River Rhine Water Research Articles

Influence of combined abiotic/biotic factors on decay of P. aeruginosa and E. coli in Rhine River water

Understanding the dynamic change in abundance of both fecal and opportunistic waterborne pathogens in urban surface water under different abiotic and biotic factors helps the prediction of microbiological water quality and protection of public health during recreational activities, such as swimming. However, a comprehensive understanding of the interaction among various factors on pathogen behavior in surface water is missing. In this study, the effect of salinity, light, and temperature and the presence of indigenous microbiota, on the decay/persistence of Escherichia coli and Pseudomonas aeruginosa in Rhine River water were tested during 7 days of incubation with varying salinity (0.4, 5.4, 9.4, and 15.4 ppt), with light under a light/dark regime (light/dark) and without light (dark), temperature (3, 12, and 20 °C), and presence/absence of indigenous microbiota. The results demonstrated that light, indigenous microbiota, and temperature significantly impacted the decay of E. coli. Moreover, a significant (p<0.01) four-factor interactive impact of these four environmental conditions on E. coli decay was observed. However, for P. aeruginosa, temperature and indigenous microbiota were two determinate factors on the decay or growth. A significant three-factor interactive impact between indigenous microbiota, temperature, and salinity (p<0.01); indigenous microbiota, light, and temperature (p<0.01); and light, temperature, and salinity (p<0.05) on the decay of P. aeruginosa was found. Due to these interactive effects, caution should be taken when predicting decay/persistence of E. coli and P. aeruginosa in surface water based on a single environmental condition. In addition, the different response of E. coli and P. aeruginosa to the environmental conditions highlights that E. coli monitoring alone underestimates health risks of surface water by non-fecal opportunistic pathogens, such as P. aeruginosa.Key pointsAbiotic and biotic factors interactively affect decay of E. coli and P. aeruginosaE.coli and P.aeruginosa behave significantly different under the given conditionsOnly E. coli as an indicator underestimates the microbiological water quality

Isolation and sequencing of a novel inovirus, "Copypasta," from Rhine River water.

We present a new inovirus named Copypasta isolated from the Rhine River that infects Escherichia coli and shows the expected filamentous morphology. Copypasta has a circular single-stranded DNA genome that is 6,408 nt long and harbors 12 protein-coding genes.

Ultrasensitive detection of polycyclic aromatic hydrocarbons in coastal and harbor water using GC-APLI-MS.

Polycyclic aromatic hydrocarbons (PAH) are a group of ubiquitous environmental pollutants among which some compounds show carcinogenic properties. The emission of PAH from anthropogenic and natural sources to the aquatic environment demands monitoring. In this study, ten different surface water samples were collected and analyzed for 48 different PAH compounds by gas chromatography-atmospheric-pressure-laser-ionization coupled to mass spectrometry (GC-APLI-MS) after liquid-liquid extraction. Results varied from 9.22 ng/L for fluoranthene in harbor water to 0.01 ng/L for 4-methylchrysene in Rhine river water. Overall low PAH concentrations were found in the samples. Toxic equivalent (TEQ) calculations were used to assess the potential environmental impact of the analyzed compounds. The results showed higher concentrations and TEQ for the samples from harbors in comparison to riverine and estuarine sampling locations. Suspected target analysis indicated the occurrence of alkylated PAH in the surface water samples.

Identification of Pharmaceuticals in The Aquatic Environment Using HPLC-ESI-Q-TOF-MS and Elimination of Erythromycin Through Photo-Induced Degradation.

Monitoring pharmaceuticals throughout the water cycle is becoming increasingly important for the aquatic environment and eventually for human health. Targeted and non-targeted analysis are today's means of choice. Although targeted analysis usually conducted with the help of a triple quadrupole mass spectrometer may be more sensitive, only compounds previously selected can be identified. The most powerful non-targeted analysis is performed through time of flight mass spectrometers (TOF-MS) extended by a quadrupole mass analyzer (Q), as used in this study. Preceded by solid phase extraction and high-performance liquid chromatography (HPLC), the non-targeted approach allows to detect all ionizable substances with high sensitivity and selectivity. Taking full advantage of the Q-TOF-MS instrument, tandem mass spectrometry (MS/MS) experiments accelerate and facilitate the identification while a targeted MS method enhances the sensitivity but relies on reference standards for identification purposes. The identification of four pharmaceuticals from Rhine river water is demonstrated. The Rhine river originates in Tomasee, Graubünden, Switzerland and flows into the North Sea, near Southern Bight, The Netherlands. Its length amounts to 1232.7 km. Since it is of prime interest to effectively eliminate pharmaceuticals from the water cycle, the effect UV-C irradiation is demonstrated on a laboratory scale. This method allows fast degradation of pharmaceuticals, which is exemplarily shown for the macrolide antibiotic erythromycin. Using the above HPLC-Q-TOF-MS method, concentration-time diagrams are obtained for the parent drug and their photodegradation products. After establishing the equations for first-order sequential reactions, computational fitting allows the determination of kinetic parameters, which might help to predict irradiation times and conditions when potentially considered as fourth stage within wastewater treatment.

