Marijan Ahel

Behaviour of alkylphenol polyethoxylate surfactants in the aquatic environment. I: Occurrence and transformation in sewage treatment

Abstract Specific analytical techniques were used to study the behaviour of alkylphenol polyethoxylate surfactants (APnEO) in several full-scale mechanical-biological sewage treatment plants in the Glatt Valley, Switzerland. Both parent compounds and the major metabolic products were quantified. Untreated sewage and primary effluents contained considerable amounts of surfactant-derived nonylphenolic compounds (3.0–9.6% of the dissolved organic carbon). Parent nonylphenol polyethoxylates (nEO = 3–20) were efficiently eliminated during biological treatment. However, the overall rate of biodegradation was limited due to the formation of biorefractory metabolites, including nonylphenol (NP), nonylphenol mono- and diethoxylate (NP1EO, NP2EO) and nonylphenoxy carboxylic acids (NPEC). The abundance of a particular metabolite was very dependent on the treatment conditions. Studies of the mass flows of nonylphenolic compounds in sewage treatment plants indicated that their fate was determined not only by microbial transformation, but also by physicochemical processes.

Behaviour of alkylphenol polyethoxylate surfactants in the aquatic environment—II. Occurrence and transformation in rivers

The behaviour of nonylphenol polyethoxylate surfactants (NPnEO) and their metabolites in the Glatt River, Switzerland was studied. Discharge of secondary effluents from municipal sewage plants into the river was the predominant source of the investigated compounds. The majority of nonylphenolic compounds in the Glatt River were in the form of persistent metabolites, the most abundant being nonylphenoxy carboxylic acids. Distribution of the various classes of nonylphenolic compounds in the river was influenced to differing extents by biological and physico-chemical processes and was dependent on the compound class and the season. Biotransformation appears to be the predominant mechanism determining the fate of nonylphenolic compounds. High concentrations of lipophilic metabolites in river sediments indicate the importance of physico-chemical processes on the distribution of the nonylphenolic chemicals in natural waters.

Partitioning of alkylphenols and alkylphenol polyethoxylates between water and organic solvents

Partition coefficients of octylphenol (OP), nonylphenol (NP) and nonylphenol ethoxylates (NPnEO, n = 1–3) were determined for n-octanolwater and n-hexanewater systems. In the octanol/water system, logarithmic values of the partition coefficients (log KOW) for the phenols were 4.12 and 4.48 for OP and NP, respectively. Slightly lower lipophilicity was found for APnEO with log KOW values of NP1EO, NP2EO and NP3EO around 4.2. The corresponding values in hexane/water system were approximately 0.8 logarithmic units lower but showed essentially the same ratio between NP and NPnEO as it was observed in the octanol water system. An attempt was made to estimate octanol/water partition coefficients for higher OPnEO and NPnEO oligomers. Application of reversed-phase HPLC for this purpose resulted in a significant overestimation. Alternatively, octanol/water partition coefficients for the higher APnEO oligomers were estimated (i) using an equation that correlates log KOW with solubility and (ii) converting the respective iso-octanewater partition coefficients to the octanol/water coefficients.

Occurrence and Fate of Emerging Wastewater Contaminants in Western Balkan Region

This paper reports on a comprehensive reconnaissance of over seventy individual wastewater contaminants in the region of Western Balkan (WB; Bosnia and Herzegovina, Croatia and Serbia), including some prominent classes of emerging contaminants such as pharmaceuticals and personal care products, surfactants and their degradation products, plasticizers, pesticides, insect repellents, and flame retardants. All determinations were carried out using a multiresidue analytical approach, based on the application of gas chromatographic and liquid chromatographic techniques coupled to mass spectrometric detection. The results confirmed a widespread occurrence of the emerging contaminants in municipal wastewaters of the region. The most prominent contaminant classes, determined in municipal wastewaters, were those derived from aromatic surfactants, including linear alkylbenzene sulphonates (LAS) and alkylphenol polyethoxylates (APEO), with the concentrations in raw wastewater reaching into the mg/l range. All other contaminants were present in much lower concentrations, rarely exceeding few microg/l. The most abundant individual compounds belonged to several classes of pharmaceuticals (antimicrobials, analgesics and antiinflammatories, beta-blockers and lipid regulators) and personal care products (fragrances). Due to the rather poor wastewater management practices in WB countries, with less than 5% of all wastewaters being biologically treated, most of the contaminants present in wastewaters reach ambient waters and may represent a significant environmental concern.

