Utilisation de l'algue oocystis sp. Pour le traitement tertiaire des eaux usees-II. Effet du conditionnement prealable des cellules en cyclostat sur leur vitesse de prise en charge de l'azote lors d'incubations de longue duree

In an attempt to examine if the rapid uptake of nitrogenous nutrients by “starved” cells occurs also during the prolonged incubation required for complete removal of nutrient from wastewater, ammonia uptake rates for Oocystis sp., in preconditioning phase (phase I) and incubation phase (phase II) are compared.When equilibrium is reached in phase I, phytoplankton cells have a relatively constant N-ammonia uptake rate per cell; this rate varies with the different water stocks used in different experiments, but it is always lower (2–6 times) than the uptake rate exhibited by these cells in phase II.At the end of the second phase (12 h) the cell nitrogen content is up to 3.5 times higher than the initial content.These characteristics of alga Oocystis sp. are discussed and commented.     

Utilisation de cultures de cellules de lignée continue hela pour la mise en evidence de potentialités toxiques in vitro

A simple and reliable test is proposed for the detection of potentially toxic substances and described in detail. This test detects the total toxic effects of chemical or compounds on Hela cells incubated in vitro, either within tubes or over plates. This test can be carried out with large number of samples and its results can be obtained within 7 days. Based on semi-quantitative readings, the final result of the test is expressed as an inhibitory dose (D.I. 50) and/or as a relative potency with respect to a reference toxic chemical: p. chlorophenol. This test has been routinely used, sometimes in association with other tests, to measure the toxic effects of water micropollutants and of atmospheric particles.     

Utilisation de la clinoptilolite en potabilisation des eaux—elimination de l'ion NH4

The objective of this study is to develop a technique to remove ammonium ion from water intended for potable purposes. An ion exchange method is used with a selective ion exchanger, a natural cation zeolite, clinoptilolite. Glass columns (Fig. 1) are used for laboratory experiments. These experiments show that the NH₄⁺ exchange capacity is very small compared to its total capacity 2.17 meq g⁻¹; its value depends essentially on the NH₄⁺ initial concentration and less on the Ca²⁺ concentration in the influent water. Figure 3 illustrates the practical exchange capacity relative to the initial concentration of ammonium ion for a soft water (Ca²⁺ = 35–50 mg l⁻¹). We were particularly interested in waters weak in ammonium ion concentration (NH₄⁺ = 1–3 mg l⁻¹). In this case and for 1 and 2 mg l⁻¹ NH₄⁺ concentration in water, the practical capacity is only 0.06 and 0.108 meq g⁻¹ respectively. The leakage is smaller than the ECC limit (European Community Council) for drinking waters (NH₄⁺ 0.5 mg l⁻¹) and the treated volume of water to breakthrough, defined at 0.5 mg l⁻¹ of NH₄⁺, is 720 BV (BV = bed volume) in both cases.In another way Fig. 6 shows that hard waters (due to Ca²⁺ ions) are more difficult to treat than soft waters. The practical capacity is smaller than before and the NH₄⁺-leakage is greater. To lessen NH₄⁺-leakage to less than 0.5 mg l⁻¹ for soft waters down-flow and up-flow, regeneration is used. Figure 7 shows that up-flow regeneration is more attractive than down-flow regeneration.Cycle reproducibility (Figs 4 and 5) shows that the regeneration conditions satisfied our requirements: in this case, the salt consumption is 180 eq of salt per eq of NH₄⁺ eliminated. This prompted us to try to reuse the regenerant (with NH₄⁺ ion). An increase of NH₄⁺-leakage is noticed in the presence of an NH₄⁺-residual in the regenerant. This increase is more significant with down-flow regeneration.After these laboratory experiments, we carried out a semi-industrial pilot-plant. Our objective was first to verify the laboratory results and secondly to study clinoptilolite behaviour relative to the time it was used. Two plexiglass columns comprise the pilot-plant shown in Fig. 9; soft water is used for these experiments. The first column is regenerated with fresh salt solution. The cycles obtained, considering their initial NH₄⁺-concentration, are reproduced in Fig. 10. For 2 mg l⁻¹ NH₄⁺ in the influent water, the leakage is about 0.2 mg l⁻¹ and the treated volume to breakthrough (0.5 mg l⁻¹ of NH₄⁺) is about 750 BV. The second column is regenerated with a recycled solution. The quality of the cycles decreases with the number of reuse of the regenerant as shown in Fig. 11. Nevertheless, it is interesting to note that after 3 reuses, the performance decrease is only 25% and the leakage, although it increases is smaller than 0.5 mg l⁻¹.Pilot results allowed us to propose a treatment of 30,000 m³ day⁻¹; the cost per cubic meter water treated, relative to NH₄⁺-removal, is about 0.165 FF (0.033 US $) for a plant and 0.77 FF (0.014 US $) for the same plant at the seaside. Using two serial columns decreased the cost by about 40–50%.     