Identification of Pharmaceuticals in The Aquatic Environment Using HPLC-ESI-Q-TOF-MS and Elimination of Erythromycin Through Photo-Induced Degradation

Monitoring pharmaceuticals throughout the water cycle is becoming increasingly important for the aquatic environment and eventually for human health. Targeted and non-targeted analysis are today's means of choice. Although targeted analysis usually conducted with the help of a triple quadrupole mass spectrometer may be more sensitive, only compounds previously selected can be identified. The most powerful non-targeted analysis is performed through time of flight mass spectrometers (TOF-MS) extended by a quadrupole mass analyzer (Q), as used in this study. Preceded by solid phase extraction and high-performance liquid chromatography (HPLC), the non-targeted approach allows to detect all ionizable substances with high sensitivity and selectivity. Taking full advantage of the Q-TOF-MS instrument, tandem mass spectrometry (MS/MS) experiments accelerate and facilitate the identification while a targeted MS method enhances the sensitivity but relies on reference standards for identification purposes. The identification of four pharmaceuticals from Rhine river water is demonstrated. The Rhine river originates in Tomasee, Graubünden, Switzerland and flows into the North Sea, near Southern Bight, The Netherlands. Its length amounts to 1232.7 km. Since it is of prime interest to effectively eliminate pharmaceuticals from the water cycle, the effect UV-C irradiation is demonstrated on a laboratory scale. This method allows fast degradation of pharmaceuticals, which is exemplarily shown for the macrolide antibiotic erythromycin. Using the above HPLC-Q-TOF-MS method, concentration-time diagrams are obtained for the parent drug and their photodegradation products. After establishing the equations for first-order sequential reactions, computational fitting allows the determination of kinetic parameters, which might help to predict irradiation times and conditions when potentially considered as fourth stage within wastewater treatment.

Disaggregation of silver nanoparticle homoaggregates in a river water matrix

Silver nanoparticles (Ag NPs) could be found in aquatic systems in the near future. Although the interplay between aggregate formation and disaggregation is an important factor for mobility, bioavailability and toxicity of Ag NPs in surface waters, the factors controlling disaggregation of Ag NP homoaggregates are still unknown. In this study, we investigated the reversibility of homoaggregation of citrate coated Ag NPs in a Rhine River water matrix. We characterized the disaggregation of Ag NP homoaggregates by ionic strength reduction and addition of Suwannee River humic acid (SRHA) in the presence of strong and weak shear forces. In order to understand the disaggregation processes, we also studied the nature of homoaggregates and their formation dynamics under the influence of SRHA, Ca2+ concentration and nanoparticle concentration.Even in the presence of SRHA and at low particle concentrations (10μgL−1), aggregates formed rapidly in filtered Rhine water. The critical coagulation concentration (CCC) of Ca2+ in reconstituted Rhine water was 1.5mmolL−1 and was shifted towards higher values in the presence of SRHA. Analysis of the attachment efficiency as a function of Ca2+ concentration showed that SRHA induces electrosteric stabilization at low Ca2+ concentrations and cation-bridging flocculation at high Ca2+ concentrations. Shear forces in the form of mechanical shaking or ultrasound were necessary for breaking the aggregates. Without ultrasound, SRHA also induced disaggregation, but it required several days to reach a stable size of dense aggregates still larger than the primary particles.Citrate stabilized Ag NPs may be in the form of reaction limited aggregates in aquatic systems similar to the Rhine River. The size and the structure of these aggregates will be dynamic and be determined by the solution conditions. Seasonal variations in the chemical composition of natural waters can result in a sedimentation-release cycle of engineered nanoparticles.

