Alkylbenzene Sulphonate Research Articles

An in vitro analysis of the rat C6 glioma cells to elucidate the linear alkylbenzene sulfonate induced oxidative stress and consequent G2/M phase cell cycle arrest and cellular apoptosis

Linear alkylbenzene Sulphonate (LAS) is the anionic surfactant component of globally consumed detergents. Exposure of sub-inhibitory fractions viz., 1/10th (T1), 1/5th (T2), and 1/2.5th (T3) of IC50 for 48 h, of LAS (5 μM, 10 μM, and 20 μM, respectively) to viable C6 glioma cells of rat, besides imparting morphological alterations leads to gross cytotoxicity. Expression of the damaged DNA coupled with cleaved PARP (p < 0.05; p < 0.01 and p < 0.001) were recorded for T1, T2 and T3, respectively. Subsequently, the cell cycle at G2/M check point was significantly arrested (p < 0.05 for T1 and T2; p < 0.01 for T3). The flow cytometric analysis reveals the initiation of apoptosis in C6 cells as is evident by a significant increase (p < 0.01 for T1, p < 0.001 for T2, and T3) in the intake of annexin-V, the calcium dependent apoptotic phospholipid binding protein. Moreover, significantly increased reactive oxygen species (ROS) (p < 0.05; p < 0.01 and p < 0.001) after 6 h of exposure for all the three sets, registered a declining trend (P < 0.001) when T3 cells were co-treated with N-acetyl cysteine (NAC). Furthermore, the significant attenuation (p < 0.01) of expression of the cleaved PARP and a consequent decrease (p < 0.05) in the cell cycle arrest at G2/M phase after scavenging ROS induced oxidative stress by treating C6 cells with NAC clearly evinces that LAS induced apoptosis is mediated by intracellular ROS. Thus, these findings provide a tangible basis for further investigations including in vivo studies, to unravel the molecular mechanism involved in ROS mediated and LAS induced cytotoxic manifestations.

Effect of detergent surfactant on some selected electrolytes and metabolites of juvenile Heterobranchus bidorsalis

The study examined the effect of sub-lethal level of Linear Alkylbenzene Sulphonates (LAS) on some selected electrolyte and metabolic indices of juvenile Heterobranchus bidorsalis. The fish were exposed to varying concentrations of LAS (0.00 mg/L, 0.01 mg/L, 0.02 mg/L and 0.03 mg/L, respectively) in a semi-static tank for 14 days. The chemical test analysis of LAS showed that only total suspended solid (196.8 mg/L), total alkalinity (56.1 mg/L) and nitrate (7.9 mg/L) exceeded Federal Environmental Protection Agency (FEPA) and Standard Organization of Nigeria (SON) permissible limits. Conductivity and dissolved oxygen (DO) of the water parameter differ significantly (p &lt; 0.05) from the control and among dose concentration. Electrolyte values (K+ and Ca2+) were not significantly (p &gt; 0.05) different at all level of LAS concentration. However, there were significant (p &lt; 0.05) differences in Na+ concentration. The highest value for Na+ (16.00 + 1.16 Mmol/L) was obtained at 0.02 mg/L, while the least (5.35 + 0.45 Mmol/L) was recorded in the control at 0.00 mg/L. There was significant (p &lt; 0.05) differences in values of urea in the experimental group, except between 0.01mg/L (1.53 + 0.05 mg/dm) and 0.02 mg/L (1.60 + 0.06 mg/dm). On the contrary, there were significant (p &lt; 0.05) differences in all the values of creatinine recorded in this study. The values increased down the experimental group in a dose dependent pattern. The highest value of creatinine (54.45 + 4.96 mg/dm) was recorded at 0.03 mg/L dose concentration while the least (30.47 + 7.65 mg/dm) was obtained in the control (0.00 mg/L). The present study concluded that LAS has impact on the metabolites and electrolytes especially creatinine and the Na+. Therefore, LAS could be very toxic at high concentrations and as such, indiscriminate discharge of LAS effluent into aquatic environment should be averted.

