Volume 1, Number 4, 1988

FR:

Le phosphore est l'élément responsable de l'eutrophisation des lacs et des cours d'eau. Ainsi, il faudrait prendre les précautions nécessaires pour que la concentration maximale de phosphate total dans l'effluent des usines d'épuration soit 1 mg/l. On sait que l'élimination biologique du phosphore peut conduire à une réduction des phosphates totaux d'environ 40 %. Ici les facteurs comme la température de l'eau et de l'air ambiant peuvent influencer les divers processus de modification des phosphates. La présente étude évalue l'importance de ces paramètres sur les modifications telles que l'orthophosphate filtrable et le phosphate total. Les résultats obtenus sont utilisés pour définir les rapports entre les diverses modifications à l'aide de modèles mathématiques simples et utilisables dans la pratique.

EN:

The presence of phosphorus is undesirable in treated wastewater effluents as it leads to eutrophication in the lakes or river systems. Municipal wastewater treatment plants should therefore give particular attention to keep total phosphate concentrations below 1 mg/l in their effluents. Phosphorus can be removed by biological methods up to about 40 % of its influent concentration. Bacteria hydrolyse and convert the condensed phosphates in to the easily removable orthophosphate form. Temperature variations of air and wastewater can have significant influence on the form of phosphate fraction present in wastewater. In the present study, the effects of temperature variations in summer and winter on the relationships between filterable orthophosphates and total phosphates in wastewater are reported. Using results from laboratory studies as well as from existing wastewater treatment plants treating domestic wastewater, simple mathematical models are developed for various phosphate species. These relationships are useful in day-to-day operation of a treatment plant in monitoring the total phosphates leaving with the treated effluent : if orthophosphate measurement is utilized to characterize the effluent total phosphate, then the plant operator will be well advised to watch the seasonal variations of the various phosphate concentrations.

FR:

L'évolution de la pollution et les modalités du transport des P.C.B. en rivière ont été étudiées en Seine à Paris en relation avec les épisodes du cycle hydrologique durant un an.

Les résultats analytiques montrent que la pollution occasionnée par les P.C.B. est supérieure à celle produite par les autres résidus de pesticides organochlorés, et ceci malgré la limitation réglementaire d'emploi des P.C.B. aux systèmes clos depuis 1975.

Pour 88 % des échantillons analysés, les concentrations en P.C.B. dissous sont supérieures aux teneurs en P.C.B. adsorbés sur M.E.S. et atteignent jusqu'à 170 ng.l^-1.

Le transport se fait en solution pour 73 %, en moyenne, de la teneur totale, contrairement aux idées admises fondées sur la faible solubilité du polluant, mais qui ne prennent pas en compte le rapport en masse M.E.S./eau voisin de 25 x 10^-6 en rivière.

L'étude de la capacité d'adsorption des particules démontre qu'elle subit une évolution inverse de celle de la charge solide et du débit, ce qui explique la dominance des P.C.B. en phase aqueuse quelle que soit la teneur en M.E.S.

Il en résulte que les valeurs élevées du coefficient de partage ne correspondent pas aux fortes teneurs en M.E.S. Les valeurs sont faibles pour la moitié d'entre elles et comprises entre 2 x 10³ et 12 x 10³ l.kg^-1.

EN:

The evolution of pollution by PCBs and their transport state in rivers was studied in the River Seine in Paris, in relation to the yearly hydrological cycle.

Sampling took place just upstream of main waste waters (output) in the Paris area, and downstream from the junction of the Marne and the Seine, in order to establish the mean quality of water pumped upstream of these two rivers for drinking water production.

Micropollutant concentrations were measured on 500 ml of raw water and 500 ml of water centrifuged at 6 000 G. Three extractions were carried out on these samples with a solvent mixture (85 % hexane, 15 % dichloromethane).

In some cases extracts were purified on unactivated Florisil. After concentration down to 1 ml, extracts were measured through GC (falling needle injector; fused silica capillry column I.D. 0.25 mm, stationary phase SPB5; E.C.D. ni 63; vector gas He, make up Ar + 10 % CH₄).

Identification and quantification were carried out using an integrator and commercial Aroclor : 1242, 1254 and 1268 standards. In natural samples, the isomer composition is generally close to that of Aroclor 1254.

