Electrocoagulation to Remove Silica from Cooling Towers Water

This paper presents the results of a study carried out about the effect of water quality on the removal of dissolved silica using an electrocoagulation process with aluminum electrodes. Silica is found in replacement water (RW), usually known as make up water, and in cooling tower blowdown water (CTBW). Tests were conducted on a small pilot scale with a continuous flow device. The treatment train consisted of electrocoagulation, flocculation, sedimentation and sand filtration. Two distinct RW and two CTBW with different physicochemical characteristics were studied. The response variables analyzed were: efficiency of aluminum to remove silica (ratio mgl super( -1) of dosed Al super( 3+)/mgl super( -1) SiO2 removed), removal efficiency of dosed Al super( 3+), hydraulic head loss throughout the electrochemical reactor and voltage. The cost of the treatment for the four types of water is discussed. The consumption costs of energy, chemicals and electrodes for RW treatment ranged from US$ 0.52 to 0.74 m super( -1), and was approximately US$0.53 m super( -3) for CTBW.