Studies on inhibition activity of chitosan against bacteria from drinking water

The effects of the inhibition activity of chitosan on the bacteria isolated from drinking water were studied. The bacteriostasis circle sizes of chitosan were observed, and the inhibitory effects with different concentration of chitosan (0.1, 0.2, 0.5 mg/l) and different cell concentration were also studied respectively. The results showed that chitosan could inhibit the growth of the bacteria isolated, and the ability was directly proportional to its concentrations. Though the bactericidal effect of chitosan with 0.2 mg/l concentration was after that of 0.5 mg/l, and longer settling time was needed, the turbidity was lower for the full flocculation of the residual bacteria. 0.2 mg/l concentration of chitosan could completely inhibit the growth of bacillus with low concentration; the holding time was extended with higher concentration of bacterial suspension and the same effect was also achieved. The actual use of chitosan as a disinfectant agent should be based on the bacterial contamination of water; tests were needed to find the optimal concentration of chitosan; and the flocculation time should be adjusted to achieve satisfactory results.