Amila Abeynayaka

Publications (3) View all

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  Available from: Amila Abeynayaka

  Article: Effect of organic loading rate on VFA production, organic matter removal and microbial activity of a two-stage thermophilic anaerobic membrane bioreactor.

  Kaushalya C Wijekoon, Chettiyappan Visvanathan, Amila Abeynayaka
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  ABSTRACT: This study focused on the VFA (volatile fatty acid) profile variation with organic loading rate (OLR) of a two stage thermophilic anaerobic membrane bioreactor (TAnMBR). The two stage TAnMBR treating high strength molasses-based synthetic wastewater was operated under a side-stream partial sedimentation mode at 55°C. Reactor performances were studied at different OLR ranging from 5 to 12 kg COD m(-3) d(-1). Operational performance of TAnMBR was monitored by assessing biological activity, organic removal efficiency, and VFA. The major intermediate products of anaerobic digestion were identified as acetate, propionate, iso-butyrate, n-butyrate and valerate. Among them acetate and n-butyrate were identified as the most abundant components. Increase of OLR changes the predominant VFA type from acetic acid to n-butyric acid and the total VFA concentration was increased with increased OLR. Moreover, increased OLR increased organic removal efficiency up to second loading rate and dropped in third loading rate while biological activity was increased continuously.
  Bioresource technology 12/2010; 102(9):5353-60. · 4.25 Impact Factor
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  Available from: Amila Abeynayaka

  Article: Performance comparison of mesophilic and thermophilic aerobic sidestream membrane bioreactors treating high strength wastewater.

  Amila Abeynayaka, Chettiyappan Visvanathan
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  ABSTRACT: This study compares membrane fouling and removal efficiencies of organic and nitrogen in thermophilic (47 and 60°C) and mesophilic (30°C) aerobic sidestream airlift membrane bioreactors (SA-MBRs). These reactors were fed with high strength molasses-based synthetic wastewater at an organic loading rate (OLR) of 24.75 kg COD/m(3)d. Removal efficiencies of COD, NH(4)(+) and TKN were compared. The sidestream filtration was conducted with microfilter and ultrafilter. SA-MBRs with microfilter were operated in continuous and intermittent operation modes, while with the ultrafilter only continuous operation mode was employed. The excessive membrane fouling observed in thermophilic SA-MBRs with microfilter under continuous filtration mode, could be significantly reduced by the application of cake layer pre-coating or replacing microfilter with ultrafilter. This membrane fouling under the thermophilic condition could be linked to higher protein generation within the reactors. Soluble COD removal efficiencies were higher in thermophilic conditions while the sludge yields were significantly low in thermophilic SA-MBRs.
  Bioresource technology 11/2010; 102(9):5345-52. · 4.25 Impact Factor
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  Available from: Amila Abeynayaka

  Article: Mesophilic and thermophilic aerobic batch biodegradation, utilization of carbon and nitrogen sources in high-strength wastewater.

  Amila Abeynayaka, Chettiyappan Visvanathan
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  ABSTRACT: This study compares organic and nitrogen removals of thermophilic and mesophilic aerobic processes. The experiments were performed in three 7.2L sequential batch reactors (SBRs) operated at 30, 47 and 60°C. Molasses based synthetic wastewater consisting chemical oxygen demand (COD): 11,200 mg/L, total kheljal nitrogen (TKN): 770 mg/L, ammonical nitrogen (NH(4)): 560 mg/L was the feed medium. Biokinetic parameters, COD, NH(4)(+) and TKN removal efficiencies were compared under six different operating conditions. Five times lower sludge production and similar COD removal were observed in thermophilic SBRs compared to mesophilic SBR under 8.25 kg COD/m(3)d loading rate. However at 24.75 kg COD/m(3)d there were no differences in terms of sludge production while COD removals were varied as 59%, 80% and 82% at 30, 47 and 60°C respectively. A mechanism was developed to understand the varying behaviors of thermophilic aerobic process. Stripping is the major mechanism for nitrogen removal in thermophilic SBRs.
  Bioresource technology 10/2010; 102(3):2358-66. · 4.25 Impact Factor