Inventaire des lipides et leur elimination au niveau de differents types de stations d'epuration de petite capacite

Analysis of 24-h samples taken at the entrance and at the exit in 4 types of domestic waste water treatment facilities, were performed for BOD, COD, surfactants, free and esterified fatty acids. Oleic, palmitic and stearic acids were the most frequently found, both in the influent and in the effluent. A good elimination (between 80–99%) was observed for these compounds.     

Traitement experimental d'epuration d'une eau de surface par lagunage: Aspects chimiques et microbiologiques

Polluted river water was treated by lagooning in an experimental bed. The evolution of the most representative parameters of the organic and bacterial pollution has been studied in relation to the period of retention. The predominant bacterial populations have been identified and their qualitative and quantitative variations have been related to the degree of pollution. The analytical results are commented upon the advantages of the method are stressed.     

Essai au bleu et nocivité des montmorillonites dans les matériaux composites

The behaviour in wet conditions of materials (aggregates, soils, rocks...) containing clay particles depends on both the latter content and its mineralogical nature. According to the technique involved (cement-treated soils, bituminous mixes, concrete...), only external surface area or both external and internal surface areas of the clays are dominantly relevant. In this paper, we describe two simple ways of using the Methylen Blue test which allow the swelling nature of the clays, through the ratio of the external to the internal surface areas as well as their amount to assessed for The operating procedures are given; potential applications are also discussed.     

Survie in vitro de Yersinia dans les eaux d'alimentation et recuperation par filtration sur membrane

This study was undertaken to determine the survival characters and optimal parameters for the recovery of Yersinia from drinking water samples. Experiments were done by artificial contamination of 4 different water samples with 4 Yersinia strains.The strains tested along this study are: Y. enterocolitica 4052, 0:3 and 4360, 0:9, Y. enterocolitica intermedia 3953, 0:17 and Y. pseudotuberculosis 0:1. The water samples are characterized by an increasing mineralization: Distillated water, Gerardmer water (

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), Nancy water (-4500 ω cm⁻¹—H = 10°) and Vittel water (-730 ω cm⁻¹, H = 71°).Total mineralization does not significantly affect the survival of Yersinia at 20°C, but causes a dramatic decrease of the Yersinia strains at 4°C for the most mineralized water. There is no pH effect from alkaline, neutral and acidic values until pH 4.4 but Yersinia is greatly affected by more acidic pH.The previous stay of Yersinia strains in artificially contaminated water causes a reduction of kinetic growth during cultivation on peptone-water but does not change the recovery rate by filtration method.The recovery rate of the filtration method using cellulose acetate membranes (mean porosity = 0.45 μm) is very poor, ranging from 0 to 8%. The efficiency is significantly higher with the aid of polyester membranes treated by laser (Nucleopore−0.40 μm) ranging from 12 to 53% according to the mineralization of the water. The best recovery rate is obtained with the moderately mineralized water.These results can explain the poor results obtained with the use of water bacteriology classical methods for the search of Yersinia.Thus the best results can be predicted from the concentration of fairly mineralized water by filtration on polyester membrane at neutral, alkaline or weakly acidic pH.     

Mesure sonique dans les roches,les sols et le beton

Bulletin of Engineering Geology and the Environment - Nous décrions les techniques d'exploration géophysique employées par l'ISMES, en collaboration avec l'ENEL, pour...     

Les problemes et les mesures a prendre pour coordonner l'exploitation des granulats et l'amenagement urbain dans les alentours de Rome (Italie)

The supply of aggregates of the surrounding areas of big cities is confronted to major problems: on the one hand, concerning the necessarily high quantities of the needed materials; on the other hand, concerning the increasing difficulty when trying to open new quarries at an economically still acceptable distance. The utilization of the available deposits is limited, due to a growing attention for values which are linked to the protection of the environment. It is essential to analyze closely the characteristics of the territory, the structure of the industrial sector and the distances of transportation, in order to maintain the production rate of aggregates, and to choose the location of excavating activities. As an example we will analyze the situation of the region surrounding the city of Rome.     

L'anisotropie des vitesses sismiques dans les massifs rocheux

Bulletin of Engineering Geology and the Environment - L'anisotropie des vitesses de propagation dans le massif rocheux est liée à la fabrique de la roche (forme des grains, foliation...     

