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Evaluation of the Utilization Rate of Organic Substrates by the Microorganisms in Fixed and Suspended Biomass Reactors Treating Sanitary Landfill Leachates

utilization rate,organic substrate,fixed biomass reactors,suspended biomass reactors,sanitary landfill leachates

In this article, the utilization rate of organic substrates contained in sanitary landfill leachates by fixed and suspended biomass reactors was evaluated. Characterization of the leachates was carried out in two sanitary landfills, Guayabal sanitary landfill (GSL) and La Cortada sanitary landfill (LCSL), Norte de Santander department, Colombia. In GSL, it implied the collection of six water samples, each one of 2.5 L volume from the effluent of the excavated cells/trenches to the evaporation ponds, both of these were placed into the area of GSL, in a sampling campaign carried out in the period from March, 3th to March, 15th for 2014. In LCSL, characterization of leachates dissolved in waters involved the execution of six sampling campaigns occurred during the period 2016-2019. Five bioreactors were designed, constructed and tested for the Chemical Oxygen Demand (COD) removal by applying three levels of organic loading in the influent for Rotating Biological Contactor (RBC) (12, 20, 25 g COD/m²/d), Trickling Filter (TF) (2.67, 5.33, 8 kg COD/m³/d), Upflow Anaerobic Blanket Sludge (UASB) (13.31, 15.98, 18.65 kg COD/m³/d), Upflow Anaerobic Filter in Two Separated Stages (UAF-2SS)  (3.71, 2.76, 1.8 kg COD/m³/d), Upflow Anaerobic Filter in Three Separated Stages (UAF-3SS) ((2.25 kg/m³/d, 3.45 kg/m³/d and 4.44 kg/m³/d). Two equations for predicting the substrate utilization rate (SUR) of organic compounds by microorganisms were calibrated and validated, modeled under a non-steady state condition and modifying the Monod’s equation, obtaining that the significant COD removal performance was represented by UASB-SUR (-400 to -800 mg/L/h), followed by UAF-3SS-SUR (-100 to - 300 mg/L/h), UAF-2SS-SUR (-100 to -200 mg/L/h), RBC and TF -SUR (-50 to -250 mg/L/h). These results were mainly influenced by the strength for being biodegraded of the organic compounds and the geometric configuration of the bioreactors in multiple separated stages allowing the influence of the solubility of the recalcitrant substances to a sub-inhibitory levels for the microbial metabolism. The Upflow Anaerobic Filters in Multiple Separated Stages (UAF-MSS) filters stimulated the separation of the microorganism species according to the three stages in the anaerobic digestion, predominantly occurring in the stage I.