Linear Alkylbenzene Sulphonate Research Articles

Conceptual analysis of the UASB/polishing pond system regarding the removal of surfactants, micropollutants and control of gaseous emissions

A conceptual and integrated analysis of the UASB/Polishing Pond system is presented in relation to the removal of specific constituents not normally covered in the pond's literature, namely surfactants (linear alkylbenzene sulphonate, LAS), micropollutants (phthalates and bisphenol A) and sulfide. Experimental studies carried out on a small full-scale UASB/PP system have shown limited overall removal efficiencies for some constituents (53% to 70% for phthalates and 50% for LAS), but excellent removal levels for bisphenol A (around 99%) and sulfide (no trace concentrations were detected in the second and third ponds of the series). Further research is needed to investigate possible limitations and to identify means to improve the performance of the UASB/PP system.

Thermodynamic parameters of micellization and transfer of amino acids from water to aqueous linear alkyl benzene sulphonate

The solution properties of linear alkyl benzene sulphonate (LABS) in water in presence of amino acids have been investigated conductometrically. The critical aggregation concentration (cac) and critical saturation concentration (csc) were determined. It has been observed that at low concentration of surfactant amino acids interact with hydrophilic head group of surfactant molecules and form molecular aggregate/micelle like structure.

Decreases in Surface Activities and Aquatic Toxicities of Linear Alkylbenzene Sulfonate and Alcohol Ethoxylates during Biodegradation

We discussed the relation between aquatic toxicity and interfacial activity during biodegradation with using LAS (Linear Alkylbenzene Sulphonate) and AE (Alcohol Ethoxylate). The change of death rate of Daphnia magna, surface tension, concentration of surfactant, and biodegradation by oxygen demand during biodegradation were measured. As a result, a rapid decrease in toxicity and rapid increase in surface tension were observed within the time before biodegradation based on oxygen demand started to increase. These rapid changes in toxicity and surface tension occurred due to the structural change of surfactant molecules in the primary biodegradation process, which was confirmed by HPLC (High Performance Liquid Chromatography) analysis. We also performed re-addition test to study the effects of acclimatization since it takes an important role on boidegradation, and found that the acclimatization significantly accelerated the primary biodegradation, which were indicated by increase in surface tension and decrease in aquatic toxicity. These results show that the environmental risk of surfactants should be considered not only with the biodegradation based on oxygen demand but also with the decrease of interfacial activity through the primary biodegradation process.

Molecular geochemical indicators of sewage input in the Antarctic coastal area (Admiralty Bay, King George Island, Antarctica)

Antarctica has been described as a pristine environment for many years. However, human presence has resulted in fossil fuel combustion, vehicular emissions, fuel spills in the marine and terrestrial environments and sewage waste discharged into the ocean. Currently, most Antarctic research stations (around 79 scientific centres) are located in coastal areas, and they release their untreated sewage containing domestic waste directly into the marine environment. A group of molecular tracers such as steroids and linear alkylbenzenes (LABs) have been successfully used to investigate domestic waste discharges and faecal contamination in different regions, including Admiralty Bay, Antarctica (Martins et al., 2002; 2005). Coprostanol (5β-cholestan3β-ol) and coprostanone (5β-cholestan-3-one) have been widely used as faecal contamination markers because they are present in human faeces (Figure 1). Additionally, epicoprostanol (5β-cholestan-3β-ol) indicates the level of treatment of the faecal matter as it is formed during the extensive anaerobic sewage treatment of wastewaters (Figure 1). Also, LABs are present at levels from 1 to 3% in surfactants and detergents with linear alkylbenzene sulphonates (LASs) due to incomplete sulfonation (Figure 2), and they are frequently discharged via sewage outfalls together with faecal matter. These compounds are usually preserved in the sediment, and can be used as molecular tracers of domestic wastes. The monitoring of environmental conditions, such as hydrocarbon levels (Martins et al., 2004; 2010) and PCBs, near the sewage discharge from the Comandante Ferraz Brazilian Research Station, located at Martel Inlet, Admiralty Bay, King George Island, has been carried out since the austral summer of 1996/97. The aim of this study is to evaluate the sewage contribution from Ferraz station to Admiralty Bay and to compare the historical trend reported in previous studies. This evaluation is based on the results of molecular geochemical indicators such as steroids and LABs from the upper layer of sediments sampled during the austral summers of 2009/10. In Antarctica, monitoring the extent of sewage pollution dispersal is essential as Antarctic Treaty signatory nations must conform to the Protocol on Environmental Protection. Admiralty Bay is the largest around King George Island. The bay area is an Antarctic Specially Managed Area (ASMA), and the Scientific Committee on Antarctic Research (SCAR) has recommended environmental studies on present-day conditions of the region. Most sampling sites were located near Ferraz station. This medium size station was established in the summer of 1984, and usually has a population of approximately 50 people during the summer. The sewage system receives intermediate primary and secondary treatment before being discharged through a short pipe (Figure 3) near the sea. The sewage treatment system has been in operation since the austral summer of 1995/96 and was designed to serve a population of 50. For analyses of steroids, sediments are extracted using a Soxhlet system for 8 hours with 70 mL of ethanol. The concentrated extract is submitted to a clean up with column chromatography with deactivated alumina and elution with 15 mL of ethanol. The extract is evaporated till completely dry and derivatized to form trimethylsilyl ethers 4