Trace element patterns in Dutch coastal dunes after 50 years of artificial recharge with Rhine River water

Trace elements (TEs) are important in water quality monitoring of managed aquifer recharge (MAR) systems, because they need to be tested against maximum permissible concentrations (MPCs), and some can be used as a tracer of either infiltration water, pollution or geochemical processes. The behavior of 55 dissolved trace elements and 20 major constituents is shown for an 800 m long, 35 m deep transect with slow groundwater flow (~0.01–0.1 m/day) and a nearby 100 m long 20 m deep transect with fast groundwater flow (0.3–2 m/day), both between a recharge and recovery canal, in the coastal dune aquifer system of the Netherlands. This study demonstrates how TEs behaved in a pH 7–8 artificial recharge system in coastal sediments, where pretreated Rhine River water has been infiltrated in the period 1957–2007. The spatial and age distribution of the infiltrated Rhine water was mapped using a combination of environmental tracers (Cl/Br, 18O, 3H, Cl and SO4), allowing the comparison between young and old Rhine water, and between Rhine and dune groundwater. It is revealed which TEs can be used in specific cases as additional tracers (B, F, Mo), which TEs showed clear redox dependent behavior (As, Mo, U) or clear sorptive behavior (B, Ba, Co, Cs, Cu, F, Li, Mo, Ni, Rb, Sb, Sr, U, W), which TEs received significant geogenic inputs (As, Sr, U, W), which ‘classical’ TEs need much less monitoring compared to the 1970s and 1980s (B, Ba, Be, Cd, Co, Ni, Hg, Pb, Zn), and which TEs can normally be neglected (rare earth elements, precious metals).

Genotoxic effects in the Eastern mudminnow (Umbra pygmaea) after prolonged exposure to River Rhine water, as assessed by use of the in vivo SCE and Comet assays

The production of drinking water from river water requires a certain minimal river water quality. The Association of River Rhine Water Works (RIWA), therefore, operates a monitoring network. In vitro mutagenicity studies have shown that the genotoxicity of the River Rhine water steadily decreased from 1981 until 2001. Compared to a study in 1978, a decrease in genotoxicity was also observed in an in vivo genotoxicity study in 2005, in which Eastern mudminnows (Umbra pygmaea) were exposed to River Rhine water, and gill cells were used for the Sister Chromatid Exchange (SCE) test and the Comet assay. In this 2005 study, the in vivo genotoxicity increased upon extending exposure of the fish from 3 to 11 days. Therefore, the objectives of this study were to investigate (i) whether new data corroborate that in vivo genotoxicity of River Rhine water is at present lower than in 1978, (ii) whether the Comet assay is a suitable alternative to the SCE assay, and (iii) whether further prolonged exposure results in a further increase in in vivo genotoxicity. The new data corroborate that in vivo genotoxicity of River Rhine water is at present lower than in 1978. The Comet assay is a useful addition but does not provide a substitute for the SCE endpoint in these in vivo genotoxicity studies. Prolonging the exposure time of Eastern mudminnows to River Rhine water from 11 to 42 days did not give a significant increase in SCEs and DNA damage (Comet assay) in gill cells.

Determination of free Zn2+ concentration in synthetic and natural samples with AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) and DMT (Donnan Membrane Technique)

The determination of free Zn2+ ion concentration is a key in the study of environmental systems like river water and soils, due to its impact on bioavailability and toxicity. AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) and DMT (Donnan Membrane Technique) are emerging techniques suited for the determination of free heavy metal concentrations, especially in the case of Zn2+, given that there is no commercial Ion Selective Electrode. In this work, both techniques have been applied to synthetic samples (containing Zn and NTA) and natural samples (Rhine river water and soils), showing good agreement. pH fluctuations in DMT and N2/CO2 purging system used in AGNES did not affect considerably the measurements done in Rhine river water and soil samples. Results of DMT in situ of Rhine river water are comparable to those of AGNES in the lab. The comparison of this work provides a cross-validation for both techniques.