Recherches sur les risques pouvant resulter de la pollution chimique des eaux d'alimentation—II. Etudes comparatives de la toxicite a long terme et de la cytotoxicite des micropolluants organiques extraits des eaux utilisees pour la preparation des eaux d'alimentation

Micropollutants extracted by chloroform from raw river waters used for preparation of drinking waters have been divided into two categories pending the degree of cytotoxicity shown by another team of research using a given cellular system: fractions with high cytotoxicity and fractions with low cytotoxicity.In parallel groups of 50 rats and 60 mice, half male and female, were fed, from weaning, diets containing those fractions.Comparison of the results showed a correlation between the two types of results, only in the case of some biochemical parameters.In regard to the long term effects (lesions of the liver, increase in the incidence of malignant tumors in treated animals), no correlation could be found.

Résumé

Des micropolluants organiques préparés par extraction chloroformique d'eaux brutes ont été répartis en 2 catégories, en fonction des résultats obtenus dans les investigations d'une autre équipe de chercheurs sur un systéme cellulaire: fractions à cytotoxicité forte et fractions à cytotocixité faible.Parallélement, des groupes de 50 rats et de 60 souris, par moitié mâles et femelles, ont reçu dans leur régime, à partir du sevrage et pendant pratiquement toute leur vie, les deux catégories de micropolluants.La comparaison des résultats obtenus dans les 2 types d'investigations nà révélé de corrélation que dans le cas de certains paramétres biochimiques et encore seulement dans une certaine mesure. En ce qui concerne les effets à long terme observés chez les lots traités des 2 espéces animales soumises aux épreuves (nettes altérations hépatique, augmentation de l'incidence des tumeurs malignes), aucune corrélation n'a pu être établie entre les critéres toxicologiques retenus et le degré de cytotoxicité des micropolluants sur le système cellulaire utilisé.     

Études des transformations des formes du carbone, azote, phosphore, soufre et des principaux éléments minéraux au cours de la mesure de la demande totale en oxygene—II. Transformation des formes de l'azote

The experiments realized with the laboratory T.O.D. meter Ionics 225 the DOW Chemical have allowed to distinguish, the stable forms of organic and inorganic nitrogen, after high temperature catalytic action. Organic and ammoniacal nitrogen are partially oxidized during the T.O.D. measurements whereas in the classic C.O.D. and B.O.D.₅ tests these forms are oxidized incompletely. Nitrous and nitric nitrogen induce negative interferences, which can be evaluated and corrected by graphical corrections.     

Recherches sur les risques pouvant resulter de la pollution chimique des eaux d'alimentation—I. Etude de la toxicite a long terme chez le rat et la souris des micropolluants organiques chloroformo-extractibles a partir d'eaux livrees a la consommation humaine

Groups of 50 weaning mice and 50 weaning rats of both sexes received organic micropollutants (extracted from drinking water by chloroform at neutral pH) in their diet for their whole life span. The doses were calculated from a 31 water daily intake by a man of 60 kg, with application of safety factors of 100 and 200. Long term toxicity studies showed:

1. 1. Biochemical changes: increase of transaminases and ornithine carbamyl-transferase activities in blood serum, which, taking into account the variation of activities of the same enzymes in liver parenchyma do not appear to be caused only by hepatic cytolysis.

2. 2. Histopathological changes: (a) liver enlargement, cellular hypertrophy of the liver, steatosis and cirrhosis; (b) significant increase of the incidence of malignant tumours in female mice and in male and female rats with, in the latter, a dose response relationship.

3. 3. Significant increase in mortality rates, in both species, beginning much earlier in males than in females.

A critical discussion is given of results in relation to their value as alarm signs regarding prediction of eventual manifestation of such toxic potentialities in man from consumption, of drinking water containing organic micropollutants.

