Stratified microbial structure and activity within anode biofilm during electrochemically assisted brewery wastewater treatment

Abstract

In a bioelectrochemical system (BES), microbial community of anode biofilm is crucial to BES performance. In this study, the stratified pattern of community structure and activity of an anode‐respiring biofilm in a BES fueled with brewery wastewater was investigated over time. The anode biofilm exhibited a superior performance in the removal of ethanol to that of an open‐circuit system. The electrical current density reached a high level of 0.55mA/cm2 with a Coulombic efficiency of 71.4%, but decreased to 0.18mA/cm2 in the late stage of operation. A mature biofilm developed a more active outer layer covering a less active inner core, although the activities of the outer and inner layers of biofilm were similar in the early stage. More Geobacter spp., typical exoelectrogens, were enriched in the outer layer than in the inner layer of biofilm in the early stage, while more Geobacter spp. were distributed in the inner layer than in the outer layer in the late stage. The inactive and Geobacter‐occupied inner layer of biofilm might be responsible for the decreased electricity generation from wastewater in the late stage of operation. This study provides better understanding of the effect of anode biofilm structure on BES performance.

Elucidating the development of cooperative anode-biofilm-structures

“…Notably, imaging of biofilm dimensions and correlating this with measured current densities can give valuable information. Hence, fluorescence microscopy as well as optical coherence tomography (OCT) studies were conducted with mixed environmental inocula and in bioelectrochemical flow cell systems of varying formats [ [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , [36] ]. In several of these studies, model presumptions were corroborated suggesting that the formation of proton gradients from anode to bulk phase will limit biofilm activity.…”

“…With regards to biological activity in different biofilm depths, there is so far no clear result within past research. While some studies revealed a live outer layer with a dead zone close to the anode [ 28 , 34 , 35 ] others reported the opposite [ 26 , 29 , 33 , 37 ]. Another recent analysis using a flow cell and an environmental inoculum suggested that most metabolic activity would be in the center of 42.5–60 μm thick anode biofilms [ 36 ].…”

Breath‐Figure Self‐Assembled Low‐Cost Janus Fabrics for Highly Efficient and Stable Solar Desalination

“…[1,2] It is essential to develop functional materials and straightforward approaches to obtain freshwater from seawater and wastewater. [3,4] While conventional electrospinning. [36] The Janus absorber demonstrated a conversion efficiency of 72% and a stable water output of 1.3 kg m -2 h -1 over 16 days under one-sun irradiation without salt deposition.…”

“…[ 1,2 ] It is essential to develop functional materials and straightforward approaches to obtain freshwater from seawater and wastewater. [ 3,4 ] While conventional methods of seawater desalination and wastewater treatment, such as reverse osmosis (RO) [ 5,6 ] and thermal desalination technologies, [ 4,7 ] not only need high technical requirements but also unavoidably cause the large consumption of fossil energy. In recent years, solar‐driven interfacial evaporation technology has aroused much attention due to its advantages of eco‐friendly features and low level of infrastructure.…”