Farshad Golbabaei Kootenaei - Department of Environmental Engineering, Faculty of Environment, College of Engineering, University of Tehran, Tehran, Iran
Nasser Mehrdadi - Department of Environmental Engineering, Faculty of Environment, College of Engineering, University of Tehran, Tehran, Iran
Gholamreza Nabi Bidhendi - Department of Environmental Engineering, Faculty of Environment, College of Engineering, University of Tehran, Tehran, Iran
Hasan Aminirad - Department of Environmental Engineering, Faculty of Civil Engineering, Babol (Noshirvani) University of Technology, Babol, Iran
Mohammad Amin Mirrezaei - Department of Environmental Engineering, Faculty of Environment, College of Engineering, University of Tehran, Tehran, Iran
Farimah Saeidi - Department of Environmental Engineering, Faculty of Environment, College of Engineering, University of Tehran, Tehran, Iran

Background: One of the most challenging and critical processes in wastewater treatment is sludge treatment. This study aimed to investigate the effects of low frequency ultrasound and high level of energy on inactivation rate of total coliform of sludge and ascertain the optimal operating parameters of the ultrasound waves.Methods: In this research, the density of ultrasound (W/mL) and time (minutes) were investigated. The effect of these parameters on the inactivation of total coliform in sludge was also investigated.Results: The results revealed that the optimum operating time and ultrasound density were ۳۰ minutes and ۲.۵ W/mL, respectively. Also, the frequency of ۲۰ kHz of total coliform removal rate in these conditions was ۹۹.۴۴% .Conclusion: Ultrasound waves as well as micro and nano bubbles could remove total coliform and decontaminate the sludge, thereby incrementing the rate of treatment.

Cavitation, Nano-Bubbles, Sludge, Total Coliform, Ultrasound Density