Appleton Wastewater Treatment Plant Enhances Its Biogas Boiler System

Appleton WI

22 April, 2022

4:46 PM

Description

From the City of Appleton: April 22, 2022 Did you know that with 209,000 therms of energy, you can drive an average car around the world 110 times? This is the amount of energy the Appleton Wastewater Treatment Plant (AWWTP) saves per year after an award-winning third biogas a.k.a. methane boiler was installed in 2019. Two biogas boilers were installed in 2011 and were already saving the AWWTP 250,000 therms of natural gas usage per year. The AWWTP has a long history of sustainability, beginning with its Hauled Waste Program more than 20 years ago. Septage hauling businesses and food processors, mainly cheese processing, can dump their liquid waste at AWWTP's High Strength Waste receiving stations. This waste, along with the waste the City produces, is then fed to two biodigesters. These are the two large spheres you see at AWWTP, which are filled with microorganisms that digest the waste and produce methane or biogas that is then used to heat AWWTP facilities. Currently 17 of the 19 buildings at AWWTP are heated using this biogas, with the long-term goal of heating all 19 buildings with biogas, eliminating the need for natural gas altogether. The latest sustainability project at AWWTP was completed at the end of March and involved converting a Dissolved Air Flotation Thickener (DAFT) system into a receiving waste tank . DAFT is a process used in wastewater treatment that floats microorganisms to the top where they can be skimmed and fed to the biodigesters. Feeding the microorganisms in the biodigesters more solids and less water means a greater reduction in waste and more biogas production. The utilization of a third receiving tank also allows for a steadier stream of waste to be fed to the biodigesters, resulting in more predictable and consistent heating of the AWWTP facilities using biogas. Before the conversion of a third receiving waste tank, AWWTP was only utilizing two tanks. As waste was dumped by Hauled Waste customers, the system would have to quickly feed the biodigesters to make more room in the tanks. This resulted in much of the methane gas produced having to be burned off and not utilized in the heating of the facilities. This also meant that by the end of the day, there was not enough methane gas left to heat the facilities at night, and the heating system would have to rely on natural gas. If you would like to learn more about Appleton's sustainability initiatives, please visit: https://www.appleton.org/government/facilities-construction-management/sustainability where you can view our sustainability master plan and 2021 Green Tier Legacy Communities annual report. This press release was produced by the City of Appleton. The views expressed here are the author's own.