A global framework to model spatial ecosystems exposure to home and personal care chemicals in Asia

This paper analyzes spatially ecosystem exposure to home and personal care (HPC) chemicals, accounting for market data and environmental processes in hydrological water networks, including multi-media fate and transport. We present a global modeling framework built on ScenAT (spatial scenarios of emission), SimpleTreat (sludge treatment plants), and Pangea (spatial multi-scale multimedia fate and transport of chemicals), that we apply across Asia to four chemicals selected to cover a variety of applications, volumes of production and emission, and physico-chemical and environmental fate properties: the anionic surfactant linear alkylbenzene sulphonate (LAS), the antimicrobial triclosan (TCS), the personal care preservative methyl paraben (MeP), and the emollient decamethylcyclopentasiloxane (D5). We present maps of predicted environmental concentrations (PECs) and compare them with monitored values. LAS emission levels and PECs are two to three orders of magnitude greater than for other substances, yet the literature about monitored levels of LAS in Asia is very limited. We observe a good agreement for TCS in freshwater (Pearson r=0.82, for 253 monitored values covering 12 streams), a moderate agreement in general, and a significant model underestimation for MeP in sediments. While most differences could be explained by uncertainty in both chemical/hydrological parameters (DT50water, DT50sediments, Koc, foc, TSS) and monitoring sites (e.g. spatial/temporal design), the underestimation of MeP concentrations in sediments may involve potential natural sources. We illustrate the relevance of local evaluations for short-lived substances in fresh water (LAS, MeP), and their inadequacy for substances with longer half-lives (TCS, D5). This framework constitutes a milestone towards higher tier exposure modeling approaches for identifying areas of higher chemical concentration, and linking large-scale fate modeling with (sub) catchment-scale ecological scenarios; a major limitation in model accuracy comes from the discrepancy between streams routed on a gridded, 0.5°×0.5° global hydrological network and actual locations of streams and monitoring sites.

Application of a spatially resolved model to contextualise monitoring data for risk assessment of down-the-drain chemicals over large scales

Many regulatory screening level exposure assessments are based on simple large scale conceptual scenarios. However, exposure, and therefore risks associated with chemicals, are characterised by high spatial variability. The Scenario assembly tool (ScenAT) is a global screening level model to enable spatially resolved local predictions of environmental concentrations of home and personal care chemicals. It uses the European Union Technical Guidance Document (TGD) equation to predict local scale freshwater concentrations (predicted environmental concentrations - PECs) of chemicals discharged via wastewater. ScenAT uses Geographic Information System (GIS) layers for the underlying socio-economic (population) and environmental parameters (per capita water use, sewage treatment plant connectivity, dilution factor). Using a probabilistic approach, we incorporate sources of uncertainty in the input data (tonnage estimation, removal in sewage treatment plants and seasonal variability in dilution factors) for two case-study chemicals: the antimicrobial triclosan (TCS) and the anionic surfactant linear alkylbenzene sulphonate (LAS). We then compare model estimates of wastewater and freshwater concentrations of TCS and LAS to UK monitoring data. Comparison showed that modeled PECs were on average higher than mean measured data for TCS and LAS by a factor 1.8 and 1.4, respectively. Considering the uncertainty associated with both model and monitoring data, the use of a probabilistic approach using the ScenAT model for screening assessment is reasonable. The combination of modelled and monitoring data enables the contextualisation of monitoring data. Spatial PECs can be used to identify areas of elevated concentration for further refined assessment.

