Effect of pH on electrochemical treatment using platinum coated titanium mesh electrodes for post treatment of anaerobically treated sugarcane vinasses

Abstract

This study examines electrochemical post treatment to remove COD, SS, K+ and Cl- from anaerobically treated sugarcane molasses vinasse (ASMV). A platinum coated titanium mesh was used as an electrode material for both the cathode and anode, with 843.18 cm2 of working area. The effects of pH on removal efficiency, as well as energy and electrode consumption, were investigated. Influent ASMV was diluted 10 times and its initial pH was adjusted by addition of HCl and NaOH. The electrolysis experiment was performed at a current density of 94.88 A/m2 with 15 minutes of reaction time, and the effluent was collected after settling for 90 minutes. The results showed that the treatment efficiency was influenced by the initial pH value. A maximal COD removal efficiency (49.25%) was obtained at a pH of 5.0. For SS removal, the maximal efficiency (46.27%) was obtained at a pH of 10.0, and the lowest level of removal occurred at neutral pH conditions. The maximal efficiency of Cl- removal (17.59%) was obtained at a pH of 8.2 (non-adjusted), and its efficiency was lower when influent was adjusted to acidic and neutral pH conditions using HCl. Maximal efficiency of K+ removal (7.23%) occurred at neutral pH conditions and did not occur at alkaline pH values. Energy consumption was lower under pH-adjusted conditions than under non-adjusted conditions, and electrode consumption was higher in both acidic and alkaline conditions relative to neutral pH conditions.