Effects of ultrasound on flocs characteristics of drinking water precipitated sludge and its impact on coagulation efficiency of sludge recycling process
Abstract：In the process of enhanced coagulation by recycling sludge, drinking water precipitated sludge was pre-treated by ultrasound and the recycle trails were subsequently carried out, in order to solve the enrichment problem of poisonous and pernicious substance. The effect of ultrasound on the variability offlocs characteristics of drinking water precipitated sludge was mainly focused on, and so was its impact on coagulation efficiency of sludge recycling process. After the exposure to ultrasound, the temperature of sonicated sludge solution was raised and floc size was decreased, even could drop to a few microns after a long-term treatment. And The floc size exhibited a linear correlation with the energy density. Zeta potential of flocs of pre-sonicated sludge was decreased while specific surface was improved with energy density of 1W/mL and 5W/mL, contrastively Zeta potential was raised and specific surface was decreased with energy density of 10W/mL and 15W/mL. The coagulation efficiency was enhanced by recycling pre-sonicated sludge with a low energy density (1W/mL) within 30min ultrasonication. The improvement of turbidity, UV254 and CODMn removal was 2.7%, 23.12% and 10.02% respectively. Comparatively, a long time of ultrasonication under high energy density (15W/mL) could reduce the coagulation efficiency. Therefore, the ultrasound technique could enhance the pollutant removal, but the ultrasound time and energy density must be well controlled.
邬艳, 杨艳玲, 李星, 周志伟, 苏兆阳, 郭璇. 超声对净水沉淀污泥絮体特性及对污泥回流效能的影响[J]. 中国环境科学, 2014, 34(5): 1166-1172.
WU Yan, YANG Yan-Ling, LI Xing, ZHOU Zhi-Wei, SU Zhao-Yang, GUO Xuan. Effects of ultrasound on flocs characteristics of drinking water precipitated sludge and its impact on coagulation efficiency of sludge recycling process. CHINA ENVIRONMENTAL SCIENCECE, 2014, 34(5): 1166-1172.
