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—III transformation des formes du soufre

Previous experiments carried out with the laboratory TOD meter Ionics 225 of the DOW Chèmical made it possible (after a high temperature catalytic action) to characterize the stable forms of organic and inorganic carbon and nitrogen (NH₄⁺, NO₂⁻, NO₃⁻), and the principal cations (Na⁺, K⁺, Ca²⁺, Mg²⁺) in the course of the total oxygen demand (TOD) measurement.The object of this study is firstly to compare the oxidation capability of different techniques of organic pollution (particularly the COD and TOD) in relation to the constituent elements of the organic matter C, N, P, S, and to calculate the possible interferences of the inorganic compounds at the time of TOD test.These investigations warrant the application of this technique to measure the amount of organic pollution in relatively mineralized conditions (Industrial wastewater, sea-water…). The present publication is concerned more with the study of the transformation of the organic and inorganic sulphur forms (S²⁻, SO₃²⁻. SO₄²⁻) in the course of the TOD measurement.The study of the oxidizability of the organic sulphur compound type C_xH_yO_zS, made it possible to establish a specific relation with a ratio of 0–50 mg of organic sulphur l⁻¹, between the oxygen demand of this element [TOD (S)] and its concentration (TOD (S) = 0.97 [S]).These tests showed a partial oxidation of the sulphur to SO₂ and SO₃ as the literature claimed. On the other hand, the oxidation of the same compounds during the COD tests varies greatly and although it is not possible to establish a correlation between these two measurements, as applies in the case of organic nitrogen, nevertheless these experiments showed a greater reliability of the TOD compared with the COD in the oxidation of organic matter in general. We then carried out experiments on the different mineral forms of sulphur in order to distinguish the possible effects and to recommend simple improvements.A relative study on sulphate ions had been carried out with standard solutions which have the same TOD (the basic TOD is obtained using potassium phthalate acid) and the same increasing concentration of the salt M₂SO₄ type. The experiments showed that the basic TOD decreases when the concentration of sulphate ions is increased (Fig. 3). Therefore, the interference is negative and taking into consideration the specific oxygen demand of the cation, we can propose an evaluation of this interference (ΔTOD (SO₄²⁻) = 0.203 [SO₄²⁻]). The same experiments have been conducted with a salt of M₂SO₃ type and similar results obtained (Fig. 5).The specific interference of the sulphite ion is negative and can be estimated by the following equation (ΔTOD (SO₃²⁻) = 0.132 [SO₃²⁻]). In both cases, we have to note that the transformation of these inorganic anions occurs between those relative to the theoretical dissociation reaction corresponding to the appearance of the oxide SO₂ and SO₃. For sulphurous on the contrary, the interference is positive and therefore corresponds to an extra oxygen demand (Fig. 8).The experiments were conducted directly with the M₂S salts (M representing K or Na) in aqueous solution.The evaluation of this interference had been made in the consideration of two concentration ranges of the sulphurous ions (0–35 mg S²⁻ l⁻¹): TOD (S²⁻) = 0.4 [S²⁻] and (35–100 mg S²⁻ l⁻¹): TOD (S²⁻) = 1.2 [S²⁻] − 30.Therefore this study confirms a better oxidation of the organic matter by TOD test in comparison with COD test.But sulphate and sulfite have a negative interference in the TOD measurement, whereas sulphurous is positive.The evaluation model of these interferences allows a correction to be made of the TOD value or to verify TOD measurement of organic pollution obtained by this technique.     

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.     

Caracterisation de la matiere organique dissoute presente dans les eaux en cours d'affinage: Influence des traitements appliques et du climat

Dissolved organic matter in treated surface waters (clarified, possibly ozonized, then GAC-filtered, Fig. 1), is fractionated by ultrafiltration into five molecular classes with MW < 300, 300–1000, 1000–5000, 5000–10000 or > 10,000. Dissolved organic carbon (DOC), oxidizability by KMnO₄ in hot alkaline medium and u.v. absorbances at 240, 254, 280, 300 nm are measured. Fourteen series of samples, distributed on an annual biological cycle are analysed (Figs 2 and 3); multivariate statistical analyses are performed.By PCA (principal component analysis), variations in water supplying the activated carbon units appear to depend for 47% on ozonation and temperature; but river flow rate and quantity of flocculant added are no longer responsible for such variations (Fig. 4). Three groups of water appear (Fig. 5), according to the applied ozone level (zero, medium, high); among the medium ozonized waters, the cold ones differ from temperate ones.Ozonation diminishes molecular size of compounds (Table 1): three major classes with MW < 5000 are present in non- or medium-ozonized waters, but only two, with MW < 1000, remain in highly ozonized waters. This treatment destroys MW > 10,000 and even 1000–5000 ones and yields MW < 300 products; it also minimizes u.v. absorbances and oxidizability. Seasonal variations occur in DOC content of medium ozonized waters, with maxima values in winter or spring and minima in summer or autumn (Fig. 6): occurrence of MW < 300 compounds follows that of DOC, but the presence of 5000–10000 ones is minimal in winter.Quality of GAC-filtered waters varies by 19% with temperature (Fig. 7); ozonation effects are minimized: only previously highly ozonized waters distinguished themselves from the others (Fig. 8). Waters, non or medium ozonized before GAC-filtration, are divided into cold, temperate and warm waters. One, two or three major classes of compounds with MW < 5000, remain in GAC-filtered waters, according to the ozone level applied previously. This filtration reduces DOC by 17%, decreases u.v. absorbances and oxidizability and gives water with the same 0.30 mg O₂ mg⁻¹ C ratio (Table 2): MW 1000–5000 class is much less oxidizable after ozonation-GAC filtration but, on the other hand, MW < 300 class appears rather less oxidizable without ozonation before biological filtration. DOC content in effluent follows that in influent (Fig. 9), but variations are less marked. Total efficiency of the filtration increases with temperature, but behaviour of compounds differs from one class to another: MW 300–1000 and 5000–10000 classes are the most affected; MW 1000–5000 is not really modified. Elimination of MW < 300 or 5000–10000 compounds depends on temperature and may be due to biological phenomena, a but that of 1000–5000 and > 10,000 classes, independent of this parameter, may be related to adsorption mechanisms.     