Interception d''hydrocarbures emulsionnes dans l''eau par des materiaux hydrophobes: mecanisme. aspects dynamique et cinetique

We study the kinetic laws and the mechanisms which control the rate of removal of hydrocarbons (dispersed phase) from water (continuous phase) using hydrophobic granular material. The main steps occurring in this process are: hydrocarbon adsorption followed by film formation caused by the interception of hydrocarbon drops and when the film is too thick, re-entrainment of the hydrocarbon from the support to the continuous phase.

A method for the determination of the hydrocarbon coalescence rate is established. The kinetic analysis of the coalescence coefficient shows that the hydrocarbon drop interception by the hydrophobic support is controlled by diffusion.

The hydrocarbon retention on the support is related to the porosity, and hydrophobicity and cannot exceed a maximum value determined by the hydrodynamics. This saturation which is obtained first near the entrance of the reactor, occurs in the reactor at a speed that we have modellised. The relationships between saturation of the column and increase of the loading rate of the column are established. An accurate modellisation of the dynamic laws of the hydrocarbon removal is given, considering both the interception and the re-entrainment step.     

Recherches pluridisciplinaires sur les granulats dans les laboratoires des ponts et chaussées en France (1964–1984)

The organization of the research on aggregates in the 18 French Road Laboratories (“Laboratoires des Ponts et Chaussées”) has always been on a multidisciplinary basis. The researches have been realized by the same teams composed by different specialists (geologists, geo-technical engineers, road engineers, etc.) working together. The paper presents the main fields in which the laboratories have been working for more than 20 years: inventories of aggregates resources at different scales; new exploration methods for the detailed investigation of deposits; environmental impact studies; improvement of the classical methods used for elaborating aggregates (crushing, grinding, sieving,...); investigations dealing with the relations between the properties of rocks, their mechanical characteristics and the choice of standard tests; experimental research work in the laboratory or on the site for the design of specifications; upgrading of different natural materials; different uses of artificial materials. A precise example of the very close connections between the apparently different fields of research is given as a conclusion.     

Recherche de developpement d'emploi des sables issus de roches massives siliceuses et silicatees dans les betons hydrauliques

Because of the depletion in some parts of France of the alluvial sands normally used for hydraulic concretes, consideration has been given to using sands produced by crushing massive rocks as a substitute. Rocks of twelve different mineralogical types, representing most of the types of rock found in France, have been investigated. Attempts were made:

- to determine the maximum acceptable filler content of the sands, in terms of the properties of the mortars and concretes in both the fresh and hardened conditions;

- to assess the risks of alkali-aggregate reactions;

- and to work out the best techniques for the industrial production of these sands, so that the filler content and particle size distribution are compatible with the results of the research on mortars and concretes.

     

Essais d'aerateurs: Enseignements tires de 500 essais en eau claire effectues dans 200 stations d'epuration differentes—II Resultats

The large number of aerator tests conducted in the field by the CEMAGREF teams has allowed developing a critical review of tests results by means of statistical analysis. Measurement quality is estimated from the variation of the transfer coefficient values from one sampling point to another. Individual transfer coefficient values are compared with the average value of the test ratios correlating with one year's data are gathered in histogramms (Fig. 1).A χ² test is used for evaluating the fit of a Normal distribution on each histogram (Tables 1 and 2 results for two kinds of surface aerators). When the Normality is not rejected, the variances between distributions are compared by means of a Fisher test. variations in a same run are independent of transfer coefficient when the K_La ranges 1–10 h⁻¹ and applied specific power ranges 15–70 W m⁻³. Those variations allow evaluating the technique of measuring, the reliability of oxygen probes and the operator's experience (Table 3).In a well mixed tank and when the recommended procedure is correctly implemented the relative error in measuring the specific oxygen input (kg O₂ kWh⁻¹) is 5%. In less favorable cases it reaches 10%.Tables 4 and 5 show the reproductibility of repetitive run results in the same plant and of tests performed with the same aerator in different plants.The histograms of the performances of the main types of mechanical surface aerators (high speed vertical shaft turbine, slow speed vertical shaft turbine, horizontal shaft aerator) are presented (Figs 2, 4, 5). Relations between oxygenation capacity and specific power consumption are plotted in Figs 3 and 6. As to other aeration systems, fewer data are available. Table 6 summarizes the usual range of performances.In 1974, after a series of measurements performed on 72 different plants, CEMAGREF stated that the oxygenation capacities claimed by manufacturers were, on the average, 40% higher than actual results. Now, the performances predicted by manufacturers in France are generally very close to the measured values. A difference higher than 10% between predicted values and measured ones now occurs as an exception.     

