Setting the Path for Resource Recovery at Iona Island with a 2100 Vision in Mind

Upgrade of the 500 ML/d Iona Island Wastewater Treatment Plant created opportunities for Metro Vancouver to incorporate resource recovery into this 21st century facility and achieve its carbon neutrality goal. When upgraded, this facility will turn wastewater into usable products, including renewable natural gas, nutrient-rich biosolids, reclaimed water, and thermal energy in the near term, and possibly phosphorus, biocrude, and other resources in the future. The upgraded plant is projected to be carbon negative (net reduction of greenhouse gas emissions) when operational and expected to be a net energy producer with the connections to off-site district energy systems. The forward-thinking design concept developed for this plant upgrade focused not only on short-term mandates but started with 2100 vision to build a regenerative facility that embraces circular economy and provides benefits to communities for seven generations and beyond. Wastewater has traditionally been viewed as a waste that must be processed and managed. In recent years, the transition from a 'take-make-dispose' model to a circular economy has emphasized the need to recover valuable resources that are inherent in wastewater. Increasingly, technological advancements allow the recovery of resources to be cost-effective and the operation of treatment processes to be more efficient, which enable water resource recovery facilities (WRRFs) to produce a broader range of products and become regenerative. Metro Vancouver is one such utility that is positioning its WRRF for the circular economy. The Iona Island Wastewater Treatment Plant (IIWWTP) in Richmond, British Columbia, Canada was originally built in the 1960s to provide primary treatment in the Vancouver Sewerage Area. The plant as shown in Figure 1 needs to be upgraded to provide secondary treatment in accordance with federal wastewater regulations. Metro Vancouver is undertaking a multi-billion program to upgrade this primary treatment plant, with resource recovery as one of the key project goals. At a regional level, Metro Vancouver is also committed to achieving carbon neutrality by 2050. Building a 1.1 million population equivalent or 500 ML/d green-field facility at an existing site provides an unprecedented opportunity to create an inspirational 21st century WRRF. The project definition phase of the IIWWTP program was delivered using an integrated design process, through which a diverse multi-specialties team with nearly 100 members from various entities was assembled to brainstorm ideas and develop concepts in a series of workshops and collaborative meetings. While the short-term mandate of the IIWWTP upgrade is to meet regulatory requirements, the vision of the team was to build a resilient and adaptive WRRF that will nurture the natural environment and provide cascades of benefits to the local inhabitants and global community for seven generations and beyond. With this perspective, the project team imagined the future in 2100 and worked backward to identify what needs to be in place by 2035 and 2050 to fulfil the ultimate goals of the program. Following a three-year long process of exploring, evaluating, and refining options, including gathering feedback from stakeholders, local communities and First Nations, a conceptual design, along with a sustainability strategy, was developed for the IIWWTP. Key resource recovery components selected for incorporation into the IIWWTP in the near term include the following: 1) Purifying biogas produced from anaerobic digestion process to biomethane for injection into local natural gas grid as a green energy source; 2) Receiving of non-domestic trucked liquid waste containing fats, oils, and grease to increase biogas generation; 3) Beneficial use of nutrient/energy-rich biosolids for land application or further drying off-site for use as a fuel at cement kilns or as fertilizer; 4) Producing reclaimed water from tertiary treatment process for on-site non-potable water applications and surrounding habitat restoration as part of the Iona Island ecological improvement program; 5) Incorporating process and building heat recovery using tertiary effluent heat pumps 6) Installing pipelines to convey treated effluent off-site for heat recovery by district energy systems in the neighboring communities in Vancouver and Richmond; 7) Washing and compacting screenings from headworks for use at a local waste-to-energy facility; 8) Washing and dewatering grit from headworks for flood protection land build-up; 9) Installation of photovoltaic arrays at building rooftop at a demonstrate scale. Recognizing that technologies will continue to evolve in the upcoming decades and market drivers may change in the growing low-carbon economy, an adaptive approach was used to develop the plant design for adopting additional resource recovery opportunities in the future. For example, Metro Vancouver is piloting a new hydrothermal liquefaction process at another facility and this process will convert sludge to oil and gas. In the future, this novel process may be able to replace anaerobic digestion as a sludge stabilization process at one or more of Metro Vancouver's plants. Because of these considerations, it was recommended to retain the existing four mesophilic anaerobic digesters at IIWWTP for up to the first 20 years of the new plant and add two new digesters to provide capacity for both Primary and future WAS. Figure 2 shows the vision for IIWWTP in year 2035. In the future, the existing digesters would be replaced with a future process. For planning, the sizing of the future process is based on thermophilic digestion but new technologies such as the hydrothermal liquification process may be developed for incorporation in the future. Space was also reserved on the site for potential implementation of phosphorus recovery. Provisions were made to allow photovoltaic arrays to be installed over process tankage to convert solar energy to electricity that in turn feeds into electrolyzers to produce renewable hydrogen and oxygen. The site layout also includes innovation, training and optimization spaces to allow side-by-side testing of new technologies in parallel with the full-scale treatment system. The upgraded IIWWTP will turn wastewater into usable products, including approximately 322,000 GJ/year of renewable natural gas, 17,000 dry tonnes/year of nutrient-rich biosolids, 40 ML/d of reclaimed water, and up to 130 GWh/year of thermal energy for the initial upgrade in 2035. The plant is also projected to be carbon negative (net greenhouse gas reduction of approximately 5,800 tonnes CO2/year) and close to energy neutral when operational, with the ultimate goal of becoming a net energy producer with future enhancements, including off-site district energy. The forward-thinking design concept developed for the IIWWTP upgrade, as approved by the Greater Vancouver Sewerage and Drainage District in 2022, set the foundation and path forward for Metro Vancouver to build a regenerative facility that embraces the global transition to a circular economy and carbon neutrality.