5 Biological Activity of Waters Containing Cationic Surfactants Cationic surfactants along with anionic and nonionogenic surfactants are one of the main classes of surfactants. The proportion of cationic surfactants in the total volume of synthetic surfactants used in the economy is approximately equal to 22% (for the .; Ainsworth 1992). Cationic surfactants enter aquatic ecosystems together with polluted waters because they are widely used in many industries including petroleum industry, oil refining industry, petrochemical industry, and gas industry. Cationic surfactants (from the group of quaternary ammonium compounds (QAC)) are used in pest control in aquaculture for combating pathogenic organisms of fish. QAC. | 5 Biological Activity of Waters Containing Cationic Surfactants Cationic surfactants along with anionic and nonionogenic surfactants are one of the main classes of surfactants. The proportion of cationic surfactants in the total volume of synthetic surfactants used in the economy is approximately equal to 22 for the . Ainsworth 1992 . Cationic surfactants enter aquatic ecosystems together with polluted waters because they are widely used in many industries including petroleum industry oil refining industry petrochemical industry and gas industry. Cationic surfactants from the group of quaternary ammonium compounds QAC are used in pest control in aquaculture for combating pathogenic organisms of fish. QAC are frequently added to water at concentrations of 1-2 mg l Austin 1985 . Cationic surfactants are the class of synthetic surfactants whose production is rapidly increasing at an annual rate of 5 Dean 1985 . Correspondingly pollution of the environment with these synthetic surfactants including quaternary ammonium compounds increases. The biological effects of synthetic surfactants were studied . in Stavskaya et al. 1988 and Lewis 1991a b however on a comparatively limited range of biological subjects. Cationic surfactants have a negative impact on many investigated species of bacteria and fungi. The minimum bacteriostatic activity MBA of QAC was equal to the following values for the species the range of MBA values for the set of 13 different QAC is given in parenthesis in pg ml Glusman et al. 1978 cited from Stavskaya et al. 1988 Aspergillus niger 2-1000 Candida albicans 1-1000 Staphylococcus aureus 1-1000 Pseudomonas aeruginosa 250-1000 Escherichia coli 16-1000 . Analysis of the literature demonstrates the following regularities Stavskaya et al. 1988 which characterize the bactericidal activity of QAC 1 bactericidal action depends on the length of hydrocarbon radicals. Maximum bactericidal action is observed for chemicals with 16-18 carbon atoms 2 .
