Ferrate (Fe(VI)) is one of the more promising novel oxidation treatment technologies in water treatment research, but there has been minimal research on its potential benefits in a water reuse paradigm. Ferrate has been shown to inactivate pathogens and support particle separation processes, in addition to a high oxidation potential and general success transforming generally recalcitrant constituents. The heterocyclic ether 1,4-dioxane has become an indicating compound for acceptable oxidative treatment under California Code of Regulations Title 22 (CCR 22), which benchmarks recycled water oxidation processes. However, the redox reaction between ferrate and dioxane has not been previously studied, and thus the potential for adequate performance under CCR 22 is unknown. Similarly, knowledge gaps exist related to ferrate disinfection of biological contaminants of emerging concern (CECs), including pathogens resistant to disinfection. Ultimately, the mechanisms of ferrate disinfection remain incompletely understood. This presentation will include results from an ongoing study evaluating the suitability for ferrate in treatment for water reuse including bench-scale examinations of 1,4 dioxane oxidation and assessments of disinfection. For the oxidation experiments, 1,4-dioxane was spiked into batch reactors of varying water quality (pH, buffer, presence of organic matter). Sub-samples were taken at frequent time intervals to quantify reaction kinetics, stoichiometry, and the role of competing oxidant demands. The role of heterogeneous catalysts, and natural organic matter will also be discussed. For the disinfection experiments, <i>Escherichia coli</i> and <i>Bacillus subtilis</i> were exposed to ferrate in various water chemistry conditions including wastewater effluent to determine the mechanisms of ferrate disinfection in the water reuse context. In particular, the relative importance of ferrate and ferrate intermediates in disinfection for water reuse will be discussed. Presented results will also show the effectiveness of ferrate to oxidize 1,4-dioxane relative to the benchmarks of CCR 22. In general, results indicate the ferrate seems viable for water reuse with possible achievement of CCR 22 parameters in full-scale applications. A discussion of future work and research needs will also be included.

Assessment of ferrate for 1,4 dioxane oxidation and pathogen inactivation towards water reuse applications

256th National Meeting (2018)

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