Start-up of an anaerobic hybrid (UASB/filter) reactor treating wastewater from a coffee processing plant.
The ability of an anaerobic hybrid reactor, treating coffee wastewater, to achieve a quick start-up was tested at pilot scale. The unacclimatized seed sludge used showed a low specific methanogenic activity of 26.47 g CH4 as chemical oxygen demand (COD)/kg volatile suspended solids (VSS) x day. This strongly limited the reactor performance. After a few days of operation, a COD removal of 77.2% was obtained at an organic loading rate (OLR) of 1.89 kg COD/m3 x day and a hydraulic retention time (HRT) of 22 h. However, suddenly increasing OLR above 2.4 kg COD/m3 x day resulted in a deterioration in treatment efficiency. The reactor recovered from shock loads after shutdowns of 1 week. The hybrid design of the anaerobic reactor prevented the biomass from washing-out but gas clogging in the packing material was also observed. Wide variations in wastewater strength and flow rates prevented stable reactor operation in the short period of the study.
Bello-Mendoza
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Centro de Investigaciones Ecologicas del Sureste (presently ECOSUR), Apartado Postal No. 36, C.P. 30700, Tapachula, Chiapas, Mexico. r.bello-mendoza@stud.umist.ac.uk
Castillo-Rivera
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