Bogdan Wyrwas

BIODEGRADATION OF FATTY ALCOHOL ETHOXYLATES IN THE CONTINUOUS FLOW ACTIVATED SLUDGE TEST

Abstract Biodegradation of two fatty alcohol ethoxylates: surfactant C12E10 (C 12 with an average 10 oxyethylene subunits (EO)) and Marlipal 1618/25 (C 16–18 with an average 25 EO) were tested under the continuous flow activated sludge conditions of the classical Husmann plant and a plant having a denitrifying chamber. Primary biodegradation and concentration of metabolites: free fatty alcohol (FFA) and poly(ethylene glycols) (PEG) were measured. PEG were divided into two fractions: short-chained (1–3 EO) and long-chained PEG (>3 EO). Tensammetric methods were used for analysis. High primary biodegradation was found (96.8±0.5% for surfactant C12E10 (C12E10) and 99.6±0.1% for Marlipal 1618/25 (Marlipal)), though with a high concentration of metabolites: FFA and PEG. FFA concentration corresponded to 30–100% of theoretically predicted concentration (presuming central fission) and dependent on the chemical structure of surfactant and type of plant used for testing. Total PEG concentration was about 20% of that predicted on the basis of central fission, while the ratio of short-chained PEG in the total PEG varied from 20 to 70% and depended on the chemical structure of surfactant and type of plant used for testing.

Application of an indirect tensammetric method for the determination of non-ionic surfactants in surface water

Abstract Three alternative procedures for the determination of non-ionic surfactants (NS) in surface water have been developed. The simplest one consists of the filtration of water samples, the extraction of NS with ethyl acetate, the evaporation of the solvent and the determination of NS using an indirect tensammetric method (ITM). The detection limit is 15 μg l −1 . The procedure using gas-stripping separation of NS shows a detection limit of 1.5 μg l −1 . Chlorophyll extracted from water plants causes a serious interference. Therefore the sample must be filtered before extraction. The extractive procedure shows good precision and recovery of spiked surfactants from river water samples. Comparative studies of the newly developed and the classical BiAS procedures were performed. The ITM procedure shows a detection limit of two orders of magnitude better than the BiAS procedure. Therefore the required volume of water sample is reduced from 5000 to 100 ml. Due to the simpler separation procedure the ITM is substantially less time-consuming, cheaper and requires no sophisticated equipment or well-trained staff. An additional advantage of the ITM compared with the BiAS procedure is the lower sensitivity to the choice of standard surfactant and the broader “spectrum” of NS that can be determined. The results of a half year current analysis of NS in river water have been included.

DETERMINATION OF SHORT-CHAINED POLY(ETHYLENE GLYCOLS) AND ETHYLENE GLYCOL IN ENVIRONMENTAL SAMPLES

A method for the determination of ethylene glycol (EG), di(ethylene glycol) (E2) and tri(ethylene glycol) (E3) in environmental samples (raw and treated sewage, river water) has been developed. These substances are important by-products in the biotransformation of non-ionic surfactants (NS). The method is based on sequential liquid-liquid extraction with ethyl acetate and chloroform (resulting in the separation of poly(ethylene glycols) (PEG) and EG from the water matrix), precipitation of long-chained PEG (PEGlch) with Dragendorff reagent, extraction of short-chained PEG (PEGsh) (EG, E2 and E3) from a filtrate with chloroform and the final determination using alternating current voltammetry. The precision of the method is 7.3%, the recovery 95% and a detection limit of 1.5 microg in the sample, i.e. 10 microg l(-1) was achieved. As evidenced by F and t tests, the developed method is equivalent to the indirect PEGsh determination by the difference approach where concentration of PEGsh is determined by the difference of the total PEG and PEGlch. The PEGsh fraction was found to be present in considerable concentrations in raw and treated sewage, river water, as well as being a major biotransformation by-product in the continuous flow activated sludge testing of fatty alcohol ethoxylates.

Biodegradation of oxo-alcohol ethoxylates in the continuous flow activated sludge simulation test.

