Fate Of Linear Alkylbenzene Sulfonate Research Articles

Modelling the Fate of Linear Alkylbenzene Sulfonate in Agricultural Soil Columns during Inflow of Surfactant Pulses from Domestic Wastewaters

Linear alkylbenzene sulfonate (LAS), a widely used anionic surfactant, is present in wastewater and can be discharged, causing environmental damage. When biodegradation is negligible, adsorption and desorption reactions play an important role, depending on the media characteristics (organic matter and clays) and hydrodynamic parameters. Previously published laboratory column data are modelled with PHREEQC (version 2.18) in three scenarios of LAS input: spill (LAS pulse), continuous discharge (LAS adsorption step) and remediation (LAS desorption step). The distribution coefficients (0.1–4.9 × 10−3 L/g) in the sand columns are lower than those determined in this paper from batch tests and in columns of 25% and 50% agricultural soil mixtures (1–70 × 10−3 L/g). Considering the Freundlich constant parameters from the modelling, the results are similar to the distribution coefficients, but the linear isotherms are more consistent throughout. The mass transfer coefficient from the sand columns is lower than the agricultural soil columns (20–40 h−1), indicating longer elution times for the heavier homologues and a higher percentage of agricultural soil. For lighter homologues, fast migration could cause contamination of aquifers. The great persistence of LAS in the environment necessitates the development of mitigation strategies using reactive transport models, which predict longer times for the remediation of LAS homologues.

Biodegradation and fate of linear alkylbenzene sulfonate in integrated fixed-film activated sludge using synthetic media

Biodegradation and fate of linear alkylbenzene sulfonate in integrated fixed-film activated sludge using synthetic media

Fate of linear alkylbenzene sulfonate in agricultural soil columns during inflow of surfactant pulses

The transport and reaction processes of linear alkylbenzene sulfonate (LAS) were characterised in columns of agricultural soil with a constant inflow of irrigation water. A pulse input of commercial LAS was performed with different mixtures of soil and sea sand (0/100%, 25/75% and 50/50%) and a continuous water flow of approximately 0.5 mL/min. LAS homologue retention was favoured at a higher soil rate, due mainly to higher clay and organic matter contents. C 10LAS and C 11LAS were less retained in soil columns, and were eluted faster and in higher proportion through soil columns than other homologues. C 12LAS and C 13LAS showed stronger interactions with soil due to their higher sorption capacity, and a lower proportion was eluted than the lightest homologues. In general, sorption of LAS was reversible and significant fractions were desorbed when the LAS input ceased and they were transported to deeper layers in the soil column, especially for short-chain homologues. Longer LAS homologues were eluted from soil columns, but required an elution of >10 pore-volumes. When there was biodegradation in the soil column, >25% of LAS could be removed, reducing percolation to deeper layers.

Fate of Surfactants in Membrane Bioreactors and Conventional Activated Sludge Plants

Two membrane bioreactors (MBRs) were operated at high sludge retention time (SRT) (between 30 and 75 d) in parallel to a conventional activated sludge plant (CASP) conducted at SRT = 10 d. The fate of linear alkylbenzene sulfonate (LAS), nonylphenol ethoxylates (NP(n)EO, n = 1-15), nonylphenoxy carboxylates (NP(n)EC, n = 1-2), and nonylphenol (NP) in these systems was investigated. All systems were very efficient in the removal of LAS (around 99%). The analysis of variance showed that the difference in the removal efficiency of LAS in the CASP and the MBR operated at SRT = 65-75 d (respectively 99.0 ± 0.43 and 99.8 ± 0.11) were significant (p < 0.05), confirming the importance of SRT in the removal of LAS. Comparison between the CASP and the MBRs in the removal efficiency of nonylphenolic compounds were conducted considering NP(3-15)EO, the sum of NP(1-15)EO, NP(1-2)EC, and nonylphenol (NP). In all cases MBRs were more efficient than the CASP. In the case of NP the removal was about 76 ± 7.5% for the CASP and 90% ± 12.1 and 82 ± 8.7% for the MBRs. Better performance of MBRs in the removal of nonylphenolic compounds can be attributed to a better degradation. For example, if the sum of NP(1-15)EO and NP(1-2)EC is considered, estimated biodegradation was about 48% for the CASP and 72% for MBRs.