Anionic Surfactant, Linear Alkyl Benzene Sulphonate Induced Oxidative Stress and Hepatic Impairments in Fish Channa punctatus

Linear alkyl benzene sulphonate (LAS), one of the main ingredients used in synthetic detergents to enhance their cleansing properties. Indiscriminate and untreated discharge of detergents and their residues in both lantic and lotic habitats pose a variety of ecological threats and also adversely affect aquatic fauna. In vivo, LAS metabolism and biotransformation occurs via monooxygenases in liver, leading to Reactive Oxygen Species, ROS, production and consequently oxidative stress by disturbing cellular antioxidant enzymatic equilibrium. Present study aims to evaluate the activities of two widely distributed antioxidant enzymes viz., catalase (CAT) and superoxide dismutase (SOD) and ROS induced histological impairments in liver of freshwater fish, Channa punctatus. For the estimation of oxidative stress and hepatic impairments, well acclimatized fishes were divided in three groups. Fish of group G1 serves as control whereas fish of the other two groups, G2 and G3 were exposed to two fractions, 1/20th and 1/10th of 96 h LC50 of LAS for 24, 48, 72 and 96 h of exposure periods. Our results showed a significant induction in CAT and SOD activities in liver tissue of C. punctatus in a dose and time dependent manner. ROS induced histopathological impairments in hepatic tissues are characterized by loosely arranged, irregularly distributed and degenerated hepatocytes with increased vacuolization and pyknotic nuclei. The results are quite suggestive that LAS intoxication generates oxidative stress by ROS production which brings about histopathological impairments in exposed fish.

Linear alkylbenzene sulfonate (LAS) removal in constructed wetlands: The role of plants in the treatment of a typical pharmaceutical and personal care product

Linear alkylbenzene sulphonate (LAS) is a major anionic surfactant used in detergents worldwide and as such is a ubiquitous constituent of domestic and municipal wastewaters. Increasingly, constructed wetlands are being employed as a low cost and sustainable alternative to traditional wastewater treatment processes. Plants are known to play a vital role both directly and indirectly in the removal of contaminants in wastewater treatment constructed wetlands. However, relatively little research has been conducted into the manipulation of the plant component in order to optimise constructed wetland performance. Furthermore, little is known about the role of plants in the removal of specific contaminants including LAS. The present study investigated the effects of plant biomass and plant species on LAS removal in a series of experimental subsurface flow wetlands. Our results confirm that the presence of vegetation enhances LAS removal, with higher biomass systems associated with higher LAS removal rates. Differences in LAS removal were also observed between different plant species, although these were not found to be statistically significant.

Removal efficiency of anionic surfactants from water during UVC photolysis and advanced oxidation process in H2O2/UVC system

AbstractSurfactants after their use are discharged into aquatic ecosystems. These compounds may be harmful to fauna and flora in surface waters or can be toxic for microorganisms of the activated sludge or biofilm in WWTP. In order to determine effectiveness of different advanced oxidation processes on the degradation of surfactants, in this study the degradation of anionic surfactants in aqueous solution using photolysis by 254 nm irradiation and by advanced oxidation process in a H2O2/UVC system was investigated. Two representatives of anionic surfactants, linear alkyl benzene sulphonate (LAS-R11–14) and ether carboxylic derivate (EC-R12–14E10) were tested. The influence of pH, initial surfactant concentration and dose of hydrogen peroxide on the degradation was also studied. Results show outstanding effectiveness of the H2O2/UVC system in the removal of surfactant from aqueous solutions.

Performance of Palm-Based C16/18 Methyl Ester Sulphonate (MES) in Liquid Detergent Formulation.

Liquid detergents are more convenient than powdered detergents as they dissolve readily in water, generate less dust and dosing is easy. However, the stability of liquid detergents is an issue of concern. Therefore, the objective of this research is to study the formulation requirement to produce heavy-duty liquid detergents based on palm-based methyl esters sulphonate (MES) with desirable properties and performance. MES is produced from renewable and sustainable feedstock suitable to replace the conventional fossil-based surfactant, linear alkyl benzene sulphonates (LAS). Five palm-based liquid detergents (PBLDs) were formulated using C16/18 MES as the primary surfactant. The physical properties, washing performance, stability and biodegradability of PBLDs were evaluated. Performance of the PBLDs was evaluated against two commercial liquid detergents which use LAS and alcohol glucoside as surfactant (benchmark product) and it was found that the PBLDs exhibited excellent performance. PBLDs can be formulated with or without phosphates and still demonstrate good detergency. The stability study of PBLDs indicated that no appreciable hydrolysis occurred. PBLDs exhibited better biodegradability profiles compared to commercial detergent containing LAS. PBLDs passed the 60% biodegradability level within 3 to 8 d, while commercial detergent took 24 d. It was shown that palm-based C16/18 MES could be potentially formulated into liquid detergents and gave better performance than LAS based liquid detergent. Attributes of C16/18 MES should not be overlooked, which include an abundant and naturally derived palm stearin as raw material and environmental safety profiles that are superior to most synthetic surfactants.