Analytical data show that pollution linked to PCBs is higher than that due to other organochlorinated products, in spite of the official PCBs use limitation for closed systems since 1975.

Except for a pollution peak of 990 ng.l^-1, concentrations in raw water are irregular and vary from 25 to 250 ng.l^-1.

For 88 % of analyzed samples, dissolved PCB concentrations are higher than the concentrations of PCBs adsorbed onto suspended matter and reach 170 ng.1^-1. The main transport (73 %) of the total flux is by solution, in contradiction with commonly accepted views based on the low solubility of PCBs.

The study of adsorption capacity of solid particles demonstrates that its evolution is negatively correlated with the water flux and the solid load, which explains the prevalence of PCBs transport through solution, whatever the suspended matter concentration. Thereafter, it appears that high values of the partition coefficient are not linked to the concentration of suspended matter. For about half of them, values are low, between 2.10² and 12.101 l.kg^-1.

FR:

L'étude de l'équilibre calco-carbonique d'une eau souterraine de l'Afrique de l'Ouest par la méthode de LEGRAND et POIRIER, a conduit à la détermination des conditions de traitement pour neutraliser l'agressivité naturelle de l'eau, due essentiellement à une forte teneur en acide carbonique et réduire ainsi son caractère corrosif. le problème de l'évolution du fer présent en relation avec la mise à l'équilibre a été également étudiée.

L'application réalisée sur un pilote de laboratoire a permis d'optimiser les principales étapes du traitement, c'est-à-dire l'addition d'une base forte, la précipitation et la filtration des hydroxydes ferriques qui se forment à la suite de la neutralisation de l'acide carbonique.

EN:

Studies on calcium carbonate equilibrium of West African ground water, a sample of potable water distributed in Lomé (Togo), were carried out using the method described by LEGRAND and POIRIER. It is a standard graphic method in which calculations include all basic (Ca⁺⁺, HCO₃^-, CO₃^--, CO₂, H₂O⁺, OH^-), and characteristic (Mg⁺⁺, Na⁺, K⁺, SO₄^--, Cl^- ...) chemical parameters of natural water. Processing of a computer program for calculations enabled the equilibrium and saturation curve [CO₂] = f[Ca⁺⁺], to be obtained. The aggressivity to the lime deposit character, different conditions of treatment, aeration, and addition of an appropriate base to neutralise the nature aggressivity of water due to its high dissolved carbon dioxide content could also be defined.

The problem of the presence of iron was studied; high concentration of iron in natural ground water lead to various problems : developing of tastes, staining and discoloration of clothes, and growth of iron bacteria in the distribution system. Its removal from water is accomplished by means of the oxidation of iron (II) to iron (III) followed by the precipitation of relatively insoluble ferric hydroxide. The oxidation rate is highly dependent on pH. Thus, the process of removal of carbon dioxide by stripping or neutralisation raises the pH of the water. If the pH is raised high enough, an insoluble form of iron will precipitate. Another important aspect of the chemical behaviour of iron is the formation of complex ions with inorganic as well as organic ligands; silica in water forms a relatively stable complex with iron (III). The difficulty in removing iron from water is often associated with this phenomenon.

Continuous flow studies were carried out to improve important steps of treatment such as addition of a strong base, and precipitation and filtration of ferric hydroxide produced during carbonic acid neutralization. They show the weak stability of silicato-iron (III) complex at high pH value and prove that practically complete iron removal may be obtained.

FR:

La matière organique présente dans une eau clarifiée et ozonée puis filtrée sur charbon a été caractérisée durant 8 mois par l'oxydabilité au KMnO₄ à chaud et en milieu acide; on a relevé les paramètres climatiques et noté les traitements de potabilisation appliqués.

Une analyse en composantes principales suivie d'une analyse discriminante effectuée sur 129 prélèvements fait ressortir que deux paramètres - la température et le pH - suffisent à classer ces eaux en 3 groupes : chacun d'eux correspond à une saison, avec un pourcentage d'erreur de 6 %.

