Removal of phosphate from landscape water using an electrocoagulation process powered directly by photovoltaic solar modules

Abstract

In this paper, removal of phosphate from landscape water using an electrocoagulation process with aluminum electrodes powered directly by photovoltaic solar modules was investigated. The results showed that total phosphate (TP) residual concentration in landscape water decreases with an increasing electrolysis time. A first order kinetics about TP removal is concluded. An optimum electrode gap of 25mm is determined. Conductivity of landscape water was adjusted by adding NaCl, and an optimum initial conductivity range of 765–1135μS/cm can be obtained. In an overcast day, a higher TP removal efficiency can be obtained by extending time. TP removal efficiency increases with an increasing number of serial photovoltaic modules during early reaction. The optimal condition, order and significance of the factors on TP removal were determined by an orthogonal test with four factors and three levels, and the predictive value for TP removal efficiency is (97.77±2.13)%. Photoelectricity conversion efficiency for an overcast day is the highest and 12.2%. However, energy for removing a unit mass of TP and energy for removing TP per volume unit are all the lowest, and values are 15.75kWh/kg and 0.71kWh/m3, respectively. The process used for removal of phosphate from landscape water is feasible.