LAS removal and biodegradation in a wastewater treatment plant

Abstract

Linear alkylbenzene sulfonate (LAS) biodegrades easily and loses its tensioactive properties quickly through a primary biodegradation process, as many works of literature testify. Many studies have been carried out in laboratories or in pilot plants, whereas few have been undertaken in a wastewater treatment plant (WWTP). In Italy, unlike in other countries, no detailed investigation has been made so far to establish LAS biodegradation in real WWTP conditions. EniChem Augusta (EA) and Consorzio Po‐Sangone (CPS) have worked together for over two years on this problem, taking into consideration the large (flow rate: approximately 400 × 103 m3/d) and central active sludge WWTP of the metropolitan area of Torino, north of Italy. Specific LAS data have been obtained, using established HPLC techniques, in influent and effluent streams, in the dissolved (waters) and adsorbed (suspended solids and sludges) phases, to reach a complete mass balance. LAS removal >99% and LAS biodegradation of approximately 85% have been observed. Attention also has been given to LAS intermediates of biodegradation, namely the sulfophenyl carboxylates (SPC), using HPLC and GC‐MS techniques, the latter after derivatization. The SPCs have been found present only in the waters and not in the adsorbed phases (SS and sludges).

Indicators of terrestrial biogenic hydrocarbon contamination and linear alkyl benzenes as land-base pollution tracers in marine sediments

“…Three LAB homologs were found in Cortiou sediments, with 11 different resolved isomers (Table 4). Technical formulations of commercial detergents contain 10-15, 25-35, 25-35, 15-30 and 0-5 % of C 10 , C 11 , C 12 , C 13 and C 14 homologs, respectively (Cavalli et al 1993). Furthermore, in Europe, more than 98 % of C 10 -C 13 homolog LABs are used as the main components of commercial detergent formulations, predominantly containing C 11 and C 12 (HERA 2007;Gordon et al 2009).…”

“…We observed higher concentrations of linear alkyl benzenes with 12 carbon atoms (C 12 -LAB), followed by C 10 -LAB and C 11 -LAB, accounting for an average of 44.9, 28.3 and 26.7 % of the total LABs, respectively. The linear alkyl chains typically have 10-13 carbon units, with approximate ratios of C 10 /C 11 /C 12 /C 13 being 3/30/33/24, with an average carbon number near 11.6 (Cavalli et al 1993;Viguri et al 2002;HERA 2007). LAS environmental fingerprints previously detected in aquatic environmental samples contained C 10 /C 11 /C 12 /C 13 at 45:30:23:2 with an average carbon number of 10.8 (Cavalli et al 1993).…”

“…The linear alkyl chains typically have 10-13 carbon units, with approximate ratios of C 10 /C 11 /C 12 /C 13 being 3/30/33/24, with an average carbon number near 11.6 (Cavalli et al 1993;Viguri et al 2002;HERA 2007). LAS environmental fingerprints previously detected in aquatic environmental samples contained C 10 /C 11 /C 12 /C 13 at 45:30:23:2 with an average carbon number of 10.8 (Cavalli et al 1993). In this study, a ratio of C 10 /C 11 /C 12 /C 13 of 25.1/25.4/45.5/0 was observed, with an average carbon number of 11.2.…”

Determination of Surfactants in Environmental Samples. Part II. Anionic Compounds

“…Determination of those biotransformation products occurred in liquid or solid environmental samples is important because it may indicate ongoing biodegradation of compounds from the group of LAS [18][19][20][21].…”

Analysis of Surfactants in Environmental Samples by Chromatographic Techniques

“…Later, these chemicals are commonly removed between 81 and 99.9% in wastewater treatment plants (WWTPs) [16][17][18], although they are frequently detected in sewage effluents showing concentrations up to 872 µg/L for LAS [16], between 0.24 and 3 µg/L for AES [19], up to 4 µg/L for QACs [20], and from 0.2 to 23 µg/L for AEOs and APEOs [21,22]. Secondary treatment in active sludge units is considered the most important process to eliminate surfactants through aerobic biodegradation, but a considerable fraction is also removed by sorption / precipitation in sludges originated from several decantations (Figure 2) (e.g., 15-37% of total LAS [14,15,23] and more than 90% of nonylphenol [24]). These sludges are also a potential source of contamination for soils, groundwater and adjacent rivers as they tend to contain high concentrations of organic contaminants and are often used in agriculture after anaerobic digestion.…”