TAILIEUCHUNG - Sludge pretreatment by sonication: Effect of temperature
The main results were that the evolution of sludge T depended on PUS. In cases of the same ES (different PUS then different US duration), for the small probe, high PUS were still beneficial for sludge disintegration. However, for the big probe, a low disintegration efficiency was achieved at high PUS due to the high sludge T which leads to a significant damp of cavitation intensity. | TAÏP CHÍ PHAÙT TRIEÅN KH&CN, TAÄP 18, SOÁ T5- 2015 Sludge pretreatment by sonication: Effect of temperature Le Ngoc Tuan University of Science, VNU-HCM (Received on April 14 th 2015, accepted on October 20 th 2015) ABSTRACT Effects of temperature (T) rise in conditions of isothermal, adiabatic sonication -US (the same power input -PUS), and sole thermal hydrolysis, then its effects associated with PUS for the same specific energy input (ES) and the same treatment duration were investigated. The main results were that the evolution of sludge T depended on PUS. In cases of the same ES (different PUS then different US duration), for the small probe, high PUS were still beneficial for sludge disintegration. However, for the big probe, a low disintegration efficiency was achieved at high PUS due to the high sludge T which leads to a significant damp of cavitation intensity. In cases of the same ES and treatment time, the sludge disintegration still benefited from high PUS if enough time was let for subsequent thermal hydrolysis. Therefore, the combined effect should be taken into account in optimization of US process: cavitation acts mainly during the early stage of the adiabatic US, then US being progressively damped by the increasing T, thermal hydrolysis takes over, being “boosted” by the initial work of US. Keywords: Adiabatic sonication, Sludge disintegration, Temperature effect, Waste activated sludge, Ultrasonic pretreatment. INTRODUCTION The wastewater treatment via the activated sludge process produces a large amount of biomass, of which improper disposal generates a significant threat to ecosystems. Thus anaerobic digestion (AD) has been widely applied as a feasible method for the sludge treatment. However, the low rate of microbial conversion of hydrolysis stage requires a pretreatment of sludge. Ultrasonic irradiation (US) is proved as a feasible and promising mechanical disruption technique for the sludge pretreatment according to the treatment time
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