Now showing 1 - 10 of 11
  • Publication
    Transformation from biofiltration unit to hybrid constructed wetland-microbial fuel cell: Improvement of wastewater treatment performance and energy recovery
    ( 2023-05-01)
    Teoh T.P.
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    Koo C.J.
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    ; ; ;
    Tan S.M.
    ;
    Yap K.L.
    ;
    This study aimed to compare the performance of biofiltration, constructed wetland, and constructed wetland microbial fuel cell (CW-MFC). The transformation from a biofiltration unit to a hybrid CW-MFC was demonstrated with the advantages of improvement of wastewater treatment while generating electricity simultaneously. The introduction of plants to the upper region of the bioreactor enhanced the DO level by 0.8 mg/L, ammonium removal by 5 %, and COD removal by 1 %. The integration of electrodes and external circuits stimulated the degradation rate of organic matter in the anodic region (1 % without aeration and 3 % with aeration) and produced 5.13 mW/m3 of maximum power density. Artificial aeration improved the nitrification efficiency by 38 % and further removed the residual COD to an efficiency of 99 %. The maximum power density was also increased by 3.2 times (16.71 mW/m3) with the aid of aeration. In treating higher organic loading wastewater (3M), the maximum power density showed a significant increment to 78.01 mW/m3 (4.6-fold) and the COD removal efficiency was 98 %. The ohmic overpotential dominated the proportion of total loss (67-91 %), which could be ascribed to the low ionic conductivity. The reduction in activation and concentration loss contributed to the lower internal resistance with the additional aeration and higher organic loading. Overall, the transformation from biofiltration to a hybrid CW-MFC system is worthwhile since the systems quite resemble while CW-MFC could improve the wastewater treatment as well as recover energy from the treated wastewater.
  • Publication
    Caffeine-containing wastewater treatment and bioelectricity generation in up-flow constructed wetland-microbial fuel cell: Influence of caffeine concentration, operating conditions, toxicity assessment, and degradation pathway
    ( 2022-04-01)
    Teoh T.P.
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    ; ; ; ;
    Oon Y.L.
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    Tan S.M.
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    Ong Y.P.
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    Yap K.L.
    This study explored the potential of caffeine being utilized as the fuel for the microbes to produce electrons for electricity generation in up-flow constructed wetland-microbial fuel cell (UFCW-MFC). The effect of caffeine concentration was investigated to identify the availability of UFCW-MFC in the conversion of caffeine to electrons for electricity production; and the effect of operating conditions (circuit connection, supplementary aeration, and plant) was studied to determine their significance in the treatment of caffeine containing wastewater. The UFCW-MFC achieved about 98% of decaffeination efficiency regardless of caffeine concentration; while a decrease of efficiency was observed when UFCW-MFC operated without supplementary aeration and plant (~93%). COD removal efficiency decreased correspondingly to the increase of caffeine concentration, which could be contributed by the higher concentration of caffeine and its intermediates. The degradation pathway of caffeine in UFCW-MFC was explored in this study. It was remarkable that ammonia was produced and converted to ammonium ions during caffeine catabolism. Supplementary aeration and macrophyte play a crucial role in removing excess caffeine, intermediates as well as accumulated ammonium ions. The toxicity assessment revealed that caffeine was degraded to less toxic products. The closed circuit connection not only contributed to electricity generation but also enhanced the caffeine and COD removal efficiency by 4.6 and 5.4% in the anaerobic region, respectively. The increase of voltage and maximum power density from phase I to phase IV indicated that caffeine could be converted to electrons by the anaerobes for electricity production.
  • Publication
    Up-flow constructed wetland-microbial fuel cell: Influence of floating plant, aeration and circuit connection on wastewater treatment performance and bioelectricity generation
    ( 2020-08-01)
    Teoh T.P.
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    ; ; ;
    Oon Y.L.
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    Oon Y.S.
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    Tan S.M.
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    Thung W.E.