Perfluorinated Compounds in Infiltrated River Rhine Water and Infiltrated Rainwater in Coastal Dunes

Different studies have shown that surface waters contain perfluorinated compounds (PFCs) in the low ng/L range. Surface waters are used to produce drinking water and PFCs have been shown to travel through the purification system and form a potential threat to human health. The specific physicochemical properties of PFCs cause them to be persistent and some of them to be bioaccumulative and toxic in the environment. This study investigates the evolvement of PFC concentrations in Rhine water and rainwater during dune water infiltration processes over a transect in the dune area of the western part of The Netherlands. The difference between infiltrated river water and rainwater in terms of PFC composition was investigated. Furthermore, isomer profiles were investigated. The compound perfluorobutanesulfonate (PFBS) was found at the highest concentrations of all PFCs investigated, up to 37 ng/L in infiltrated river water (71 ± 13% of ΣPFCs). This is in contrast with the predominant occurrence of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS) reported in literature. The concentrations of PFBS found in infiltrated river Rhine water were significantly higher than those in infiltrated rainwater. For perfluorohexanesulfonate (PFHxS) the opposite was found: infiltrated rainwater contained more than infiltrated river water. The concentrations of PFOA, perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), PFBS, PFOS, and PFHxS in infiltrated river water showed an increasing trend with decreasing age of the water. The relative contribution of the branched PFOA and PFOS isomers to total concentrations of PFOA and PFOS showed a decreasing trend with decreasing age of the water.

Utilization of oligo- and polysaccharides at microgram-per-litre levels in freshwater byFlavobacterium johnsoniae

To obtain a bacterial strain that can be used to quantify biodegradable polysaccharides at concentrations of a few micrograms per litre in freshwater. Flavobacterium johnsoniae strain A3 was isolated from tap water supplemented with laminarin, pectin or amylopectin at 100 microg C l(-1) and river Rhine water. The organism utilized 14 of 23 oligo- and polysaccharides, and 1 of 9 monosaccharides, but none of the sugar acids, sugar alcohols, carboxylic acids or aromatic acids tested at 10 microg C l(-1). Amino acids promoted growth of strain A3, but not in coculture with assimilable organic carbon (AOC) test strain Pseudomonas fluorescens P17, which utilized these compounds more rapidly than strain A3. Compounds released by strain P17 and AOC test strain Spirillum sp. NOX grown on acetate promoted the growth of strain A3 at N(max) values of > or = 2 x 10(5) CFU ml(-1) of strain P17 and > or = 5 x 10(5) CFU ml(-1) of strain NOX. Significant growth of strain A3 was observed in surface water and in tap water in the presence of strain P17 (N(max) P17 < 2 x 10(5) CFU ml(-1)). Strain A3 utilizes oligo- and polysaccharides at microgram-per-litre levels. In surface water and in tap water, the organism was able to utilize compounds that were not utilized by strain P17. These compounds may include oligo- and/or polysaccharides. Phytoplanktonic and bacterial polysaccharides can constitute an important biodegradable fraction of natural organic matter in water and may promote growth of heterotrophic bacteria during water treatment and drinking water distribution. Strain A3 can be used to quantify a group of compounds that includes oligo- and polysaccharides at microgram-per-litre levels in freshwater.

Lipophilic organic contaminants in the Rhine river, Germany

Detailed gas chromatographic–mass spectrometric analyses applied to eight Rhine river water samples constituted a comprehensive characterization of the low molecular weight organic contamination. Within the group of predominant anthropogenic contaminants, only a few compounds were characterized as frequently detected or priority pollutants. Numerous compounds exhibiting physiological or ecotoxicological properties are only rarely reported or still unnoticed riverine contaminants. Information on environmental behaviour or ecotoxicological effects is still limited for most of these substances. In particular, several brominated compounds (mono- and dibrominated (methoxyphenyl)propionic acids and hydroxymethylacetophenones) were identified for the first time as environmental contaminants. Quantitative analyses differentiated five groups of pollutants with respect to their concentration profiles. The spatial distribution and the intensity of emission sources on the one hand and the environmental stability as well as the tendency to adsorb on the particulate matter on the other hand determined the quantitative occurrence of individual compounds.