Detection and quantification of anionic detergent (lissapol) in milk using attenuated total reflectance-Fourier Transform Infrared spectroscopy.

Adulteration of milk to gain economic benefit is rampant. Addition of detergent in milk can cause food poisoning and other complications. Fourier Transform Infrared spectroscopy was evaluated as rapid method for detection and quantification of anionic detergent (lissapol) in milk. Spectra of pure and artificially adulterated milk (0.2-2.0% detergent) samples revealed clear differences in wavenumber range of 4000-500cm-1. The apparent variations observed in region of 1600-995 and 3040-2851cm-1 corresponds to absorption frequencies of common constituents of detergent (linear alkyl benzene sulphonate). Principal component analysis showed discrete clustering of samples based on level of detergent (p⩽0.05) in milk. The classification efficiency for test samples were recorded to be >93% using Soft Independent Modelling of Class Analogy approach. Maximum coefficient of determination for prediction of detergent was 0.94 for calibration and 0.93 for validation, using partial least square regression in wavenumber combination of 1086-1056, 1343-1333, 1507-1456, 3040-2851cm-1.

The effect of calcium on the foam behaviour of aqueous sodium alkyl benzene sulphonate solutions. 4. The role of particles in triglyceride-based antifoam mixtures

Mixtures of triolein with stearic acid were significantly less effective as antifoams than mixtures with tristearin. Measurements of contact angles at oil-water and air-water surfaces combined with consideration of crystal morphology have permitted exploration of the possibility that these differences concern the relative effectiveness of particles in rupturing triolein-water-air pseudoemulsion films. No significant difference in the theoretical effectiveness of tristearin and stearic acid in their potential to rupture pseudoemulsion films is however apparent. This suggests that the earlier finding that relative antifoam effectiveness rather concerned particle size and aggregation where stearic acid particles were, for example, more than an order of magnitude larger than the tristearin particles, implying lower probabilities of presence in drops and films.

The effect of calcium on the foam behaviour of aqueous sodium alkyl benzene sulphonate solutions. 3. The role of the oil in triglyceride-based antifoams

A feature of mixtures of triolein with either stearic acid or tristearin particles as antifoams for certain micellar solutions of sodium dodecyl benzene sulphonate is that they are effective only during foam generation but no longer function after foam generation has ceased. Antifoam action by the antifoam oil is determined by positive values of the bridging coefficient. Bridging coefficients were found to be negative under the near equilibrium conditions prevailing after foam generation ceased. However measurements of dynamic surface tensions indicated that if surface ages >0.1s prevailed under the dynamic conditions of foam generation then that would alter the sign of the bridging coefficients. Such dynamic conditions were replicated by drawing single foam films at different rates from solutions containing triolein-based antifoam. Antifoam effectiveness was significantly reduced in the case of foam films drawn at extremely slow rates so that near equilibrium conditions prevailed.

The effect of calcium on the foam behaviour of aqueous sodium alkyl benzene sulphonate solutions. 2. In the Presence of triglyceride-based antifoam mixtures

Here we have sought to establish the likely key ingredients which determine the antifoam behaviour of model sebum together with key specific aspects of their mode of action. Since the overall composition of sebum is dominated by unsaturated triglycerides we selected triolein as the oil. Tristearin and stearic acid were selected as particulate components since both are only sparingly soluble in triolein and are likely to replicate the absence of strong dependence upon changes in pH or [Ca2+] found with sebum. Triolein/tristearin mixtures were, under most circumstances, at least as effective as the model sebum but totally unaffected by changes in [Ca2+] and pH. However triolein/stearic acid mixtuures replicated the weak dependence upon [Ca2+] of model sebum and pH but were less effective. The ineffectiveness of the former appeared to concern the relatively large size of stearic acid particles crystalizing from a melt in triolein – at least an order of magnitude larger than the particle sizes of tristearin prepared in a similar manner, showing a tendency to aggregate and form large, ineffective, triolein/stearic acid agglomerates. The large particle size of stearic acid particles also leads to a high probability of formation of ineffective particle-free drops upon dispersal in solution.