    The influence of floating plant (Eichhornia crassipes), supplementary aeration and circuit connection on wastewater treatment performance and electricity production using up-flow constructed wetland-microbial fuel cell (UFCW-MFC) were investigated in this study. This study was operated for four stages, where stage I was conducted without plant and aeration; stage II was planted with Eichhornia crassipes; supplementary aeration was provided in stage III; stage IV was operated in open circuit. The supplementary aeration showed the most significant effect on the performance of UFCW-MFC compared to floating plant and circuit connection. The optimum performance of wastewater treatment and electricity production was found in stage III as the oxygen was supplied by the floating plant and supplementary aeration for the degradation of organic matters as well as the generation of bioelectricity. The chemical oxygen demand (COD), NH4+ and NO3− removal efficiencies were 99 %, 96 % and 44 %, respectively. E. crassipes and supplementary aeration improved the dissolved oxygen (DO) concentration at the cathodic region and enhanced the NH4+ removal by 10 % (Stage II) and 67 % (Stage III) compared to the non-planted bioreactor (stage I). Closed circuit also performed 6 % better than open circuit at sampling point 1 (S1) in COD reduction. The maximum power density, voltage output, coulombic efficiency and normalized energy recovery were 45.46 ± 3.83 mW/m3, 291 ± 62 mV, 2.15 %, 15.09 Wh/kg COD and 0.31 W/m3, respectively.
  • Publication
    Insights into the decolorization of mono and diazo dyes in single and binary dyes containing wastewater and electricity generation in up-flow constructed wetland coupled microbial fuel cell
    ( 2023-02-01)
    Teoh T.P.
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    ; ; ; ;
    Oon Y.L.
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    Tan S.M.
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    Ong Y.P.
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    Yap K.L.
    The treatment of single and binary azo dyes, as well as the effect of the circuit connection, aeration, and plant on the performance of UFCW-MFC, were explored in this study. The decolorization efficiency of Remazol Yellow FG (RY) (single dye: 98.2 %; binary dye: 92.3 %) was higher than Reactive Black 5 (RB5) (single: 92.3 %; binary: 86.7 %), which could be due to monoazo dye (RY) requiring fewer electrons to break the azo bond compared to the diazo dye (RB5). In contrast, the higher decolorization rate of RB5 in binary dye indicated the removal rate was affected by the electron-withdrawing groups in the dye structure. The closed circuit enhanced about 2% of color and 4% of COD removal. Aeration improved the COD removal by 6%, which could be contributed by the mineralization of intermediates. The toxicity of azo dyes was reduced by 11–26% and the degradation pathways were proposed. The dye removal by the plants was increased with a higher contact time. RB5 was more favorable to be uptook by the plant as RB5 holds a higher partial positive charge. 127.39 (RY), 125.82 (RB5), and 58.66 mW/m3 (binary) of maximum power density were generated. The lower power production in treating the binary dye could be due to more electrons being utilized for the degradation of higher dye concentration. Overall, the UFCW-MFC operated in a closed circuit, aerated, and planted conditions achieved the optimum performance in treating binary azo dyes containing wastewater (dye: 87–92%; COD: 91%) compared to the other conditions (dye: 83–92%; COD: 78–87%).
  • Publication
    Enhancement of energy recovery from caffeine wastewater in constructed wetland-microbial fuel cell through operating conditions
    ( 2023-01-01)
    Teoh T.P.
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    ; ; ; ;
    Tan S.M.
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    Ong Y.P.
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    Yap K.L.
    The enhancement of up-flow constructed wetland-microbial fuel cell (UFCW-MFC) performance in energy retrieval from caffeine containing wastewater has been explored via various operating conditions (hydraulic retention time (HRT), multianode (MA), multicathode current collector (MC), external resistance). The anaerobic decaffeination and COD removal improved by 37 and 12% as the HRT extended from 1 to 5 d. The increment in contact time between the microbes and organic substrates promoted the degradation and contributed to higher power output (3.4-fold), CE (eightfold), and NER (14–16-fold). The MA and MC connections facilitated the electron transfer rate and the degradation rate of organic substrates in the multiple anodic zones, which enhanced the removal efficiency in the anaerobic compartment (Caffeine: 4.2%; COD: 7.4%) and led to higher electricity generation (Power: 4.7-fold) and energy recovery (CE: 1.4-fold; NER: 2.3–2.5-fold) compared to SA. The lower external resistance favored the growth of electrogens and induced higher electron flux, where the best treatment performance and electricity production was obtained when the external resistance approached the internal resistance. Overall, it was noteworthy that the optimum operating conditions were achieved with 5 d HRT, MA, and MC connection along with external resistance of 200 Ω, which significantly outperformed the initial conditions (1 d HRT, SA connection, and 1000 Ω) by 43.7 and 29.8% of caffeine and COD removal in the anaerobic compartment, respectively as well as 14-fold of power generation.
