Studies on the biodegradation of nonionic surfactants applied in the polyestre fibre industry. III. Effect of adaptation on the respiratory activity of organisms and on the biocenosis of inoculated sludge.

Manometric studies were conducted in 3 series. In the first one the sludge used for inoculation was non adapted to water purification containing surfactants. In the second and third series it was adapted to the sludge load 0.11 and 0.28 mg surfactant/mg d.w./day respectively. Increase in oxygen uptake was proportional to the degree of the adaptation of microorganisms only within limited range of surfactant concentration not exceeding 500 mg/l for Cirrasol FP and 1000 mg/l for Cirrasol SF and Cirrasol TCS. The toxic action of surfactants against Ciliata was noted at concentration above 100 mg/l and for Mastigota and Sarcodina above 500 mg/l, even by using adapted sludge for inoculation.