The behaviors of Microcystis aeruginosa cells and extracellular microcystins during chitosan flocculation and flocs storage processes.

This work aimed to study the effects of chitosan on cell integrity and extracellular microcystins (MCs) of Microcystis aeruginosa cells during flocculation and flocs storage processes. The impacts of chitosan addition, flocculation stirring and flocs storage time were comprehensively detected to prevent or reduce cell lysis and MCs release. Response surface method (RSM) was applied to optimize the chitosan flocculation. Under chitosan concentration 7.31 mg/L and optimized mechanical conditions, 99% of M. aeruginosa cells were integrated removed. Furthermore, amounts of extracellular MCs were adsorbed by chitosan polymers in this process. With chitosan flocs protect, though cells showed some damage, extracellular MCs concentration in flocculated samples lower than background level within first 2 d. However, lots of MCs release was observed after 4d which may result from chitosan degradation and cells lysis. Therefore, chitosan flocs should be treated within 2d to prevent the adsorbed MCs releasing again.

Purification Comparison and Influence of Ethanol Precipitation and Chitosan Flocculation Methods on Paeoniflorin Content in Shuyu Compound Granules / 中国中医药信息杂志

Objective To compare the refining effects between ethanol precipitation and chitosan flocculation methods on extracting solutions of Shuyu compound granules.Methods Orthogonal experiment was utilized to examine the influence of liquid concentration, alcohol concentration and standing time on refining of Shuyu compound granules extracting solution by ethanol precipitation method, and compare the impact of ethanol precipitation and chitosan flocculation methods on the contents of solids and paeoniflorin.Results The optimized condition of ethanol precipitation method was 0.8 g/mL solution concentration (crude drug) with 20% ethanol standing for 6 h. Both ethanol precipitation method and chitosan flocculation method reduced the extraction ratio of Shuyu compound granules decoction, but chitosan flocculation method caused a great loss of paeoniflorin.Conclusion Low concentration ethanol precipitation method can be used for the purification of Shuyu compound granules. Whether chitosan flocculation method is suitable requires further study.