Screening and flocculating properties of bioflocculant-producing microorganisms

Screening of bioflocculant-producing microorganisms was carried out. A strain that secreted excellent bioflocculant was isolated from municipal sewage using the spread plate technique, identified as Klebsiella sp. by the analytical profile index (API) identification system, and named A9. Several important factors that had an effect on A9's bioflocculant-producing and flocculating activity were studied. A total of 4 g/L Kaolin suspension was used to measure the flocculating activity of the bioflocculant from A9. It was found that maltose and urea were A9's best carbon and nitrogen sources, respectively, and the flocculating activity of the flocculating agent from A9 was markedly increased by the addition of trivalent cations such as Fe3+ and Al3+; furthermore, the bioflocculant produced by A9 was most effective when the pH value was 6.0.