Walter Giger

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.

Poly cyclic aromatic hydrocarbons in Recent lake sediments—II. Compounds derived from biogenic precursors during early diagenesis

Abstract Five groups of polycyclic aromatic hydrocarbons (PAH) thought to be derived by early-diagenetic transformations of biogenic precursors are apparently present in Recent sediments of four lakes (Lake Lucerne. Lake Zurich, and Greifensee. Switzerland, and Lake Washington, northwest U.S.A.) These natural PAH include: 1. (1) perylene. 2. (2) an extended series of phenanthrene homologs. 3. (3) retene and pimanthrene derived from diterpenes. 4. (4) a series of tetra- and pentacyclic PAH derived from pentacyclic triterpenes of the amyrin-type. 5. (5) tetra- and pentacyclic PAH formed from pentacyclic triterpenes with five-membered E-rings. Since these PAH are abundant in very young sediment layers, the transformation reactions involved appear to be faster than previously thought and may be microbially mediated. There is no evidence that anthropogenic or petrogenic sources can account for the distributions of these groups of PAH in cores of Recent lake sediments.

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.

Polycyclic aromatic hydrocarbons in Recent lake sediments—I. Compounds having anthropogenic origins

Abstract Polycyclic aromatic hydrocarbons (PAH) in sediment cores from Lake Lucerne, Lake Zurich, and Greifensee, Switzerland, and Lake Washington, northwest U.S.A., have been isolated, identified and quantified by glass capillary gas chromatography and gas chromatography/mass spectrometry. Surface sediment layers are greatly enriched in PAH—up to 40 times—compared to deeper layers. In addition, concentration increases in upper sediments generally correspond to increasing industrialization and urbanization in the catchment basins of the lakes. Few PAH could be detected in pre-industrial revolution sediments, indicating that background levels for most PAH in aquatic sediments are extremely low. These results are consistent with an anthropogenic source for most of the aromatic hydrocarbons present in the modern sediments. A comparison of PAH distributions in the sediments and in possible source materials shows that urban runoff of street dust may be the most important PAH input to these lacustrine sediments. There is evidence that a significant contribution to the PAH content of street dust comes from material associated with asphalt.

Bioaccumulation of the lipophilic metabolites of nonionic surfactants in freshwater organisms

Nonylphenol (NP), nonlyphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate (NP2EO) were determined in different freshwater organisms from the surface waters in the Glatt Valley, Switzerland. Rather high concentrations of the compounds investigated have been found to occur in macrophytic algae, particularly Cladophora glomerata (up to 38 mg kg(-1), 80 mg kg(-1), and 28 mg kg(-1) of NP, NP1EO and NP2EO, respectively), the bioconcentration factors of NP reaching up to 10,000. The concentrations in fish were much lower (NP: < 0.03-1.6 mg kg(-1), NP1EO: 0.06-7.0 mg kg(-1), and NP2EO: <0.03-3.1 mg kg(-1) indicating that biomagnification did not take place. Similar concentrations to those in the fish were determined in different tissues of a wild duck. The estimated bioconcentration factors in fish tissues ranged from 13 to 410 for NP, 3 to 300 for NP1EO and 3 to 330 for NP2EO.

Occurrence and fate of antibiotics as trace contaminants in wastewaters, sewage sludges, and surface waters

Environmental analytical studies show that trace concentrations of antibacterial agents (antibiotics) occur in hospital and municipal wastewaters and in the aquatic environment. Fluoroquinolones and macrolides, two important human-use antibiotic classes, were studied in detail. The results are discussed regarding input sources and behavior in wastewater treatment and rivers. The fluoroquinolones ciprofloxacin and norfloxacin are substantially eliminated in wastewater treatment (80-90%) by sorption transfer to sewage sludge. In digested sludges the fluoroquinolones occur at mg/kg levels. Ciprofloxacin and norfloxacin are further removed in the Glatt river by 66 and 48%, respectively. The most abundant macrolide clarithromycin was detected at 57 to 330 ng/l concentrations in treated wastewater effluents. Different compositions of the macrolides (clarithromycin and erythromycin-H 2 O) determined in treated effluents of three wastewater treatment plants can be explained by distinct consumption patterns, in one case due to an international airport located in the catchment area. Residual levels of clarithromycin in the Glatt river were up to 75 ng/l with no apparent removal in the river. These results provide important information on environmental exposures, which can be incorporated into environmental risk assessments of the particular chemicals.

