Now showing 1 - 2 of 2
  • Publication
    Constructed wetland–microbial fuel cell for azo dyes degradation and energy recovery: Influence of molecular structure, kinetics, mechanisms and degradation pathways
    ( 2020-06-10)
    Oon Y.L.
    ;
    ; ;
    Wong Y.S.
    ;
    ;
    Oon Y.S.
    ;
    Teoh T.P.
    ;
    Lehl H.K.
    ;
    Thung W.E.
    Complete degradation of azo dye has always been a challenge due to the refractory nature of azo dye. An innovative hybrid system, constructed wetland-microbial fuel cell (CW-MFC) was developed for simultaneous azo dye remediation and energy recovery. This study investigated the effect of circuit connection and the influence of azo dye molecular structures on the degradation rate of azo dye and bioelectricity generation. The closed circuit system exhibited higher chemical oxygen demand (COD) removal and decolourisation efficiencies compared to the open circuit system. The wastewater treatment performances of different operating systems were ranked in the decreasing order of CW-MFC (R1 planted-closed circuit) > MFC (R2 plant-free-closed circuit) > CW (R1 planted-open circuit) > bioreactor (R2 plant-free-open circuit). The highest decolourisation rate was achieved by Acid Red 18 (AR18), 96%, followed by Acid Orange 7 (AO7), 67% and Congo Red (CR), 60%. The voltage outputs of the three azo dyes were ranked in the decreasing order of AR18 > AO7 > CR. The results disclosed that the decolourisation performance was significantly influenced by the azo dye structure and the moieties at the proximity of azo bond; the naphthol type azo dye with a lower number of azo bond and more electron-withdrawing groups could cause azo bond to be more electrophilic and more reductive for decolourisation. Moreover, the degradation pathway of AR18, AO7 and CR were elucidated based on the respective dye intermediate products identified through UV–Vis spectrophotometry, high-performance liquid chromatography (HPLC), and gas chromatograph-mass spectrometer (GC–MS) analyses. The CW-MFC system demonstrated high capability of decolouring azo dyes at the anaerobic anodic region and further mineralising dye intermediates at the aerobic cathodic region to less harmful or non-toxic products.
      27  1
  • Publication
    Role of macrophyte and effect of supplementary aeration in up-flow constructed wetland-microbial fuel cell for simultaneous wastewater treatment and energy recovery
    ( 2017-01-01)
    Oon Yoong Ling
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    ; ; ; ;
    Oon Yoong Sin
    ;
    Harvinder Kaur Lehl
    ;
    Thung Wei Eng
    ;
    Noradiba Nordin
    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 0 mL/min and a control reactor was operated without supplementary aeration. 600 mL/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 ± 25 mV, 184.75 ± 7.50 mW/m3, 204.49 W/kg COD, 1.29 W/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 60 mL/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.
      32  1