Ozonation of Carbamazepine in Drinking Water: Identification and Kinetic Study of Major Oxidation Products

Kinetics and product formation of the anti-epileptic drug carbamazepine (CBZ) were investigated in lab-scale experiments during reactions with ozone and OH radicals. Ozone reacts rapidly with the double bond in CBZ, yielding several ozonation products containing quinazoline-based functional groups. The structures for three new oxidation products were elucidated using a combination of mass spectrometric and NMR techniques. The three products were determined to be 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one (BQM), 1-(2-benzaldehyde)-(1H,3H)-quinazoline-2,4-dione (BQD), and 1-(2-benzoic acid)-(1H,3H)-quinazoline-2,4-dione (BaQD). Additional kinetic studies of the ozonation products showed very slow subsequent oxidation kinetics with ozone (second-order rate constants, kO3 = approximately 7 M(-1)s(-1) and approximately 1 M(-1)s(-1) at pH = 6 for BQM and BQD, respectively). Rate constants for reactions with OH radicals, kOH, were determined as approximately 7 x 10(9) M(-1)s(-1) for BQM and approximately 5 x 10(9)M(-1)s(-1) for BQD. Thus, mainly reactions with OH radicals lead to their further oxidation. A kinetic model including ozone and OH radical reactions allows a prediction of the time-dependent product distribution during ozonation of natural waters. In Rhine River water, CBZ spiked at 500 ng/L was completely oxidized by ozone with applied doses > or =0.3 mg/L. To confirm that the two major ozonation products BQM and BQD are produced as a result of the ozonation of a CBZ-containing natural water, Lake Zurich water samples were spiked with CBZ (1 microM, 236 microg/L). The oxidation products were identified via LC-UV. Concentrations of 0.48 and 0.15 microM for BQM and BQD, respectively, were measured for an ozone dose of 1.9 mg/L. BQM and BQD were also identified in ozonated water from a German waterworks containing CBZ in its raw water with 0.07-0.20 microg/L. Currently, there are no data available on the biological effects of the formed oxidation products.

The River Rhine as a source of micropollutants in the canal sediments of the city of Delft (The Netherlands)

This paper presents a statistical analysis of the pollution levels for heavy metals and organic micropollutants at 182 sediment stations in the city canals of Delft. High pollution levels were especially observed in the inner city canal sediments, probably related to the import of polluted river Rhine water. In contrast, the more-or-less isolated outer city sites were generally much less polluted. Regression analysis on the database generally showed highly significant correlations between individual heavy metal contents. The heavy metal contents were usually significantly correlated with polycyclic aromatic hydrocarbons (PAHs) as well. This points to one or more common sources for these micropollutants. Factor analysis and the K-means cluster analysis technique were applied on the above database; it showed a large cluster of stations, nearly all located in the outer city of Delft, characterized by relatively low heavy metal and organic micropollutants' contents. Another cluster of 18 stations, mostly located in the inner city of Delft, possessed intermediate pollution levels, directly related with the supply of river Rhine water. Finally, the stations of a third cluster, situated in the inner city as well, were highly polluted, especially by local pollution sources. The above hypotheses were further supported by a more detailed statistical analysis for a number of inner city stations, together with 10-year river Rhine pollution data.

Estrogenicity of solid phase-extracted water samples from two municipal sewage treatment plant effluents and river Rhine water using the yeast estrogen screen

In the present study, the yeast estrogen screen (YES) was used to estimate the estrogenic potential of solid phase-extracted water samples from the effluents of two municipal sewage treatment plants (STPs 1 + 2) and from four lanes (left to right) of the river Rhine at Worms, Germany, i.e. downstream the STPs. Estrogenic activities of extracted water samples were expressed as 17β-estradiol equivalents (E 2-EQs). Estrogenic activity was detected in the effluents of both STPs with values of 0.242±0.038 n m (65.96±10.4 ng/l) and 0.125±0.026 nM E 2-EQs (34.1±7.18 ng/l) at STP 1 and 2, respectively. In river Rhine water, estrogenic activity was lower, however, displaying significant differences between the left and right bank of the river (0.044±0.003 n m E 2-EQs [11.97±0.7 ng/l] for lanes 1–3; 0.071±0.01 n m E 2-EQs [19.42±2.8 ng/l] for lane 4). Chemical analysis of corresponding water samples resulted in a potential estrogenic response in the YES, expressed as E 2-EQs for the known estrogens and phytoestrogens in the STP effluents with values up to 0.0662 n m E 2-EQs (18.04 ng/l). In Rhine water from lane 4, however, total estrogenic activity of steroidal estrogens was equal to 0.014 nM E 2-EQs (3.8 ng/l). Furthermore, total concentrations of flavonoids, fecal- and phytosteroids and resorcyclic lactones were about 1.2 μg/l at STP 1, 0.62 μg/l at STP 2 and 0.25 μg/l at the river Rhine, lane 4. Results indicate that estrogenic activity can clearly be measured in SPT effluents as well as in river Rhine water using the YES in combination with chemical analysis. Results from the bioassay, however, indicated a higher estrogenic potential (expressed as E 2-EQs) than that obtained by chemical analysis.

