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Water Res. 2016 Mar 1;90:354-368. doi: 10.1016/j.watres.2015.12.027. Epub 2015 Dec 19.

Design of a fixed-bed ion-exchange process for the treatment of rinse waters generated in the galvanization process using Laminaria hyperborea as natural cation exchanger.

Author information

1
LSRE - Laboratory of Separation and Reaction Engineering, Associate Laboratory LSRE-LCM, Chemical Engineering Department, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal.
2
Laboratório de Transferência de Massa e Simulação Numérica de Sistemas Químicos, Federal University of Santa Catarina, PO Box 476, CEP 88040-900 Florianópolis, SC, Brazil.
3
LSRE - Laboratory of Separation and Reaction Engineering, Associate Laboratory LSRE-LCM, Chemical Engineering Department, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal. Electronic address: vilar@fe.up.pt.

Abstract

In this study, the removal of zinc from galvanization wastewaters was performed in a fixed bed column packed with brown macro-algae Laminaria hyperborea, acting as a natural cation exchanger (resin). The rinse wastewater presents a zinc concentration between 9 and 22 mg/L, a high concentration of light metals (mainly Na and Ca), a high conductivity (0.5-1.5 mS/cm) and a low organic content (DOC = 7-15 mg C/L). The zinc speciation diagram showed that approximately 80% of zinc is in the form of Zn(2+) and ≅20% as ZnSO4, considering the effluent matrix. From all operational conditions tested for zinc uptake (17 < bed height<27 cm, 4.5 < flow rate<18.2 BV/h, 0.8 < particle equivalent diameter<2.0 mm), the highest useful capacity (7.1 mg Zn/g algae) was obtained for D/dp = 31, L/D = 11, 9.1 BV/h, τ = 6.4 min, corresponding to a service capacity of 124 BV (endpoint of 2 mg Zn/L). Elution was faster and near to 100% effective using 10 BV of HCl (1 M, 3.0%, 363 g HCl/L of resin), for flow rates higher than 4.5 BV/h. Calcium chloride solution (0.1 M) was selected as the best regenerant, allowing the reuse of the natural resin for more than 3 saturation/elution/regeneration cycles. The best operation conditions were scaled-up and tested in a pre-pilot plant. The scale-up design of the cation exchange process was proposed for the treatment of 2.4 m(3)/day of galvanization wastewater, resulting in an estimated reactants cost of 2.44 €/m(3).

KEYWORDS:

Elution; Galvanization wastewater; Natural cation exchanger; Regeneration; Scale-up; Zinc

PMID:
26766159
DOI:
10.1016/j.watres.2015.12.027
[Indexed for MEDLINE]

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