Adsorption de surfactants sur le dechet lainier de carbonisage surfactant adsorption on the wool carbonizing waste

Although wool carbonizing waste is available in large amounts (8.000 tonnes per year, in France), no process has been developed for its valorization. Wool carbonizing waste is made up of chemically modified short-sized wool fibres and of plant material particles which are considered as sulphuric lignins. Owing to the physical structure as well as to the polar and apolar characteristics of its macromolecules, wool carbonizing waste was likely to be a suitable material for the adsorption of ionic organic solutes. The adsorption of various surfactants on wool carbonizing waste was therefore investigated so as to assess the optimal conditions of use of this substrate in water pollution control. The adsorption isotherms of anionic (SDS; Figs 1 and 2). cationic (CPC; Figs 3 and 4), and non-ionic (NPPO; Fig. 5) surfactants were drawn, for various pH and temperature conditions, so as to determine the adsorption mechanisms involved as well as the adsorption capacity of the carbonizing waste and the optimal adsorption conditions. The adsorption was shown to be enhanced by temperature as a result of changes in adsorbent structure. Wool carbonizing waste is therefore liable to be used for the purification of hot effluents. The processing of anionic surfactant solutions by wool carbonizing waste requires acidic media (pH < 3), whereas alkaline media are more suitable for effluents containing cationic surfactants. Ionic bonding is involved in both cases. The adsorption rates of SDS and CPC range from 15 to 26% and from 35 to 55%, respectively, depending on the temperature, and are thus markedly higher than that of NPPO (7%) of which adsorption proceeds mainly through hydrophobic bonding. Although these adsorption rates are lower than those of ion-exchange resins, they are higher than those of charcoals (Table 3). The L-shape of the adsorption isotherms corroborates the successive involvement of ionic and hydrophobic interactions in the case of ionic surfactants. The models of Langmuir and Freundlich (Tables 1 and 2) were used for the modelization of water processing units. Besides, the column processing of a SDS solution showed the effect of pH on the efficiency of the operation (Fig. 6) as well as the beneficial effect of temperature (Fig. 7). The processing of industrial effluents in a stirred reactor corroborated the outstanding ability of wool carbonizing waste to adsorb cationic surfactants (Table V). Furthermore, these tests showed that the removal of non-ionic surfactants is improved when they are mixed with anionic surfactants (Table 4).     

Adsorption de colorants ioniques sur le dechet lainier de carbonisageAdsorption of ionic dyes on wool carbonizing waste

Wool carbonizing waste is not used although large amounts are available in the countries where wool is processed. Wool carbonizing waste is made up of two components: the plant particles can be considered as sulfo lignins; the short-size wool fibres have undergone chemical modifications. Owing to its physical structure and to the polar as well as apolar properties of its macromolecules, this waste is liable to adsorb ionic organic solutes. The adsorption of ionic dyes on wool carbonizing waste was therefore investigated so as to evaluate its possible use for the decolourization of dyeing effluents. The effect of the solution-substrate reaction time on the adsorption at various temperatures was studied first. Temperature had a marked effect on the adsorption of the acid dye (AB 80) (Fig. 1) whereas the basic dye (BR 22) (Fig. 2) was characterized by its faster diffusion within the wool carbonizing waste particles. These differences can be ascribed to the higher steric hindrance of the AB 80 molecules and to their possible aggregation. The L-type adsorption isotherms corroborated the temperature effect already mentioned as well as the high affinity of the wool carbonizing waste with acid (Fig. 3) and basic (Fig. 4) dyes. The shape of the adsorption isotherms suggests that the adsorption proceeds through ionic bonding; as the dye molecules are oriented flatwise on the surface of the waste, the dye-substrate hydrophobic interactions can be maximum. The amounts adsorbed were 0.744 mmol g^?1 (i.e. 52.5%) for AB 80 at pH 2 and 0.193 mmol g^?1 (i.e. 5.5%) for BR 22 at pH 4. Higher amounts of basic dyes might however be expected to be adsorbed since the adsorption maximum is reached at pH 9 in the case of BR 22 (Fig. 5), as a result of the increasingly electronegative charge of the substrate. The Langmuir and Freundlich equations (Table 1) were used to have a mathematical model for the operation of a waste water processing unit. As shown by the L-type adsorption isotherms, the wool carbonizing waste used is suitable for the processing of low concentration effluents, such as dyeing waste waters: the decolourization of synthetic solutions was therefore considred. The column processing of an AB 80 solution showed the effect of the reaction time on the efficiency of the material used (Table 2). Investigation of the processing of a BR 22 solution in a stirred reactor led to the determination of the optimum carbonizing waste concentration (Fig. 6). as well as of the optimum effluent-substrate reaction time and the number of reactors to be used (Fig. 7). Eventually, the adsorptive power of the wool carbonizing waste used was compared with that of various materials (Table 3): the uptake capacity of wool carbonizing waste is lower than or equal to that of other substrates in the case of basic dyes but it is 6–10-fold higher in the case of acid dyes.     