Aqueous solubility of alkylphenols and alkylphenol polyethoxylates

Abstract Aqueous solubilities of nonylphenol (NP), octylphenol (OP) and their ethylene oxide adducts with 1–5 ethoxy groups were determined using a generator column technique followed by subsequent off-line HPLC analysis of the aqueous solutions. The solubilities of OPnEO oligomers (8.0–24.5 mg/L) were significantly greater than those of the corresponding NPnEO oligomers (3.02–9.48 mg/IL) indicating a predominant influence of the hydrophobic chain length on APnEO solubility. A linear relationship between solubility and the number of EO groups was established for both oligomer series. However, nonethoxylated alkylphenols showed irregularly enhanced solubilities as compared to the corresponding ethoxylated compounds probably caused by different impacts of phenolic and alcoholic OH functional groups. NP and NP1EO showed a gradual solubility increase towards higher temperatures in the temperature range examined (2–25 °C), while an irregular behaviour was observed for NP2EO. The concentrations of individual oligomers in solutions of APnEO oligomer mixtures were below their saturation levels, while the oligomer composition in the solution showed significant change compared with the original one, reflecting different solubilities of the individual oligomers as pure substances.

Persistent organic chemicals in sewage effluents. 3. Determinations of nonylphenoxy carboxylic acids by high-resolution gas chromatography/mass spectrometry and high-performance liquid chromatography.

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BEHAVIOUR OF ALKYLPHENOL POLYETHOXYLATE SURFACTANTS IN THE AQUATIC ENVIRONMENT--III . OCCURRENCE AND ELIMINATION OF THEIR PERSISTENT METABOLITES DURING INFILTRATION OF RIVER WATER TO GROUNDWATER

Abstract The behaviour of various persistent metabolites derived from nonylphenol polyethoxylate (NPnEO) surfactants was studied during infiltration of river water to groundwater at two field sites situated in the northern part of Switzerland (Glatt River and Sitter River). Nonylphenol (NP), nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), nonylphenoxy acetic acid (NP1EC) and nonylphenoxy(ethoxy) acetic acid (NP2EC) were observed in the two investigated rivers at relatively high concentrations with average values of the individual types of nonylphenolic compounds ranging from 1.8 to 25 μg/l. The average concentrations of NP, NP1EO and NP2EO in groundwater were significantly lower (range NP1EO > NP > PCP > NP1EC = NP2EC.

Illicit drugs in wastewater of the city of Zagreb (Croatia) – Estimation of drug abuse in a transition country

A comprehensive study of various psychoactive substances and their metabolites was performed in the wastewater treatment plant of the city of Zagreb (780 000 inhabitants) using liquid chromatography/tandem mass spectrometry (LC-MS-MS). The estimation of drug abuse for five different illicit drugs, including heroin, cocaine, marijuana, amphetamine and ecstasy, was made on the basis of their representative excretion rates, which were determined over a period of 8 months. Marijuana (1000 kg/year), heroin (75 kg/year) and cocaine (47 kg/year) were found to be the most frequently consumed illicit drugs, while the consumption of amphetamine-type drugs was much lower (1-3 kg/year). A comparison with other reports indicated that drug abuse profiles in transition countries might be different from those reported for Western Europe, in particular with respect to the comparatively increased consumption of heroin. Enhanced consumption of stimulating drugs (cocaine and ectasy) was systematically detected during weekends.

Photochemical degradation of nonylphenol and nonylphenol polyethoxylates in natural waters

Abstract The rates of photochemical transformation of nonylphenol (NP) and nonylphenol polyethoxylates (NPnEO) in natural waters were assessed by exposing their solutions in filtered lake water (DOC=4 mg/L) to sunlight. The first-order rate constant of sunlight photolysis (k p ) for NP was estimated at 0.09 m 2 /(kWh). This corresponds to a half-life of 10–15 hours under continous clear sky, noon, summer sunlight in the surface layer of natural waters. The photolysis rate in the deeper layers is strongly attenuated, being approximately 1.5 times slower at depths of 20–25 cm than at the surface. The photochemical oxidation of NPnEO was shown to be significantly slower than that of NP. Additional laboratory experiments using a merry-go-round reactor (MGRR) have shown that the photochemical degradation of both NP and NPnEO was due mainly to sensitized photolysis whilst direct photolysis was comparatively slow. Moreover, experiments with D 2 O revealed that singlet oxygen was not an important photooxidant of NP at pH values usually found in natural waters.

Assessment of toxicological profiles of the municipal wastewater effluents using chemical analyses and bioassays.

The hazardous chemical contamination of untreated wastewater and secondary effluent from the wastewater treatment plant (WWTP) of the city of Zagreb, Croatia was comprehensively characterized using large-volume solid-phase extraction (SPE) and silica gel fractionation, followed by a detailed analysis of the resulting extracts by a combination of chemical and bioassay methods. Over 100 individual contaminants or closely related-contaminant groups were identified by high-resolution gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/quadrupole time-of-flight mass spectrometry (LC-QTOF). Ecotoxicity profiling of the investigated samples, including cytotoxicity, chronic toxicity and EROD activity; inhibition of the multixenobiotic resistance (MXR), genotoxicity and estrogenic potential, revealed the most significant contribution of toxic compounds to be present in polar fractions. Wastewater treatment using conventional activated sludge process reduced the initial toxicity of raw wastewater to various extents, ranging from 28% for algal toxicity to 73.2% for an estrogenic activity. The most efficient toxicity removal was observed for the polar compounds.