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Keywords:

  • liquidized food waste;
  • UASB reactor;
  • COD;
  • VFA;
  • TOC;
  • biogas and methane

Abstract

Anaerobic treatment of liquidized food waste (LFW) was carried out in an upflow anaerobic sludge blanket reactor (UASBR) by stepwise increase in organic loading rate (OLR) and temperature. The chemical oxygen demand (COD), total organic carbon (TOC), biogas and methane production were measured at hydraulic retention time (HRT) of 10 to 4d, and start up strategy of the reactor was monitored for 10 weeks. Thermophilic condition was achieved by increasing the temperature from 30 to 55°C, and pH was maintained at 7 ± 0.5 throughout the experiment. Maximum COD removal efficiency was 93.67% (r = 0.84) at an OLR of 12.5 g-COD/L·d and 4d HRT. Maximum TOC removal efficiency was 79.14% (r = −0.94) at an influent TOC concentration of 3.59 g/L. Biogas and methane yield were recorded to a maximum of 1.364 L/g-CODremoved·d (r = 0.81), 0.912 L/g-CODremoved·d (r = 0.83), and average methane content of biogas was 63%. The reactor was fully acclimatized at 55°C and achieved stability with high removal efficiency and biogas production. An OLR of 12.5 g-COD/L·d and HRT of 4 days were suitable for the treatment of LFW in UASBR. The treatment process can also be extendable for more than 10 weeks without any measurable problem. © 2011 American Institute of Chemical Engineers Environ Prog, 2012