Modelisation de l'evolution du parathion dans le milieu naturel sur un pilote de laboratoire

The evolution of parathion in a river, and its degradation by the principal natural factors (hydrolysis, photochemical oxidation, biological transformations and retention by sludge and sediments) has been studied on a laboratory pilot plant. The experimental period was 55 days. On the first 34 days, the plant was fed with a solution containing 13 mg l⁻¹ of the pesticide, and during the following 21 days, the effluent was continuously recycled.In the condition in which our experiences were conducted, the main phenomena were biological degradation of the pesticide into non poisonous amino-parathion and its adsorption on the sediments. The quantity of the parathion reduced is proportionated to the quantity of the ATP found in the activated sludge tank.This biological method being the more important, the shock effect of the parathion on a bacterial population was studied by varying the organo-phosphorous concentration (5-10-15 mg l⁻¹) and the quantity of volatile suspended solid (1-2-3 mg l⁻¹).The microorganisms were not affected by the poison and a reduction to aminoparathion was obtained. The quantitative results may be expressed by the following equation On the other hand a very large dose of parathion (1 mg l⁻¹) destroyed the living organism.The presence of anionic or cationic surfactant plays no part in the toxicity of the parathion (15 mg l⁻¹) on the biomass but the degradation of the organo-phosphorous pesticide is totally inhibited.     

Problemes geologiques lies aux impacts de l'extraction des granulats sur le milieu marin

Supported by their substantial experience on sea dredging, the Authors examine the geological and sedimentological aspects pertaining to marine aggregates exploitation, the different dredging ways as well as their effects on sea floot topography and seashore equilibrium. Stress is laid on the difference between dredging for pure sand exploitation and dredging for harbour maintenance which, unlike the firstone, dislodges muds that are often enough putrid and contaminated by human doings. Particular attention is paid to the turbid “plumes” which are limited only to the instance of pure sand dredging: some examples are given in order to show their real consequences that are, in effect, much more reduced than often believed. Demonstration is made on the necessity of distinguishing the “feathers” turbidity from the torbidities of the ambient environment and their seasonal variations in the proximity of the coastline or river estuaries. Lastly, some suggestions are made in order to reduce troubles, i.e. the usage of trailing dredges, the limitation of surfaces, the profiling of declivities in a slighter gradient, the filling ratio dredge buckets.     

Adsorption des acides humiques sur charbon active en poudre. Influence du triphosphate de sodium