Influence of Linear Alkyl Benzene Sulphonate on Corrosion of Iron in Presence of Magnetic Field: Kinetic and Thermodynamic Parameters

Implementation of linear alkyl benzene sulphonate, LAS, as corrosion inhibitor on the surface of iron metal in acidic media and in the absence and presence of magnetic field has been investigated. Adsorption of inhibitor molecules on iron surface showed Langmuir adsorption isotherms fit in acidic media. In the absence of magnetic field, apparent activation energy values (Ea) in 2.0 M HCl solutions provide evidence of the inhibitory effect of LAS on iron; similarly, the enthalpy of activation values (ΔH≠) was in accordance with activation energy values. Apparent entropy of activation shows that at larger inhibitor concentration, solvent entropy decrease in 1.0 M HCl and solvent entropy increase in 2.0 M HCl were obtained. Furthermore, spontaneity, through equilibrium constant (Kads.) values and free energy value (ΔGads.) of the adsorption process, shows a drastic decrease upon temperature increase. In the presence of magnetic field, lower rates of corrosion, larger activation energies, solvent entropy increase, larger equilibrium constant (Kads.) value, and lower free energy value (ΔGads.) have been investigated.

The use of marine benthic diatoms in a growth inhibition test with spiked whole-sediment

The benthic diatom Cylindrotheca closterium was exposed to whole-sediment spiked with the synthetic surfactant Linear Alkylbenzene Sulphonate (LAS), as commercial mixture or individual homologues (C10-LAS, C11-LAS or C12-LAS). Separately, the diatoms were exposed to C12-LAS in a water-only system. The algal growth was determined after 72 h. The 72-h ErC50 values ranged from ≤4 to 29 mg/kg sediment, suggesting that C. closterium was sensitive to LAS. The outcomes were reproducible with a variation factor lower than 3, showing the reproducibility of the method. The test set up was cost effective, used little bench space and employed a micro-phytobenthos species that fulfilled most of the criteria for a suitable test species in sediment systems. The 72-h ErC50 obtained in a water-only system (0.141 mg/L) was ca. 2 orders of magnitude lower (0.002 mg/L). This was likely due to an indirect effect of the use of fresh sediment.

Lethal toxicity of industrial detergent on bottom dwelling sentinels

Abstract We used fresh and brackish water shrimp ( Desmoscaris trispinosa and Palaemonetes africanus), in sediment bioassays to assess the toxicity of an industrial detergent containing high levels of anionic surfactant (linear alkylbenzene sulphonate (LAS)). The Organization for Economic Cooperation and Development (OECD), # 218 direct sediment toxicity assessment was employed. The organisms were exposed to different concentrations (31.25, 62.5, 125, 250 and 500 mg/kg) of the chemical (Neatex) in replicate treatments. Percentage mortality was measured as the ecological endpoint. Mean mortality and estimated lethal concentration LC 50 values varied with species type, concentration and exposure duration. The statistical variation in the observed mean mortality of the test organisms in the chemical and the control treatment shows that mortality may be induced by the effect of the chemicals. The lethal concentration ( LC 50 s) was significantly different at levels of p < 0.05 for the fresh and brackish water experiments. Consequently, assessment of water and sediment quality as a result of chemical pollutants was necessary for protecting some of the more sensitive benthic invertebrates representing the major proportion of the diet of many species in the Niger Delta ecological zone.

