Abstract
This study investigates the results of electrocoagulation (EC) using aluminum (Al) electrodes as anode and stainless steel (grade 316) as a cathode for removing silica, calcium, and magnesium ions from simulated cooling tower blowdown waters. The simulated water contains (50 mg/l silica, 508 mg/l calcium, and 292 mg/l magnesium). The influence of different experimental parameters, such as current density (0.5, 1, and 2 mA/cm2), initial pH(5,7, and 10), the temperature of the simulated solution(250C and 35 0C), and electrolysis time was studied. The highest removal efficiency of 80.183%, 99.21%, and 98.06% for calcium, silica, and magnesium ions, respectively, were obtained at a current density of 1 mA/cm2, initial PH=7, the temperature of 250C and treatment time 60 min. The results have shown the ability of the EC process to remove silica and hardness ions from CTB water.
Highlights
Along with growing water contamination, and the severe shortage of water, the reuse of water has gained attention from the managers in diverse industries
4.1 Effect of current density The current density is an important parameter for controlling the process of electrocoagulation by influencing the rate of anodic dissolution to produce coagulant and increase the rate formation of hydroxide flocs of metal so the removal efficiency of silica sand hardness ions increases (Akyol et al, 2018)
The removal efficiency of silica, calcium and magnesium are increased from 91.54%, 33.622%, and 85.48%, respectively at a current density (0.5 mA/cm2) to maximum value 99.21%, 80.182%, 98.06% at a current density of (1 mA/cm2)
Summary
Along with growing water contamination, and the severe shortage of water, the reuse of water has gained attention from the managers in diverse industries. Cooling towers are large construction to extract heat via evaporation of waters. Continuous evaporation of circulating water inside the tower causes an increase in the concentration of solids and insoluble mineral salts and leads to scale formation on heat transfer surfaces. Chemical coagulation treatment which utilizes conventional coagulant such as alum and ferric chloride (Fecl3); these salts produce undesired ions for cooling water like chloride (corrosive) and sulfate (scalene) (Gelover – Santiago et al, 2014). One of these conventional processes to defeat the drawbacks of traditional water and wastewater treatment is electrocoagulation. The cost of treatment declines (Khandegar and Saroha, 2013; Naje et al, 2017; Hakizimana et al, 2017)
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