Pretreatment for capacitive deionization: Feasibility tests using activated filter media and granule activated carbon filtration

Dissolved organic matter and scaling are the main causes of electrode fouling, blocking activated carbon pores and reducing their performance. However, limited information exists on fouling by low molecular weight organic matter in the capacitive deionization (CDI) process. This study therefore systematically investigated for the first time a pretreatment process to prevent the accumulation of organic and inorganic matter as well as scaling in the CDI process. During various pretreatments, activated filter media and granule activated carbon were considered promising for drinking water treatment. The higher the turbidity and organic matter concentration in the CDI feed solution was, the greater the reduction of salt removal efficiency, production rate, and energy consumption became. Divalent ions, such as Ca2+, had no noticeable effect on CDI treatment performance because of the neutralization effect of the dispersant, whereas iron had a noticeable effect on CDI electrode fouling. The results of this study are foreseen to help minimize its negative impact by reducing organic matter fouling and enabling water reuse. (C) 2020 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Automated summary

Dissolved organic matter and scaling are major causes of electrode fouling in CDI, but limited information exists on fouling by low molecular weight organic matter. This study investigated a pretreatment process to prevent organic and inorganic matter accumulation and scaling in CDI, finding activated filter media and granule activated carbon to be promising for drinking water treatment. Higher turbidity and organic matter concentration in CDI feed solution lead to greater reductions in salt removal efficiency, production rate, and energy consumption, while divalent ions like Ca2+ have no noticeable effect on CDI treatment performance but iron has a noticeable effect on CDI electrode fouling.