Low-Cost, Sustainable Treatment of Meat Processing Wastewater: A Decade Of Success

Learning Objectives:
1. How can we use an Asset Management Framework to successfully strengthen an Advance Facilities Plan Business Case?
2. How can advanced planning techniques such as Adaptive Pathways Planning to add flexibility and robustness to the decision-making process?
Introduction
The Milwaukee Metropolitan Sewerage District (MMSD or District) is a regional water reclamation and flood management agency serving 1.1 million people in 28 communities in the state of Wisconsin (Figure 1). MMSD houses two facilities: Jones Island Water Reclamation Facility (JIWRF) and South Shore Water Reclamation Facility (SSWRF). At these facilities, MMSD produces a commercially available fertilizer called Milorganite. In 2021, The Biosolids Advanced Facilities Plan (AFP) was created, which focused on the 2045 planning horizon and addressed three major questions: 1. What is the best way to produce Milorganite? 2. What drivers influence the long-term viability of Milorganite? 3. How can the District adapt to changing drivers?
Methodology
Perhaps the most important aspect of a successful Business Case is to ensure the decisions made align with predefined organizational goals and required Levels of Service (LOS) (Figure 2). Typical strategies when using an Asset Management Framework to assist with this alignment include: - Present and Future Loadings Analysis - Technology Screening - Capital Expenditure (CAPEX) and Operational Expenditure (OPEX) Analysis - Risk Assessment (including Risk Reduction effectiveness) Though these strategies do well to address current drivers affecting the organization's decision making, they often do not consider potential changes to these drivers and how that can affect the long-term viability of a plan. Adaptive Pathways Planning (different from Adaptive Planning) is a recently developed practical planning approach, designed to assist with planning for uncertain futures. By contrast, Adaptive Planning alone is designed to measure the success of the plan and make changes as the plan is implemented (reactive approach). The goal of Adaptive Pathways Planning is to be proactive, adding flexibility and resilience into strategic and facilities planning based on the principle that significant uncertainty exists in the future. Decision-makers benefit from focusing on what triggers influence decisions to move forward along a recommended path, or instead indicate when there is a need to change course. This is in comparison to traditional scenario planning, in which work estimates and timing are developed based on the best information and judgements today, but it is unclear what to do when conditions change and how to know when conditions have changed enough to warrant a change.
Results
Biosolids production projections for the year 2045 were estimated by employing a process model that used the future condition flows and influent loadings and assumed that chemically enhanced primary treatment was implemented at SSWRF. These values form the basis for design for subsequent evaluation of solids handling alternatives (Figure 3). In the case of MMSD, a traditional Alternatives Analysis was conducted to address what the best decision would be for the future of the organization. An initial technology screening resulted in four alternatives to analyze as part of the detailed Business Case. Each alternative included the production of Milorganite at JIWRF using a 2:1 waste activated sludge to digested sludge ratio. This ratio as selected based on the desired nutrient balance for Milorganite. The following alternatives were evaluated: - Baseline: 'Business-as-usual' alternative with upgrades and rehabilitation projects to address capacity constraints and physical mortality concerns. - Alternative 1: Production of Milorganite at both JIWRF and SSWRF, with upgrades and rehabilitation projects. - Alternative 2: Production of Milorganite at JIWRF and production of a Class A dried product made from digested sludge at SSWRF, with upgrade and rehabilitation components. - Alternative 3: Production of Milorganite at JIWRF and production of biochar made from dried digested sludge at SSWRF, with upgrades and rehabilitation projects. These alternatives underwent a detailed alternatives analysis to ensure alignment with MMSD's required LOS. This multifaceted approach included the following: - Risk assessment – A total of 66 risks were identified and broken up into LOS categories. The Business Risk was calculated by multiplying the consequence of failure by the likelihood of failure. The total risk score was calculated by applying the maximum risk scores for each LOS category for each alternative (Table 1). - Life Cycle Cost Analysis – Based on each alternative's capital and operating and maintenance costs, a cashflow analysis was created for each alternative that looks at capital and operating costs for a 20-year study period. A 20-year Net Present Value (NPV) for each alternative was calculated, with an assumed discount rate of 3.375% (Figure 4). A Cost/Risk Reduction value was calculated using a Business Case Tool provided by MMSD. This value is equal to the total risk reduction from baseline divided by the calculated NPV, allowing for normalization of results. Six additional criteria were included in the alternatives analysis. Each criterion was assigned a weighting and the alternatives were ranked. The results of this can be seen in Figure 5. Through this analysis, Alternative 1 was shown to be the favored alternative. Though this alternative aligns best with MMSD's LOS and current drivers, other factors must be considered for a more well-rounded analysis. Though current drivers are well addressed in this initial analysis, it does not consider the risk of these drivers changing and potentially affecting the viability of Milorganite production. This includes: - Regulations affecting the disposal of Class B biosolids - Regulations affecting the disposal of Class A biosolids without PFAS disposal - Regulations prohibiting land application of Milorganite
In the future, the risk of these regulations passing is increased, so it will become increasingly crucial to plan for these circumstances. Adaptive Pathways Planning was implemented to show differing futures MMSD could expect based on the circumstances. The four alternatives were combined into a phased plan that allows for alignment with MMSD's required LOS and organizational goals while also allowing for adaptation to changing regulations. A key feature of this approach is the representation of the adaptive pathways plan on a diagram, called the 'Adaptive Pathways Map' (Figure 6). This map illustrates potential pathways, their corresponding timelines, and methods to switch between options or implement new strategies as the future unfolds. This includes the identification of thresholds (turning points) at which an option is no longer feasible, as well as defining triggers (decision) points for when decisions must be made.
Consequences
Choosing to use Adaptive Pathways Planning in conjunction with traditional asset management strategies allows for organizations to reduce costs associated with risk by having plans already in place for changing drivers. Adaptive Pathways Planning aims to avoid over- or under-investment due to lock-ins or path dependences, if the future unfolds differently than today's best possible predictions.