Enhancing excess sludge aerobic digestion with low intensity ultrasound

1 INTRODUCTIONExcess sludge from waste water treat mentplant may result in potential environmental pollu-tion. Aerobic digestion is one of the applied tech-niques for sludge treat ment . The researchers a-broad suggested that aerobic digestion should bethe opti mum design considering the stability ofsludge andthe environment protection1],if the de-sign flow of wastewater is below 2 .0×104m3/d.Many small sewage treat ment plants in the U.S.and European countries have adopted aerobic dig…

Enhancing excess sludge aerobic digestion with low intensity ultrasound

In order to enhance the efficiency of aerobic digestion, the excess sludge was irradiated by low intensity ultrasound at a frequency of 28 kHz and acoustic intensity of 0.53 W/cm^2. The results show that the sludge stabilization without ultrasonic treatment can be achieved after 17 d of digestion, whereas the digestion time of ultrasonic groups can be cut by 3 - 7 d. During the same digestion elapsing, in ultrasonic groups the total volatile suspended solid removal rate is higher than that in the control group. The kinetics of aerobic digestion of excess sludge with ultrasound can also be described with first-order reaction.