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 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 reactor's surface and these flocks have been left from water using a grazer [4] and [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 investigated on effects of system parameters.
Electrocoagulation is a process consisting of creating metallic 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 electrocoagulation, coagulation and precipitation are not conducted by delivering chemicals – called coagulants – to the system but via electrodes in the reactor [8].
Suitable electrode choice is very important in electrocoagulation. Most common electrode materials are iron and aluminum. Both of these are cheap, easily found and effective materials [9].
When aluminum is used as electrode materials, the reactions are as follows:
At the cathode: