Effects of Al3+ on the microstructure and bioflocculation of anoxic sludge |
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Authors: | Lanhe Zhang Jing Zheng Shulei Tian Haifeng Zhang Xiaohui Guan Suiyi Zhu Xiaoyu Zhang Yuxuan Bai Ping Xu Jian Zhang Zheng Li |
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Institution: | School of Chemical Engineering, Northeast Electric Power University, Jilin 132012, China;Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China;School of Chemical Engineering, Northeast Electric Power University, Jilin 132012, China;Institute of Soil and Solid Waste, Chinese Research Academy of Environmental Sciences, Beijing 100012, China;School of Environment, Northeast Normal University, Changchun 130117, China;Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China |
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Abstract: | The aluminum ions generated from mining aluminum, electrolytic aluminum and the industrial production of aluminum-based coagulants (such as AlCl3 and Al2(SO4)3) enter sewage treatment plants and interact with activated sludges. An anaerobic/anoxic/oxic (A2O) process was used to reveal the effects of Al3+ on the pollutant removal efficiencies, bioflocculation and the microstructure of sludge. The results showed that a low concentration of Al3+ improved the pollutant removal efficiencies and increased the sludge particle size. However, a high concentration of Al3+ hindered microbial flocculation and reduced the pollutant removal efficiencies. With a 10 mg/L Al3+ addition, the chemical oxygen demand (COD), total nitrogen (TN) and NH4+-N increased by 3%, 16% and 27%, and reached as high as 68%, 60% and 87%, respectively. At the same time, the dehydrogenase activity, flocculation ability (FA) and contact angle of the sludge reached their maximum levels at 41.3 mg/L/hr, 45% and 79.63°, respectively. The specific surface area of the sludge decreased to 7.084 m2/g and the sludge pore size distribution shifted to concentrate in the mesoporous range. Most of Al3+ was adsorbed on the surface of sludge, changing the physicochemical properties and physical structure of the sludge. |
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Keywords: | Wastewater treatment Specific surface area Sludge properties Pollutant removal efficiency |
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