The objective of this work was to investigate effects of some key operation parameters serving sludge ultrasonication (US). First, a stirrer speed of 500 rpm was found to be convenient for sludge US pretreatment. | Science & Technology Development, Vol 18, 2015 Sonication pretreatment of sludge: preliminary study of operation parameters Ngoc Tuan Le University of Science, VNU-HCM (Bài nhận ngày26 tháng 08 năm 2014, nhận đăng ngày 02 tháng04 năm2015) ABSTRACT The objective of this work was to DDCOD increase as a result of sludge floc investigate effects of some key operation disruption, apparent viscosity decreased as parameters serving sludge ultrasonication a function of ES during US pretreatment. (US). First, a stirrer speed of 500 rpm was Finally, sequential isothermal US showed found to be convenient for sludge US significant improvement of sludge pretreatment. A slight decrease in sludge US disintegration in some cases, especially at high US power and pressure. pretreatment efficacy due to the erosion of the probe surface was observed. Apart from Keywords: Sequential sonication; Sludge disintegration; Ultrasonic pretreatment; Waste activated sludge. INTRODUCTION Activated sludge processes for wastewater treatment produce large quantity of sludge, commonly treated by anaerobic digestion (AD) -a complex and slow process requiring high retention time to convert degradable organic compounds to CH4 and CO2 in the absence of oxygen, allowing mass reduction, odor removal, pathogen decrease, and energy recovery in the form of methane. However, hydrolysis -the first stage, is known as the rate-limiting step of microbial conversion. Therefore, biological, mechanical, thermal, and chemical methods, as well as intense electric fields, etc. have been applied in sludge pretreatment [1-5] to rupture the cell wall and facilitate the release of intracellular matter into the aqueous phase to improve biodegradability and enhance AD. Ultrasonic irradiation (US) is claimed a feasible and promising mechanical disruption technique for sludge pretreatment due to efficient sludge disintegration [6], improvement in biodegradability and bio-solid quality [7], Trang 88 increase in .
