Cascade degradation of organic matters in brewery wastewater using a continuous stirred microbial electrochemical reactor and analysis of microbial communities

Abstract

A continuous stirred microbial electrochemical reactor (CSMER), comprising of a complete mixing zone (CMZ) and microbial electrochemical zone (MEZ), was used for brewery wastewater treatment. The system realized 75.4 ± 5.7% of TCOD and 64.9 ± 4.9% of TSS when fed with brewery wastewater concomitantly achieving an average maximum power density of 304 ± 31 m W m−2. Cascade utilization of organic matters made the CSMER remove a wider range of substrates compared with a continuous stirred tank reactor (CSTR), in which process 79.1 ± 5.6% of soluble protein and 86.6 ± 2.2% of soluble carbohydrates were degraded by anaerobic digestion in the CMZ and short-chain volatile fatty acids were further decomposed and generated current in the MEZ. Co-existence of fermentative bacteria (Clostridium and Bacteroides, 19.7% and 5.0%), acetogenic bacteria (Syntrophobacter, 20.8%), methanogenic archaea (Methanosaeta and Methanobacterium, 40.3% and 38.4%) and exoelectrogens (Geobacter, 12.4%) as well as a clear spatial distribution and syntrophic interaction among them contributed to the cascade degradation process in CSMER. The CSMER shows great promise for practical wastewater treatment application due to high pre-hydrolysis and acidification rate, high energy recovery and low capital cost.

A Pilot-scale Benthic Microbial Electrochemical System (BMES) for Enhanced Organic Removal in Sediment Restoration

“…At the initial stage of deployment, the BMES could obtain high voltage outputs, but over a long operational period, nutrient depletion, mass transfer resistance, and anode/cathode fouling, could lower the system performance2930. Several factors, such as spatial and temporal variability, natural fluctuations, temperature changes, pressure variations, water flow changes, salinity and conductivity changes, and dissolved oxygen affect the BMES functions29.…”

(Bio)electrochemical ammonia recovery: progress and perspectives

“…The study of the interactions between EAB and non-EAB is crucial, especially in wastewater streams like urine that are rich in complex organics (Parameswaran et al 2009 ). The co-existence of fermentative bacteria, acetogenic bacteria, methanogenic archaea, and EAB has been reported for BES using complex substrates (Jung and Regan 2007 ; Yang et al 2012 ; Wang et al 2016 ). Better understanding of these interactions could be useful to optimize BES operation and to ensure that most of the (complex) COD will be available for current generation at the bioanode.…”

Sustainable Waste-to-Energy Technologies: Bioelectrochemical Systems

“…Brewery wastewater has high concentrations of carbohydrates and sugars which have high energy content and can be easily biodegraded (Wang et al, 2016). Due to wastewater generation patterns and variability among brewery and winery wastewater sources, traditionally biological wastewater treatment technologies are employed, including sequencing batch reactors (SBRs) and up-flow sludge blankets (USABs) systems (Simate et al, 2011).…”

“…A 4-L single-chamber MFC was investigated using diluted brewery wastewater (3707 mg COD/L); it produced 304 mW/m 2 and achieved >75% COD reduction (Wang et al, 2016). Despite this large COD removal, the coulombic efficiency was low which indicates that the organic matter might have been oxidized by fermentative and methanogenic microorganisms instead of exoelectrogens.…”