title: Performance and mechanism of low-frequency ultrasound to regenerate the biological activated carbon.
abstract: Biological activated carbon (BAC) filter has been widely used as an effective water treatment but regenerations of BAC are costly. Ultrasound has been successfully applied for regeneration of activated carbon but has been less frequently applied to the regenerate the BAC. In this study, bench-scale and pilot-scale experiments were conducted to evaluate the regeneration performance and mechanism of BAC with low-frequency ultrasound. Adsorption indices, microbiological parameters, pore structure and removal efficiencies were further investigated. The results showed that low-frequency ultrasound could regenerate the BAC effectively. The regeneration effects were significantly affected by the frequency, sonication intensity, sonication time, and water temperature, but not the usage time of the BAC. The optimized conditions were identified as 40kHz of frequency, 115×10-3W/cm3of sonication intensity, 25-30°C of water temperature and 5min of sonication time. The iodine value and methylene blue value increased from 480mg/g and 100mg/g to 680mg/g and 133mg/g respectively, the biomass decreased from 310nmolP/gC to 245nmolP/gC, while the biological activity increased from 0.03mg O2/hgC to 0.0355mg O2/hgC under the optimized condition. After three months of continuous operation, removal efficiencies of regenerated BAC were still high for the removal of organic contaminants, atrazine, and 2-MIB. Analysis of pore structure, BET surface area, and scanning electron microscopy indicated that ultrasound mainly acted on surface and macro-pores of BAC through the high-speed microjets and high-pressure microstreams resulted from the collapse of cavitation bubbles.
authors: Key Laboratory of Integrated Regulation and Resource Development Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China.
authors: Cheng
authors: C
authors: Liu
authors: College of Environment, Hohai University, Nanjing 210098, China.
authors: Yakun
authors: Y
authors: Sun
authors: College of Environment, Hohai University, Nanjing 210098, China.
authors: Dongying
authors: D
authors: Wang
authors: College of Environment, Hohai University, Nanjing 210098, China.
authors: Zhehao
authors: Z
authors: Sun
authors: Division of Environmental and Ecological Engineering, Purdue University, West Lafayette, IN 47907, USA.
authors: Ming
authors: M
authors: Chen
authors: Division of Environmental and Ecological Engineering, Purdue University, West Lafayette, IN 47907, USA.
authors: Zhi
authors: Z
authors: Zhou
authors: Key Laboratory of Integrated Regulation and Resource Development Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China. Electronic address: liucheng8791@sina.com.
authors: Wei
authors: W
authors: Chen
mesh_terms: D002606:Charcoal / Q000737:chemistry* / Q000378:metabolism; D059027:Recycling / Q000379:methods*; D013010:Sonication; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; D002606:Charcoal
keywords: Biological activated carbon; Drinking water; Mechanism; Regeneration; Ultrasound