Results from raw slaughterhouse wastewater treatment in a new jet-loop Anaerobic Filter Membrane Bioreactor (AnFMBR) are presented. The innovation consists in integrating an attached growth anaerobic reactor and a filtration tank as an external loop gas-lift bioreactor, taking advantage of the gas-lift effect caused by the gas sparging used for fouling mitigation. A jet-loop AnFMBR pilot plant was operated for 18 months with a hydraulic retention time of 19.5–21.3 h, a solid retention time of 60 d and organic loading rates between 3.5 and 7.4 kg COD/m3·d, depending on the wastewater concentration, with peaks of up to 10.9 kg COD/m3·d. Organic matter removal efficiency was maintained between 92 and 97%. Most of the biomass in the jet-loop AnFMBR, 82%, was retained by the carrier material so the membrane was in contact with low concentration biomass suspension.
Effects of different backwash scenarios and filtration fluxes on reversible and irreversible fouling rates were studied by short-term and mid-term assays, using Box-Behnken experimental designs. Fouling consolidation due to the fouling layer compression was the main cause of irreversible fouling. Pilot-scale results have shown that jet-loop AnFMBR is a promising technology for real scale complex wastewater treatment.
