关键词: 电极过程, 锌, ZnCl2–NH4Cl溶液

Abstract: The effect of culture conditions on microbial flocculant production from Nocardia sp. CCTCC M201005, a newly isolated bioflocculant producing bacterium, was investigated. Sucrose was proved to be an optimum carbon source. Complexity of organic and inorganic nitrogen sources stimulated both bacterial growth and flocculant synthesis, among which corn steep complexed with urea was the most efficient. Proper corn steep concentration accelerated bacterial growth while relatively low corn steep concentration was more favorable for bioflocculant formation. The highest flocculation activity was obtained at C/N 20~30. The medium supplemented fermentation was designed and carried out. The results showed that the final flocculation activity and cell density were increased more than 10% and 35% respectively compared with those in the fermentation with no medium supplementation. Flocculation conditions of bioflocculant produced by Nocardia sp. CCTCC M201005 (named REA-11) were also discussed. The thermostability of REA-11 was high at pH 3.0 to 6.5 and its activity was markedly improved by the addition of CaCl2. As a co-flocculant, the optimum concentration of CaCl2 was 8 mmol/L in this flocculation system.

Key words: electrode process, Zn, ZnCl2–NH4Cl electrolyte