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Updated: Aug 17, 2025

Extraction of Structural Extracellular Polymeric Substances from Aerobic Granular Sludge
Published on: September 26, 2016
Revealing calcium ion behavior during anaerobic phosphorus release process in aerobic granular sludge system
Jixiang Wang1, Zejiao Li1, Qian Wang1
1Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
Abstract:
Calcium ions (Ca2+) are important for biological phosphorus (P) removal from wastewater, but its behavior has not been well documented during the anaerobic P release process. This study is aimed to explore the mechanisms of Ca2+ release in bacterial aerobic granular sludge (AGS) system. During the non-aeration (anaerobic) phase, nearly 40 % increase in Ca2+ concentration was detected at the bottom of AGS reactor where decrease in pH and increase in Mg2+ concentration occurred. The pH decrease due to anaerobic P release caused CaCO3 dissolution inside the granules, leading to Ca2+ release. In addition, the increased Mg2+ ions from hydrolysis of polyphosphates were detected to reversibly exchange with Ca2+ in granules at a molar ΔCa/ΔMg ratio of 0.51-0.65. Results from this work revealed that dissolution of CaCO3 and ions exchange between Ca2+ and Mg2+ were the two major contributors to Ca2+ release during anaerobic P release process.
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