Yoong-Ling Oon

Hybrid system up-flow constructed wetland integrated with microbial fuel cell for simultaneous wastewater treatment and electricity generation.

An innovative design of upflow constructed wetland-microbial fuel cell (UFCW-MFC) planted with cattail was used for simultaneous wastewater treatment and electricity generation. The electrodes material employed in the study was carbon felt. The main aim of this study is to assess the performance of the UFCW coupling with MFC in term of ability to treat wastewater and the capability to generate bioelectricity. The oxidation reduction potential (ORP) and dissolved oxygen (DO) profile showed that the anaerobic and aerobic regions were well developed in the lower and upper bed, respectively, of UFCW-MFC. Biodegradation of organic matter, nitrification and denitrification was investigated and the removal efficiencies of COD, NO3(-), NH4(+) were 100%, 40%, and 91%, respectively. The maximum power density of 6.12 mW m(-2) and coulombic efficiency of 8.6% were achieved at electrode spacing of anode 1 (A1) and cathode (15 cm).

Synergistic effect of up-flow constructed wetland and microbial fuel cell for simultaneous wastewater treatment and energy recovery.

This study demonstrated a successful operation of up-flow constructed wetland-microbial fuel cell (UFCW-MFC) in wastewater treatment and energy recovery. The goals of this study were to investigate the effect of circuit connection, organic loading rates, and electrode spacing on the performance of wastewater treatment and bioelectricity generation. The average influent of COD, NO3(-) and NH4(+) were 624 mg/L, 142 mg/L, 40 mg/L, respectively and their removal efficiencies (1 day HRT) were 99%, 46%, and 96%, respectively. NO3(-) removal was relatively higher in the closed circuit system due to lower dissolved oxygen in the system. Despite larger electrode spacing, the voltage outputs from Anode 2 (A2) (30 cm) and Anode 3 (A3) (45 cm) were higher than from Anode 1 (A1) (15 cm) as a result of insufficient fuel supply to A1. The maximum power density and Coulombic efficiency were obtained at A2, which were 93 mW/m(3) and 1.42%, respectively.

A highly efficient single chambered up-flow membrane-less microbial fuel cell for treatment of azo dye Acid Orange 7-containing wastewater.

Single chambered up-flow membrane-less microbial fuel cell (UFML MFC) was developed to study the feasibility of the bioreactor for decolorization of Acid Orange 7 (AO7) and electricity generation simultaneously. The performance of UFML MFC was evaluated in terms of voltage output, chemical oxygen demand (COD) and color removal efficiency by varying the concentration of AO7 in synthetic wastewater. The results shown the voltage generation and COD removal efficiency decreased as the initial AO7 concentration increased; this indicates there is electron competition between anode and azo dye. Furthermore, there was a phenomenon of further decolorization at cathode region which indicates the oxygen and azo dye are both compete as electron acceptor. Based on the UV-visible spectra analysis, the breakdown of the azo bond and naphthalene compound in AO7 were confirmed. These findings show the capability of integrated UFML MFC in azo dye wastewater treatment and simultaneous electricity generation.

Role of macrophyte and effect of supplementary aeration in up-flow constructed wetland-microbial fuel cell for simultaneous wastewater treatment and energy recovery

This study investigates the role of plant (Elodea nuttallii) and effect of supplementary aeration on wastewater treatment and bioelectricity generation in an up-flow constructed wetland-microbial fuel cell (UFCW-MFC). Aeration rates were varied from 1900 to 0mL/min and a control reactor was operated without supplementary aeration. 600mL/min was the optimum aeration flow rate to achieve highest energy recovery as the oxygen was sufficient to use as terminal electron acceptor for electrical current generation. The maximum voltage output, power density, normalized energy recovery and Coulombic efficiency were 545.77±25mV, 184.75±7.50mW/m3, 204.49W/kg COD, 1.29W/m3 and 10.28%, respectively. The variation of aeration flow rates influenced the NO3- and NH4+ removal differently as nitrification and denitrification involved conflicting requirement. In terms of wastewater treatment performance, at 60mL/min aeration rate, UFCW-MFC achieved 50 and 81% of NO3- and NH4+ removal, respectively. E. nuttallii enhanced nitrification by 17% and significantly contributed to bioelectricity generation.

Microbial fuel cell operation using monoazo and diazo dyes as terminal electron acceptor for simultaneous decolourisation and bioelectricity generation.

