ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Membrane processes used for separation of effluents from wire productions

Krzysztof Karakulski, Marek Gryta, and Antoni W. Morawski

Department of Water Technology and Environment Engineering, Institute of Chemical and Environment Engineering, Szczecin University of Technology, ul. Pułaskiego 10, 70-322 Szczecin, Poland

E-mail: krzysztof.karakulski@ps.pl

Received: 21 July 2008  Revised: 27 November 2008  Accepted: 1 December 2008

Abstract: Metal wires are produced from different metals using drawing methods. The metal used influences both the technology applied and the composition of effluents generated during wires production. Ultrafiltration and nanofiltration are used for the separation of waste emulsions from cable factories. Membrane distillation was proposed for the treatment of acidic saline wastewater generated during steel wire manufacturing (etching). The possibility of the previously mentioned processes application for water reuse is presented. The application of poly(vinylidene fluoride) (PVDF) membranes (FP 100) with the molecular weight cut-off (MWCO) of 100 kDa in the ultrafiltration process resulted in the reduction of 99 % of oil and lubricants in the treated emulsions and allowed complete removal of suspended solids and colloidal substances. Such pre-treated emulsion was subsequently purified by nanofiltration (NF-90-2540) and a 98 % rejection of copper ions was achieved, resulting in a decrease of the permeate electrical conductivity from 3200 μS cm⁻¹ to 260 μS cm⁻¹. The obtained permeate was suitable for preparation of fresh oil emulsion utilized for lubrication in the wire drawing process. The spent etching baths (from steel wire production), which mainly contained FeSO₄ and about 1 mass % of sulfuric acid, were separated by membrane distillation. The obtained permeates were: clean water with electrical conductivity at a level of 3–5 μS cm⁻¹. Concentrates (190–200 g of Fe per L) from the MD process were cooled to 295 K, which enabled the FeSO₄ crystallization. Application of the above-mentioned membrane processes allows producing high quality product water, over 90 % of water was recovered from the treated wastewaters.

Keywords: ultrafiltration - nanofiltration - membrane distillation - emulsion - wire drawing

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-009-0006-x

Chemical Papers 63 (2) 205–211 (2009)