Comparison of Mg2＋- and Ca2＋-enhancing anaerobic granulation in an expanded granular sludge-bed reactor

• Published in: Science China. Chemistry 2014-11, Vol.57 (11), p.1596-1601
• Main Authors: Cao, XiaoLei, Sheng, YuXing, Cao, HongBin, Zhang, Yi
• Format: Article
• Language: English
• Subjects: Calcium ions; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; EGSB; Granular materials; Granulation; Magnesium; Nuclei; Polysaccharides; Rigid structures; Sludge bed reactors; X-ray spectroscopy; X射线光谱仪; 厌氧污泥; 实验室规模; 成核阶段; 能量色散; 膨胀颗粒污泥床反应器; 造粒过程
• ISSN: 1674-7291; 1869-1870
• DOI: 10.1007/s11426-014-5197-5

The mechanisms responsible for the fast granulation of anaerobic sludge caused by Mg2＋ and Ca2＋ addition was examined in four lab-scale expanded granular sludge bed（EGSB） reactors. Results indicated that both Mg2＋ and Ca2＋ accelerated the sludge-granulation process and increased the amount of polysaccharides and proteins in the sludge. Energy dispersive x-ray spectrometry（EDX） analysis revealed that, in a mature granule, both Mg2＋ and Ca2＋ composed as phosphate and calcium was distributed primarily in the periphery of the granule, while magnesium distributed mainly in the interior. The addition of Mg2＋ was more favorable for the nuclei formation, whereas the addition of Ca2＋ was more favorable for subgranule growth and maintaining the granules’ rigid structure. Results showed that the addition of Mg2＋ in the nuclei formation stage and Ca2＋ in the granule-growth stage accelerated granulation more than adding only one of them in the granulation process.