Production of polyhydroxyalkanoate (PHA) copolymer from food waste using mixed culture for carboxylate production and Pseudomonas putida for PHA synthesis.

Production of polyhydroxyalkanoates (PHAs) with high concentration of carboxylate, that was accumulated from solid state fermentation (SSF) of food waste (FW), was tested using Pseudomonas putida strain KT2440. Mixed-culture SSF of FW supplied in a high concentration of carboxylate, which caused a high PHA production of 0.56 g PHA/g CDM under nutrients control.

Periodic step polarization accelerates electron recovery by electroactive biofilms (EABs).

Relatively low rate of electron recovery is one of the factors that limit the advancement of bioelectrochemical systems. Here, new periodic polarizations were investigated with electroactive biofilms (EABs) enriched from activated sludge and Geobacter sulfurreducens biofilms. When representative anode potentials (E ) were applied, redox centers with midpoint potentials (E ) higher than E were identified by localized cyclic voltammetry.

An integrated leachate bed reactor - anaerobic membrane bioreactor system (LBR-AnMBR) for food waste stabilization and biogas recovery.

This study developed an integrated LBR - AnMBR system for efficient stabilization and biogas recovery from food waste (FW) at room temperatures (21-22 °C). First, the leachate recirculation rate (4.4-13.

Optimization of biofilm conductance measurement with two-electrode microbial electrochemical cells (MECs).

This study was conducted to develop a standardized and consistent method for biofilm conductance measurement for an improved comprehension of extracellular electron transfer. Biofilm conductance (2.12 ± 0.

Biohydrogen production and purification: Focusing on bioelectrochemical systems.

Innovative technologies on green hydrogen production become significant as the hydrogen economy has grown globally. Biohydrogen is one of green hydrogen production methods, and microbial electrochemical cells (MECs) can be key to biohydrogen provision. However, MECs are immature for biohydrogen technology due to several limitations including extracellular electron transfer (EET) engineering.

Microbial electrolysis cells for the production of biohydrogen in dark fermentation - A review.

To assess biohydrogen for future green energy, this review revisited dark fermentation and microbial electrolysis cells (MECs). Hydrogen evolution rate in mesophilic dark fermentation is as high as 192 m H/m-d, however hydrogen yield is limited. MECs are ideal for improving hydrogen yield from carboxylate accumulated from dark fermentation, whereas hydrogen production rate is too slow in MECs.

Acidogenic fermentation of food waste in a leachate bed reactor (LBR) at high volumetric organic Loading: Effect of granular activated carbon (GAC) and sequential enrichment of inoculum.

This study investigated the impact of different granular activated carbon (GAC) loadings and inoculum enrichment on acidogenic fermentation of food waste in a leachate bed reactor (LBR) operated at a high volumetric organic loading of 49 g VS/L. LBR with a high GAC loading of 0.51 g GAC/g VS achieved hydrolysis yield of 620 g SCOD/kg VS, significantly (P ≤ 0.

Nitrite reduction using a membrane biofilm reactor (MBfR) in a hypoxic environment with dilute methane under low pressures.

Methane-based membrane biofilm reactors (MBfRs) can be an effective solution for nitrogen control in wastewater, but there is limited information on nitrite reduction for dilute wastewater (e.g., municipal wastewater) in hypoxic MBfRs.

Butyrate production and purification by combining dry fermentation of food waste with a microbial fuel cell.

This study developed and evaluated a high-purity butyrate producing bioprocess from food waste by combining dry fermentation (DF) with a microbial fuel cell (MFC). Acclimatization of a DF reactor with an enrichment culture resulted in high food waste degradation (VS removed, %) and butyrate production. A high VS degradation of 81%, butyrate concentration of up to 24 gCOD/L and butyrate yields of 497 gCOD/kg VS was obtained in the DF reactor.

State-of-the-art management technologies of dissolved methane in anaerobically-treated low-strength wastewaters: A review.

The recent advancement in low temperature anaerobic processes shows a great promise for realizing low-energy-cost, sustainable mainstream wastewater treatment. However, the considerable loss of the dissolved methane from anaerobically-treated low-strength wastewater significantly compromises the energy potential of the anaerobic processes and poses an environmental risk. In this review, the promises and challenges of existing and emerging technologies for dissolved methane management are examined: its removal, recovery, and on-site reuse.

Anaerobic membrane bioreactors for wastewater treatment: Challenges and opportunities.

Anaerobic membrane bioreactors (AnMBRs) have become a new mature technology and entered into the wastewater market, but there are several challenges to be addressed for wide applications. In this review, we discuss challenges and potentials of AnMBRs focusing on wastewater treatment. Nitrogen and dissolved methane control, membrane fouling and its control, and membrane associated cost including energy consumption are main bottlenecks to facilitating AnMBR application in wastewater treatment.

Recovery of dissolved methane from anaerobically treated food waste leachate using solvent-based membrane contactor.

The difficulty of dissolved methane recovery remains a major hurdle for mainstream anaerobic wastewater treatment processes. We recently proposed solvent-based membrane contactor (SMC) for high (>90%) methane recovery over a wide temperature range and net-energy production. Here, we investigate the methane recovery efficacy of the SMC process by using an AnMBR effluent from treating food waste leachate.

