Anaerobic Treatability of Sanitary Landfill Leachate in a Fluidized Bed Reactor


Abstract: The treatability of leachate from Odayeri Sanitary Landfill, located in the European part of İstanbul, in an anaerobic fluidized bed reactor (AFBR) was investigated. The experiments were performed in a pilot-scale fluidized bed reactor having an inner diameter of 10 cm, a height of 165 cm and an effective volume of 13 l. The reactor medium was a typical filter sand having an arithmetic mean diameter of 0.5 mm and a fixed bed height of 70 cm. The AFBR experiments were carried out by increasing gradually the organic loading rate (OLR) from 2.5 to 37 kg COD/m^3 per day in 8 operating steps. During the 240 days of operation, the feed rate (Q_f) and the hydraulic retention time (HRT) were 13 l/day and 1 day, respectively. The measured variables were chemical oxygen demand (COD), alkalinity, pH, volatile and suspended solids, ammonia, and gas rates. Ammonia removal efficiency appeared to be very low. However, ammonia inhibition has not occured during the study. COD removal increased from 80% to 90 % with increasing organic loading rates and the AFBR attained steady state conditions with a COD removal of 90% after 80 days. A good biogas production yield (Y_{gas}) was obtained; 0.50-0.52 l of biogas per g COD_{rem} with a methane (CH_4) content of 75%. The attached biomass concentration (X_{att}) comprised about 90% of the total biomass concentration and showed an increase throughout the bed in the range of 3 to 38%. The mean attached biomass concentration also increased up to 70,000 mg/l in the last 2 months (for days 164-220).

Keywords: Anaerobic treatability, Biogas production, Fluidized bed reactor, Landfill leachate, Organic loading, Process efficiency

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