Ultrasound membrane hybrid processes for dairy wastewater treatment: pilot-scale analysis

Novel wastewater treatments are necessary to effectively decrease the organic load of dairy wastewater before disposal. In this work the feasibility of a hybrid process of membrane filtration combined with ultrasonication to decrease organic load was investigated. The efficiency of the advanced hybrid process that simultaneously applies ultrasonic irradiation and pressure-driven membrane ultrafiltration was examined. Polyethersulfone ultrafiltration membranes with 20 and 50 kDa molecular weight cut-off were tested. The effects of the continuous and half intermittent ultrasonic irradiation during the ultrafiltration were compared. Ultrafiltration fluxes, chemical oxygen demand retentions and membrane, pore fouling and polarization layer resistances were analyzed in a combined process. Furthermore, mass transfer coefficients, fouling coefficients and concentrations on membrane surface were also calculated and compared. The results showed that the best correlation were achieved by plotting the cake filtration model, but the other models also have given relatively good correlations using gradual pore blocking and intermediate filtration models. For this reason the membrane filtration ultrasonication should be further investigated for future applications