The effect of calcium on the foam behaviour of aqueous sodium alkyl benzene sulphonate solutions. (1). In the absence of antifoam

The foam behaviour of solutions of both a sodium p-dodecyl 4-phenyl sulphonate and an equivalent commercial sodium linear alkyl benzene sulphonate solution has been measured as a function of Ca2+ concentration representing a slice, at constant surfactant concentration, through the precipitation phase diagram. Regardless of foam generation methodology foamability is constant in the micellar region, declining markedly with the onset of precipitation of the surfactant as a lamellar phase. Foamability could not then be restored to any extent by filtration to remove the precipitate, which indicates an absence of antifoam action by the lamellar phase. Measurement of dynamic surface tensions however revealed a marked increase with the onset of precipitate formation which corresponded to the decline in foamability. The increase in dynamic surface tension is attribu to the non-labile nature of lamellar phase leading to depleted levels of surfactant adsorption under the conditions of rapid surface formation during foam generation.

PHOTO-DEGRADATION OF SURFACTANT COMPOUNDS USING UV RAYS WITH ADDITION OF TIO2 CATALYSTS IN LAUNDRY WASTE

The utility of synthetic cleaners or commonly called as detergents have developed far indeed in this century. The effective and efficient use of detergents in cleaning process, was attracted to be used in laundry’s industry commercially, though, it has some drawback to the society and environments. Since the active materials in the compounds can cause irritating to the skins, cataracts to mature eyes and some other environmental issues due to the excess of foams can prevent oxygen dilution in the water so it be hazardous to water living organisms. Once the promising method to solve this problem is by photo-degradation using photo-catalyst. Photo-catalyst is the process using light and catalyst in order to accelerate chemical transformation, thus, solar or uv-rays can be used as light sources. This research aims at to show the ability of catalyst TiO 2 to degrade active material in linear alkyl benzene sulphonate (LAS) and alkyl benzene sulphonate (ABS) which is available in commercial detergent. Photo-degradation of LAS and ABS compounds was determined by optimum capacity TiO 2 and irradiance time. Whereas, for environmental application, the degrade compounds such Rinso® and Wipol® was chosen since it is commonly used in daily life. Beside, artificial water waste and laundry water was chosen to show the environmental effect. The result shows that the optimum number of catalyst TiO 2 addition for LAS degradation was 1.5 g, and optimum time was 120 minute. Whereas the optimum number of catalyst TiO 2 addition for ABS degradation was 2.0 g, and optimum time was 120 minute as well. Thus, for detergent Rinso®, at optimum catalyst addition, we found degradation number was 75.83%, and for detergent Wipol®, at optimum catalyst addition, we found degradation number was 57.94%. Whereas, for artificial waste at optimum catalyst addition, we found degradation number was 91.32%, and for laundry water waste at optimum catalyst addition, we found degradation number was 70.27%. Key words : Photodegradation, surfactant, TiO 2 , photocatalyst

SINTESIS SURFAKTAN METIL ESTER SULFONAT DARI PALM OIL METHYL ESTER DAN NATRIUM METABISULFIT DENGAN PENAMBAHAN KATALIS KALSIUM OKSIDA

