater sector, using wastewater treatment plants (WWTPs) as resource-recovery centres. A comprehensive literature review on the global status of CE in the water sector and the International Water Association (IWA) framework was conducted. The emerging multi-biomass processing Enhanced Hydrothermal Polymerization (EHTP) technology was selected as the case study. An EHTP pilot reactor was installed ata local municipality's WWTP which processes sludge, community waste biomass, and faecal sludge from VIP toilets. Laboratory analyses were performed on the feedstock, hydrochar, and process effluent. The hydrocharshowed potential uses as biofuel, soil conditioner, adsorption media, and building material. Technologies that can be coupled with the EHTPprocess within the IWA pathways were identified. Key factors impacting the transition to a CE in the water sector were evaluated in the South African context, with recommendations for WSAs to address these factors. The project demonstrated that multi-biomass processing technologies like EHTP can be incorporated into WWTPs to convert them into resource recovery centres, with strong government leadership needed to drive the transition.
Start/End Date: 2018/2022
Project Title: The Role of Emerging Innovative Wastewater Sludge to Energy Technologies in Transitioning to a Circular Economy in the Water Sector: A South African Case Study
Energy Use Reduction at BNR ASPs
Country: South Africa
This project was part of the client's energy efficiency in the water sector initiative. The project was investigated through two case studies, to determine feasible practical aeration energy conservation measures (ECMs) that can be implemented at a typical South African BNR activated sludge plants that not only result in aeration energy use reduction but also ensure final effluent compliance with permit requirements. For the outputs of the project to be applicable on a broader scale, two BNR activated sludge plants were selected as case studies namely
•WWTP A which has a design capacity of 85 Ml/d average dry weather flow (ADWF) and uses a fine bubble diffused aeration (FBDA) system.
•WWTP B, with a design capacity of 15 Ml/d ADWF. The plant uses surface aeration.
The study found that identified aeration ECMs can potentially save 9-40% of aeration energy consumption and cost. Implementing the identified ECMs which include optimal process and aeration control results in improved biological nutrient removal and compliance with final effluent nitrogen and phosphorus limits. In order to realise these savings, local authorities need to develop a clear energy management strategy and put in place robust systems and structures towards achieving this strategy.
Start/End Date: 2014/2016
Project Title: Energy Use Reduction at BNR Activated Sludge Plants Wastewater Treatment Plants Hydraulic and Treatment Capacity Study
Wastewater Treatment Energy Efficiency Assessment
Country: Canada
TruSense acted as process specialist sub-consultant for a project to assess the energy consumption and efficiency improvement potential of wastewater treatment plants in five small municipalities (population range 2 000 to 12 000) in Canada. The goal of the assignment was to provide recommendations to reduce energy consumption, greenhouse gas emissions, and operating costs, as well exploring opportunities for renewable energy generation. The facilities were unique with different capacities and configurations as follows:
• SBR activated sludge
• Package plant activated sludge
• Aerated and polishing lagoons
• Rotating biological contactor
• Oxidation ditch
For the five plants, eighteen measures were identified with a savings value of $175,000 per year and an overall payback of less than ten years, with many measures in the two to three-year range. Many communities are working on plans to implement the measures.
Start/End Date: 2012/2012
Project Title: Wastewater Treatment Energy Efficiency Assessment