16 / 2023-12-17 23:52:04

Kinetics of Microbial Cell Growth, Utilization of Organic Substrates and Methane Production in Upflow Anaerobic Filters in Two and Three Separated Stages Treating Sanitary Landfill Leachates

microbial cell growth,organic substrate utilization rate,methane production,upflow anerobic filters

This paper deals with the kinetics of microbial cell growth, utilization of organic substrates and methane production in Upflow Anaerobic Filters in Two and Three Separated Stages (UAF-2SS and UAF-3SS) treating sanitary landfill leachates, under three temperatures (20, 27, and 34 ºC), fed with Volumetric Organic Loads (VOLs) for UAF-2SS (1.8, 2.25, 2.76, 3.45, 3.71, 4.64 kgCOD (Chemical Oxygen Demand)/m³/d) and UAF-3SS (1.7, 2.25, 2.44, 2.6, 3.15, 3.45, 3.5, 4.57, 4.64, 6.31, 11.61, 14.18, 17.48 kgCOD/m³/d). Kinetic parameters were obtained at temperature (20-34 ºC), pH (8.8-9.1), each one of three stages within the UAF-2SS and UAF-3SS reactors containing methanogenic bacteria (methanococcus sp, and methanobacterium sp) and Clostridium sp: Maximum substrate utilization rate (r_m,s) resulted in 100 mg COD/L/h, maximum microbial cell growth rate (m_m) varied 100 - 1000 CFU (Colony Forming Units)/mL/h, methane (CH₄) production rate (rm,CH₄)  tended to vary 1-10 mg CH₄/d and the maximum production coefficient (Y) varied 0-100 CFU/mL/h/mgCOD/L/h. The performance of UAF-2SS and UAF-3SS reactors in the organic matter removal, expressed as Chemical Oxygen Demand (COD), contained in sanitary landfill leachates at strong levels of pollution, was influenced by the increase of the temperature at 20 ºC, 27 ºC and 34 ºC, comparatively obtaining a reduction of approximately 1.5 times in the COD in the effluent to the reactor with fractionation in three stages. For both, UAF-2SS and UAF-3SS reactors, the maximum substrate utilization rate (r_s) was in the order of 100 mg/L/h. For the sample of examined bacteria (methanogenic –methanobacterium and methanococcus-, clostridium), the maximum growth rate (r(g,m)) was similar at temperatures of 20 ºC and 27 ºC and significantly rose at temperature of 34 ºC (10,000 CFU/mL/h for Methanobacterium sp) in the order of 100-1,000 times, as well as it was found that the microbial cell growth rate (rg) was maintained for 100-1,000 CFU/mL/h for each one of stages in UAF-3SS reactor at 34 ºC. The microbial cell production coefficient per unit of utilized substrate (Y) was sensible to the temperature and the microbial species climbing from 1 to 100 (CFU/mL/h)/(mg/L/h). The methane production rate (rCH₄) and the methane production coefficient per utilized substrate rate were steady and similar independently of the sequence and number of stages in UAF-MSS reactors as well as of the temperature, taking values in the former of 1-10 mg/d and 0.01 (mg/d)/(mg/L/h).