MXPA94004735A - Procedure for the biological treatment of ag - Google Patents

Abstract

Procedure of biological treatment of the waters that puts in work a biological reactor that contains a culture of micro-organisms, fixed on a granular support material. According to which a consumable pulverulent material is injected into this reactor, this procedure is characterized in that it is put into operation in order to ensure self-selection and self-regulation of the support material of the granulometry necessary for the biological process.

Description

PROCEDURE FOR THE BIOLOGICAL TREATMENT OF WATERS OWNER: DEGREMONT, a company of French nationality, domiciled at: 183, avenue du 18 Juin 1940 - 92508 REUIL MALMAISON, FRANCE. INVENTORS: Pavel CHUDOBA, residing at: 34, r é du Pt. Wilson - 78230 LE PECQ, FRANCE; Michéle PANNIER, residing at: 13, allée des Noireaux - 78290 CROISSY S / SEINE, FRANCE; Roger PUJOL, residing at: 152, boulevard H. Fayer - 69007 LYON, FRANCE; all of French nationality.

DESCRIPTIVE SUMMARY Biological treatment procedure of the water put into work by a biological reactor containing a culture of micro-organisms, fixed on a granular support material, according to which a consumable pulverulent material is injected in that reactor; This procedure is characterized in that it is put into work • way to ensure self-selection and self-regulation of the support material of the granulometry necessary for the biological process.

DESCRIPTION The present invention relates to a method of biological treatment of waters. It is known that recent procedures of • water treatment, they turn more and more every day to the fixed crops. When the biomass is fixed on a support material, this allows to increase its concentration per unit volume of the biological treatment facility. In this way, biological reactions and mass transfer are generally carried out with faster kinetics. On the other hand, it is known that biomass activity plays an essential role in the biodegradation process. It is used more and more every day, as a support material, granular materials that are put into work in expansion, movement, turbulence or in fluidization, in mobile bed reactors, preferably in three-phase medium (gas-water-particles). The movements of the particles cause more or less frequent and brutal collisions between the gas bubbles and the particles. These shocks contribute strongly to an improved control of a thin and active biofilm on the surface of the bioparticles (attractive and shear forces). In the implementation of certain procedures, a material-support / biomass, exterior separation system is necessary. The surface of the support material available for the fixation of the biomass is the decisive element of the efficiency of the process, and this imposes, either the selection of a fine material (which therefore contributes a high surface), either the use of a coarse material that then imposes a higher biological reactor filling rate. The drawback associated with the use of a fine material, lies in the risk of loss of that material by washing at the time of operation of the reactor. The implementation of a thicker support material that causes a high filling rate of the reactor, produces hydrodynamic efforts linked mainly to reduced oxygen transfer, and high energy consumption. In spite of these drawbacks, the biological treatment methods of the water, usually put into work, a thick material, as a support material for the biomass; this material then has well-defined granulometric characteristics. The present invention proposes to provide a method of biological treatment of water, which implements a biomass support material with a low granulometry; this procedure ensures a self-selection of the support material in the biological process of water treatment. Therefore, this invention has as its object, a biological treatment process of the water put into work by a biological reactor containing a culture of micro-organisms, fixed on a granular support material, according to which it is injected in that reactor , a consumable powder material; this procedure is characterized in that it is put into operation in order to ensure self-selection and self-regulation of the support material of the granulometry necessary for the biological process. According to a feature of the present invention, that consumable powder material has a granulometry comprised between 0 and 500 microns, preferably comprised between 0 and 250 microns, a density greater than 1500 kg / m2 and an available surface of the order of 800 5000 m2 / m3.

According to the present invention, the injection of consumable powder material can be continuous or discontinuous. According to a preferred embodiment of the process, object of the invention, this pulverulent material, for example, can be constituted by kaolin waste. According to the present invention, the filling rate of the biological reactor is less than 5% by volume. As it is understood, the method according to the invention consists, therefore, in a continuous or discontinuous injection of a fine granular material in a suitable biological reactor containing a culture of micro-organisms [inoculum]. The biological reactor is fed with the water to be treated; the supply of air is ensured by a fine / medium bubble aeration device. In an anoxia medium (denitrification treatment) or anaerobic (dephosphating treatment), the aeration device is suppressed, of course. The movement of the liquid and gaseous fluids is carried out counter-current and in the ascending direction (according to defined gas and liquid velocities). The reactor may also comprise mechanical mixing means (stirred reactor).