En moyenne, l'oxydabitité de l'eau à l'entrée du filtre ne varie pas d'une saison à l'autre; mais la dispersion des valeurs est plus importante au printemps. La politique de traitement appliquée n'apparaît pas clairement. Des analyses de variance suivies de régressions linéaires multiples montrent que cette oxydabilité dépend à la fois de la séquence et du traitement d'ozonation : moins de 30 % de La variance se trouvent ainsi expliqués.

La filtration sur charbon à 5 m.h^-1 abaisse l'oxydabilité de G à 0,8 mg O₂ par litre et diminue sa variabilité. On note cependant des relargages en fin de printemps lors du rééquilibrage du filtre. L'oxydabilité de l'eau filtrée dépend à la fois de celle mesurée à l'entrée du filtre et de la température : les modèles retenus, déterminés par régression linéaire multiple, diffèrent d'une saison à l'autre, indiquant un fonctionnement différent du réacteur. Il est alors possible de définir des périodes où elle est minimale.

La qualité d'une eau affinée varie ainsi avec les saisons, ceci malgré un lissage dû aux effets des traitements appliqués en amont.

EN:

Oxidizability by KMnO₄ in a hot acidic medium was used for 8 months to estimate organic matter in clarified-ozonized then GAC-filtered waters, treated on a pilot plant (Figure 1).

Flowrate of the River Seine (DEB), temperature (TEM), pH (PHE) and oxidizability of the waters before GAC-filtration (OXE) are shown to vary with time (Figures 2 to 5). The first two parameters are generally used to classify raw waters but here they are not enough (Figure 6). Then, multivariate statistical analyses - principal component analysis and discriminant analysis - are carried out on 129 samples : they show (Figure 7) that two parameters, one in connection with climate only - temperature - and the other in connection with both climate and treatments - pH - are able to classify these waters into three groups equivalent to three seasons; the error coefficient is of 6 % only. Seasonal characteristics of these waters are given in Table 1. Average values of oxidizability (OXE) do not vary with the seasons, but standard-deviation is the greatest in Spring.

There is no apparent connection between the different treatments - preozonation level (PO₃), quantity of flocculant added (WAC), land-filtration velocity (VFS), ozonation level (O₃F), residual ozone level (O₃R), GAC-filtration flowrate (DAL) - except between the two ozonation treatments (Figure 3). Their seasonal variations are given in Table 2.

Variance analyses show that the 3 factors, quantity of floccutant (WAC), sand-filtration velocity (VFS) and absence of preozonation (PO₃), have no effect upon the oxidizability of the water supptying the GAC-filter (OXE). This parameter is a function of preozonation (PO₃), interozonation (O₃F) and residual ozone levels (O₃R) and sequency (SEQ) : the models achieved, determined by linear multiple regression, account for less than 30 % of the variance (Figure 9).

The GAC-filtration at 5 m.h^-1 diminishes the oxidizability values of zero to 0.8 mg O₂l^-1 and their variability; however, some releases appear at the end of Spring, during the re-equilibration phase of the filter (Figure 10). By linear multiple regression, we can express the oxidizability of the filtered waters (OXS) as a function of (OXE) and temperature (TEM). The models achieved differ from one season to another (Figure 11) and account for 32 to 73 % of the variance; thus the working of the GAC-filter is dependent on the seasons.

Many authors assume that the risk of bacterial regrowth in the distribution network is minimal when the oxidizability of the treated waters is minimal. Here, the oxidizability of the filtered waters (OXS) is at its lowest when temperature (TEM) and (OXE) are lowest (Figures 12 and 13). These conditions are often met in the middle of the seasons, when the quantity and the quality of the organic matter vary little; the fitter is then balanced.

The quality of a treated water therefore varies with the seasons, despite polishing obtained through treatments applied upstream, which tend to improve it and diminish its variability.

FR:

L'influence du facteur thermique sur la contamination de la carpe par le ⁶⁰Co a été étudiée pour 4 températures : 8 °C, 15 °C, 20 °C et 25 °C. Pour chaque expérience, un lot homogène de 10 individus, d'une masse initiale d'environ 2,3 g et nourris ad libitum, est introduit dans 5 litres d'eau, renouvelée tous les 3 à 4 jours et contaminée à raison de 1,2.10⁵ Bq.l-1.