Résumé

Des micropolluants organiques, obtenus par extraction au chloroforme à pH neutre à partir d'une eau offerte à la consommation humaine (obtenue par traitements classiques, comportant une préchloration, une ozonation et une post-chloration terminale, d'une eau brute de riviére), ont été administrés, ˜a partir du sevrage, après incorporation au régime, á des lots de 50 rats et de 50 souris, par moitié mâles et femelles. Les doses ont été calculées à partir de la consommation quotidienne moyenne de 31 d'eau pour un homme de 60 kg, avec application de facteurs de sécurité de 100 et 200.Les résultats obtenus mettent en evidence les faits principaux suivants:

1. 1. Sur le plan biochimique: Augmentation des activités des transaminases et de l'ornithine transférase au niveau du sérum sanguin traduisant une atteinte du foie qui, d'aprés les observations relatives á l'évolution des taux des mêmes enzymes au niveau du parenchyme hépatique, ne parait pas pouvoir être rapportée à une simple action cytolytique.

2. 2. Sur le plan histologique: (a) phénoménes d'hypertrophie cellulaire au niveau du tissu hépatique avec tendance à la dégénérescence graisseuse et lésions de type cirrhotique; (b) augmentation significative du nombre des tumeurs chez les souris femelles et chez rats des deux sexes avec, au moins chez cette derniére espéce, une corrélation avec la dose.

3. 3. Parallélement, accroissement significatif du taux de mortalité chez les deux espéces, augmentation débutant beaucoup plus précocément chez les mâles.

Discussion critique des résultats obtenus en ce qui concerne notamment leur valeur comme signes d'alarme quant à la manifestation éventuelle de potentialités toxiques pouvant résulter, chez l'homme, de l'ingestion prolongée d'eaux d'alimentation renfermant des traces de micropolluants.     

Photodecomposition du bioxyde de chlore et des ions chlorite par irradiation U.V. en milieu aqueux—partie I. Sous-produits de reactionPhotodecomposition of chlorine dioxide and chlorite by U.V.-Irradiation—Part I. Photo-products

Literature data about the photochemistry of oxychlorine compounds in aqueous solutions (flash photolysis, pulse radiolysis, solar radiation) indicate that the products (ClO, Cl, O, O⁻,…) generated from the primary photochemical reactions of decomposition of chlorine dioxide and hypochlorite can then initiate complex reactions which lead to the formation of many secondary products (Cl₂O₂, Cl₂O₁, ClO⁻,…) and of chlorate, chloride and molecular oxygen as end-products (Table 1). The aim of this work was to study the photodecomposition of aqueous solutions of chlorine dioxide and chlorite in u.v. reactors equipped with low pressure mercury vapour lamps in order to show the effects of pH and of the initial concentrations on the nature of photoproducts and on the rate of photodecomposition of ClO₂ and ClO₂⁻. This paper presents the data obtained for the identification of photoproducts. The kinetics of photodecomposition will be presented in another paper (Part II).     

Etudes des transformations des formes du carbone, azote, phosphore, soufre, et des principaux elements mineraux au cours de la mesure de la demande totale en oxygene—I. Transformation des formes du carbone et des principaux cations

Les expériences réalisées sur le D.T.O. mètre de laboratoire IONICS 225 de la Dow Chemical, ont permis de caractériser, aprés l'action catalytique à haute température, les formes stables du carbone, de l'hydrogéne et des cations sodium, potassium, calcium, magnésium.Dans l'intervalle 0–250 mg O₂ l ou la réponse du capteur d'oxygène est proportionnelle à la concentration en matière organique nous avons démontré expérimentalement que le carbone organique ou minéral est transformé en CO₂ l'hydrogène en H₂O, et les cations sodium, potassium, calcium, magnésium en leurs oxyde et hydroxyde correspondants.Les ions bicarbonates et carbonates sont réduits et créent une interference négative: par contre les cations sont oxydés et creent une interférence positive dans la mesure de l'équivalent oxygéne par le D.T.O. métre.     