Biodegradation of two alpha-methyl branched oxo-alcohol ethoxylates (OAE) of different polydispersity: LIAL 125/14 BRD (LIALB) (broad M.W. distribution) and LIAL 125/14 NRD (LIALN) (narrow M.W. distribution), both having an average of 14 oxyethylene subunits (EO) and a C(12-15) alkyl moiety were tested under the continuous flow activated sludge conditions of the classical Husmann plant. Primary biodegradation and concentration of metabolites: free oxo-alcohol fraction (FOA) and poly(ethylene glycols) (PEG), were measured. PEG were divided into two fractions: short-chained PEG (PEGshch) (1-4 EO) and long-chained PEG (PEGlch) (>4 EO). The indirect tensammetric technique combined with an adequate separation was used for analysis. Central fission was found to be a highly dominating pathway, as is the case with fatty alcohol ethoxylates. OAE are highly primarily biodegraded (above 95%). High concentrations of FOA and PEG are formed. Once formed the PEGlch are further fragmented into the PEGshch. Free alcohol fraction compounds are biodegraded sooner when alkyl moiety is shorter. OAE polydispersity has an influence on the kinetics of biodegradation; PEG formed from LIALN are biodegraded slower and to a lower degree than those from LIALB.

Tensammetric studies of separation of surfactants

Abstract Precipitation of surfactants with modified Dragendorff reagent, being a part of the bismuth active substance (BiAS) standard procedure, was investigated with the use of adsorptive stripping tensammetry and an indirect tensammetric method. Triton X-100 was used as a representative surfactant. The washing step with glacial acetic acid part of the investigated procedure, was found to be a serious source of loss of precipitate and therefore the main source of error of determination in the BiAS procedure. The concentration of surfactant in the filtrate and adsorptive losses on the filter were also determined.

Tensammetric determination of non-ionic surfactants combined with BiAS separation procedure (Wickbold) 2. Optimisation of the precipitation and investigation of interferences.

The precipitation step in the developed procedure (BiAS-ITM) was optimised with the aim of achieving a lower detection limit. Losses during filtration using Triton X-100 as representative non-ionic surfactant (NS), the indirect tensammetric method (ITM) and adsorptive stripping tensammetry (AdST) for the determination of the concentration of the surfactant in the precipitate and in the filtrate were investigated. The G4 glass filter recommended up to now was found to be insufficiently effective and a source of loss. The new version of the procedure developed works within the range 2-1000 mug of NS in the sample, and thus two orders of magnitude lower than the former version of the procedure, showing satisfactory recovery and precision. The detection limit (3 x S.D.) was found to be below 1.5 mug in the sample. Interferences of anionic surfactants (ASs) e.g. sodium dodecylbenzenesulphonate and sodium lauryl sulphate, lipids, e.g. glycerol trioleate (GTO), and chlorophyll were investigated. GTO and AS show no effect on the BiAS-ITM results although strong adsorption of ASs on the glass filter as well as a slight adsorption on the precipitate was found. Chlorophyll does not interfere with the determination up to 30 mug in the sample, whereas higher concentrations produce results that are too high.

Determination of non-ionic surfactants adsorbed on particles of surface water by an indirect tensammetric method combined with the BiAS separation scheme

Abstract Procedures have been developed for the determination of non-ionic surfactants (NS) adsorbed on particles in water samples, NS dissolved in water and a total flux of NS (comprising both fractions). Two procedures for the determination of NS adsorbed on particles were developed: direct determination and a differential method. In the direct determination (detection limit of 3 μg l −1 ), NS adsorbed on particles are separated by filtration and subsequent extraction of NS adsorbed on particles with ethyl acetate. The further separation and quantification follows the separation scheme of the BiAS method (bismuth active substances) combined with the indirect tensammetric method (BiAS-ITM). In the differential approach (detection limit of 8 μg l −1 ), the concentration of NS in filtered water (as determined by the BiAS-ITM) is subtracted from the corresponding result for non-filtered water. The results for concentration of NS in non-filtered water, as determined by the BiAS-ITM, represent a total flux of NS in river water (dissolved fraction and fraction of NS adsorbed on particles). The detection limit of the determination is 6 μg l −1 . In the tested samples, NS adsorbed on particles ranged from 4% to 32% (average 20%) of total concentration of NS in river water. The BiAS-ITM shows a fundamental advantage vs. the indirect tensammetric method (ITM) used as a separate procedure in the determination of NS adsorbed on particles or contained in non-filtered water samples, due to tolerance to chlorophyll. On the other hand, the ITM can be recommended for the determination of NS in filtered water samples.