Recent and historical discharge of a large European river system – oxygen isotopic composition of river water and skeletal aragonite of Unionidae in the Rhine

Seasonal variations in the oxygen isotopic composition of Rhine River water were analyzed in detail and compared with the oxygen isotopic record from recent and historical specimens of freshwater bivalves (Unionidae). The purpose of this study was to investigate the potential use of these aragonitic bivalves as proxy recorders for varying amounts and sources of discharge, and thereby infer climate change. Seasonal variations in the river water δ 18O are on the order of 1–2‰. During summer, Alpine melt-water contributes significantly to the total discharge, resulting in average values of −10 to −10.5‰, whereas the non-Alpine contribution is higher during winter, as indicated by mean δ 18O values of −8.5 to −9‰. The basic pattern of the modern seasonal variation of δ 18O of river water can be described by a numerical mass balance approximation of the various contributions from the Alpine and non-Alpine catchments with their average δ 18O composition. The δ 18O of growth increments in the prismatic shell layer of Anodonta corresponds perfectly to what is predicted by known fractionation of 18O between water and aragonite. Shell growth is restricted to water temperatures above 8–10°C, so variations in δ 18O and the river water temperature are faithfully recorded by relatively large growth increments during summer. The distinctive isotopic signatures of individual flood events during summer and autumn are also recorded in the shells.

Long term capacity of biological activated carbon filtration for organics removal

Since March 1995 Amsterdam Water Supply has applied biological activated carbon filtration (BACF) in the treatment process of the Leiduin plant. In this plant (capacity 70 × 106 m3/y) pretreated River Rhine water is infiltrated in the dune area, west of Amsterdam, for artificial recharge. Post treatment comprises rapid sand filtration, ozonation, hardness removal, biological activated carbon filtration and slow sand filtration. At the start the carbon reactivation frequency was set at 18 months, based on removal efficiencies for AOX (adsorbable organic halogens), DOC, pesticides and micropollutants. After four years of operation of a pilot plant (10 m3/hour) in parallel with the full-scale plant, the remaining removal capacity and the break-through profile of the carbon filters was investigated. In contrast to the full-scale plant, no carbon reactivation was applied in the pilot plant during the operation of 4 years. Spiking experiments were carried out after ozonation, in the influent of the biological activated carbon filtration with a cocktail of different pesticides after 1.5, 3 and 4 years. Influent concentrations varied between 2 to 10 μg/l. Without carbon reactivation the filter effluent still complies with the Dutch drinking water standards and guide lines, as well as with the Amsterdam Water Supply standards: DOC is less than 2 mg/l (actually 1.2 mg/l) and AOX remains below 5 μg/l. After four years, with spiking concentrations of 2 μg/l still no pesticide break-through was observed in the two-stage biological activated carbon filtration process. It can be concluded that a running time of 3 years between two reactivations in the two stage biological active carbon filtration is achievable, without negatively affecting the finished water quality. Average DOC concentrations will increase up to 1.2 mg/l, from 1 mg/l with running times of 2 years. After four years or 100,000 bedvolumes the AOC content is equal to or lower than 10 μg/l after biological activated carbon filtration. With slow sand filtration at the end and as polishing step AOC will be less than 10-5 μg/l. With every extension of six months duration time a saving of Euro 305,000 on reactivation costs is possible. With every 6 month extension of the running time of the carbon filters a saving of €610,000 is realised on the reactivation costs of the Leiduin treatment plant.

