Electricity generation from industrial wastewaters in bioelectrochemical systems
|Tila||Julkaistu - 4 lokakuuta 2019|
|Nimi||Tampere University Dissertations|
biodegradable wastewaters that need to be treated prior to discharge. These
wastewaters are generally treated with conventional activated sludge process,
producing good quality effluent. To avoid energy intensive aeration, anaerobic
methods are another option for the treatment. In microbial fuel cells (MFCs),
electrochemically active microorganisms degrade organic compounds with
simultaneous electricity generation. Compared to more traditional methanogenic
treatment, MFCs can be operated at lower temperatures and with less concentrated wastewaters.
The aim of this work was to study the applicability of MFCs for treatment and
resource recovery from synthetic wastewaters and real brewery and
thermomechanical (TMP) wastewaters. Varying wastewater flow rates and
compositions are typical for industrial operations, but challenging for biological
treatment processes. For this reason, as a preparation to possible process upsets, different start-up methods were studied to accelerate the start-up of
bioelectrochemical treatment. In addition, stable operation was optimized by
comparing different anode electrode materials and organic loading rates.
The start-up was studied in semi-continuously operated air-cathode and three-
chamber MFCs, and process optimization in a continuously fed up-flow MFC.
Among studied electrochemical methods, -200 mV vs. Ag/AgCl adjusted anode
potential resulted in the highest average power density of 0.65 Wm-3 after the start-up in brewery wastewater fed reactors. MFCs inoculated with stored (at +4 or -20 °C) anolyte demonstrated for the first time that power densities recovered after one month storing, but not after six months storing. Granular activated carbon was the most potential anode electrode material among the studied electrode materials. In xylose-fed up-flow MFC, organic loading rates of 0.31 and 0.53 gCODL-1d-1 enabled the highest power densities.
This study demonstrates the applicability of brewery and for the first time TMP
wastewaters for bioelectrochemical treatment in MFCs. Power densities can likely be further increased by optimizing MFC design and operation. Partial removal of
degradable compounds in brewery and TMP wastewater indicated the need for e.g. aerobic post-treatment.