Comparative behavior of ionic and nonionic surfactants and its primary biodegradation in sediments and sludges

The study is focused on the biodegradation rates of different types of surfactants in medium as sediments and sludge and its comparative studies, which may be useful in the bioremediation of polar and nonpolar compounds in soils. The extent and rate of primary biodegradation of anionic surfactants i.e., sodium dodecyl benzene sulphonate (SDBS) and sodium dodecyl sulfate (SDS), a nonionic surfactant iso-octyl phenoxy-hexaethoxyethanol (CTX) and a cationic surfactant n-cetyl trimethyl ammonium bromide (CTAB) each at 0.01, 0.10, 1.00 and 10.00 mg/L were studied using different types of sediments and sludges in aerobic shaker flasks. In the order SDS > CTX > SDBS > CTAB, surfactants were biodegraded by the microorganisms. In the presence of Sludge A, SDS underwent degradation by more than 80% after 4 days, showing that the microorganisms enhance the rate of cleave C-C bonds after inoculation by bacterial action. SDBS did not biodegrade even up to 60% within 4 days of the investigation as the benzene ring in its structure protects it against degradation, while SDS was found 10 times more biodegradable than SDBS. The increasing surfactant concentration significantly decreased the primary biodegradation. The biodegradation was found to be completed with activated sludge within 3.5 days for 0.01 mg/L, 4.5 days for 0.10 mg/L, 7 days for 1 mg/L and 10 days for 10 mg/L SDS at 25 °C. Primary degradation followed the Monod kinetic model according to which the biodegradation is the function of surfactant concentration and microbial growth.