Authors: S. Malamis, E.Katsou, S. Di Fabio, N. Frison, F. Cecchi, F. Fatone
This work was conducted at the largest petrochemical membrane bioreactor (MBR) plant in the world. The effectiveness of MBR technology to treat petrochemical effluents was studied. The treated effluent is discharged in a very sensitive water body and needs to satisfy strict limits. To optimize MBR operation a pilot-scale MBR was set-up that received the same petrochemical effluents as the full scale. In the pre-denitrification configurations, ammonification was not effective. Variable removal of heavy metals/metalloids was obtained by the MBR with As, B, Ba, Mo, Al, Ni, Se, Sb, V and Zn removal being less than 40%, Pb, Hg, Cu, Ag, Cr, Mn and Co removal of 40–70% and only Fe removal being higher than 70%. Sludge clogging was observed in the membrane module; the accumulation of COD, N, P, As, Zn, Mo, Ni, Cd, Sb, Fe, Se and Co in the clogged sludge was higher than that in the activated sludge. The adoption of MBR coupled with suitable physicochemical pre-treatment was able to safeguard the treated effluent quality.