The process object of the invention allows to obtain a pre-selection of the granulometry of the granular material, adapted to fix a thin and active biofilm, very quickly, forming bio-particles; these constitute almost all of the biomass in the system; the hydrodynamic conditions and the extremely short residence times do not allow the development of a free biomass. The finer mineral particles are washed with the biomass, produced in the course of the biological reaction in the reactor. This released biomass results from the collisions between the particles themselves and the gas bubbles. In this way, a state of equilibrium is established in the system, in the course of time; a part of the fine granular material is evacuated with the biomass produced; periodic contributions of new material allows to keep the necessary filling rate of the biological reactor. This process is repeated periodically depending on the desired filling rate.

Almost all of the biomass (autotrophs + heterotrophs) is fixed on the bioparticles and, therefore, the exchanges favored by the thin biofilm obtained, favor rapid kinetics and consequently short hydraulic residence times in the reactor.

Taking into account the energetic agitation of the medium, the biofilm has a tendency not to thicken "statistically", because the phenomena of attrition and shearing are very important. However, the particles, for one reason or another, can adapt to these conditions and therefore the growth of the crop can cause an increase in the thickness of the biofilm, which leads to an increase in the diameter of the bioparticle and a consecutive reduction. of its density, which has as consequence, a washing of the bioparticle of the system. The losses are compensated in the process according to the invention, by periodic or continuous injections of virgin material and the rapid formation of these bioparticles has no influence on the state of equilibrium established previously. In other words, even if the concentration of the bioparticles in the system fluctuates around a set value, the yields do not vary and remain very high. • On the other hand, the method according to the invention makes it very easy to adjust the filling rate as a function of the temperature, possibly of the foreseeable load (areas of variable population, temporary industrial, etc ...), in order to compensate the variations of the kinetics and to conserve, in this way, a constant and maximum performance of the procedure. Thus, from a gross consumable powdery material of a well-defined granulomethyl, on a wide scale, it is selected and retained by the process according to the invention., an appropriate fraction that offers a large fixing surface. Figure 1 of the attached drawings is a block diagram illustrating the different steps of the method according to the present invention. This scheme is sufficiently explicit so as not to be the subject of supplementary comments. The selection of consumable powder material imposes, on the one hand, a very rapid colonization by the micro-organisms of the newly injected fraction and, on the other hand, a low cost of the raw product used. As already mentioned above, this fine granular material injected into the biological reactor, for example, can be constituted by kaolin waste. The characteristics that this material must present are indicated below:. small granulometry (0 to 500 microns). density >; 1500 kg / m3. Small fill rate (less than 5% vol.). surface available high (800 to 5000 m2 / m3). important roughness of the material. "Consumable", allowable losses, can be replaced.

