Optimization of an anaerobic membrane bioreactor (anmbr) treating winery wastewater

Abstract

The interest in anaerobic membrane bioreactors (An-MBR) has increased in the last years due to the several advantages of combining the anaerobic digestion with filtering membrane systems. Moreover, the necessity to reduce energy consumption and space by means of new technologies development in water treatment is of big concern nowadays. The main aim of the present project is to operate an An-MBR with real winery wastewater, with special emphasis on how its COD fluctuations disturb biogas production. The experimental development of the current study was carried out with real winery wastewater generated during the vintage period, observing COD concentrations between 0.5 and 7.6 g COD L-1, and OLRs from 0.4 up to 3.7 kg COD m-3 d-1. Effluent COD concentrations were detected to be low, achieving an average organic matter removal efficiency of 97 % during the 132 days of study. Biogas production increased progressively according to the organic load applied in each period. Its production varied from 0.04 to 0.3 m3 CH4 m-3digester d-1, for COD concentrations from 1 to 5.2 g L-1, respectively. Energy demands were estimated to be 7.5 kWh m-3, and biogas production was able to cover the energy costs when inlet COD was 3,200 mg L-1. The co-digestion of winery wastewater with reject water from a municipal WWTP was developed, aiming to provide the former with nutrients avoiding external chemicals. An average COD removal of 89 % was achieved treating an OLR of 1.8 kg COD m-3 d-1. However, economic data showed that its viability would be fulfilled at distances shorter than 10 km.