Etude du transfert DE Cd, Pb, Cu ET Zn dans les chaines trophiques neritiques et estuariennes—I. Etat dans l'estuaire interne de la loire (France) au cours de l'ete 1978

In order to determine the behaviour of some trace elements (Cd, Pb, Cu, Zn) in estuarine biota, different species of crustaceans and fishes were taken up from the Loire estuary. The concentrations of metals were determined by atomic absorption.Except for Zn, the accumulation of metals is higher in crustaceans than in fishes and the phenomenon is particularly important for copper, a constituent of crustaceans respiratory pigment. The concentrations of metals are no more important for bottom-feeders than for other fishes. The highest levels are encountered for Zn followed by Cu, Pb and Cd. The Loire organisms are not so contaminated than those of the same species taken up from heavily polluted estuaries (Severn and Medway, G.-B.).Transfers in food chains were quantified with the transfer factor: f.t. = Concentration in the consumer/Concentration in the prey.For Cd, Pb and Cu, the transfer factor is generally inferior to 1, attaining exceptionally 2.01. Except in one case, it is higher than 1 for Zn. The concentration of trace elements in intestine content is higher than in stomach content, probably as a consequence of faeces enrichment by unassimilated metals. So, there is probably no biomagnification in estuarine food chain for Cd, Pb and Cu, the case of Zn being more ambiguous.     

Caracterisation de la matiere organique dissoute presente dans les eaux en cours d'affinage: Influence des traitements appliques et du climatCharacterization of dissolved organic matter in surface waters through polishing treatment: Influence of applied treatments and climate

Dissolved organic matter in treated surface waters (clarified, possibly ozonized, then GAC-filtered, Fig. 1), is fractionated by ultrafiltration into five molecular classes with MW < 300, 300–1000, 1000–5000, 5000–10000 or > 10,000. Dissolved organic carbon (DOC), oxidizability by KMnO₄ in hot alkaline medium and u.v. absorbances at 240, 254, 280, 300 nm are measured. Fourteen series of samples, distributed on an annual biological cycle are analysed (Figs 2 and 3); multivariate statistical analyses are performed.

By PCA (principal component analysis), variations in water supplying the activated carbon units appear to depend for 47% on ozonation and temperature; but river flow rate and quantity of flocculant added are no longer responsible for such variations (Fig. 4). Three groups of water appear (Fig. 5), according to the applied ozone level (zero, medium, high); among the medium ozonized waters, the cold ones differ from temperate ones.

Ozonation diminishes molecular size of compounds (Table 1): three major classes with MW < 5000 are present in non- or medium-ozonized waters, but only two, with MW < 1000, remain in highly ozonized waters. This treatment destroys MW > 10,000 and even 1000–5000 ones and yields MW < 300 products; it also minimizes u.v. absorbances and oxidizability. Seasonal variations occur in DOC content of medium ozonized waters, with maxima values in winter or spring and minima in summer or autumn (Fig. 6): occurrence of MW < 300 compounds follows that of DOC, but the presence of 5000–10000 ones is minimal in winter.

Quality of GAC-filtered waters varies by 19% with temperature (Fig. 7); ozonation effects are minimized: only previously highly ozonized waters distinguished themselves from the others (Fig. 8). Waters, non or medium ozonized before GAC-filtration, are divided into cold, temperate and warm waters. One, two or three major classes of compounds with MW < 5000, remain in GAC-filtered waters, according to the ozone level applied previously. This filtration reduces DOC by 17%, decreases u.v. absorbances and oxidizability and gives water with the same 0.30 mg O₂ mg⁻¹ C ratio (Table 2): MW 1000–5000 class is much less oxidizable after ozonation-GAC filtration but, on the other hand, MW < 300 class appears rather less oxidizable without ozonation before biological filtration. DOC content in effluent follows that in influent (Fig. 9), but variations are less marked. Total efficiency of the filtration increases with temperature, but behaviour of compounds differs from one class to another: MW 300–1000 and 5000–10000 classes are the most affected; MW 1000–5000 is not really modified. Elimination of MW < 300 or 5000–10000 compounds depends on temperature and may be due to biological phenomena, a but that of 1000–5000 and > 10,000 classes, independent of this parameter, may be related to adsorption mechanisms.