Relation entre les caracteristiques des granulats et les proprietes des materiaux qu'ils permettent d'elaborer. Recherches en laboratoire et sur chantier

The introduction of the report presents data concerning the evolution of the traffic in the Cracow District between 1965 and 1983, and the aggregates used for road construction during the same period. The most important characteristics aggregates made of crushed rocks in the district are dealt with. Mineral aggregates usually belong to II–III class, and require improvements to achieve better physico-mechanical properties and after improvement they are commonly used for roadbases, basecourses and wearing courses. This report also deals with the relations between the characteristics of aggregates and the properties of same stabilized materials:

1. Mechanical stabilization for sub-base,
2. Stabilization of aggregates with granulated slag and hydrated lime for roadbases,
3. Stabilization of aggregates with granulated slag and with cement for roadbases,
4. E. Fly-ash concrete and stabilization of sand with cement for roadbases,
5. Hot bituminous mixtures/with asphalt as a binder/for basecourses,
6. Hot bituminous mixtures/with coal tar pitch as a binder/for wearing courses.

For all stabilized materials, the main results of the laboratory tests achieved during the preparation of mixes are presented, as well as the tests realized on compacted mixtures inside the road, under the traffic. It proved that satisfactory road-bases, base-courses and wearing courses could be made of aggregate of a rather poor quality. The choice of the technique must derive from the quality of the aggregates. The permanent technical control of the laboratory is necessary at all stages: designing, realization and maintenance.     

Essais d'aerateurs: Enseignements tires de 500 essais en eau claire effectues dans 200 stations d'epuration differentes—I. Methodologie

Aeration represents the main part of energy consumption in the activated sludge process and the evaluation of aeration systems efficiency is becoming more important, especially as energy cost increases. Since 1972, CEMAGREF teams have carried out more than 500 non-steady state clean water tests in sewage treatment plants. The first aim of these measurements was to compare the results collected in plants with those predicted by manufacturers.The distribution of the different types of aerators tested in the field by the CEMAGREF is given in Table 1. All tests are conducted using tap water under non-steady state conditions: the initial dissolved oxygen (DO) level is brought down to zero by adding cobalt chloride as catalyst and sodium sulfite. When all the sodium sulfite has been used, the increase in water dissolved oxygen content is monitored vs time in various places in the tank by means of membraned probes.The graphical procedure used for estimating the oxygen transfer coefficient (K_La) is shown in Fig. 1; this procedure is usually called “log deficit method”. The results are expressed for “standard conditions” (θ = 10°C; P = 760 mm Hg). The influence of temperature on oxygenation capacity is illustrated in Fig. 2.The water quality parameters that may affect oxygen transfer are investigated: it appears that only the presence of surfactants, flocculated suspended solids, or high salinity (conductivity > 1500 μS cm⁻¹—Table 2) are liable to have any appreciable effect on oxygen transfer. The unflocculated SS, pH and alkalinity have no effect on oxygenation results in the common range of values occurring in the tests (Table 3).Authors differ about the operational procedure in non-steady state clean water test. After 7 years' field-measurements the CEMAGREF teams have developed their own recommendations about test procedures; their main conclusions are the following:Dissolved oxygen analysis: the differences observed between the results ( ) obtained simultaneously by Winkler titration of piped samples and those from in-tank probes never exceed 4% (Table 4). Reliable dissolved oxygen probes are suitable for accurate measurements of oxygen transfer.The number of sampling points should be no smaller than three for aeration tanks with a volume below or equal to 500 m³. It should be recommended to add one sampling point for every additional 500 m³.Location of sampling points requires attention. Differences may appear according to the locations of probes in the basin (Tables 5, 6 and 7).Sulfite pre-dissolution has no influence on results and should be avoided whenever possible.