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 behaviour of linear alkylbenzenesulphonates, nonylphenol, nonylphenol mono- and nonylphenol diethoxylates in sewage and sewage sludge treatment

The fluxes of linear alkylbenzenesulphonates (LAS), nonylphenol (NP), nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate (NP2EO) through sewage and sludge treatment of 29 Swiss sewage treatment plants were investigated. Reversed-phase high-performance liquid chromatography (HPLC) was used to determine LAS. Normal-phase HPLC was employed to measure NP, NP1EO and NP2EO which are metabolites of the nonionic surfactants of the nonylphenol polyethoxylate type (NPnEO). Quantitative determinations were performed of raw sewage, primary and secondary effluents and of sewage sludge. Under normal conditions of sewage and sludge treatment, LAS were efficiently removed from the raw wastewater (> 99% w/w) and were partly transferred to the sewage sludge (15–20% w/w). About 50% (molar base) of NPnEO in the sewage were transformed to NP and accumulated in the digested sludge. Large variations existed among different sewage treatment plants. It was estimated that 1.0 g m−2 y−1 of LAS and 0.3 g m−2 y−1 of NP are applied with sewage sludge to Swiss soils.

Occurrence, fate and antibiotic resistance of fluoroquinolone antibacterials in hospital wastewaters in Hanoi, Vietnam

Occurrence and behavior of fluoroquinolone antibacterial agents (FQs) were investigated in hospital wastewaters in Hanoi, Vietnam. Hospital wastewater in Hanoi is usually not treated and this untreated wastewater is directly discharged into one of the wastewater channels of the city and eventually reaches the ambient aquatic environment. The concentrations of the FQs, ciprofloxacin (CIP) and norfloxacin (NOR) in six hospital wastewaters ranged from 1.1 to 44 and from 0.9 to 17 micrgl(-1), respectively. Total FQ loads to the city sewage system varied from 0.3 to 14 g d(-1). Additionally, the mass flows of CIP and NOR were investigated in the aqueous compartment in a small wastewater treatment facility of one hospital. The results showed that the FQ removal from the wastewater stream was between 80 and 85%, probably due to sorption on sewage sludge. Simultaneously, the numbers of Escherichia coli (E. coli) were measured and their resistance against CIP and NOR was evaluated by determining the minimum inhibitory concentration. Biological treatment lead to a 100-fold reduction in the number of E. coli but still more than a thousand E. coli colonies per 100ml of wastewater effluent reached the receiving water. The highest resistance was found in E. coli strains of raw wastewater and the lowest in isolates of treated wastewater effluent. Thus, wastewater treatment is an efficient barrier to decrease the residual FQ levels and the number of resistant bacteria entering ambient waters. Due to the lack of municipal wastewater treatment plants, the onsite treatment of hospital wastewater before discharging into municipal sewers should be considered as a viable option and consequently implemented.

Persistent organic chemicals in sewage effluents. 2. Quantitative determinations of nonylphenols and nonylphenol ethoxylates by glass capillary gas chromatography

Nonylphenols and nonylphenol ethoxylates with one and two oxyethylene groups have been quantitatively determined in the effluents of six mechanical-biological sewage treatment plants. In three plants total concentrations of nonylphenolic compounds in the effluents ranged from 36 to 202 pg/L, representing from 0.5% to 2.3% of the total residual dissolved organic carbon. In three plants operated at low loading conditions nonylphenolic compounds were not detectable (<lo pg/L). These compounds are believed to be refractory metabolites of nonionic surfactants of the nonylphenol polyethoxylate type. In particular, the nonylphenols must be considered as compounds of high toxicity to aquatic organisms.