An example of an installation in which the procedure object of the invention can be put into operation will now be described, by way of indication and without any limiting character. This description refers to figures 2 and 3 of the accompanying drawings, which respectively represent a biological treatment plant for water, comprising respectively a three-phase reactor (figure 2) and two-phase and three-phase reactors (figure 3). Referring to FIGS. 2 and 3, it is seen that the device intended to implement the method according to the invention essentially comprises a mobile bed biological reactor, either three-phase 2 (nitrification-figure 2), or a reactor of a diphasic moving bed 7 (denitrification) and a three-phase moving bed reactor 2 (nitrification) according to the exemplary embodiment illustrated in figure 3. This device further comprises a water separator 2 + sludges / bioparticles and a final clarifier 5, or a float The water to be treated 1 is pumped, either in the reactor 2, either in the reactor 7, where it is put in contact with the bioparticles 3, in the presence (three-phase reactor 2) or in the absence (two-phase reactor) 7) of air. These reactors 2 and 7 have a very low filling rate, lower than 5% in volume, contrary to the procedures currently used. After having eliminated the contamination (C / N), the water is separated from the bioparticles in the separator 4 that can be placed, either inside, or outside the biological reactor. The treated water containing suspended matter, and especially the fine particles of support material, is then brought to the clarifier 5 in which the clarification of the water and the extraction of fine particles and of the biomass produced are carried out. The clarified water is then released into the natural environment. The bioparticles that are retained in the separator 4, are continuously recirculated by means of a recirculation duct 6, in the reactor 2 for a new treatment cycle, A second recirculation circuit 8, ensures the contribution of the nitrates to the beginning of the installation in the reactor 7 of the embodiment of figure 3, where they are transformed, by means of the bioparticles 3, into nitrogen gas 9. According to the invention, the purges of the particles systematically eliminated are compensated by the periodic injections of the virgin material 10, either in the three-phase reactor 2 (figure 2), and / or in the diphasic reactor 7 (figure 3). The extraction of the biomass that is produced at the time of the biological process, is performed from the final clarifier 5, for example, with the help of a valve 11. The advantages provided by the process object of the present invention, are the following: - selection of a support material of the micro-organisms, adapted from a gross product having a wide granulometric scale; use of a renewable and consumable material with a low cost price, of the order of 50 to 100 times lower than the materials traditionally used in this type of biological treatment procedures (sand, activated carbon, Biolite ...); fixing and high exchange surface with a small filling rate; - high kinetics (up to 20 times higher than that of activated sludge); - Mud of good quality for its treatment (small volume / concentration ratio, obtaining high concentration sludge, which improves the quality); - high mass flow (up to 600 kg / m / per hour) in relation to the activated sludge (5 to 10 kg / m2 / per hour); - wide field of application in the treatment * of the waters; nitrogen (tertiary nitrification): three-phase mobile bed 2 (Figure 2); carbon / nitrogen (nitrification): three-phase mobile bed; carbon / global nitrogen (nitrification / denitrification): coupling of the fl-phasic 7 and three-phase mobile beds 2 (Figure 3); . phosphorus: if the system is coupled to a denitrification and an anaerobic zone.

A comparison of the kinetics of the process according to the invention with other known methods is given in the table below.

Claims (6)

1. TABLE Procedure Kinetics (average value) (mg N / gMV.h) at 13-15 ° C According to the invention, filling rate of 1.6% 10-20 Sludge activated 1 - 3 Biofilter 4 - 5 Activated sludge + crops fixed on solid support Fixed crop air lift at the filling rate of 10% 3 - 14 Of course it is understood that the present invention is not limited to the examples of implementation or implementation described and / or represented in the present specification, but covers all variants. NOVELTY OF THE INVENTION Having described the invention, we consider it as a novelty and, therefore, claim as our property, what is contained in the following clauses. 1. - Procedure of biological treatment of the water put on site by a biological reactor containing a culture of micro-organisms, fixed on a granular support material, according to which a consumable powdery material, characterized in which is put into action in order to ensure self-selection and self-regulation of the support material of the granulometry necessary for the biological process.
2. 2. Processing method according to clause 1, characterized in that the filling rate of the biological reactor is less than 5% by volume.
3. 3. Process according to clause 1, characterized in that the consumable powder material has a granulometry comprised between 0 and 500 microns, preferably comprised between 0 and 250 microns, a density greater than 1500 kg / m3 and an available surface of the order from 800 to 5000 m2 / m3.
4. 4. Process according to any of the preceding clauses, characterized in that the injection of the pulverulent material is carried out continuously.
5. 5. Process according to any of clauses 1 to 3, characterized in that the injection of the pulverulent material is carried out discontinuously.
6. 6. Process according to any of the preceding clauses, characterized in that the consumable powder material is constituted by kaolin waste. Under protest to tell the truth, we declare that the best method to carry out the present invention is the one described in this application. In testimony of which, we signed the present in Mexico, D. F., on June 22, 1994. DEGREMONT and / or LIC. JOSÉ B. DUMONT and / or JACQUELINE KOURILSKY