Separation and Purification Technology 52 (2006) 218–223 The effects of current density and phosphate concentration on phosphate removal from wastewater by electrocoagulation using aluminum and iron plate electrodes S ¸ ahset ˙ Irdemez ∗ , Nuhi Demircio ˘ glu, Yalc ¸ın S ¸ evki Yıldız, Z¨ uleyha Bing¨ ul Atat¨ urk ¨ Universitesi M¨ uhendislik, Fak¨ ultesi C ¸ evre M ¨ uhendisli˘ gi B ¨ ol¨ um¨ u, 25240 Erzurum, Turkiye Received 26 January 2006; received in revised form 10 April 2006; accepted 10 April 2006 Abstract In this study, effects of initial phosphate concentrations and current densities on the phosphate removal by electrocoagulation using either aluminum or iron plate as electrodes were investigated. In the experiments, the results indicate that increase of initial phosphate concentration has reduced removal rate. But energy consumption has decreased because of wastewater conductivity increase. Efficiency of 100% using aluminum electrodes has been obtained in all of initial phosphate concentration, whereas removal efficiency has decreased by increasing initial phosphate concentration in iron electrodes. Either aluminum or iron electrodes were used to investigate effect of current density. It was found that removal rate and removal efficiency have increased by increasing current density. But, system energy consumption has increased by increasing current density. It can be said that aluminum electrode is more suitable than iron electrode by taking into account either removal rate and removal efficiencies on phosphate removal by electrocoagulation. Consequently, electrocoagulation is comparatively suitable process for phosphate removal from wastewater. © 2006 Published by Elsevier B.V. Keywords: Aluminum electrode; Electrocoagulation; Electrochemical treatment; Iron electrode; Phosphate removal 1. Introduction Phosphorus is one of basic nutrients alive. Phosphorus is found in ATP, cell membranes, tooth and bones. The most important of phosphorus sources is basic rock in earth and the other source is water. Phosphorus movement from land to sea and from sea to land is at the heart of phosphorus circle. Phosphorus might be controlled in wastewater treatment plant, since phosphorus is a nutrient in biological treatment. The most common problem of phosphorus compounds is eutrophication. This phenomenon, that is responsible for the dramatic growth of algae occurring in internal and coastal waters, is caused by the excess phosphorus concentration in the effluents from municipal or industrial plants discharged in the environment [1]. If phosphate removal is provided by electrocoagulation, it can be profited from advantage of electrocoagulation. Among these ∗ Corresponding author. Fax: +90 4422314810. E-mail address: sirdemez@atauni.edu.tr (S ¸. ˙ Irdemez). advantages, it could be indicated that there is no need of addition of chemical matter after or before treatment, relatively low area demand, low investment cost [2] and formation intensive sludge [3]. Besides, because of formation of electroflotation in addition to electrocoagulation, formed flocks have accumulated in reac- tor’s surface and these flocks have been left from water using a grazer [4,5]. In this way, there is no need of sedimentation and filtration pounds. Because of these causes, in this study, phosphate removal from wastewaters has been studied by electrocoagulation. As parameters in experiments, current density and initial phosphate concentration were selected and these parameters were investi- gated on effects of system parameters. Electrocoagulation is a process consisting of creating metal- lic hydroxide flocks within the wastewater by electrodissolution of soluble anodes, usually made of iron or aluminum [6]. The difference between electrocoagulation and chemical coagulation is mainly in the way aluminum ions are delivered [7]. In elec- trocoagulation, coagulation and precipitation are not conducted by delivering chemicals – called coagulants – to the system but via electrodes in the reactor [8]. 1383-5866/$ – see front matter © 2006 Published by Elsevier B.V. doi:10.1016/j.seppur.2006.04.008