Combined Electrocoagulation and Physicochemical Treatment of Cork Boiling Wastewater

Carolina Vicente, João R. Silva, Andreia D. Santos, Rosa M. Quinta-Ferreira and Luis M. Castro
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Carolina Vicente: Polytechnic Institute of Coimbra—Department of Chemical and Biological Engineering, Rua Pedro Nunes, 3030-199 Coimbra, Portugal
João R. Silva: Polytechnic Institute of Coimbra—Department of Chemical and Biological Engineering, Rua Pedro Nunes, 3030-199 Coimbra, Portugal
Andreia D. Santos: Polytechnic Institute of Coimbra—Department of Chemical and Biological Engineering, Rua Pedro Nunes, 3030-199 Coimbra, Portugal
Rosa M. Quinta-Ferreira: CIEPQPF—Chemical Engineering Processes and Forest Products Research Center, Department of Chemical Engineering, University of Coimbra, 3030-790 Coimbra, Portugal
Luis M. Castro: Polytechnic Institute of Coimbra—Department of Chemical and Biological Engineering, Rua Pedro Nunes, 3030-199 Coimbra, Portugal

Sustainability, 2022, vol. 14, issue 7, 1-12

Abstract: Cork boiling wastewater (CBW) is a highly polluted and difficult to treat effluent resultant from the cork manufacturing industry. This study aims to evaluate a new, reliable, efficient, and sustainable process to treat this effluent. This paper tested electrocoagulation as a pre- and post-treatment to improve the already existing physicochemical treatment in a cork production facility in Portugal. In the physicochemical procedures (PC), the addition of different volumes of coagulant (ferric chloride (III) 40% w / w ), neutralizer (sodium hydroxide, 32% w / w ), and flocculant (polyacrylamide, 0.2 g/L) were evaluated. Electrocoagulation (EC) was performed in a bench-scale reactor, using aluminum and stainless-steel electrodes. For EC, different initial pH, current density, and current tension values were tested. When electrocoagulation was used as a post-treatment, better performances were achieved. However, treatment costs were increased significantly. Coagulation/flocculation offers a viable and cheap treatment, achieving removal efficiencies of 88.2%, 81.0%, 76.9%, and 94.2% for total chemical oxygen demand (tCOD), total carbon (TC), total nitrogen (TN), and soluble chemical oxygen demand (sCOD), respectively. With a PC-EC combination, it is possible to achieve removal efficiencies of 92.4%, 88.0%, 91.4%, and 91.4% for tCOD, TC, TN, and sCOD, respectively. The increased TN removal efficiency can translate into great benefits for certain discharge conditions and should be taken into consideration for improving the sustainability of cork industry. On the other hand, when EC is used as a pre-treatment, there are no benefits either in terms of treatment performance or operating costs.

Keywords: cork boiling wastewater; cost assessment; electrocoagulation; physicochemical treatment (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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