Automated Determination of Linear Alkylbenzene Sulphonate (LAS) in Wastewater Treatment Plants Effluents Using on Line Solid-phase Extraction Followed by HPLC with Fluorescence Detection

Abstract An on line SPE (solid-phase extraction) method followed by HPLC with fluorescence detection has been developed and validated for determining the LAS in inlet and outlet effluents of wastewaters treatment plants. Filtered effluent samples were on line concentrated on a small polymeric reversed phase column, then the trapped LAS are separated on a specialty polar-embedded reversed-phase column and detected by a fluorimeter. The on line SPE method with fluorescence detection showed very good repeatability (from 1.5 to 11.7% depending on the sample loading volume) and robustness with detection limits of 1.5 μg l−1 for total C10–13 LAS loading a 5 ml sample volume. This automated method is a cost-effective way to determine LAS also in routine monitoring of inlets and outlets of wastewater treatment plants allowing to optimize treatment procedures.

Organic contaminants in sewage sludge (biosolids) and their significance for agricultural recycling

Organic chemicals discharged in urban wastewater from industrial and domestic sources, or those entering through atmospheric deposition onto paved areas via surface run-off, are predominantly lipophilic in nature and therefore become concentrated in sewage sludge, with potential implications for the agricultural use of sludge as a soil improver. Biodegradation occurs to varying degrees during wastewater and sludge treatment processes. However, residues will probably still be present in the resulting sludge and can vary from trace values of several micrograms per kilogram up to approximately 1 per cent in the dry solids for certain bulk chemicals, such as linear alkylbenzene sulphonate, which is widely used as a surfactant in detergent formulations. However, the review of the scientific literature on the potential environmental and health impacts of organic contaminants (OCs) in sludge indicates that the presence of a compound in sludge, or of seemingly large amounts of certain compounds used in bulk volumes domestically and by industry, does not necessarily constitute a hazard when the material is recycled to farmland. Furthermore, the chemical quality of sludge is continually improving and concentrations of potentially harmful and persistent organic compounds have declined to background values. Thus, recycling sewage sludge on farmland is not constrained by concentrations of OCs found in contemporary sewage sludges. A number of issues, while unlikely to be significant for agricultural utilization, require further investigation and include: (i) the impacts of chlorinated paraffins on the food chain and human health, (ii) the risk assessment of the plasticizer di(2-ethylhexyl)phthalate, a bulk chemical present in large amounts in sludge, (iii) the microbiological risk assessment of antibiotic-resistant micro-organisms in sewage sludge and sludge-amended agricultural soil, and (iv) the potential significance of personal-care products (e.g. triclosan), pharmaceuticals and endocrine-disrupting compounds in sludge on soil quality and human health.

Data requirements of GREAT-ER: Modelling and validation using LAS in four UK catchments

Higher-tier environmental risk assessments on “down-the-drain” chemicals in river networks can be conducted using models such as GREAT-ER (Geography-referenced Regional Exposure Assessment Tool for European Rivers). It is important these models are evaluated and their sensitivities to input variables understood. This study had two primary objectives: evaluate GREAT-ER model performance, comparing simulated modelled predictions for LAS (linear alkylbenzene sulphonate) with measured concentrations, for four rivers in the UK, and investigate model sensitivity to input variables. We demonstrate that the GREAT-ER model is very sensitive to variability in river discharges. However it is insensitive to the form of distributions used to describe chemical usage and removal rate in sewage treatment plants (STPs). It is concluded that more effort should be directed towards improving empirical estimates of effluent load and reducing uncertainty associated with usage and removal rates in STPs. Simulations could be improved by incorporating the effect of river depth on dissipation rates.

Effect of laundry activities on in-stream concentrations of linear alkylbenzene sulfonate in a small rural South African river

In many parts of the world clothes are washed near to or in rivers and streams. Little information is available on resulting concentrations of detergent ingredients or on any potential effects caused. In this study, the fate of a commonly used anionic surfactant, linear alkylbenzene sulphonate (LAS) was investigated in a reach of the Balfour River (Eastern Cape Province, South Africa) which was regularly used as a site for laundry activity. Samples of river water were collected upstream of the main washing site and at a number of locations downstream on several occasions in winter and summer. Sediment samples were also collected and analysed. In addition, a household survey was conducted to ascertain the amount of detergent used and the distribution of washing practices. The results of the survey suggested that the use of riverside locations for laundry activities was seasonal. Most washing tended to be done at home during the winter with riverside sites used more frequently during the summer months. The monitoring data showed that LAS concentrations in water were very variable. They were occasionally high in the immediate vicinity of the laundry site (up to 342 µg L − 1 ) but were generally very low (< 11 µg L − 1 ) at downstream monitoring stations, suggesting that LAS was rapidly dissipated by a combination of degradation, hydrodynamic dispersion and dilution. Concentrations in the immediate vicinity of the washing site were lower than expected on the basis of the household survey because most waste water was disposed of on the river bank rather than directly in the river. No ecological effects are expected from LAS emissions at this site.

