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Abstract
Electrochemical methods can help manage sulfide in wastewater, which poses environmental and health concerns due to its toxic, odorous, and corrosive nature. Yet, as a crucial element for agriculture and chemical manufacturing processes, sulfur could be recovered as fertilizer and commodity chemicals from sulfide-containing wastewaters. Wastewater characteristics vary widely and even within one type of wastewater over time; however, it remains unclear how these characteristics affect electrochemical sulfate production. In this study, we evaluated how four characteristics of influent wastewaters (electrolyte pH, composition, sulfide concentration, and buffer strength) affect sulfide removal metrics (sulfide removal rate, sulfide removal efficiency) and sulfate production metrics (sulfate production rate, sulfate production selectivity). We identified that electrolyte pH (3x differences in sulfide removal rate within the studied pH range) and sulfide concentration (16x difference in removal rate) were the most influential factors for electrochemical sulfide removal. Sulfate production was most sensitive to buffer strength (6x difference in sulfate production rate) and insensitive to electrolyte composition. Together, these results provide recommendations for the design of wastewater treatment trains and the feasibility of applying electrochemical methods to varying sulfide-containing wastewaters. In addition, we investigated a simultaneous multi-nutrient recovery (i.e., sulfur and nitrogen) process that leverages electrochemical stripping to further enhance the versatility and compatibility of electrochemical nutrient recovery methods.
Supplementary materials
Title
Supporting information
Description
The supporting information contains a summary of characteristics for sulfide-containing wastewaters, synthetic wastewater recipe, composition of real wastewaters, one-way ANOVA analysis of electrolyte effects on electrochemical sulfate production, pH changes during experiments, sulfur speciation and elemental sulfur deposition, total charge passed during experiments, the performance of electrochemical sulfur oxidation from electrolytes with different buffer strengths, nitrogen removal and recovery efficiencies via ECS, pH in three chambers during ECS experiments, N-to-S ratios of sulfide-containing wastewaters, and locations of separation processes in ECS.
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