Anionic Surfactants Removal and Biodegradation in a Large Treatment Plant

A full scale study was conducted to investigate the destination of LAS (Linear Alkylbenzene Sulfonate) in Italy's greatest WWTP (Waste Water Treatment Plant): the Turin central plant. Specific LAS data, using established HPLC techniques, have been obtained in the influent and effluent streams, in the dissolved phase (waters) and in the adsorbed one (suspended solids and sludges) to reach a complete mass balance. LAS removal higher than 99% and LAS biodegradation ca. 85% have been observed. Attention has been also given to LAS intermediates of biodegradation, namely the sulfo fenil carboxylaters (SPC) resorting to HPLC and GC-MS techniques, the latter after derivatization. On the basis of SPC data it is possible to measure esperimentally also the biodegradation in sewers before the WWTP (at least 12%) and the mineralization degree of LAS in the WWTP (ca. 80% vs. total biodegraded LAS). The impact of the WWTP on the LAS concentration of the Po river waters has been also considered.