The most widely used surfactant is an anionic surfactant which is synthesized from petroleum namely Linear Alkylbenzene sulphonate (LABS). Methyl Ester Sulfonate which is currently being developed. Surfactant can produced from palm oil methyl ester via sulfonation sulfonate. When in this research using sodium metabisulphite. The aims of this work is to synthesize Methyl Ester Sulfonate surfactant from Palm Oil Methyl Ester using Sodium Metabisulphite and a catalyst Calcium Oxide. The effects of time and the mole ratio are also investigated. Sulfonation process carried out in 4, 5, 6 hours with mole ratio of 1: 0,5, 1:1, 1: 1,5, temperature of 80° C and with stirring speed of 450 rpm. It haven been found that the surfactant produced has density of (0.89490 g/cm3 - 0.89545 g/cm3), viscosity (2.0323 cP - 2.1329 cP), pH (2,03 - 2,48), surface tension (32.60 mN/m - 33.60 mN/m), interfacial tension (30.45 mN/m - 30.94 mN/m), and the stability emulsion (59.17% - 89, 17%).

Purification of Raw Cane Sugar by Micellar-Enhanced Ultrafiltration Process Using Linear Alkylbenzene Sulphonate

Raw sugars need to be refined again for attainment of superior quality. In recent years, membrane technology has been widely used in food industry, including sugar refining. One way for improving the separation power of membrane processes like ultrafiltration is the use of surfactant as complexing agent that is known as micellar-enhanced ultrafiltration (MEUF) process. In this study, linear alkylbenzene sulphonate was used as an anionic surfactant in MEUF process. In order to study the refining potential of this method, the effect of temperature at three levels (30C, 40C and 50C), transmembrane pressure at levels 2, 3.5 and 5 bar and the surfactant concentration at three levels (0, 1 and 2 CMC) on flux, turbidity, color and ash content of refined juice was investigated by response surface methodology. The results showed that turbidity, color and ash content of permeate decreased about 5.915 NTU, 407 ICUMSA and 0.059%, respectively. The permeate flux decreased with increasing the surfactant concentration, too. Practical Applications One way to improve the ultrafiltration process is using of the surfactant. Effects of temperature, pressure and concentration of surfactant were investigated. High concentrations of surfactant were effective on removal of the impurities. High pressures and temperatures did not succeed in removing of impurities. MEUF process with anionic surfactant was successful in refining raw sugar.

Determination of the four major surfactant classes in cleaning products by reversed-phase liquid chromatography using serially connected UV and evaporative light-scattering detection

A method for the simultaneous determination of the most frequently used surfactant families –linear alkyl benzenesulphonates (LAS), alkyl ether sulphates (AES), fatty alcohol ethoxylates (FAE) and oleins (soaps, fatty acid salts) – in cleaning products, has been developed. The common reversed phase octyl (C8), pentafluorophenyl and biphenyl columns were not capable of separating the anionic LAS and AES classes; however, since only LAS absorbs in the UV, these two classes were independently quantified using a C8 column and serially connected UV and ELSD detection. The best compromise to resolve the four surfactant classes and the oligomers within the classes was achieved with a C8 column and an ACN/water gradient. To enhance retention of the anionic surfactants, ammonium acetate, as an ion-pairing agent compatible with ELSD detection, was used. Also, to shift the olein peaks with respect to that of the FAE oligomers, acetic acid was used. In the optimized method, modulation of the mobile phase, using ammonium acetate during elution of LAS and AES, and acetic acid after elution of LAS and AES, was provided. Quantitation of the overlapped LAS and AES classes was achieved by using the UV detector to quantitate LAS and the ELSD to determine AES by difference. Accuracy in the determination of AES was achieved by using a quadratic model, and by correcting the predicted AES concentration according to the LAS concentration previously established using the UV chromatogram. Another approach also leading to accurate predictions of the AES concentration was to increase the AES concentrations in the samples by adding a standard solution. In the samples reinforced with AES, correction of the predicted AES concentration was not required. FAE and olein were quantified using also quadratic calibration.