Monoazo and diazo dyes [New coccine (NC), Acid orange 7 (AO7), Reactive red 120 (RR120) and Reactive green 19 (RG19)] were employed as electron acceptors in the abiotic cathode of microbial fuel cell. The electrons and protons generated from microbial organic oxidation at the anode which were utilized for electrochemical azo dye reduction at the cathodic chamber was successfully demonstrated. When NC was employed as the electron acceptor, the chemical oxygen demand (COD) removal and dye decolourisation efficiencies obtained at the anodic and cathodic chamber were 73±3% and 95.1±1.1%, respectively. This study demonstrated that the decolourisation rates of monoazo dyes were ∼50% higher than diazo dyes. The maximum power density in relation to NC decolourisation was 20.64mW/m2, corresponding to current density of 120.24mA/m2. The decolourisation rate and power output of different azo dyes were in the order of NC>AO7>RR120>RG19. The findings revealed that the structure of dye influenced the decolourisation and power performance of MFC. Azo dye with electron-withdrawing group at para substituent to azo bond would draw electrons from azo bond; hence the azo dye became more electrophilic and more favourable for dye reduction.

Decolorization and mineralization of Amaranth dye using multiple zoned aerobic and anaerobic baffled constructed wetland

ABSTRACT The objective of this study is to determine the reduction efficiency of Chemical Oxygen Demand (COD) as well as the removal of color and Amaranth dye metabolites by the Aerobic–anaerobic Baffled Constructed Wetland Reactor (ABCW). The ABCW reactor was planted with common reed (Phragmite australis) where the hydraulic retention time (HRT) was set to 1 day and was fed with synthetic wastewater with the addition of Amaranth dye. Supplementary aeration was supplied in designated compartments of the ABCW reactor to control the aerobic and anaerobic zones. After Amaranth dye addition the COD reduction efficiency dropped from 98 to 91% while the color removal efficiency was 100%. Degradation of azo bond in Amaranth dye is shown by the UV–Vis spectrum analysis which demonstrates partial degradation of Amaranth dye metabolites. The performance of the baffled unit is due to the longer pathway as there is the up-flow and down-flow condition sequentially, thus allowing more contact of the wastewater with the rhizomes and micro-aerobic zones.

Up-flow constructed wetland-microbial fuel cell for azo dye, saline, nitrate remediation and bioelectricity generation: From waste to energy approach

This study explored the influence of azo dye concentration, salinity (with and without aeration) and nitrate concentration on bioelectricity generation and treatment performance in the up-flow constructed wetland-microbial fuel cell (UFCW-MFC) system. The decolourisation efficiencies were up to 91% for 500 mg/L of Acid Red 18 (AR18). However, the power density declined with the increment in azo dye concentration. The results suggest that the combination of salinity and aeration at an optimum level improved the power performance. The highest power density achieved was 8.67 mW/m2. The increase of nitrate by 3-fold led to decrease in decolourisation and power density of the system. The findings revealed that the electron acceptors (AR18, nitrate and anode) competed at the anodic region for electrons and the electron transfer pathways would directly influence the treatment and power performance of UFCW-MFC. The planted UFCW-MFC significantly outweighed the plant-free control in power performance.

Sustainable green technology on wastewater treatment: The evaluation of enhanced single chambered up-flow membrane-less microbial fuel cell

This study demonstrated the potential of single chamber up-flow membrane-less microbial fuel cell (UFML-MFC) in wastewater treatment and power generation. The purpose of this study was to evaluate and enhance the performance under different operational conditions which affect the chemical oxygen demand (COD) reduction and power generation, including the increase of KCl concentration (MFC1) and COD concentration (MFC2). The results showed that the increase of KCl concentration is an important factor in up-flow membrane-less MFC to enhance the ease of electron transfer from anode to cathode. The increase of COD concentration in MFC2 could led to the drop of voltage output due to the prompt of biofilm growth in MFC2 cathode which could increase the internal resistance. It also showed that the COD concentration is a vital issue in up-flow membrane-less MFC. Despite the COD reduction was up to 96%, the power output remained constrained.

Pilot scale single chamber up-flow membrane-less microbial fuel cell for wastewater treatment and electricity generation

Pilot scale up-flow membrane-less microbial fuel cell (UFML-MFC) was constructed to study feasibility of the bioreactor for simultaneous degradation of organic substance and electricity generation. The performance of the UFML-MFC was evaluated with different anode electrode (cube carbon felt and stacked carbon felt) in terms of voltage output, chemical oxygen demand (COD) and Coulombic efficiency (CE). Carbon flake were used as cathode in the UFML-MFC. UFML-MFC was operated in three stages where included batch-fed, end of batch fed and semi-continuous. The Cube carbon felt as anode have the better performance in terms of voltage output and electricity generation in all 3 stages. Maximum voltage output was 0.311 ± 0.004 V at 75% of COD reduction and thus CE was 0.15%. The result shows the operational mode is the key to improve the voltage output and also COD reduction.