Metals and linear alkylbenzene sulphonate as inhibitors of the algae Pseudokirchneriella subcapitata acid phosphatase activity

Sewage sludge applied to soils as a fertilizer often contains metals and linear alkylbenzene sulphonate (LAS) as contaminants. These pollutants can be transported to the aquatic environment where they can alter the phosphatase activity in living organisms. The acid phosphatase of algae plays important roles in metabolism such as decomposing organic phosphate into free phosphate and autophagic digestive processes. The order of in vitro inhibition of Pseudokirchneriella subcapitata acid phosphatase at the highest concentration tested was LAS > Hg2+ = Al3+ > Se4+ = Pb2+ > Cd2+. A non-competitive inhibition mechanism was obtained for Hg2+ (Ki = 0.040 mM) and a competitive inhibition for LAS (Ki = 0.007 mM). In vivo studies with treated algae cultures showed that the inhibition of specific activity was observed in algae exposed during 7 days, in contrast to short term (24 h) treatments with both these chemicals. Our results suggest that the inhibition parameters in vitro did not markedly differ between the two chemicals. On the other hand, in vivo evaluations showed strong differences between both pollutants regarding the concentration values and the degree of response.

Presence of organic pollutants in sludge from anaerobic wastewater stabilization ponds

One of the most common disposal options of sewage sludge is its application to agricultural lands. During wastewater treatments, pollutants tend to be concentrated into sludge so it is important to evaluate the concentration of those pollutants to avoid negative effects to the environment. To control the quality of the sludge that is going to be applied to soil, the European Union (EU) published in 2000 the third draft of a future sludge Directive entitled “Working Document on Sludge” where concentration limit values for some organic compounds (AOX, DEHP, LAS, NPE, PAH, PCB and PCDD/F) are fixed. The implementation of the future Directive could imply the application of post-treatment processes to sludge to reduce the concentration levels of the organic pollutants to levels that enable safe application of sewage sludge as soil fertilizer. Several authors have reported concentration levels of the above cited pollutants in anaerobic and aerobic treatment plants. However, there is no much information about concentration levels in lagoon sludge from anaerobic wastewater stabilization ponds which are the most common wastewater treatments applied in small communities with equivalent inhabitants in the range up to 10,000. In the present work, concentration levels of several of the organic compounds included in the EU directive draft have been measured in sewage sludge samples from three wastewater stabilization ponds operating in small communities located in the south of Spain. Organic compounds measured were di- (2-ethylhexyl)phthalate (DEHP), sum of nonylphenol and nonylphenol ethoxylates with 1 and 2 ethoxy groups (NPEs), linear alkylbenzene sulphonates (LAS), sum of nine polycyclic aromatic hydrocarbons (PAHs) and sum of seven polychlorinated byphenyls (PCBs). Sludge applicability to soil, in relation with the limit values fixed in the EU sludge directive draft, has been evaluated. The highest concentration levels were found for LAS (mean value 5373 mg/kg dry matter), NPE (mean value 177.1 mg/kg dry matter) and DEHP (mean value 72.3 mg/kg dry matter), in this order. PAHs were detected at lower concentration levels (concentrations lower than 0.80 mg/kg dry matter) whereas no PCB was detected in the analyzed samples.

Optimization of the solution parameters during the degradation of Orange II in a photo-reactor mediated by Fe-Nafion membranes

The Fenton and photo-Fenton mediated degradation process of Orange II was investigated in a flow photo-reactor. The degradation was monitored as a function of the wavelength of the applied light, recirculation flow rate, amount of H(2)O(2) and the initial concentration of Orange II. Optimization of the photo-Fenton degradation mediated by Fe-Nafion membranes indicated that an Orange II (0.25 M) solution discolored above 95% within 2.5 hours at an H(2)O(2)/Orange II ratio of 20. A concomitant mineralization of 40% of Orange II was observed after 5 h reaction. Homogeneous photo-Fenton processes were able to fully discolore Orange II within 1 hour and concomitantly fully mineralize the dye in the presence of Fe(III) (2 ppm) and an H(2)O(2)/Orange II ratio of 20. Surfactants such as linear alkylbenzene sulphonates (LAS) and K-perfluoroalkyl sulphonate (FT 800) slowed down the Orange II abatement in photo-Fenton processes.

