A new performance evaluation method is proposed for microbial electrolysis cells, with acclimation to domestic wastewater improving the treatability of an industrial wastewater.
Microbial electrolysis cells (MECs) are potential candidates for sustainable wastewater treatment, as they allow for recovery of the energy input by producing valuable chemicals such as hydrogen gas.
Evaluating the effectiveness of MEC treatment for different wastewaters requires new approaches to quantify performance, and the establishment of specific procedures and parameters to characterise the outcome of fed-batch treatability tests.
Researchers at Pennsylvania State University show here that Coulombic efficiency can be used to directly calculate energy consumption relative to wastewater treatment in terms of chemical oxygen demand (COD) removal. They also report that the average current, not maximum current, is a better metric to evaluate the rate of the bioelectrochemical reactions.
The utility of these methods is demonstrated using simulated current profiles and actual wastewater tests. Industrial and domestic wastewaters were evaluated using small volume MECs, and different inoculation strategies.
Slightly less energy was needed for treatment of industrial wastewater than for domestic wastewater, but when these wastewaters were combined in equal amounts, the energy required was significantly reduced.
Acclimation of the microbial electrolysis cell to domestic wastewater, prior to tests with industrial wastewaters, was the easiest and most direct method to optimise MEC performance for industrial wastewater treatment.
A pre-acclimated MEC accomplished the same removal as a reactor acclimated to only the industrial wastewater, but treatment was achieved much more quickly.
