Anaerobic thermophilic fluidized bed treatment of industrial wastewater: Effect of F : M relationship

This paper describes the thermophilic (55 degrees c) anaerobic biodegradati on of wine distillery wastewater (vinasses) in a laboratory fluidized bed r eactor (AFB) with a porous support media. The experimental protocol was def ined to examine the effect of the increase of organic loading rate on the e fficiency of AFB and to report on its steady-state performance. The AFB rea ctor was subjected to a programme of steady-state operation over a range of hydraulic retention time, HRTs, of 2.55 - 0.37 days and organic loaging ra te, OLRs, up to 5.88 kgCOD/m(3).d in order to evaluate its treatment capaci ty. Porous support media particles used in AFB were previously colonized in semicontinuous anaerobic fixed-bed reactors treating wine-vinasses. The AF B reactor was initially operated with organic loading rate of 5.88 kgCOD/m( 3).d and HRT of 2.55 days. The COD removal efficiency was found to be 96.5% in the reactor while the volumetric methane produced in the digester reach ed 1.08 m(3)/m(3).d. Over 94 days operating period, an OLR of 32 kgCOD/m(3) .d at an F:M ratio of 0.55 kgCOD/kgVS(all).d was achieved with 81.5% COD re moval efficiency in the experimental AFB reactor. At this moment, the metha ne content of biogas produced in the digester reached 9.0 m(3)/m(3).d. Furt hermore, the increase of OLR at 40.5 kgCOD/m(3).d, corresponding to 0.37 da ys HRT, provokes malfunction of the process with a sudden drop in COD remov al efficiency and stopping the biogas production. (C) 1999 Elsevier Science Ltd. All rights reserved.