Implementation of a Sulfide-Air Fuel Cell Coupled to a Sulfate-Reducing Biocathode for Elemental Sulfur Recovery.

Enric Blázquez,Albert Guisasola,Pablo Ledezma,Stefano Freguia,David Gabriel,Juan Antonio Baeza

doi:10.3390/ijerph18115571

Abstract

Bio-electrochemical systems (BES) are a flexible biotechnological platform that can be employed to treat several types of wastewaters and recover valuable products concomitantly. Sulfate-rich wastewaters usually lack an electron donor; for this reason, implementing BES to treat the sulfate and the possibility of recovering the elemental sulfur (S0) offers a solution to this kind of wastewater. This study proposes a novel BES configuration that combines bio-electrochemical sulfate reduction in a biocathode with a sulfide–air fuel cell (FC) to recover S0. The proposed system achieved high elemental sulfur production rates (up to 386 mg S0-S L−1 d−1) with 65% of the sulfate removed recovered as S0 and a 12% lower energy consumption per kg of S0 produced (16.50 ± 0.19 kWh kg−1 S0-S) than a conventional electrochemical S0 recovery system.

Highlights

Bio-electrochemical systems (BES) are a novel technology based on electrochemical processes where the oxidation and/or reduction reactions are catalyzed by microorganisms [1]
Sulfate-rich wastewaters are produced by several large-scale industrial activities such as pulp and paper production, food processing, dye and detergent manufacturing, among others [10], and if released untreated onto the environment may lead to several environmental problems–e.g., due to the biological formation of sulfide when microorganisms use sulfate as terminal electron acceptor [11]–such as odor nuisance, corrosion and toxicity [12]
Reactor introduced an extra input of oxygen in the reactor during the whole operation. This is because the modified carbon cloth used as air-cathode allowed for the passive diffusion of oxygen into the reactor from the atmosphere, irrespective of whether the fuel cell (FC) electrical circuit was open or closed

Summary

Introduction

Bio-electrochemical systems (BES) are a novel technology based on electrochemical processes where the oxidation and/or reduction reactions are catalyzed by microorganisms [1]. Sulfate-rich wastewaters are produced by several large-scale industrial activities such as pulp and paper production, food processing, dye and detergent manufacturing, among others [10], and if released untreated onto the environment may lead to several environmental problems–e.g., due to the biological formation of sulfide when microorganisms use sulfate as terminal electron acceptor [11]–such as odor nuisance, corrosion and toxicity [12]. Sulfate is the highest oxidation form of sulfur and requires a reduction reaction to be removed and recovered as S0. There are several wastewaters with high concentrations of sulfate that lack the electron donors required for this reduction [13,14]

Methods

Results

Conclusion