Hydrophilic graphene aerogel anodes enhance the performance of microbial electrochemical systems.

The hydrophilic three-dimensional (3D) structure of graphene materials was produced with reducing agent-ethylene glycol through hydrothermal reduction. Numerous microorganisms with diverse community structure were established in anode surface, as the hydrophilicity of the graphene anode increased; more populations of Proteobacteria and Firmicutes families were identified in a higher hydrophilic anode. In addition, the start-up time of a microbial fuel cell (MFC) equipped with hydrophilic 3D graphene anode was only 43 h, which is much shorter than traditional 3D graphene-based anode systems.

High-rate carboxylate production in dry fermentation of food waste at room temperature.

Dry fermentation of food waste was optimized to achieve the maximum solid loading rate for carboxylate production without clogging events in a dry fermenter run at neutral pH. High inoculum-to-substrate ratio improved food waste solubilization and carboxylate yield, but the ratio 15% completely clogged the dry fermenter. Higher leachate circulate rate tended to enhance food waste fermentation, but partial clogging was observed at 13.

Mixed dye wastewater treatment in a bioelectrochemical system-centered process.

The feasibility of mixed dye wastewater treatment was evaluated with a novel integrated bioprocess that consisted of a hybrid anaerobic reactor (HAR) with a built-in bioelectrochemical system, an aerobic biofilm reactor (ABFR) and a denitrification reactor (DR). The position of the DR significantly affected chemical oxygen demand (COD) and colority in effluent, and placing the DR after the ABFR improved effluent quality probably due to minimization of the undesired autoxidation of aromatic amine in dye wastewater. The optimal integrated process of HAR + ABFR + DR efficiently treated mixed dye wastewater, and concentrations of COD and TN were decreased down to 75 ± 18 mg/L and 12.

Kinetics of anaerobic methane oxidation coupled to denitrification in the membrane biofilm reactor.

Anaerobic oxidation of methane coupled to denitrification (AOM-D) in a membrane biofilm reactor (MBfR), a platform used for efficiently coupling gas delivery and biofilm development, has attracted attention in recent years due to the low cost and high availability of methane. However, experimental studies have shown that the nitrate-removal flux in the CH -based MBfR (<1.0 g N/m -day) is about one order of magnitude smaller than that in the H -based MBfR (1.

Food waste treatment with a leachate bed reactor: Effects of inoculum to substrate ratio and reactor design.

This study evaluated the effects of different inoculum to substrate ratios (ISRs) (5, 10, 15%) on hydrolysis and acidogenesis of food waste in a conventional leachate bed reactor (LBR-C) and a novel fractionalized LBR (LBR-F). At ISR of 10%, LBR-C experienced clogging and thus the solid removal and VFA production reduced significantly. Without any clogging events at high ISR of 10%, LBR-F achieved significantly higher (p < 0.

Induction of cathodic voltage reversal and hydrogen peroxide synthesis in a serially stacked microbial fuel cell.

We developed an innovative strategy to address the inhibition of anode-respiring bacteria due to voltage reversal in serially stacked microbial fuel cells by inducing cathodic voltage reversal and HO production. When platinum-coated carbon (Pt/C) cathodes were employed (stacked MFC) and the MFC was operated with acetate medium, the last unit (MFC 4) caused a voltage reversal of -0.8 V with a substantial anode overpotential of 1.

Algal biorefinery: A sustainable approach to valorize algal-based biomass towards multiple product recovery.

In recent years, ever-increasing socio-economic awareness, and negative impact of excessive petro consumption have redirected the research interests towards bio-resources such as algal-based biomass. In order to meet current bio-economy challenges to produce high-value multiple products at a time, new integrated processes in research and development are necessary. Though various strategies have been posited for conversion of algal-based biomass to fuel and fine chemicals, none of them has been proved as economically viable and energetically feasible.

Food waste fermentation in a leach bed reactor: Reactor performance, and microbial ecology and dynamics.

Food waste fermentation was investigated in a leach bed reactor operated at acidic, neutral and alkaline conditions. Highest solids reduction of 87% was obtained at pH 7 in 14 days of reaction time with minimum mixing. The concentration of volatile fatty acids increased to 28.

Hydrogen peroxide production in a pilot-scale microbial electrolysis cell.

A pilot-scale dual-chamber microbial electrolysis cell (MEC) equipped with a carbon gas-diffusion cathode was evaluated for HO production using acetate medium as the electron donor. To assess the effect of cathodic pH on HO yield, the MEC was tested with an anion exchange membrane (AEM) and a cation exchange membrane (CEM), respectively. The maximum current density reached 0.

Electrokinetic analyses in biofilm anodes: Ohmic conduction of extracellular electron transfer.

This review explores electron transfer kinetics from an electron donor to the anode in electrically conductive biofilm anodes. Intracellular electron transfer (IET) from the donor to the anode is well described with the Monod equation. In comparison, mechanisms of extracellular electron transfer (EET) conduction are unclear yet, complicating EET kinetics.