Henri Roques

Kinetics of the Formation Conditions of Carbonate Tartars

Abstract The experimental results of CaCO 3 precipitation kinetic are reported. The relation between the crystallography variety and the supersaturation degree was established at 10, 30 and 50°C. An empirical correlation between the nucleation velocities and the initial crystal growth velocity was as given. The surface energy of the allotropic variety is measured. A mathematic model of the precipitation rate is proposed and verified. The definition of the stirring of the solution is studied from the point of view of the power wasted within the experimental device. The influence of this stirring on the nucleation speed, the initial growth speed, and the resulting allotropic variety of CaCO 3 is studied. These results are compared with those obtained in a solution which is not mechanically stirred.

Traitement des effluents urbains ou industriels par entrainement des polluants a l'occasion d'une precipitation de CaCO3

Abstract Studies carried out in our laboratories on calcium carbonate precipitations have led to the conclusion than substantial amounts of organic matter could be entrained by the crystals that are produced and in particular when the precipitate is in the form of vaterite. Moreover entrainments of this type are used currently in sugar-refining for the purification of sugar juices. Such CaCO 3 precipitation may be easily induced by means of the reaction of lime with a current of CO 2 -enriched gas which is bubbled through the solution. Given also the well-known coagulating properties of lime, it has been considered worthwhile investigating the treatment of certain wastes by means of this method. The initial trials were sufficiently conclusive for the SOAF Company to taken an interest in the project and for a decision to be made to construct a pilot plant of 10 cm h −1 capacity. Concurrently with this, a 301 h −1 laboratory unit was also built, and it is this which has provided the initial results that we propose to set out here.

Etude comparative de divers systemes d'aeration

Abstract Comparative study of three standard aeration systems: bubble diffuser; turbine aeration (Rushton type): Rushton turbine as surface aerator, with use of original correlation functions. This comparative study is carried out by relating: oxygen efficiency (kg O 2 kW·h −1 ), to unitary power (Wm −3 ).

Etude theorique et methodologique du phenomene de demande biologique en oxygene

Abstract We establish a Biological Oxygen Demand, BOD, model in a pure culture during growing phases. This model, exprimed in reduced coordinates, is used to do a methodologic study of the BOD measure on urban and industrial effluents and on river waters. The different types of curves observed are described using dimensionless numbers. We study the influence of the method used and of the initial concentration in present or introduce micro-organisms on the numerical value of result obtained for a limited period (5 days). We show that this model corresponds for weak values of the dimensionless number n, to the FAIRs model of first pseudo order. The dimensionless number n represent the ratio between the initial substrate concentration and the substrate equivalent of the biomass initially present.

Problemes de l'idendification parametrique des modeles de croissance en traitement biologique

Abstract The parametric adjustment of the growth models in water biological treatment is an important step for the modelisation of the westewater treatment process. Two methods of adjustment have been used (Hooke and Jeeves; Newton‐Gauss) to estimate the parameters of five growth models. It should be noted that the good adjustment of these parameters does not imply the validity of the model. It is essential to determine the experimental domain utilized for identify these parameters.