Reductive electrochemical technologies to target macroconstituents : in potable reuse, wastewater discharge, and agricultural fumigation

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Most current methods of water and wastewater treatment systems involve the purchase and transport of chemicals to centralized treatment facilities. Interest in decentralized treatment systems is growing, partly because pumping water to and from treatment facilities constitutes a significant fraction of the overall energy used within the water cycle. Electrochemical treatment systems are particularly attractive for these decentralized systems, since their modular nature enables them to be placed in locations such as the basements of apartment buildings. They also have the potential to be operated remotely, thereby avoiding the need to hire highly trained operators for each treatment site. An additional advantage is the potential to generate chemical reagents on-site, avoiding the purchase and shipping of reagents to these distributed sites and the associated CO2 emissions. While electrochemical treatment technologies are a potentially powerful tool for advancing decentralized treatment, there have been three main limitations that have inhibited scale-up. First, research has focused on oxidative (anodic) systems, but these systems can oxidize chloride and other halides, which are ubiquitous, into toxic halogenated products (e.g., perchlorate). Second, expensive materials are used to fashion anodes to combat their degradation under oxidative conditions (e.g., boron-doped diamond). Third, research has often targeted oxidation of contaminants that are microconstituents (< μg/L), but competition by macroconstituents (e.g., mg/L of dissolved organic matter) results in low process efficiencies and treatment timescale in excess of the ~1 h timescales typical of full-scale water and wastewater treatment processes. In this thesis, I offer a novel approach to address these three challenges. First, I focus on reductive (cathodic) processes, thereby avoiding halide oxidation to toxic byproducts. Second, I use inexpensive materials to construct cathodes (e.g., stainless steel, carbon), which was possible because their use as cathodes avoided their oxidative degradation. Third, I focused on three applications relevant to three separate sub-fields of environmental engineering where the cathode targeted macroconstituents, enhancing process efficiency and enabling treatment over reasonable timescales. For each application, I evaluate the impact of various performance metrics (e.g., voltage/current, pH, ionic strength, and electrode materials) to determine the optimal operational conditions. Using this data and real water or matrix conditions, I develop initial cost estimates against currently used technologies to assess whether the electrochemical process is feasible and where improvements need to be made in future work on the treatment processes.


Type of resource text
Form electronic resource; remote; computer; online resource
Extent 1 online resource.
Place California
Place [Stanford, California]
Publisher [Stanford University]
Copyright date 2023; ©2023
Publication date 2023; 2023
Issuance monographic
Language English


Author Weng, Cindy
Degree supervisor Mitch, William
Thesis advisor Mitch, William
Thesis advisor Criddle, Craig
Thesis advisor Luthy, Richard
Degree committee member Criddle, Craig
Degree committee member Luthy, Richard
Associated with Stanford University, School of Engineering
Associated with Stanford University, Civil & Environmental Engineering Department


Genre Theses
Genre Text

Bibliographic information

Statement of responsibility Cindy Weng.
Note Submitted to the Civil & Environmental Engineering Department.
Thesis Thesis Ph.D. Stanford University 2023.

Access conditions

© 2023 by Cindy Weng
This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).

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