      17  2
  • Publication
    Intermolecular degradation of aromatic compound and its derivatives via combined sequential and hybridized process
    ( 2023-03-01)
    Lau Y.Y.
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    ; ; ; ;
    Teng T.T.
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    Eng K.M.
    The under-treated wastewater, especially remaining carcinogenic aromatic compounds in wastewater discharge has been expansively reported, wherein the efficiency of conventional wastewater treatment is identified as the primary contributor source. Herein, the advancement of wastewater treatments has drawn much attention in recent years. In the current study, combined sequential and hybridized treatment of thermolysis and coagulation–flocculation provides a novel advancement for environmental emerging pollutant (EP) prescription. This research is mainly demonstrating the mitigation efficiency and degradation pathway of pararosaniline (PRA) hybridized and combined sequential wastewater treatment. Notably, PRA degradation dominantly via a linkage of reaction: thermal cleavage, deamination, silication and diazene reduction. Thermolysis acts as an initiator for the PRA decomposition through thermally induced bond dissociation energy (BDE) for molecular fragmentation whilst coagulation–flocculation facilitates the formation of organo-bridged silsesquioxane as the final degradation product. Different from conventional treatment, the hybridized treatment showed excellent synergistic degradability by removing 99% PRA and its EPs, followed by combined sequential treatment method with 86% reduction. Comprehensive degradation pathway breakdown of carcinogenic and hardly degradable aromatic compounds provides a new insight for wastewater treatment whereby aniline and benzene are entirely undetectable in effluent. The degradation intermediates, reaction derivatives and end products were affirmed by gas chromatography–mass spectrometry, Fourier transform infrared spectroscopy and ultraviolet–visible spectrophotometry (GC–MS, FTIR and UV–Vis). This finding provides valuable guidance in establishing efficient integrated multiple-step wastewater treatments. Graphical abstract: [Figure not available: see fulltext.].
      50  2
  • Publication
    Revealing the influences of functional groups in azo dyes on the degradation efficiency and power output in solar photocatalytic fuel cell
    ( 2020-12-01)
    Khalik, Wan Fadhilah
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    ; ;
    Yusoff N.A.
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    ;
    Lee, Sin-Li
    In this study, the degradation efficiency and electricity generation of the azo dyes affected by the functional groups and molecular structure in a solar photocatalytic fuel cell (PFC) system were investigated and discussed in detail. Four different azo dyes such as, Acid Orange 7 (AO7), Acid Red 18 (AR18), Reactive Black 5 (RB5), Reactive Red 120 (RR120) with different molecular structure were evaluated. The degradation efficiency of AO7, AR18, RB5 and RR120 achieved 5.6 ± 0.3%, 11.1 ± 0.6%, 41.9 ± 0.9% and 52.1 ± 1.3%, respectively, after 6 h irradiated under solar light. In addition, the maximum power density, Pmax for AO7, AR18, RB5 and RR120 was 0.0269 ± 0.01, 0.111 ± 0.03, 1.665 ± 0.67 and 4.806 ± 1.79 mW cm−2, respectively. Meanwhile, the concentration of COD for AO7, AR18, RB5 and RR120 reduced to 16 ± 0.1, 10 ± 0.3, 7 ± 0.6 and 3 ± 0.9 mg L−1, respectively. The concentration ratio of benzene / naphthalene, benzene / azo bond and naphthalene / azo bond, respectively, was analyzed to investigate the impact of the functional groups over photodegradation of the azo dyes in PFC. Electron releasing groups (-OH and –NH2) and electron withdrawing groups (-SO3Na) which attached to the naphthalene or benzene ring also played a pivotal role in the degradation mechanism.