Retention of herbicides and pesticides in relation to aging of RO membranes

Amsterdam Water Supply (AWS) intends to increase the capacity of the Leiduin production plant. In the existing plant (capacity 70×10 6 m 3/y) pretreated Rhine River water was infiltrated in the dune area west of Amsterdam for artificial recharge and after a residence time of approximately 100 days extracted and posttreated to achieve drinking water quality. In the extension (capacity 13×10 6 m 3/y) the pretreated (coagulation, sedimentation, filtration) Rhine River water was not infiltrated in the dunes, but was treated directly without soil passage. First, an additional pretreatment (ozonation, biological activated carbon filtration and slow sand filtration) was carried out, and finally reverse osmosis (RO) was used for desalination, hardness removal, disinfection and removal of pesticides and others micro-pollutants. Former research on removal of pesticides has already showed a removal of >99.5% with the ozonation/BACF preceding RO. To prove high retention of RO membranes as a second barrier and to examine the influence of aging of the membranes, several dosing experiments were carried out by AWS and Kiwa. During the period before March 1997, Toray SU 710L membranes were used. From then on Fluid Systems 4821 ULP membranes have been used in the RO pilot plant. The RO feed flow is 9 m 3/h and the recovery is 85%. To compare the removal of pesticides and herbicides with the two different applied RO membranes, six dosing experiments were carried out: two with the Toray membranes and four with the Fluid Systems membranes. A cocktail of pesticides was dosed with a feed concentration of approximately 5 μg/l. The results of the test showed an equal retention for bentazon, DNOC and pirimicarb for both types of membranes. The removal of metamitron and metribuzin was substantially higher with the Fluid Systems membranes. As a result, it was concluded that RO is a second barrier for pesticides in this treatment concept as biological activated carbon filtration in the first barrier. Retention of the Fluid Systems membranes is higher than the retention of the Toray membranes. After 3 years of operation with the Fluid Systems membranes, no pesticide retention decline was observed.

Analysis of Sulfonated Naphthalene−Formaldehyde Condensates by Ion-Pair Chromatography and Their Quantitative Determination from Aqueous Environmental Samples

An ion-pair solid-phase extraction (IPE), ion-pair chromatography (IPC) procedure with fluorescence detection for the quantitative analysis of sulfonated naphthalene-formaldehyde condensates (SNFC) was developed, which provides full resolution of SNFC up to a degree of condensation n = 5 and partial resolution up to n = 15. Liquid chromatography-electrospray ionization-mass spectrometry confirmed that SNFC elute in the order of condensation. Response factors in fluorescence detection proved to be mass-constant, thereby allowing us to determine total SNFC amounts. With this IPC method, the weight- and the number-average molecular weights of these high-volume production chemicals (kiloton per annum), used as synthetic tanning agents, concrete plasticizers, and dispersants, can be determined. Recoveries in IPE range from 73 to 85% in river Rhine water and from 79 to 93% in tap water for n = 2 to n = 7 with limits of detection of 3-8 ng/L for individual homologues from 500 mL of water. The IPE-IPC procedure was applied to samples of secondary industrial effluents, river Rhine water, a river bank filtrate, and a groundwater sample. SNFC up to n = 6 were detected in the treated effluents. Total concentrations ranged from 208 micrograms/L in a secondary treated SNFC production effluent to < 1.4 micrograms/L in groundwater. These first analyses suggest a widespread occurrence of the lower oligomers of SNFC in the aquatic environment.

RO treatment: selection of a pretreatment scheme based on fouling characteristics and operating conditions based on environmental impact

Amsterdam Water Supply investigated the possibilities of increasing the capacity of the River Dune production plant from 70 to 83 million m 3/year. Two possibilities concern the direct treatment of pretreated Rhine River water (C/S/F) by reverse osmosis, without soil passage. In scheme 1, the RO feedwater is pretreated by ozonation, biologically activated carbon filtration and slow sand filtration. In scheme 2 only slow sand filtration is applied as pretreatment of the RO feedwater. To avoid scaling problems with BaSO 4 and CaCO 3, the RO feedwater was acidified with HCl up to a LSI in the concentrate of 0.0 and the RO units were operated with a recovery of 85%. The use of an anti-scalant (Flocon 100) in combination with H 2SO 4 dosage (LSI in the concentrate 2.0) and a recovery of 90% was also successful to control scaling, but this operation mode resulted in severe biofouling as the anti-scalant acted as a nutrient for microbial regrowth in the membrane elements. Both pretreatment schemes resulted in an excellent RO feedwater quality with respect to MFI, DOC, AOC and BFR (biofilm formation rate) with an accompanying very stable operation of the RO units. Over a period of 11 months the MTC of the RO units only showed a decrease of 16% and 23% for pretreatment schemes 1 and 2, respectively, while the differential pressure remained constant. Pretreatment scheme 1 is preferred above pretreatment scheme 2 as it results in additional capacity related to disinfection and organic micropollutant removal. Also the RO concentrate is easier to be disposed of from an environmental point of view. Possibilities are mentioned to further optimize scheme 1 with respect to chemical costs and environmental impact.