Biosolids Management and Cryptic Currencies - Net Zero, Emerging Contaminants, and New Biosolids Markets

This paper tends to showcase how the path of a biosolids management planning (BMP) project transitioned from a single, linear solution toward a multifaceted 'Road Map' with multiple options and key decision points based on probable future scenarios. A 35-year BMP was developed which provided flexibility to accommodate future changes in environmental, regulatory, cost, public perception and technology development aspects of biosolids treatment and beneficial use. Keywords: Biosolids Management Planning; Triple Bottom Line Plus; Greenhouse Gases. This decade has seen an unprecedented increase in global awareness of environmental and human health concerns, climate change, 'forever' pollutants like plastics and per- and polyfluoroalkyl substances (PFAS), and viral infections. National and regional governments and private entities have implemented significant responses, from net zero commitments, biosolids land application bans due to PFAS, elimination of single use plastics, and monitoring human infection rates through wastewater. This paper presents the findings of a biosolids management planning (BMP) project, showcasing how the project path transitioned from a single, linear solution toward a multifaceted 'Road Map' with multiple options and key decision points based on the probable future scenarios considering the upcoming regulatory changes. EPCOR owns and operates the wastewater management facilities in the City of Edmonton, Alberta, Canada, including Gold Bar Water Resource Recovery Facility (GBWRRF) and Clover Bar Biosolids Recycling Facility (CBBRF). The CBBRF also receives the sludge generated at Alberta Capital Region Wastewater Treatment Plant (ACRWWTP), which is owned and operated by ACR Wastewater Commission, a partnership of 13 municipalities surrounding Edmonton. In both plants, the blend of fermented and thickened primary sludge and thickened secondary sludge are fed to anaerobic digesters, and then is sent to the CBBRF. The CBBRF uses lagoon treatment and produces thickened biosolids for land application and dewatered biosolids for agricultural land application, silviculture (biomass trees), and mine land reclamation sites. The GBWRRF currently treats the wastewater from approximately 1.0M population equivalent (PE) whereas the ACRWWTP treats the wastewater from approximately 0.36M PE. Both plants are planned to expand substantially as the population in the Edmonton region grows. The total projected serviced population of these two plants in 2060 (2.9M) is more than double the current population (1.4M). A BMP project was conducted to address the expected increase in biosolids production, in which the trending topics including treatment technology advances, environmental and social impacts, and resource recovery were recognized and incorporated. A regulatory review was first conducted to understand the provincial, federal, and global regulatory contexts for biosolids management and their influences on provincial legislation. Then, a total of 38 product/market combinations and 28 technologies were evaluated within a triple bottom line + technical framework, by assigning importance weight factors of 25%, 25%, 30%, and 20% to environmental, social, economic, and technical categories, respectively. Several criteria under each category were defined and the options were scored from 1 to 5 per criterion, with the lowest scores and the lowest costs being the most favourable. A total weighted score was achieved per option, based on which the options were ranked and compared. Six product categories, nine market categories, seven technology functional groups were evaluated (Table 1). Thereafter, the market and technology options were aggregated into eight potential 'Strategies' that included technology sequences to create biosolids treatment trains and the range of markets available for the products created by those treatment trains. Evaluation of the eight Strategies (Figure 1) highlighted that there are critical decisions that will need to be made to determine the path forward to ensure the best use of capital infrastructure budget allocations. Therefore, rather than selecting one or two linear Strategies for more detailed evaluation, a Road Map approach (Figure 2) was developed that identified key decision points and capital projects required along the BMP planning horizon. Strategies 1, 3, and 6 scored the lowest (Figure 1) and were selected for the Road Map development (Figure 2). The Road Map identified two key future decision points - the first decision point is based on digester capacity expansion and the second is whether to continue with seasonal biosolids markets or transform to non-seasonal markets. At each decision point, the Road Map provides a path forward, developing three pathways for the BMP. The 'Diversified Pathway' continues with digestion but diversifies the biosolids markets with non-seasonal products. The 'Traditional Pathway' is most like the current approach, continuing with digestion and biosolids products for seasonal agronomic markets. The 'Transformational Pathway' is based on discontinuing digestion and generating biosolids products suitable for non-seasonal markets. A rough (i.e., one) order of magnitude cost analysis indicated that the three pathways had essentially the same net total cost (capital, O&M, and market costs) through the BMP horizon (2024 through 2059), with the cost of the Transformational Pathway being slightly higher (15%) than the others (Figure 3a). The GHG emissions showed a much wider difference between the three pathways, identifying the Traditional Pathway facilities was about 40-50% higher than the others (Figure 3b). The Traditional Pathway was the only pathway with lagoons still in use in 2059, and 60% of the 2059 GHG emissions for this pathway would be derived from the lagoons. The Transformational Pathway showed the highest potential for carbon sequestration through the product/market options considered for this Pathway (Figure 3b). The findings of this project can inform the scientists and practitioners through a real-time example, that traditional linear budgeting and planning approaches no longer provide the agility required to meet the uncertainties and rapid changes facing utilities. This multidimensional BMP analysis indicates that other factors than cost will also be likely to be significant considerations in the BMP decision points, such as GHG emissions, regulations such as potential limits on emerging contaminants, further development of the emerging thermal technologies, public perception, risks, and demands on the footprint and facilities.