Biodegradation of synthetic detergents in wastewater

A total of 76 wastewater samples were randomly collected from pharmaceutical, textile, and detergentmanufacturing industries as well as the Agbara Sewage Treatment Plant (STP). Thirty-eight samples each in 2-L plastic containers were collected for morning and evening effluent used for this study. Composite samples were later developed and the physico-chemical properties of these samples determined. The physico-chemical properties of the composite wastewater influenced the selected microbial population adapted to utilization of detergent components. The optimum temperature range of the composite wastewater was 33.9 – 34.3oC while the mean optimum pH ranged from 6.9 – 8.8 for the laboratory simulated biodegradation of test detergents. Although, the fungal consortium was eliminated as the medium approached the alkaline pH, this is as a result of the metabolites produced. The macroelements, the BOD and the hydrocarbon concentration of the composite effluent were above the EU and FEPA limits for discharged effluent. The composite effluent was thereafter spiked with test detergents (Elephant, Omo, Klin, Ariel Persil, Teepol, and SDS) at 0.01% (w/v) and its progressive degradation monitored for 30 days. The microbial detergent-degraders population changed between Day 0 and 15, thereafter it stabilized. The heterotrophic bacterial count from the seventy-six randomly collected effluent samples was 42.9 x 106 cfu/ml, while the mean bacterial detergent-degrader population was 20.94 x 106 cfu/ml. The mean fungal population from the randomly collected effluent sample was 4.5 x 106 cfu/ml. The bacterial detergent-degraders characterized and identified include Pseudomonas aeruginosa, Escherichia coli, Enterococcus majodoratus, Klebsiella liquefasciens, Enterobacter liquefasciens, Klebsiella aerogenes, Enterobacter agglomerans, Staphylococcus albus, Proteus sp., Klebsiella oxytoca and Brevibacterium sp., while the fungal detergent-degrader included; Myceliophthora thermophila, Geomyces sp., Alternaria alternata, Fusarium sp., Aspergillus flavus and Asperigillus oryzae. The primary biodegradability of synthetic detergent was confirmed by the Methylene Blue–Active Substance (MBAS) method. Gas chromatography (GC) provided the convincing evidence of synthetic detergent mineralization within the 30 day period in a sewage treatment plant. The detection of unusual peaks in the GC profiles provided the scientific evidence of inclusion of certain hydrocarbons in detergent formulation outside that of industry specifications. The unusual peaks are attributable to inclusion of certain chemical optical brighteners (C17–C24). Linear alkyl benzene sulphonates (LAS) which is the principal synthetic detergent component are thus biodegradable and its use in detergent formulation is environment - friendly.

Limitation of the concentration of organic pollutants in sewage sludge for agricultural purposes: A case study in South Spain

In 2000, the EU published the third draft of a future sludge directive entitled "Working document on sludge" where limit values for some organic compounds, including di-(2-ethyhexyl)phthalate (DEHP), sum of nonylphenol (NP), nonyphenol mono-(NP1EO) and diethoxylates (NP2EO), seven polychlorinated biphenyl congeners (PCB), polycyclic aromatic hydrocarbons (PAH) and linear alkylbenzene sulphonates (LAS), are fixed. In the present work, the monitoring of these organic compounds in sludge samples from four wastewater treatment plants (WWTPs) is reported. All WWTPs use anaerobic biological stabilization of sludge. The highest concentration levels were found for LAS, NPE and DEHP, in this order, with, in general, anaerobically-digested dehydrated sludge and compost samples being the most contaminated samples. DEHP, NPE, LAS and PAH were found at concentration levels above the limit values fixed in the third draft of the future EU sludge directive in the 44%, 88%, 13% and 6% of the analyzed anaerobically-digested dehydrated sludge and compost samples.