The use of activated carbon beds for the removal of natural humic and fulvic substances found in water supplies, has recently received considerable attention in water treatment operation (Lee et al., 1980; Le Cloirec et al., 1983). Moreover, the use of carbon adsorption for the reduction of haloform precursors (Anderson et al., 1981) and trihalomethanes produced by chlorination process, has contributed to a comprehensive investigation of adsorption characteristics of natural organic compounds (McCreary and Snoeyink, 1981). Many recent works showed the influence of adsorption system characteristics, such as pH, salt type, salt concentration and ionic heterogeneity in multicomponent adsorption systems, on the removal efficiency of humic and fulvic substances by activated carbon (McCreary and Snoeyink, 1980; Randtke and Jepsen, 1982; Weber et al., 1983). The purpose of this study is to examine the effect of a main component of domestic detergents, sodium triphosphate (STP), on the adsorptive capacities of powdered activated carbon (PAC) for commercially supplied humic acids, at different pH values in distilled water. Also, the effect of STP concentration and pH on the adsorption affinity of the PAC for humic acids, is discussed in relation with electrokinetic properties of carbon particles (zeta potential measurements).A first batch equilibrium study (Figs 1 and 2), showed an effective enhancement of adsorption capacity for humic acids as a function of STP concentration, in a non buffered media (pH of distilled water, close to 5.0). For example, visible absorption analysis of humic acids indicates an increase of 93% (500 mg l⁻¹ PAC) and 133% (1000 mg l⁻¹ PAC) in the carbon adsorption efficiency for a STP concentration from 0.2 to 1.0mM. A second batch equilibrium study (Figs 3 and 4) led to adsorption isotherms for humic acids in distilled water, as a function of STP concentration and initial pH value of the non buffered multicomponent system. Freundlich isotherms showed an increase in the adsorption capacity of the PAC for humic acids, with a decrease in pH and an increase in STP concentration. However, the adsorption capacity for humic acids is quite reduced at high pH values in presence of STP, in comparison with results obtained with distilled water.Electrokinetic measurements on PAC suspensions (Fig. 5) indicates that both humic acids and STP induce a negative variation of the zeta potential of carbon particles. In such a binary system, the zeta potential is a linear function of the pH; the negative surface charge of the carbon increasing with an elevation of pH (Fig. 6). Therefore, it appears that some adsorption of triphosphate polyanion from solution could occur, contributing then to the apparent negative surface charge of PAC particles.It has been previously showed that the type of anion in sodium salts, had little effect on the enhancement of adsorptive capacities of activated carbon for humic substances (Lafrance and Mazet, 1985), due to Na⁺ ions. However, adsorption of TP anions on the carbon surface may produce a source of repulsive charges, unfavourable to the co-adsorption of humic acids as the pH of the binary system reach more basic conditions. The influence of possible electrostatic interactions between adsorbates at the carbon surface, on the adsorption efficiency for humic acids, could then be studied by zeta potential measurements of PAC particles during the adsorption process.     

Le laser a impulsions pour le denombrement en fluorescence de Escherichia coli enteropathogene sur membrane filtrante

Reproducible results in fluorescence are obtainable with a pulsed dye laser as the excitation source for the enumeration of enteropathogenic E. coli directly on a membrane filter; an electronic detection and recording system is used and the technique may be completely automated.     

Relation Entre le Sens et le Changement de La Place de L'adjectif Qualificatif

La place de l’adjectif qualificatif commeépithète est une question compliquée en franais,il peutêtre placésoit avant,soit après le nom qu’il qualifie.Pour certains adjectifs,leur place différence résulte du changement de leur sens,mais pour certains adjectifs,le changement de place ne produit pas un changement de sens.Cet article porte sur le deuxième cas.     

Adsorption de substances humiques sur flocs d'hydroxyde d'aluminium preformesAdsorption of humic acids onto preformed aluminium hydroxide flocs

Introduction. Humic substances are acidic, coloured, chemically complex polymeric macromolecules. They arc naturally occurring constituents of soil, sediment and surface water. Much of the reactivity of humic substances in aqueous solution is attributed to their functional groups that contain oxygen, including carboxyl, carbonyl, phenolic and methoxyl; carboxyl and phenolic groups provide most of the negative charge that adds to the mobility of humic substances in the environment, and are believed to react with metals (Edwards and Amirtharajah, 1985; Mantoura et al., 1978; Vik et al., 1985; Chadik and Amy, 1987; Backes and Tipping, 1987).

