Grantee Research Project Results
Final Report: Decreasing the Energy Use in Wastewater Treatment
EPA Grant Number: SU839330Title: Decreasing the Energy Use in Wastewater Treatment
Investigators: Lampert, David , Stine, James , Thomison, David , Ogle, Stephen , Hendrickson, Greg , McCutchan, Aubrey , Overacker, Nick , Wiseman, Rabecca
Institution: Oklahoma State University
EPA Project Officer: Page, Angela
Phase: I
Project Period: October 30, 2017 through October 30, 2018
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2017) RFA Text | Recipients Lists
Research Category: Sustainable and Healthy Communities , P3 Awards , P3 Challenge Area - Safe and Sustainable Water Resources
Objective:
Previous estimates indicate that municipal wastewater treatment plants (WWTPs) consume between 0.8% and 3% of all electricity in the United States. Energy savings measures in WWTPs have the potential for substantial pollution reduction. WWTPs reduce concentrations of organic matter and nutrients in effluent to prevent dissolved oxygen (DO) concentrations from dropping in water bodies receiving effluent, since organic matter consumption simultaneously reduces DO and disrupts the downstream ecology. Aeration processes in WWTPs facilitate the growth of microorganisms that consume biochemical oxygen demand (BOD), a measure of the oxygen-consuming potential of wastewater, to protect receiving water bodies. BOD quantification is a labor-intensive, five-day process, which complicates oxygen delivery operations. Blowers used in activated sludge processes, which are the most common aeration process in larger facilities, consume substantial amounts of electricity to supply the air. Many facilities supply excess oxygen to ensure water quality compliance with little thought to the energy costs. The problem is pervasive in smaller communities with limited resources and WWTP personnel.
The overall goal of this project was to develop a simple operational technology to reduce aeration costs in WWTPs and assess the potential for such a technology to reduce energy usage and the associated pollution. The technology will make use of a network of sensors and algorithms to adjust the aeration inputs to activated sludge processes as DO and BOD fluctuate to meet regulatory constraints while simultaneously minimizing energy consumption. The specific objectives of the first phase of this project were to: 1) Construct a lab-scale experiment to analyze the relationships between critical biological process parameters including DO, BOD, and applied aeration; 2) Build a simple, automated process control to adjust aeration inputs as conditions fluctuate; 3) Assess opportunities for aeration energy savings in other facilities; 4) determine the potential energy, greenhouse gas emissions, and cost savings associated with this design using life cycle analysis
Summary/Accomplishments (Outputs/Outcomes):
Progress to date includes construction of a lab-scale aeration system, compilation of data from Stillwater and other WWTPs in Oklahoma, and development of a business plan for commercialization. The lab-scale aeration system utilizes continuous flow of wastewater with recirculating sludge from a settling unit in a series of glass tanks. An air pump, diffuser, and flow control valve provide variable aeration. The dissolved oxygen, nitrates/ammonia, turbidity, pH, and conductivity data are monitored using an array of sensors and uploaded automatically to an online DropBox folder every 5 seconds. A database of water quality estimates and energy usage at the Stillwater facility over the past five years has been compiled from monthly records. Energy consumption, flow, and BOD data have been collected from 28 WWTPs serving populations between 10,000 and 100,000 people and used to assess current wastewater energy consumption and the associated life cycle emissions. Interviews have been conducted with professionals in the wastewater industry to assess perspectives on the issue. A business plan to outfit mid-sized WWTPs with the control system has been developed. The team won the $20,000 1 st place in the High Growth Graduate Division at the Love’s Entrepreneur’s Cup.
Conclusions:
Aeration at the Stillwater WWTP accounts for 73% of its total energy consumption. Dissolved oxygen concentrations frequently approach saturation in the facility’s aeration basin, and BOD discharged is well below permitted limits. The Stillwater facility could maintain BOD reduction whilst saving substantial amounts of energy and indirect emissions. A lab-scale WWTP aeration basin has been constructed to make use of the Stillwater WWTP aeration basin influent and develop a control system to reduce energy usage. Data from the analysis of the statewide survey imply that the indirect emissions from treatment of one gallon of wastewater in Oklahoma are 130 grams of CO2 per gallon of wastewater treated. WWTPs in Oklahoma could save an estimated total of $2.7 million and 30,000 metric tons of CO2 per year after implementing this technology, which is equivalent to removing 6,500 passenger vehicles from the road each year.
Relevant Websites:
2018 Love’s Entrepreneur’s Cup Winners Exit
P3 Phase II:
Decreasing the Energy Use in Wastewater Treatment | 2019 Progress Report | 2020 Progress Report | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.