Partitioning of hydrophobic pesticides within a soil–water–anionic surfactant system

Surfactants can be added to pesticide-contaminated soils to enhance the treatment efficiency of soil washing. Our results showed that pesticide (atrazine and diuron) partitioning and desorbability within a soil–water–anionic surfactant system is soil particle-size dependent and is significantly influenced by the presence of anionic surfactant. Anionic surfactant (linear alkylbenzene sulphonate, LAS) sorption was influenced by its complexation with both the soluble and exchangeable divalent cations in soils (e.g. Ca 2+, Mg 2+). In this study, we propose a new concept: soil system hardness which defines the total amount of soluble and exchangeable divalent cations associated with a soil. Our results showed that anionic surfactant works better with soils having lower soil system hardness. It was also found that the hydrophobic organic compounds (HOCs) sorbed onto the LAS-divalent cation precipitate, resulting in a significant decrease in the aqueous concentration of HOC. Our results showed that the effect of exchangeable cations and sorption of HOC onto the surfactant precipitates needs to be considered to accurately predict HOC behavior within soil–water–anionic surfactant systems.

Suitability of the marine prosobranch snail H ydrobia ulvae for sediment toxicity assessment: A case study with the anionic surfactant linear alkylbenzene sulphonate (LAS)

Individuals of the mudsnail Hydrobia ulvae (Pennant) (Mollusca: Prosobranchia) were exposed to sediments spiked with increasing concentrations (1.59–123.13 mg kg −1 dry weight) of the anionic surfactant linear alkylbenzene sulphonate (LAS) which is employed in the formulation of laundry powders and liquids, as well as hand dishwashing products. The suitability of the selected organism, H. ulvae for routine sediment toxicity testing was evaluated by measuring acute toxicity recording survival. Sublethal toxicity was evaluated as total number of produced veliger larvae per treatment throughout the test (9 d). Mortality has shown to be a reliable and reproducible indicator of acute toxicity. LC 50 values were comprised between 203.4 (48 h) and 94.3 mg kg −1 (9 d) dry weight. As sublethal endpoint, the total number of produced larvae showed to be a useful indicator of toxicity for this organism. The number of produced larvae increased at lower exposure concentrations, whereas at the highest LAS concentration, the number of produced larvae decreased. This is the first report of acute and sublethal toxicity of sediment associated LAS for this species.

Response of soil enzymes to Linear Alkylbenzene Sulfonate (LAS) addition in soil microcosms

Soil enzymatic activities (phosphatases, arylsulphatase and dehydrogenase) were measured in microcosm systems designed for the study of the impact of a commercial mixture of Linear Alkylbenzene Sulphonate (LAS) homologues on a xerofluvent agricultural soil. The soil microcosms consisted of glass columns filled with 800 g of dry soil which were fed with sterile commercial LAS solutions at concentrations of 10 or 50 mg l −1 for periods of time up to 21 days. A soil microcosm fed with sterile distilled water was included in this study and considered as control. Our results showed that the continuous application of the anionic surfactant to soil increased the values of the enzymes acid and alkaline phosphatases and arylsulphatase. On the contrary, the dehydrogenase activity was decreased by the continuous application of 10 or 50 mg l −1 LAS when compared with control microcosms. In addition, a statistically negative correlation was found between this enzymatic activity in the upper portion of the soil columns amended with LAS and the viable counts of heterotrophic aerobic microorganisms. Moreover, in order to test the influence of LAS on nutrient availability and, consequently, on bacteria populations and soil biological activities, phosphate concentration was regularly determined in the microcosm leachates. The phosphate concentration tested in the leachate of the microcosm continuously amended with 50 mg l −1 LAS solution was significantly lower than the concentrations detected in the leachate of the microcosms continuously amended with 10 mg l −1 LAS throughout the experiment.

Relevant approach to assess performances of wastewater biosolids composting in terms of micropollutants removal

The presence of organic pollutants in wastewater biosolids and their possible impact to the environment contribute to decrease interest for the agricultural spreading of biosolids. It is thus important to have a better overview of sewage sludge quality in terms of organic pollutant content and ecotoxicity assessment. It is also necessary to better understand the impact of biosolid composting processes on the pollutant and toxicity removal. Therefore, concentrations of oestrogens (E), nonyphenol ethoxylates (NPE), polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and linear alkyl benzene sulphonates (LAS) and some of their associated toxic effects were determined at different stages of a composting process using, respectively, chemical analysis and in vitro bioassays (estrogen receptor alpha, dioxin receptor and pregnan X receptor reporter cell lines). Pollutants concentrations were higher in the final compost than in biosolid due to dry matter reduction through composting. Mass balance calculation shows a positive impact of the aerobic treatment on the removal of the most degradable pollutants. The three toxicological activities were measured in both biosolids and in the initial and final compost: oestrogenic activity increased whereas dioxin-like and pregnan X activities decreased. The difficulty in correlating chemical and toxicological results underlines the importance of combining both approaches in order to improve the assessment of the compost quality.