Determination of non-ionic surfactants and their biotransformation by-products adsorbed on alive activated sludge

A procedure has been developed for the determination of non-ionic surfactants (NS) adsorbed on particles of alive and dead activated sludge. The procedure also enables the determination of adsorption of major biodegradation by-products: short-chained ethoxylates, long- and short-chained PEG. The basis of measurement is the determination of NS concentration in a slurry of activated sludge and in a solution phase. The difference between these two concentrations represents the NS adsorbed on activated sludge. Separation of NS and their biotransformation by-products from samples and then on narrower fractions was performed by a sequential liquid-liquid extraction and precipitation with modified Dragendorff reagent. The indirect tensammetric technique (ITT) was applied for the final determination. The developed method was checked using the example of the treatment of the surfactant C12E10 (oxyethylated fatty alcohol) (C12E10) in the continuous flow activated sludge facility. No statistically significant accumulation of C12E10 on the alive activated sludge was detected, probably because of faster C12E10 fission than its adsorption. However, significant adsorption of the short-chained ethoxylates (including free alcohol) on the alive activated sludge was found, as well as statistically significant adsorption of long- and short-chained PEG. The adsorption of surfactant C12E10 and its biodegradation by-products on dead activated sludge was found to be higher than the species adsorption on alive activated sludge.

Tensammetric determination of non-ionic surfactants combined with BiAS separation procedure (wickbold)—I. precipitation of different ethoxylates with modified Dragendorff reagent in the proposed and classical BiAS procedures

The proposed procedure (BiAS-ITM) combines BiAS separation scheme of non-ionic surfactants with their determination by indirect tensammetric method (ITM). The method is based on (i) gas stripping separation of ethoxylates, (ii) their precipitation with modified Dragendorff reagent and (iii) determination of their concentration in the dissolved precipitate using ITM. Washing of the precipitate with glacial acetic acid, necessary in classical BiAS procedure which is a source of serious error, is omitted in the proposed separation scheme. The presented method determines the non-ionic surfactants instead of bismuth in the classical BiAS. The precipitation of 12 oxyethylated alcohols, four oxyethylated alkylphenols and four other ethoxylates were investigated according to the proposed procedure. Adsorptive stripping tensammery (AdST) was applied for additional control of investigated surfactants in the precipitate and in the filtrate. Simultaneously 13 ethoxylates were precipitated and determined according to classical BiAS procedure. The BiAS-ITM procedure shows significantly better recoveries and lower sensitivities vs. the chemical structure of the determined surfactants and thus BiAS-ITM is less sensitive to the composition of determined mixture than classical BiAS procedure. It enables the determination of ethoxylates having three or more oxyethylene subunits, while classical BiAS determines only those having five or more.

Biodegradation of diesel fuel by a microbial consortium in the presence of 1-alkoxymethyl-2-methyl-5-hydroxypyridinium chloride homologues

Fast development of ionic liquids as gaining more and more attention valuable chemicals will undoubtedly lead to environmental pollution. New formulations and application of ionic liquids may result in contamination in the presence of hydrophobic compounds, such as petroleum mixtures. We hypothesize that in the presence of diesel fuel low-water-soluble ionic liquids may become more toxic to hydrocarbon-degrading microorganisms. In this study the influence of 1-alkoxymethyl-2-methyl-5-hydroxypyridinium chloride homologues (side-chain length from C3 to C18) on biodegradation of diesel fuel by a bacterial consortium was investigated. Whereas test performed for the consortium cultivated on disodium succinate showed that toxicity of the investigated ionic liquids decreased with increase in side-chain length, only higher homologues (C8–C18) caused a decrease in diesel fuel biodegradation. As a result of exposure to toxic compounds also modification in cell surface hydrophobicity was observed (MATH). Disulphine blue active substances method was employed to determine partitioning index of ionic liquids between water and diesel fuel phase, which varied from 1.1 to 51% for C3 and C18 homologues, respectively. We conclude that in the presence of hydrocarbons acting as a solvent, the increased bioavailability of hydrophobic homologues is responsible for the decrease in biodegradation efficiency of diesel fuel.