Using ultrasound as a pretreatment in ultraviolet disinfection of municipal wastewater

The ultraviolet disinfection performance of municipal wastewater is influenced by the presence of biological particles in the wastewater. This study aims to quantify the improvement of sonication pretreatment on UV performance. The study found that sonication lowers the tailing of a dose response curve by breaking large particles into smaller ones. Also, it was found that the initial slope of dose response curve exhibits an increasing trend as sonication prolongs. The effect of sonication on UV disinfectability depends on effluent quality. The degree by which the tailing level was lowered by ultrasound increases in the following orders: activated sludge effluent < primary effluent < trickling filter effluent. The study also explored effect of intensity, energy and volume on particle breakage by ultrasound and found that energy density governs the extent of particle breakage. It was concluded that to optimize improvement; focus should be placed on optimizing particle breakage by ultrasound.