REMOVAL OF TOXIC METALS USING AS BIOADSORBENTS NON-VIABLE BACTERIAL BIOMASS AND INDUSTRIAL WASTES

BOERIS P.S.; MERINGER, A; A.S. LIFFOURRENA; HEREDIA R.M; BERGERO M F; G.I. LUCCHESI

San Luis

Jornada; XXXVII Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2019

Al3+, Cu2+ and Zn2+ are emerging pollutants found in soils and industrial and domestic wastewater. Removal of these metals from soils would contribute to the better development of horticultural crops, while, the treatment of aqueous effluents, would lead to obtaining quality recycled water suitable for the irrigation of these crops. The removal of toxic metals can be carried out through biosorption process, in both discontinuous (batch) and continuous (fixed bed column) modes of operation, using biological materials capable of retaining metal ions on their surface. Non-viable biomass of Pseudomonas putida A (ATCC 12633) entrapped in agar-agar beads is able to attach Al3+, Cu2+ and Zn2+ binding them to -NH, -OH, -COOH, -CO and ?PO groups on their cellular surface. With these beads, in batch mode, the adsorption equilibrium was reached at 45 min, 4 h and 6 h, for Al3+, Cu2+ and Zn2+, respectively, showing a maximum sorption capacity (q) of 0.09 mg Al3+/g beads, 0.270 mg Cu2+/g beads and 0.102 mg Zn2+/g beads. Adsorbent efficiency was stable, at least, until 8 successive cycles of adsorption/desorption. For the continuous mode assays, 47 g of beads were packed in a glass tube with an inner diameter of 2 cm. Aqueous solutions at pH 4.3 with different Al3+, Cu2+ and Zn2+ concentrations (6-210 mg/l) were filter through the fixed bed column at different flow rates (0.5-1.5 ml/min). Fixed bed column showed q values between 0.15 and 0.20 mg metal/g beads and the removal percentage was close to 70% for the three evaluated metals. Industrial wastewater supplemented with 30 mg/l of Cu2+ and Zn2+ (simulated effluent) were filter through the fixed bed column at a flow rates of 0.5 ml/min. q value was 0.15 mg metal/g beads and the removal percentage was close to 66%. The fixed bed column was stable, at least, until 12 successive cycles of adsorption/desorption. In all conditions evaluated, complete desorption of metals was achieved with HCl 0.01 N. When was used as alternative adsorbent the barley bagasse, low cost waste from brewing industry, in batch mode the adsorption equilibrium was reached at 6 h for Al3+ and Zn2+ and at 16 h for Cu2+. This adsorbent showed q values significantly higher respect to obtained with beads with biomass trapped (3.57 mg Al3+/gr bagasse, 8.33 mg Cu2+/gr bagasse and 0.518 mg Zn2+/gr bagasse). The results, as a whole, show the high efficiency of the beads with non-viable biomass of Pseudomonas putida A (ATCC 12633) trapped and of the barley bagasse to attach Al3+ Cu2+ and Zn2+, and support the notion of their potential use for the removal of these metals from soils and industrial and domestic wastewater containing them.