On the fate of LAS, NPEOs and DEHP in municipal sewage sludge during composting

The fate of hydrophobic xenobiotic pollutants such as linear alkylbenzene sulfonates (LAS), nonylphenol ethoxylates (NPEO) and di-ethyl-hexyl phthalate (DEHP) during sewage sludge composting was addressed in this work. The experiments were conducted in a fully automated in-vessel autothermal composting system which was fed with a mixture of primary and secondary sludge and manure. The mixture composition was determined to achieve satisfactory humidity, C/N ratio and free air space (FAS). The effect of various parameters, such as the initial xenobiotic concentration, the presence of multiple xenobiotic compounds and the temperature of composting material sustained during the process on the xenobiotics biodegradation kinetics was investigated. It was generally established that significant xenobiotic reduction is achievable through composting under all conditions tested. According to the obtained results, the presence of LAS, NPEO and DEHP even at higher concentrations was not inhibitory to the bioprocess. However, the presence of multiple xenobiotic compounds such as NPEO, NP and DEHP in the sludge can influence LAS removal during LAS composting.

Simultaneous extraction and fate of linear alkylbenzene sulfonates, coconut diethanol amides, nonylphenol ethoxylates and their degradation products in wastewater treatment plants, receiving coastal waters and sediments in the Catalonian area (NE Spain)

The efficiency of six wastewater treatment plants (WWTPs) in the Catalonian region to remove several classes of ionic and non-ionic surfactants was investigated, using solid-phase extraction (SPE) followed by liquid chromatography–mass spectrometry (LC–MS). Occurrence and distribution of linear alkylbenzene sulfonates (LASs), coconut diethanol amides (CDEAs), nonylphenol ethoxylates (NPEOs) and their degradation products were studied in coastal areas receiving WWTP effluents. For the analysis of sediment samples pressurized liquid extraction (PLE) followed by SPE extract clean-up and LC–MS detection was used for simultaneous extraction of all target compounds. Concentrations of parent long ethoxy chain NPEOs in raw water entering WWTPs ranged from 60 to 190 μg/L. In effluents concentrations ranged from 2.8 to 6.6 μg/L, which corresponded to an average primary elimination of 93–96%. Nonylphenol (NP) was found in concentrations from 0.2 to 18 μg/L in WWTP influents and up to 5 μg/L in the treated water, showing a clear declining trend with respect to concentrations reported in the last 5 years. The elimination of LASs and CDEAs varied depending on the WWTP and was higher than 85% in well operated WWTPs with secondary treatment and only 56% (for CDEAs) and 30% (for LAS) in WWTPs with primary treatment. Levels up to 86 mg/kg of LAS, 1.7 mg/kg of NP, 400–760 μg/L for NPEOs and NPECs were detected in sediments at sampling points near the discharge of WWTP effluents, clearly showing that in coastal area receiving WWTP effluents surfactants and their degradation products are widespread contaminants.

Dynamic in-stream fate modeling of xenobiotic organic compounds: a case study of linear alkylbenzene sulfonates in the Lambro River, Italy.

Using a conceptual hydraulic model, a one-dimensional dynamic river water quality model has been developed to assess the short-term fate of linear alkylbenzene sulfonates (LAS) in the river compartments water and benthic sediment. The model assumes local equilibrium sorption and that both dissolved and sorbed chemical are available for biodegradation. To investigate the interaction of nutrient dynamics and organic contaminant fate, the model is coupled with a basic water quality model. On the basis of the Lambro River (Italy) as a case study, the result shows that the model predictions agree well with the measured data set. The model output sensitivity to model parameters has been tested, and the results depict that the model is highly sensitive to the biodegrading parameters. Also, a comparison of a steady state with a dynamic simulation and the effect of nutrient dynamics on the LAS fate in the Lambro River as a scenario analysis are presented. The results indicate the usefulness of the proposed model for the short-term simulation of organic contaminant fate in unsteady environmental conditions.

