Electrocoagulation as a Promising Defluoridation Technology from Water: A Review of State of the Art of Removal Mechanisms and Performance Trends

Abstract

Fluoride ions present in drinking water are beneficial to human health when at proper concentration levels (0.5–1.5 mg L−1), but an excess intake of fluoride (>1.5 mg L−1) may pose several health problems. In this context, reducing high fluoride concentrations in water is a major worldwide challenge. The World Health Organization has recommended setting a permissible limit of 1.5 mg L−1. The application of electrocoagulation (EC) processes has received widespread and increasing attention as a promising treatment technology and a competitive treatment for fluoride control. EC technology has been favourably applied due to its economic effectiveness, environmental versatility, amenability of automation, and low sludge production. This review provides more detailed information on fluoride removal from water by the EC process, including operating parameters, removal mechanisms, energy consumption, and operating costs. Additionally, it also focuses attention on future trends related to improve defluoridation efficiency.

Concept of Flocks Fragmentation and Averaging Method for the Application of Electrocoagulation in Process for Coke Oven Wastewater Treatment

“…The economic analysis presented for the replacement of conventional coagulation with electrocoagulation for coke oven wastewater showed that if the process was applied to plants with an external power supply, its economics were not yet justified, but if a coke oven plant possessed its own power supply, the electrocoagulation treatment was more beneficial than conventional coagulation. However, it is worth noting, that the process of electrocoagulation is also used in other industries [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. The process has considerable potential for practical applications.…”

“…Currently, the electrocoagulation process is widely used for different types of pollution [ 29 , 30 , 31 ]. It has found application in many different industries, including the cleaning and neutralization of oil emulsions used in machining and abrasive handling, wastewater from the textile industry, wastewater from agro-food processing businesses, wastewater from car washes, heavy metals, and other pollutants such as coke oven wastewater [ 32 , 33 , 34 , 35 ].…”

Electrocoagulation as a revived wastewater treatment method‐practical approaches: a review

“…It should be noted that this process has not been widely applied for drinking water treatment due to several factors that must be considered, such as the sacrificial electrodes being in compliance with the WHO guidelines 72 or the possibility that the treated effluents could still present high concentrations of metal ions that would need further treatment, 70,73 leading to hybrid schemes 74,75 being needed to meet the standards for drinking water set by legal entities. 76 Currently, there are a few small capacity plants for the defluorination of potable water described by Castañeda et al 72 in India and Africa; meanwhile, there are several studies on the field devoted to the removal of turbidity, organic matter, 77 nitrate, 78,79 pathogens, 80 etc.…”

“…87 Even though EC has limited chemical cost requirements (or none ehatsoever) compared to CC, it might require higher maintenance or further sludge handling costs. 73 In Table 4, differences with regards to flocs and sludge characteristics are presented.…”

Fluoride Adsorption Comparison from Aqueous Solutions Using Al- and La-Modified Adsorbent Prepared from Polygonum orientale Linn.

“…Various techniques have been developed to remove excess fluoride from drinking water, such as adsorption, coagulation, ion exchange, microbial-induced precipitation [10,11], electrocoagulation [12], electrostatic unit [13] and electrodialysis [5,14]. Among these techniques, adsorption is effective, economical, convenient, and environmentally friendly [3,4,15,16].…”