Entre deux renouvellements, la concentration du ⁶⁰Co dans l'eau décroît sensiblement et l'état ionique du radionucléide, introduit à 100 % sous forme cationique, évolue vers des formes anioniques et neutres. Ces deux faits sont liés au métabolisme des poissons dont la croissance pondérale est corrélée à la température, la distribution de la nourriture étant adaptée aux besoins des individus.

Globalement, la quantité totale de radiocobalt fixée par les carpes apparaît très fortement liée au facteur thermique mais, selon le niveau des températures, des situations différentes se dégagent pour des mêmes écarts. Il n'y a pas proportionnalité comptéte entre élévation de température et accumulation du ⁶⁰Co mais une augmentation discontinue témoignant de l'existence de paliers, dont le plus important se situe à 20 °C.Le facteur de concentration du ⁶⁰Co est, par contre, peu influencé par le facteur thermique pour les écarts inférieurs à 10 °C ou quand la température maximale est inférieure à 20 °C. L'incidence de la température devient sensible quand les écarts dépassent 10 °C et notamment lorsque sont atteintes des valeurs correspondant à l'optimum thermique des carpes. A l'équilibre, le facteur de concentration moyen du ⁶⁰Co est de 3,6 à 8 °C, 4,4 à 15 °C, 5,1 à 20 °C et 6 à 25 °C.

EN:

The problems of simultaneous thermal and radionuclide pollutions have led to a number of laboratory and field studies of the temperature effects on the radioactive contamination of aquatic organisms. AMIARD and KHALANSKI (1981) concluded from their bibliographic study that a temperature rise generally has a positive effect on biological accumulation of radionuclides in freshwater organisms. Due to insufficient data, however, this conclusion does not appear to be substantiated for ⁶⁰Co uptake by fish. An experimental study was therefore undertaken to assess the effect of temperature on ⁶⁰Co uptake by Caprinus carpio.

The importance of ⁶⁰Co results from the fact that, apart from tritium, radioactive cobalt isotopes represent the major components of liquid wastes discharged from pressurized water reactors, which are widely operated in France (BARDIN et al., 1982; PICAT et al., 1986). The common carp (Caprinus carpio L.) was selected as the subject of this experimentation because of its wide geographic distribution and the frequency with which it is found in field samples, making it a suitable biological indicator (D'AUBENTON and SPILLMANN, 1978; FOULQUIER and PALLY, 1982; FOULQUIER et al., 1985).

The effect of temperature on ⁶⁰Co contamination of the carp was investigated by conducting the same experiment at four temperatures (8 °C, 15 °C, 20 °C and 25 °C) determined by ecological and physiological criteria. In each experiment, young carps with a mean weight of 2.3 g were placed in a tank containing 5 liters of water contaminated with 1.2 x 105 Bq.l^-1 of ⁶⁰Co. The water was renewed at intervals of 3 - 4 days. Modifications in the ionic form of the radio-active cobalt dissolved in the water were monitored by percolating filtered water samples through ion exchange resin columns. The carps were fed to satiation with an industrial food containing 12 % minerals, 8 % fats and 58 % proteins (dry weight) together with vitamins and trace elements including 0.2 mg.kg^-1 of cobalt. Radioactivity levels in the fish were measured, after mild anesthesia, with a single-channel amplitude selector equipped with a thallium-activated flat sodium iodine probe.

Between successive water renewals, the ⁶⁰Co concentration diminished (Table 1) and the ionic form of the radionuclide remaining in solution was significantly modified. The ⁶⁰Co was introduced in chloride form and was initially found exclusively as a cation; anionic or neutral forms appeared and became dominant after a few days (Figure 1). These two phenomena are probably related to the fish metabolism which is temperature dependent. Thus, food was distributed according to the individual requirements, and an exponential correlation was observed between the temperature and the weight gain in the carps (Table 1). The appearance of anionic and neutral forms may be attributed to excessive amounts of organic matter due to the presence of the fish and food (FUKAI and MURRAY, 1973; KILLEY et al., 1984). This evolution also results from a significant increase in ions such as HCO₃^-, Cl^-, SO₄^--, PO₄^-- and NH₄⁺ (FRITSCH and BAUDIN, 1984) which may combine with Co++ ions to form neutral molecules and anionic complexes (TRISHAN et al., 1981). Radioactive decay in the mater is also temperature-dependent : the amount of fecal matter, which strongly adsorbs radioactive cobalt, is proportional to the metabolic intensity in the fish.