An ecosystem model of the lower Po river for use in ecological risk assessment of xenobiotics

Ecological modelling has the potential to increase the realism of chemical risk assessment for better informed risk management and decision making meeting the protection goals and requirements of the EU's chemicals- and water-related regulations. We developed a food web model of the final lowland section of the longest Italian river (Po) to assess the importance of ecological interactions in setting protective thresholds for river ecosystems exposed to chemicals discharged via wastewater. An integrated 14 compartment model was setup using AQUATOX 3.1, providing a dynamic, quantitative representation of the main functional groups in the food web. To our knowledge, this is the first time that the functioning of the Po ecosystem is quantitatively described. The model was calibrated against observations of biomass density of riverine biota, as typically available for a large lowland river in Europe. The role of ecological interactions on the response of the modelled organisms to chemical exposure was tested on realistic and hypothetical exposure scenarios for two compounds contained in home and personal care products: the anionic surfactant linear alkylbenzene sulphonate and the antimicrobial triclosan. At realistic exposure concentrations the model showed no significant effect compared to control simulations. At hypothetical higher exposure, effects resulting from complex ecosystem-scale interactions emerge. Depending on the organism's position in the food web, indirect effects due to ecological interactions can either amplify or mitigate the effect of direct toxicity. Model results indicate that organisms’ responses to chemicals in real ecosystems is poorly correlated to their direct toxicity (i.e. measured by L/ECX values) for a range of simulated exposure, including concentrations equal to the reported PNEC values. AQUATOX is a useful tool to investigate the relative importance of direct toxicity and ecological interactions, but at this stage it is difficult to use it for prospective chemical risk assessment, given the underlying model uncertainties and the practical limitations of field scale evaluations. An improvement of the quantitative monitoring of feeding preferences and abundance over time of the most representative species within each functional group would be of great help to refine the model parameterisation and calibration. Nonetheless, the development of river ecosystem model scenarios is a stepping stone towards the incorporation of ecological modelling in risk assessment. When extensively tested on different scenarios AQUATOX provides a useful platform, which can be linked to mechanistic effect models as long as this component can be evaluated in controlled settings (i.e. laboratory or mesocosm scale).

Membrane fouling control and performance enhancement of ultrafiltration of latex effluent

AbstractThe objective of the present study was to minimize membrane fouling of a latex solution either through improving the membrane surface charge or using a pretreated feed. Hydrophilic polysulphone (PSU) and Ultrafilic flat membranes, with a molecular weight cut‐off (MWCO) of 60 000 and 100 000 dalton, respectively, were implemented under a constant flow rate and cross‐flow mode in ultrafiltration of simulated latex effluent. Hydrophobic polyvinylidene difluoride membrane (PVDF) with a MWCO of 100 000 dalton was also tested. The influence of linear alkyl benzene sulphonate (LAS) on the ionic strength of the simulated latex effluent and the surface charge of latex particles at different LAS concentrations was investigated. LAS was also used, at different concentrations and various treatment times, to ensure the enhancement of the antifouling characteristics of the membrane surface. It was concluded that the LAS‐treated membrane surface is much more favourable than the pH‐changed feed pre‐treatment. As such, the total mass of fouling decreased by 44.00 % and 29.60 % in the cases of treated PVDF membrane surface with LAS at a concentration of 0.0001 g/L, and treated latex feed at pH 11, respectively. Nevertheless, LAS was considered to be an ineffective pre‐treatment for limiting the fouling propensity of latex solutions using hydrophilic membranes even at high concentrations and long treatment times.

Grey water treatment by the slanted soil system with unsorted soil media

This study evaluated the performance of unsorted soil media in the slanted soil treatment system, in terms of removal efficiency in suspended solids (SS), chemical oxygen demand (COD), linear alkylbenzene sulphonate (LAS) and Escherichia coli, and lifetime until clogging occurs. Unsorted soil performed longer lifetime until clogging than sorted fine soil. Removal of SS, COD, and LAS also performed same or better level in unsorted soil than fine soil. As reaction coefficients of COD and LAS were described as a function of the hydraulic loading rate, we can design a slanted soil system according to the expected hydraulic loading rate and the targeted level of COD or LAS in effluent. Regarding bacteria removal, unsorted soil performed sufficient reduction of E. coli for 5 weeks; however, the removal process occurred throughout all four chambers, while that of fine soil occurred in one to two chambers.