Investigation of an onsite wastewater treatment system in sandy soil: Site characterization and fate of anionic and nonionic surfactants

This study reports on the fate of linear alkylbenzene sulfonate (LAS), alcohol ethoxylate (AE), and alcohol ether sulfate (AES) surfactants in a home septic system near Jacksonville (FL, USA) that has been used since 1976. The drainfield at this site resides in fine sand (< 6% silt and clay) with an unsaturated zone that ranges from 0 to 1.3 m. During the wettest times of the year, it is likely that effluent from the septic system passes directly into the groundwater without exposure to an unsaturated zone of soil. Groundwater was collected during two sampling events, representing seasonal high and low groundwater table levels, and analyzed for the surfactants LAS, AES, and AE. During the wet season, the unsaturated zone was approximately 0.01 m beneath the drainfield. During the dry season, the unsaturated zone was about 0.4 m below the drainfield. Alcohol ethoxylate was not detected in any groundwater samples during either sampling. Alcohol ether sulfate was not found in the dry season sampling, but traces of AES had migrated downgradient about 4.7 m horizontally and 1.8 m vertically in the wet season. Linear alkylbenzene sulfonate was detected in some dry season samples and had moved downgradient some 11.7 m horizontally and 3.7 m vertically in the wet season. These observations demonstrate that these surfactants were removed to a great extent; otherwise, they would have traveled more than 260 m downgradient, which is the calculated distance that a conservative tracer like bromide would have moved downgradient over the life of the system. The most likely removal mechanisms for these surfactants were biodegradation and sorption. Therefore, this study indicates that LAS, AE, and AES are readily removed from groundwater in soils below septic system drainfields even in situations with minimal unsaturated soil zones.

How adaptation and mass transfer control the biodegradation of linear alkylbenzene sulfonate by activated sludge.

We use a nonsteady-state model to evaluate the effects of community adaptation and sorption kinetics on the fate of linear alkylbenzene sulfonate (LAS) in batch experiments conducted with activated sludge that was continuously fed different concentrations of LAS. We observed a sharp decrease in the biodegradation rate between 30 and 60 minutes and the presence of an LAS residual at the end of the batch experiments. The modeling analysis indicates that these phenomena were caused by relatively slow inter-phase mass transport of LAS. The modeling analyses also showed that the amount of LAS-degrading biomass increased when the continuous activated sludge was fed a higher LAS concentration. Although community adaptation to LAS involved accumulation of more LAS degraders, the increase was not proportional to the feed concentration of LAS, which supports the concept that LAS degraders also utilized portions of the general biochemical oxygen demand (BOD) fed to the continuous activated sludge systems.

Fate of Linear Alkyl Benzenesulfonates, Coproducts, and Their Metabolites in Sewage Treatment Plants and in Receiving River Waters

While much attention has been paid to assess contamination levels of linear alkyl benzenesulfonate (LAS) surfactants in the environment, only a few papers have reported on the levels of breakdown products of LAS and coproducts. Major LAS coproducts are dialkyl tetralinsulfonates (DATS) and methyl-branched isomers of LAS (iso-LAS). A previous method (accompanying paper) based on solid-phase extraction (SPE) and liquid chromatography/mass spectrometry has been modified for monitoring the above analytes in aqueous samples of sewage treatment plants (STPs) and in river waters. Analytes were extracted from 25, 200, and 1000 mL of respectively raw sewage, treated sewage, and river water samples by a 0.5-g Carbograph 4 SPE cartridge. Recovery studies of some authentic short-chain LAS metabolites suggested that the SPE cartridge was able to quantitatively extract all the compounds of interest from the three types of aqueous matrixes. Under full-scan conditions, limits of detection of the method for metabolites of...

