Removal of zinc and nickel ions by complexation  membrane filtration process from industrial wastewater G abor Borb ely, Endre Nagy* Research Institute of Chemical and Process Engineering, University of Pannonia, H-8200 Veszpr em, P.O. Box 158, Hungary Tel. +36 88 624 040; email: nagy@mukki.richem.hu Received 20 September 2007; revised 16 November 2007; accepted 23 November 2007 Abstract Many industrial wastewater streams contain toxic metal cations, for example, Ni 2+ , Zn 2+ , etc. or their oxyanions in up to few hundred mg/dm 3 , which must be removed before water recycling or discharging directly into surface waters. The conventional processes to treat this kind of wastewater are, e.g. chemical precipitation, ion exchange, membrane separations (such as electrodialysis, nanofiltration, reverse osmosis and ultrafiltration), adsorption or biosorption. In this work a membrane technique, ultrafiltration, completed with complexation was investigated. During the experiments, impact of conditions of membrane, pH and polymer/metal ratio have been investigated. The study series were carried out both of zinc and nickel. According to our studies, the most effective composition both tested metals is the following: PES-10 membrane, PAA complexation agent and pH  /8. The volume ratio of the polymer bounding agent and metal ion because of environmental and economical aspects should be about unit. Keywords: Heavy metal; Complexation  membrane filtration; Operating condition 1. Introduction Water has increasing key position also in the field of industries in last few decades, many industrial wastewater streams contain toxic metal cations, for example, Ni 2+ , Zn 2+ , etc. or their oxyanions in up to few hundred mg/dm 3 . These metal ions are also toxic, similar to several other heavy metals. Impact of nickel can be mani- fested in allergic reactions, chronic toxicity (dermatitis nausea, chronic asthma, coughing, abdominal cramps, diarrhea, vertigo and lassi- tude), but acute toxicity is not typical. It is Presented at the Third Membrane Science and Technology Conference of Visegrad Countries (PERMEA), Siofok, Hungary, 2–6 September 2007. *Corresponding author. Desalination 240 (2009) 218  226 0011-9164/09/$– See front matter # 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2007.11.073