      2  25
  • Publication
    Sustainable utilization of anthraquinone-rich Rheum officinale as electron shuttle in microbial fuel cell: Strategy for stimulating monohydric phenols degradation and bioelectricity generation
    In an aim to completely degrade refractory phenolic compounds for effective wastewater treatment, a sustainable strategy using anthraquinone-rich herbal plant contents as electron shuttles is presented. This study is the first attempt of treating four different chemical structures of monohydric phenols, while simultaneously generate low-carbon electricity in a microbial fuel cell. An electron shuttle-mediated strategy was introduced to investigate the effect of electron shuttle against the degradation of phenolic pollutants and bioelectricity generation, by employing Rheum officinale extract as electron shuttle. Results revealed that there was a two-fold increase in chemical oxygen demand (COD) removal, degradation extent of phenol and cresol isomers, output voltage and power density of MFC, compared to the mediator-free MFC system. The degradation of phenol yielded higher COD removal, degradation efficiency, output voltage and power generation over cresol isomers, with and without the application of electron shuttle. A complete removal of COD and phenol, with output voltage of 620.06 mV and power density of 252.49 mW/m2 were obtained. Phenol outperformed cresol isomers with regard to its sole activating hydroxy (−OH) group, lower dipole moment and higher electronic conductivity (8.53 mS/cm). Conversely, meta-cresol exhibited the lowest removal efficiency and power generation, ascribed to greater inductive influence of methyl group in meta position on the dissociation energy of the − OH group. Moreover, detection of the phenolic intermediates by gas chromatograph-mass spectrometer analysis was conducted, and detailed degradation pathways were presented.
      21  1
  • Publication
    Intermolecular mechanistic treatment of recalcitrant environmental pollutants: Azo, benzene, naphthalene and vinyl sulfone
    A new class of coagulant, from natural resource namely laterite soil has demonstrated efficiency in degrading a wide range of industrial organic pollutants into simple hydrocarbon structures or less toxic compounds. The composition study revealed the relative Si/Al/Fe: 0.57/0.33/0.10 ratios in laterite soil and surface morphology of laterite soil were investigated to analyze the fundamental degradation that drive the decolorization of Reactive Black 5 (RB 5). The interfacial and colloid aspects of laterite soil colloidosomes and dye particles were distinguished with the corresponding mechanism of coagulation–flocculation process. RB5 structure was destabilized by activation of laterite soil colloidosomes through charge neutralization and subsequent siloxane polymerization through enhancement of siloxanes monomers. This research also evaluated the rate laws and reaction mechanism for each of the main chemical network strands of RB 5. The result implied that all the chemical network strands followed the pseudo first order of reactions. Research approach has utilized Fourier Transform Infrared Spectroscopy, Gas Chromatography Mass Spectrometry and Ultraviolet–visible Spectrophotometry (FTIR, GCMS and UV–vis) to study the degradation intermediates structure, chemical derivatives and final products after coagulation–flocculation process.
      2  26
  • Publication
    Discerning the effect of operating conditions on the improvement of up-flow constructed wetland-microbial fuel cell performance in treating mixed azo dyes wastewater and bioelectricity generation
    ( 2024-06-01)
    Teoh Tean Peng
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    ; ;
    Tan Sing Mei
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    ; ;
    Ong Yong Por
    ;
    Yap Kea Lee
    This study assessed the effect of implementing multiple circuit connections and operating parameters (hydraulic retention time (HRT), organic loading rate (OLR), and external resistance) on the improvement of up-flow constructed wetland-microbial fuel cell (UFCW-MFC) in treating the mixed azo dyes wastewater and bioelectricity generation. The multiple-circuits UFCW-MFC facilitated the organic substrate degradation, which improved the removal efficiency of dyes by 8% and COD by 7%, as well as power production by 6.5 times, compared to single-circuit UFCW-MFC. The prolonged HRT from 1 to 3 d extended the interaction time between the pollutants and microbes, which further enhanced the removal efficiency of dyes by 9% and COD by 6%. The decrease in power generation by 1.3 times could be ascribed to the lower OLR at a higher HRT (0.864–0.288 g COD/d when HRT extended from 1 to 3 d) as the utilization of electrons was prioritized for decolorization compared to bioelectricity generation. The increase in OLR (0.288 to 0.754 g COD/d) with the same HRT (3 d) exhibited an improvement of 4% in decolorization and 2.4 times in power generation. This could be attributed to more electron production from the higher COD removal. The lower external resistance benefited the UFCW-MFC performance, where the best performance was obtained at 200 Ω as it approached the internal resistance (150 Ω).
      2  15