Investigation of the Fate of Linear Alkyl Benzenesulfonates and Coproducts in a Laboratory Biodegradation Test by Using Liquid Chromatography/Mass Spectrometry

Major coproducts of commercial mixtures of linear alkyl benzenesulfonate (LAS) surfactants are dialkyl tetralinsulfonates (DATS) and methyl-branched isomers of LAS (iso-LAS). As a total, DATS and iso-LAS can account for up to 15% of LAS. Unlike LAS, little and contrasting information on the fate of DATS and iso-LAS is available. We have used liquid chromatography/mass spectrometry with an electrospray interface to follow biotransformation of LAS coproducts. Structure elucidation of their breakdown products was obtained by in-source collision-induced decomposition (CID) spectra. However, metabolites of LAS and iso-LAS could not be distinguished from each other by their CID spectra. According to the OECD 301 B protocol, a laboratory biodegradation experiment of LAS and coproducts was conducted. DATS were more resistant than iso-LAS to primary biodegradation. Biotransformation of both LAS-type compounds and DATS produced, besides expected sulfophenyl alkyl monocarboxylated (SPAC) LAS and sulfotetralin alkylcarboxylated (STAC) DATS metabolites, significant amounts of dicarboxylated (SPADC and STADC) species. SPADCs were less persistent than STADCs. After more than 5 months from the beginning of the experiment, 40% and 35% of the initial amounts of DATS and iso-LAS, respectively, were not mineralized. About 64% of refractory SPACs contained 2-5 alkanoyl carbons in the alkyl chain, while the number of alkanoyl carbons in the free alkyl chains of refractory STACs and STADCs averaged respectively 2.4 and 1.1. On the basis of the results of this study and LAS consumption, we roughly estimated that 200 000 ton of refractory organics is each year dispersed in the environment as the result of use of the above surfactants.

Behavior and fate of linear alkylbenzene sulfonate in different soils

To investigate the behavior of surfactants in soil ecosystems, the sorption of linear alkylbenzenesulfonate on soils from three different areas of Northern Greece and with different organic matter content was studied. LAS sorption on these soils decreased with increasing pH and correlated positively with the organic matter content of the soils.

Fate of LAS in activated sludge wastewater treatment plants: A model verification study

Mathematical models that predict the fate of chemicals in Wastewater Treatment Plants (WWfPs) are used as an integral part of risk assessment process in many countries. In this paper, the predictive power of two mathematical models, SIMPLETREAT and UWWREAT, is checked against linear alkylbenzene sulfonate (LAS) fate data collected at five WWTPs located across Europe. The temporal variability in WWTP streams was identified using statistical methods.

Fate of Linear Alkylbenzene Sulfonate in the Mississippi River

The 2 800-km reach of the Mississippi River between Minneapolis, MN, and New Orleans, LA, was examined for the occurrence and fate of linear alkylbenzene sulfonate (LAS), a common anionic surfactan...

LAS homolog distribution shift during wastewater treatment and composting: Ecological implications

The behavior of LAS (linear alkylbenzene sulfonate) in different environmental compartments was studied through wastewater treatment process steps in sewage treatment plants of Alicante and Benidorm (activated sludge type) as well as in Guardamar (lagoons). The fate of LAS, using a specific HPLC method, was monitored during treatment sludge compostage and soil amendment operations. Finally, the marine sediments close to a submarine wastewater sewer outfall were analyzed. The results show significant differences between distribution of LAS homologs in water and solids (sludges, sediments, and soils), as compared to the original distribution in detergent formulations, yielding a lower LAS average molecular weight in water samples. The change observed in the homolog distribution of LAS implies a reduction in the toxicity to Daphnia, because a lower average molecular weight of LAS is less toxic.

