Effect of LAS (Linear alkylbenzene Sulphonates) on organic matter biodegradation

LAS (linear alkylbenzene sulphonates) are still the main surfactants used in formulated detergent products and are an important component of urban sewage. Surfactants could be toxic for microorganisms responsible for the degradation treatment and to organisms present in natural ecosystems. However, sewage treatment plants are not designed to eliminate surfactants. It is interesting therefore to study the effect of LAS on microorganisms in microbiological treatment units to determine the residual LAS concentration reaching the collector channels. This article discusses the effect of LAS on the purification efficiency of aerobic sewage treatment plants, and LAS biodegradation itself in such plants. The results of this study suggest that LAS influence pH self-regulation capacity in aerobic degradation of organic matter when its concentration is greater than 20 ppm. For this, external neutralisation is required in such cases. Likewise, LAS influence the degradation capacity of both organic matter and itself in aerobic processes, reducing the biodegradation rate and increasing the residual COD and LAS concentrations obtained.