| Abstract |
Linear alkylbenzene sulfonates (LAS) comprise the major surfactant group which is mainly applied to synthetic detergents and cleaners. Considering their overconsumption and possible consequent environmental effects LAS behaviour is studied in a sink of great importance for their fate, as it is a municipal waste water treatment plant. In this study LAS concentration is determined in dissolved phase, suspended solids and sludges in the different stages of the purification process and the effect of the latter on these surfactants is investigated. For this scope high performance liquid chromatography (HPLC) analytical method is used. It can be concluded from the results that sorption and biodegradation are the two basic mechanisms which decisively affect the fate of LAS resulting in a net removal from the solution that exceeds 99.9%. The highest elimination occurs in primary settler and aeration tank: 40% due to sorption precipitation is found in the sludge settling tank and 38% is biodegraded. Compared with the commercial products, influents are enriched in dissolved homologues with shorter alkyl chain length while in suspended solids and sludges longer homologues are predominant. This implies that longer homologues show a stronger tendency to adsorption and biodegradation than shorter ones. From the monitoring of the diurnal variation in LAS concentration, it can be pointed out that the influx of these surfactants is maximized during noon hours. The extent of sorption phenomenon is different for each purification stage. Apart from the composition, the amount of suspended solids seems to play a crucial role; the more it augments the more the sorption is inhibited. Besides, the use of isotherm expressions makes the correlation between dissolved and adsorbed amount of LAS feasible, especially as far C10 and C11 homologues are concerned. However, generally biodegradation brings about strong deviations in the case of C12 and C13 homologues. The experimental values of influents of primary settler, aeration tank and secondary settler are introduced to mathematical equations in order to predict the effluents of the above systems. The application of simple simulation models proves to be sufficiently successful not only for the individual stages but for the whole system, after coupling of the equations, as well.
|
Μελέτη του Γίγνεσθαι των Γραμμικών Αλκυλοβενζοσουλφονικών Αλάτων σε Μονάδα Επεξεργασίας Λυμάτων μέσω Μετρήσεων Πεδίου και Μαθηματικών Προσομοιώσεων