Fate of linear alkylbenzene sulfonate in the environment

AbstractAn extensive monitoring study was conducted to determine the fate of linear alkylbenzene sulfonate (LAS) during wastewater treatment and in the environment. Results showed that LAS was highly removed during activated sludge (99.3 ± 0.6%), lagoon (98.5 ± 1.8%), oxidation ditch (98.0 ± 4.2%), and rotating biological contact (96.2 ± 6.1%) treatment, with poorer removals observed at trickling filter (77.4 ± 15.5%) facilities. Concentrations of LAS in anaerobically digested sludge (10,462 ± 5170 μg/g) were one to two orders of magnitude greater than those observed for aerobically digested sludge (152 ± 119 μg/g), illustrating that LAS is rapidly degraded during aerobic sludge treatment. Receiving water concentrations of LAS in rivers of low effluent dilution were generally &lt; 50 μg/L. Elevated river sediment concentrations of LAS were observed only below the outfall of trickling filter treatment plants (59.7‐182.1 μg/g). Alkyl chain lengths of LAS averaged 12.0 carbon units in most environmental compartments, with the exception of sludge solids and river sediments, in which an enrichment of longer chain lengths was observed. Measured concentrations of LAS in river waters under critical low flow conditions were in agreement with PG‐GRiDS model predictions [5], thus supporting the validity of the modeling approach.

Fate of Linear Alkylbenzenesulfonates in a Lake Estuary

The concentration of linear alkylbenzenesulfonates(LAS)in the Lake Teganuma estuary indicated a seasonal variation and a downstream decrease. The downstream decrease in the studied section varied between 28% and 100% seasonally, and the average was 66(±25)% during 1987-1988. As to explain the decrease, we investigated biodegradation of LAS in water, diffusive exchange of dissolved phase LAS through the sediment/water interface, and settling of adsorbed phase LAS. Adsorption experiments were performed between 0.3-9 ppm of the initial concentrations of LAS. The experimental equation used to estimate the adsorption coefficient of LAS was verified by using adsorption data from field observations. The averaged value 2.4×10−5 cm2 sec−1 for the diffusion coefficient in the sediment interstitial water was obtained from the experiments using the sediment core samples. The biodegradation rate constant (between 0.06 and 3.33 day−1) in water and the diffusive flux rate (between −0.157 and 0.022 mg m−2 hour−1) from water to sediment were obtained from field observations and experiments. Based on this information, a mathematical model was applied to simulate the downstream decrease of LAS in water. With this model, nearly 10% of the total LAS from the river was found to be transported to sediment both in summer and winter. The settling flux of LAS in the lake estuary was ten times greater than the diffusive flux. The settling flux was ten times smaller than the disappearing flux by biodegradation in summer but was the same level in winter.

Application of Basin Wide Ecological Models (Bawems) to the Fate of LAS in Tokyo Bay

The primary purpose of this study was to simulate the environmental fate of the homologues of linear alkylbenzene sulfonates (LAS). These were selected as representative chemicals with middle-range aquatic toxicity and environmental persistence, which are used in rather large amounts. A secondary purpose was to determine the composition ratio (i.e., the relative percentages of LAS homologues) of LAS products which results in the minimum risk potential in sediments. The following results were obtained from model simulations: 1. By applying basin wide ecological models (BAWEMs) to Tokyo Bay and the surrounding watershed, distribution patterns of LAS homologues in river water, river sediment, seawater, and sea sediment were relatively well simulated. 2. The minimum risk composition ratio of LAS, with the constraint of considering detergent cleaning capacity, is capable of reducing by about 60% the risk potential of the composition ratio of popularly supplied LAS. Reported composition ratios of LAS in existing consumer products are all in the same or rather low risk level categories. It can be concluded that one of the effective strategies of chemical risk management, particularly with reference to alkylbenzene-based synthetic detergents, is alteration of the composition ratio of LAS.