Influence de la duree d'exposition sur la bioaccumulation par voie directe de deux derives du mercure par Salmo gairdneri (alevins) et relation “poids des organismes-concentration en mercure”

In the context of ecotoxicological research on the contamination of continental aquatic systems by mercury compounds, the analysis of bioaccumulation at different consumer levels (especially fish) shows that the weight of the organism affects the concentration factors measured. However, after a bibliographic synthesis it is not possible to define precisely what this effect might be, since published results show either an absence of any relationship, or a positive or negative correlation, depending on the authors and on the conditions of intoxication.Our research is based on the direct contamination of newly hatched rainbow trout (weight when time factor = zero : 0.20 g); concentration of mercury in the water was 1 μg l⁻¹ (1 ± 0.1 ppb for the duration of the experiment). Two compounds were studied : HgCl₂ and CH₃HgCl. By using automated contamination modules we were able to maintain constant biotic conditions (number of fish per tank) and abiotic conditions (temperature: 15 ± 0.5°C; photoperiod; 16h/8h; concentration of Hg in the water) for the two contaminants.An analysis of the mercury bioaccumulated was carried out after 15, 30, 60 and 83 days of exposure. For each experimental condition—e.g. HgCl₂, 15 days—25 fish were kept at time factor zero. The mercury concentration was determined by flameless atomic absorption spectrophotometry (VARIAN AA 475). A polynomial regression method, with or without transgeneration of the dependent variable, was used in order to demonstrate a possible relationship between the “weight of organism” and “concentration of mercury” parameters.A comparison of the development in weight of the organisms in all the different populations contaminated by HgCl₂ and CH₃HgCl (Fig. 1) shows that this is identical up to 30 days. Between 30 and 83 days it may be seen that methylmercury has a very strong influence on this parameter which is coupled with a reduction in food intake and a considerable increase in mortality.The dynamics of the average mercury content—μg per organism—and the corresponding concentrations (μg g⁻¹ fresh weight) over the 83 days exposure period (Fig. 2) show that the mercury content and concentration in the fish are much higher for methylmercury than for mercuric chloride and this does not depend on the length of exposure period, e.g. at 60 days the ratio between CH₃HgCl and HgCl₂ concentrations is about 7.Although the concentration of the two contaminants in the environment was kept constant (1 ppb), the curves representing mercury accumulation—expressed as a concentration—are not linear and show a fairly pronounced plateau.The relationship between “organism weight” and “concentration of mercury” was studied for both two mercury compounds during each experimental exposure period (Figs 3 and 4).The noticeable grouping of points corresponding to each population studied indicates a relationship between the weight and concentration parameters; in both contaminants the concentration factor develops in relation with the exposure period. Although it is rather simple and approximate, the linear model displays quite satisfactorily the phenomenon we are studying and its development (Table 1). However a logarithmic relationship gives a better adjustment of the results.Analysis of the results shows:A negative correlation between the weight of the organisms and their mercury concentration for both compounds. This correlation decreased as the exposure period increased. In the case of HgCl₂, after 83 days exposure, the weight no longer seemed to have an influence on the amounts of metal bioaccumulated by the fish.A difference between the adjusted straight lines for HgCl₂ and CH₃HgCl, the organism weight has a greater influence on concentration in the case of contamination by the organic compound.Observations conducted in a natural environment usually show a positive relationship between concentration and the weight of the organisms. When compared with these, our experimental results cannot be said to be contradictory since they deal with different biotic conditions: contamination methods, growth rate and age of individuals.An assessment of the level of contamination in aquatic ecosystems is usually based on an estimation of concentration levels found in the organisms, and, especially for fish, in the skeletal muscles. Our results however, show the necessity of taking organism weight into consideration; the influence of this parameter on the processes of bioaccumulation is particularly important in the case of mercury contamination in the newly hatched stage, and probably in other species with a rapid growth rate. In the case of experimental research into these processes influence of organism weight is considerable and therefore necessitates its examination especially when the object of the study is the development of a standardised toxicological test.     

Direct influence of wastewater pollutants on flocculation and sedimentation behaviour in biological wastewater treatment—I model system E. coli B

The influence of different chemicals on flocculation and sedimentation in wastewater was investigated in a model system of washed E. Coli B harvested at the end of the logarithmic phase. It was found that the amount of extracellular polymeric material present in the system affected the coagulation by neutral salts and also the degree of influence of the model pollutants investigated. Considerable effects on sedimentation could be found for several of the pollutants when the cells were in the state of slow coagulation close to the critical coagulation concentration (ccc). These effects were attributed to interactions between the extracellular polymers and pollutants influencing the bridging between cells.