Quantification of Carbon Footprint of the Reno-Stead Water Reclamation Facility
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Authors
Triest, Samantha R.
Issue Date
2024
Type
Thesis
Language
Keywords
Carbon Footprint , Decarbonization , Wastewater , Water Reclamation Facility
Alternative Title
Abstract
Due to the steadfast rate greenhouse gases (GHG) are being emitted globally, alliances worldwide are calling for to improve energy efficiency and decrease emissions generated. Water reclamation facilities (WRFs) contribute notably to the carbon footprint of municipal operations, and are also important to reduce carbon footprint of the water sector through biogas recovery from wastewater. A review of recent critical literature highlights the protocols, models, and direct measurement methods used to quantify the carbon footprint at the WRF level. The methodologies include the International Panel on Climate Change Guidelines for National Greenhouse Gas Inventories, the Local Government Operations Protocol (LGO) for Greenhouse Gas Assessments, and the Greenhouse Gas Protocol. The LGO Protocol is the main methodology used within the United States to quantify carbon footprint of municipal facilities; thus, it is used to estimate the Reno-Stead Water Reclamation Facility's (RSWRF) carbon footprint in this research. Carbon footprint calculations take into consideration the emission factors and global warming potentials of primary GHGs, including N 2 O, CH 4 , and CO 2 . Scope 1 emissions from WRFs include nitrification/denitrification processes, effluent discharge, stationary combustion of natural gas and on-site generator electricity generation, and mobile combustion sources from the vehicle fleet. Scope 2 emissions include electricity purchased from an outside provider. Scope 3 emissions, not included in this study of the RSWRF, may include GHG emissions from employee commutes, upstream energy emissions, and chemical footprint of the plant. The estimated combined Scope 1 and Scope 2 carbon footprint of the RSWRF is 1,051 – 1,064 MT CO 2e/yr . Five other WRFs in the U.S. were compared with the RSWRF to account for the variability between their respective carbon footprints and to assess decarbonization strategies. Analyses show that four main factors influence the carbon footprint and justify variability among the WRFs: facility utilization versus installed capacity, permitted effluent limits, individual unit operations/processes employed, and sludge processing methods. Potential strategies to achieve decarbonization goals include optimization of unit processes to reduce energy inputs, implementation of UV disinfection, use of alternate energy sources, and resource recovery through advanced water reclamation. Further research is necessary to improve the quantification of the carbon footprint of the RSWRF. Recommendations include acquiring sensors to measure nitrous oxide emissions through a flux-chamber method over a minimum one-year period at the RSWRF. A spreadsheet model was developed during this study for the Reno-Stead Water Reclamation Facility to track its carbon footprint as it increases its utilization. Finally, analysis of additional case studies of WRFs within the United States and their respective carbon footprints is crucial to future research on decarbonization of RSWRF. More data on facilities with nuances such as non-potable reuse to potable reuse will aid in identifying decarbonization strategies at the RSWRF, which intends to send effluent to the Advanced Purified Water Facility in the future.