A Process-Resolved Modeling Framework for Estimating National Wastewater Treatment Electricity Demand via Integrated Facility Data and Literature-Derived Energy Use Intensities

Abstract

Although wastewater treatment plants in any town are primary contributors to total local energy consumption, at around 35% of typical U.S. municipal energy budgets, with an expected increase over the next 10 years, levels of energy consumption and exact breakdown at the national level is uncertain. So, this paper proposes an integrative inventory of national energy consumption by the wastewater infrastructure by using literature and facility data to guide proper estimation of the energy consumption by the wastewater industry. To guide this estimate, EUIs were developed and researched for the following 11 most employed secondary treatment processes: Conventional Activated Sludge (CAS), Lagoon, Trickling Filter (TF), Contact Stabilization (CS), Membrane Bioreactor (MBR), Sequencing Batch Reactor (SBR), Bardenpho, Oxidation Ditch (OD), Anoxic/Oxic (A/O), Aerobic/Anoxic/Oxic (A2O), and Multiple Processes. These EUIs therefore represent plant-wide energy use in kWh per m3 of influent treated with respect to one, or multiple, of the secondary treatment processes employed at the plant. Then using plant data from the EPA’s Clean Water Need Survey (CWNS) and national energy consumption across all sectors of industry, the wastewater sector is estimated to be attributable to 0.76% ± 0.25% of national energy usage. In the end, this research supports national infrastructure planning/investment, research of process technologies, and further advances the sector toward a circular economy; for which specific case studies are included at a state, facility, and treatment level.