For water treatment, aluminium salts are the most widely used coagulants. Therefore it is necessary for the water specialist to have a good knowledge of the chemistry and the speciation of aluminium in the aqueous environment. Because of the complicated chemistry of aluminium in this environment, many researchers disagree about the exact nature of the hydrolysed spedes and the mechanism (reaction) involved in the coagultion-flocculation process (Dempsey et al., 1985; Randtke, 1988; Hundt and O'Melia, 1988; Dentel and Gossett, 1988; Jekel, 1986a, b; Tippin8 et a/., 1988a, b). Specific conditions and aluminium species that exist during the charge neutralixation-precipitation-adsorption and simultaneous predpitaon reaction mechanisms are often discussed (Hundt and O'Melia, 1988).

The objectives of the research presented here were only to evaluate the removai of humic substances, humic acids, fulvic acids by preformed fioes, to compare the adsorption capacities of the fiocs to the capacities of other adsorbing materials such as activated carbon and ionic exchange resins.     

Influence de sediments argileux incorpores au milieu d'insemination sur le succes de la fecondation chez la truite arc-en-ciel (Salmo Gairdneri)

The aim of this paper is to determine whether clay sediments suspended in water can prevent trout eggs from being fertilized. Kaolinite-rich clays (granulometric fraction: <2μm) (Fig. 1) were suspended in an artificial insemination diluent in doses ranging between 0 and 20 g l⁻¹. The eggs were exposed for 1, 10 or 20 min (experiment A) or inseminated (experiment B) in the diluent-sediment mixture. In experiment (C), the eggs were exposed to this mixture at three different temperatures (10, 15, 20°C). After insemination, the eggs were incubated for 10 days at 10°C and the percentage of eyed-eggs was used as an approximation of the fertility rate. The presence of clay sediments in the medium in which artificial insemination was carried out did not affect fertilization rate after the ovules had been exposed during 1 min to clay suspensions, at any of the temperatures used (8°C: Fig. 3; 10–15 or 20°C: Fig. 5) or at any of the sperm dilution rates (10⁻², 10⁻³, 10⁻⁴) (Fig. 3). On the contrary, there was a significant decline (P < 0.01) in the fertilization rate after the eggs had been exposed for 10 min at 8°C to doses of sediment exceeding 1.2 g l⁻¹ (Fig. 2). The fertilization rate also decreased significantly (P < 0.05) when the dose of sediment in the medium increased after 20 min at 20°C and 40 min at 15°C (Fig. 4). The 15 and 20°C temperatures were unfavourable for the eggs anyway. It is probable that fertility decreased due to micropyle clogging when the eggs were exposed longer than 10 min to the sediments. It is concluded that presence of sediments in the medium in which the gametes meet does not prevent fertilization.     

Mecanismes de l'epuration biologique sur charbon actif

Activated carbon was used for the treatment of waste water, and a study made of the fixing-properties of the adsorbent and the part played by micro-organisms. The process of “fixing” remains to be demonstrated because it has not yet been proved that bacteria are fixed on carbon. Study of the biological mechanism of activated carbon was carried out in three stages. The first was a survey of the adsorption on this material of various products present in waste water [amino-acids, enzymes, total organic matter (COD)]. In the course of these tests, the part played by the micro-porosity of activated carbon in regard to such molecules was observed. In the second stage, by using various techniques (electron microscope, scanning and transmission, X-ray fluorescence, Castaing micro-gauge), we determined the part played by fixation-spots initially present on carbon (surface functions, heavy metals) during bacterial development. In the third stage, we correlated the eliminated organic pollution with the bacterial mass present on the adsorbing material.The conclusions drawn were that the micro-porosity of carbon does not play a fundamental part in the adsorption of organic matter in sewage, but it does come into play in the adsorption of certain molecules taken separately (amino-acids, enzymes), and that the presence of fixation-spots (metals, surface functions) can have some influence during bacterial development. Experiments are in progress to determine the part played by the specific surface in regard to the adsorbable molecules and its correlation with the bacterial mass and also, to observe the part played the adsorbing material and the bacteria in regard to the non-adsorbable molecules (ethanol, methanol).     

