Biosolids Management Diversification and Optimization Study - Sustainability Analysis
The Metro Wastewater Reclamation District (Metro District) updated its biosolids management program by focusing on specific issues at the District's facilities. Results of this study will be incorporated into the next Wastewater Facility Plan update or design definition reports for future upgrades at the District's treatment facilities.
HDR completed a Phase 1 sustainability study to prepare a framework for analysis of treatment plant and biosolids management alternatives. This analysis used HDR's unique Sustainable Return on Investment (SROI) process to evaluate alternatives based on the triple bottom line - economic, social, and environmental costs and benefits - associated with the biosolids management approaches. The SROI process applies economic principles and evidence-based data assessment to perform transparent alternatives analyses. The process builds from clients' perspectives on sustainability and their evaluation criteria to determine a ranking of project alternatives with dollar-based metrics of sustainability.
Our team focused on alternatives that provide a high SROI, meet community values, and minimize Metro District costs. This business plan approach combined all the District-wide biosolids projects either completed, underway, or being planned in the near future, and included components from both existing and proposed treatment plants. The plan focuses on three initiatives:
Biosolids Diversification – Alternatives evaluated include composting, thermal drying, cell lysing and enhanced digestion using CAMBI thermal hydrolysis.
Farm Optimization – This initiative evaluated means to optimize farm operations, including converting a portion of the farm into a 100 MW wind farm.
Biosolids Treatment Optimization – Alternatives evaluated include combustion of biosolids using waste heat to thermally dry biosolids to Class A product, and combined heat and power (CHP).