The overall ⁶⁰Co uptake by the carps (Table 2) appears to be strongly related to the temperature, but the effect of a given temperature rise varied with the initial temperature (Table 4). The ⁶⁰Co uptake was not fully proportional to the temperature rise, but was observed to increase in stepwise fashion indicating the existence of various thresholds. The most significant of these was noted at 20 °C, which is the lower limit of the optimum temperature range for carps.

The ⁶⁰Co concentration in th fish (Table 3) was influenced to a much lower extent by the temperature than the total uptake. Small temperature variations (5 - 7 °C) had little or no effect on the concentration factor; this was also true for larger variations, from 8 °C to 20 °C (Table 4). Temperature effects were only significant between 8 °C and 25 °C, and between 15 °C and 25 °C.

The ⁶⁰Co concentration variation in time was similar for all four temperatures, with two successive phases (Figure 2). It can be expressed mathematically by an exponential model based on the existence of several compartments in living organisms characterized by the influx and efflux rates for the element under consideration (GOLSTEIN and ELWOOD, 1971; AOYAMA and INOUE, 1973; PENTREATH, 1975; GONTIER, 1983). The maximum value and the time required to reach equilibrium were determined by extrapolation from the equations for the concentration factor variations. The results were 3.6 and 510 days at 8 °C, 4.4 and 220 days at 15 °C, 5.1 and 125 days at 20 °C, and 6 and 110 days at 25 °C. These values indicate that a temperature rise diminishes the time required to reach equilibrium and slightly increases the concentration factor by an amount that is statistically significant only for major temperature differences (Table 4).

Detailed investigations of various freshwater species, notably Caprinus carpio, have demonstrated the decisive effect of temperature on metabolic activity in these animals (LEVESQUE, 1980). The results presented here indicate that the ⁶⁰Co uptake rate in the carp is not proportional to the temperature rise as is generally the case for physiological processes. From a radiation protection standpoint, this observation suggests that the temperature is not an essential factor in ⁶⁰Co contamination of freshwater fish.

FR:

Ce travail a pour objet de présenter une nouvelle méthode de dénombrement des Salmonella dans différents types d'eaux (de rivière, saumâtre, eaux usées brutes et épurées) basée sur l'utilisation d'un milieu d'enrichissement au sélénite additionné de Novobiocine et de Pril et sur une adaptation de la technique du N.P.P. à l'ensemencement d'échantillons de grands volumes après filtration permettant de quantifier les très faibles concentrations de Salmonella. Les vérifications des performances de cette méthode d'isolement et de quantification sont basées sur l'étude des croissances de différentes souches de Salmonella et d'autres espèces bactériennes dans le milieu d'enrichissement modifié, ainsi que sur les résultats quantitatifs et qualitatifs fournis par cette méthode lorsqu'elle est appliquée à des échantillons d'eau en provenance de l'environnement aquatique. Ces résultats montrent notamment que la méthode proposée est suffisamment sensible pour détecter 1 à 2 Salmonella dans 10 litres d'eau analysée et qu'elle ne parait pas exclure de sérotypes, du moins parmi ceux les plus fréquemment isolés en France. L'efficacité de la méthode standardisée API Z pour l'identification enzymatique du genre Salmonella a été également testée en référence aux résultats de la sérotypie.

EN:

This paper presents a new method for enumerating Salmonellae in environmental waters (freshwater, brackishwater, sewage and treated waters) using the F Selenite enrichment broth modified by the addition of Novobiocin and Pril, and an adaptation of the M.P.N. method for the inoculation of large amounts of water after filtration to improve the enumeration of low concentrations of Salmonellae. The verification of the performance of this detection and enumeration method are based on the study of the growth of different Salmonellae species and of others bacterial species in the modified enrichment broth, and on the quantitative and qualitative results obtained by the application of this methodology to aquatic environmental samples. These results show on one hand, that the sensitivity of the proposed method allows to enumerate 1 to 2 Salmonellae in 10 liter samples, and on the other hand that this method to net exclude any serovar from those which are the most frequently isolated in France. The efficiency of the API Z standardized method for the Salmonellae enzymatic identification versus serological identification was also verified.