Concentration du virus de l'hepatite a sur des membranes de cellulose

Viral hepatitis type A is the most prevalent waterborne disease in U.S.A. and the number of cases has been increasing in recent years (Melnick et al., 1978). Till now, few works were performed on Hepatitis A Virus (HAV) concentration in water (Hejkal et al., 1982, Elkana et al., 1983). In this paper the filter adsorption-elution method, widely used with other viruses (Wallis and Melnick, 1967; Fields et Metcalf, 1975; Smith and Gerba, 1982), was selected to concentrate HAV from experimentally-contaminated distilled water. Filtration was performed through two cellulose membranes (RAWP 04700 and HAWP 04700 Millipore). Eluate or filtrate viruses were precipitated by polyethylene glycol 6000. HAV is detected by solid phase radioimmunoassay according to a previously described method (Deloince et al., 1982). Figure 1 shows the results of adsorbing HAV at different pH levels. Analysis of variance pointed out that, for the pH levels between 3 and 4, the differences were not significant (P = 0.05). Table 1 shows the effects of pH and number of passages of 3% beef extract or 0.2 M glycin buffer on HAV elution. For both eluents the differences in function of pH levels and number of passages of eluent through the membrane were not significant (variance analysis P = 0.05). On the other hand, the comparison between the two eluents pointed out the higher efficiency of beef extract (t-test, P = 0.001). After this procedure, HAV replication occurred in human hepatocarcinoma cells PLC/PRF/5 (Fig. 2) inoculated according to a previously described method (Crance et al., 1983). As poliovirus (Sobsey et al., 1973), HAV adsorption is the most efficient at acid pH levels. Between pH 4.5 and 5, the remarkable adsorption decrease might be related to the inversion of the HAV electrostatic charges sign, i.e. to the occurrence of an isoelectric point. The HAV elution is different from the poliovirus one, the efficiency of which increased with pH (Wallis et al., 1972) and eluent passage numbers (Farrah et al., 1976). That might suggest that from pH 7.5, both the HAV particles and membranes have negative charges which give enough repulsive forces to allow a good elution efficiency. Improvement of HAV elution efficiency by beef extract is similar to a result obtained with poliovirus by Landry et al. (1978). This effect might be explained by the proteinous material presence in beef extract. HAV replication in cell cultures shows the biological properties preservation after this procedure.     

Evaluation de la charge virale dans les eaux d''une station d''epuration biologique au moyen de deux methodes de concentration de virus par adsorption-elution sur poudre de verre ou sur microfibre de verre

Two methods of adsorption-elution on glass powder or on glass microfibre have allowed to determine the virus quantity at the entrance and at the exit of a biologic sewage farm. Almost the same results are obtained by comparing the two techniques. The frequency of virus isolation is very important both in the affluent and in the effluent. The rate of reducing the quantity of virus in the effluent is in the region of 78%. The identification of the virus has shown the systematic existence of Enterovirus. If one has to choose between the two techniques, the method of adsorption-elution on glass powder is more advisable, because there is no problem of blockage.     

Problems poses par le decapage et le stockage de la terre vegetale

The paper presents the main results achieved from the present researches realized by the French Road Laboratories, concerning the behaviour of the tillable earth during the different steps of earthmoving. Some advices infered from those results are presented, concerning the desirable procedures for the stripping, the storage and the reutilization of the tillable earth, so as to secure, after the restoration of the site, a soil with good agricultural characteristics.     

Mode d'action du bioxyde de chlore sur les composes organiques en milieu aqueux: Consommations de bioxyde de chlore et reactions sur les composes phenoliques

The aim of our work was to study the reaction between chlorine dioxide (ClO₂) and organic substances. In the first part of our survey, chlorine dioxide demands were measured in diluted aqueous solutions of various kinds of organic compounds (5 × 10⁻⁵ −10 M) at pH 7. In the second part, the study of the action of chlorine dioxide on phenols (phenol, di and triphenols) was undertaken by observing the change of the organic substance through global parameter controls (COT, u.v. spectrum) and by trying to identify a certain number of oxidation products by means of chromatographic analysis (HPLC and GC), of mass spectrometry and of Nuclear Magnetic Resonance spectrometry (NMR).