Biosorption of chromium, copper and zinc on rice wine processing waste sludge in fixed bed

Abstract Wine processing waste sludge (WPWS) has shown effective removal of heavy metals in batch studies, but the adsorption in a fixed-bed WPWS column has not been examined and the mass transport in this column remains unclear. This study aimed to investigate: (1) the retardation factor ( R ) and the dispersion coefficient ( D ) of WPWS, employing one-dimensional convective–dispersive model with breakthrough curve (BTC) and using chromium, copper and zinc as the adsorbates; and (2) explore the adsorption mechanism of WPWS column for heavy metals. The retardation factor for various metal treatments is shown in the following order: Cr(18.3) > Cu(13.0) > Zn(7.2), indicating their binding affinity toward WPWS. The dispersion coefficients were calculated to be 2.36 × 10 −6 , 5.89 × 10 −7 and 6.83 × 10 −7  m 2  s −1 for Cr, Cu and Zn treatments, respectively. The high charge density for Cr 3+ ion makes it longer for the Cr column to attain exhaustion state, about 4.0 and 8.2 times the time required for the Cr and Zn columns. However, the least retardation and adsorption amount for Zn can be attributed to its full orbital in electronic configuration.