ANAEROBIC PURIFICATION OF BREWERY WASTE-WATER IN BIOFILM REACTORS WITH AND WITHOUT A METHANATION CASCADE

A laboratory scale anaerobic treatment process for brewery wastewater has been investigated. It utilised a continuously stirred tank (CST) a cidification reactor (11.3 l) plus an anaerobic treatment system which consisted of either a downflow stationary fixed film (DSFF) reactor ( 20.7 l) or a DSFF reactor in series with a flee (FLOC) or sludge blank et reactor (20.8 l). At the same residence time the combination of DSF F and FLOC reactor performed better than a single methane digester. Us ing low and high strength wastewater, degradation yields of 80-90% wer e obtained at total loading rates B-R,B-COD up to 10 kg COD m(-3) x d and a residence time t less than one day. Mean values of methane yield were 0.31 m(STP)(3) kg-1 COD or 2.91 m(STP)(3) m(-3)x d. Inert suppor t media investigated consisted of inorganic materials such as porous K erapor 1000 and glass sponge (Siran) with macro- and micropores or pol yurethane foam (Filtren TR 30) with an open net structure. In all case s SEM showed appropriate surface characteristics for microbial attachm ent. After 4 months of operation biofilm thickness on inorganic suppor t media was 0.4-0.9 mm at a superficial linear velocity (SLV) of 10-5 mm min(-1). Under these conditions biofilm on Filtren TR 30 was notice ably thicker (up to 2 mm). Concerning metal contamination of biofilm o n Filtren TR 30, Al, Fe and Zn showed elevated levels above 2000 ppm.