Improvement of hydraulic loading rate by optimization of internal characteristics of dissolved air flotation

Abstract

a b s t r a c tThe increasing concentration of phosphorous in the water system is presented as a cause of the algal bloom, which is spreading severely as the climate changes. It is therefore necessary to develop the technology to remove algae and phosphorus effectively. Dissolved air flotation (DAF) is effective in removing algae and phosphorous in water systems by using micro-bubbles. This study aims to increase the hydraulic loading rate by optimizing the internal hydraulic characteristics of the DAF process. The number of orifices in the nozzle has been diversified in order to optimize the volume and the size of micro-bubbles. Further, the slope baffle was optimized by enhancing the collision efficiency of micro-bubbles through the current control of the contact zone. An increase in the hydraulic loading rate as a function of the flow of the fluid was achieved by using a horizontal baffle and a perforated panel. According to the results of the tests, when the number of orifices in the nozzle is five, six, or seven, the diameter of the micro-bubbles decreases by approximately 37% and the bubble volume concentration increases by approximately 15%. In addition, the turbidity and T-P removal achieved were 96% and 98%, respectively. This represents increases of 28% and 23%, respectively, and was achieved by changing the height ratio of the slope baffle, including a horizontal baffle, and changing the perforation ratio of the perforation panel, as compared with the conventional DAF process.