Effects of Activated Carbon and Cationic Exchange Resin Pretreatments on Groundwater Defluoridation by Reverse Osmosis Process

Abstract

Abstract. The objective of this research was to study the effects of a pretreatment using activated carbon and cationic exchange resin on groundwater defluoridation by a reverse osmosis membrane. Actual groundwater containing a high fluoride concentration was collected and examined. Experiments were operated under controlled conditions: a transmembrane pressure of 0.6 MPa and temperature of 25 °C. The reverse osmosis system with activated carbon and cationic exchange resin pretreatments had higher fluoride removal than the one without the pretreatments, 97% compared to 95%, respectively. Additionally, the reverse osmosis system with the pretreatments also produced a higher permeate flux, 1.1 10 -5 compared 9.6 10 -6 m 3 /m 2 ·s without the pretreatment. When the reverse osmosis systems with and without pretreatments were fouled, they showed a decrease in fluoride rejection, as well as a permeate flux decline. After the fouled reverse osmosis membranes were chemically cleaned, the permeate flux recovery and the fluoride rejection of the osmosis system with the pretreatments improved. It could be concluded that the activated carbon and cationic exchange resin played an important role in improving the reverse osmosis system as they contributed to high fluoride rejection and high permeate flux.

Adsorption of Fluoride onto Acid-Modified Low-Cost Pyrolusite Ore: Adsorption Characteristics and Efficiencies

“…It is necessary to have both an awareness of fluoride’s dispersion and a comprehensive grasp of its many probable sources and especially removal technologies for management to be effective. Various water and groundwater treatment technologies have been applied to remove fluoride from water sources, such as electrodialysis [ 7 , 8 ], membrane filtration [ 9 , 10 , 11 ], and adsorption processes [ 12 , 13 , 14 , 15 , 16 ]. Of these technologies, when applied in a local community, adsorption is considered an excellent choice for defluorination due to its low cost, ease of design and operation, and high level of effectiveness [ 17 ].…”

Efficiencies of NF and RO Membranes on Pharmaceutical Removal and Membrane Fouling Effects

“…There are several types of membrane filtration methods; microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO), and the use of a membrane bioreactor [11][12] are well known methods. RO and NF membranes, in particular, can reject problematic compounds such as fluoride [13], have a small footprint, and are flexible for future application [14][15]. The rejection mechanisms of RO and NF membranes include size exclusion, electrostatic repulsion, and diffusion [16][17][18].…”