FR2763855A1 - Treatment for odour nuisance from sewage works - Google Patents

Abstract

Process for treating olfactory nuisances, in particular those generated by vital processes or the degradation of natural organic material, in vessels, tanks, settling tanks, lagoons, or similar containers for similar odorous liquid(s) with relatively large surfaces. The process involves delivering in a controlled manner, predetermined quantities of an active liquid component via one or more injectors (2) immersed in the container(s) concerned, and to diffuse in a continuous or sequential manner the active liquid component via ejection openings in the surface of the odorous liquid(s) stored in the container(s). Device to carry out the above process comprising a feed unit (1) in a protective cover (5), a reservoir for a liquid component which is active against the odorous molecules, and means of controlled distribution of the active liquid component, provided with means of control and at least one diffusion line (9). Each distribution module is immersed in a storage tank (3) containing the odorous liquid and each has a supply line (9) from which the diffusion tubes (2) form injection units (2') at the surface (4') of the stored liquids.

Description

DESCRIPTION
The present invention relates to the field of environment and comfort of people working or living near settling ponds, lagoons or treatment or purification stations receiving waste liquids or liquid waste discharged by industries, I agriculture and urban agglomerations, such as industrial process water to be treated by lagooning, and relates to a method and a device for treating and eliminating olfactory nuisances in settling basins, lagoons or the like.

 Many types of industries require significant amounts of liquids in their various manufacturing or processing processes and are currently obliged, particularly as a result of new environmental regulations, to treat their liquid waste, for example process water before re-injecting them into the natural cycle or reusing them.

 However, these liquid wastes or co-products, often loaded with organic matter, are generally discharged, in a first stage, into settling ponds or lagoons, in order to separate solid particles, in particular biological particles, by sedimentation, and generate significant nuisances related to smelly odors they emit, amplified by their open-air situation and their spread over large areas.

 Various solutions to the aforementioned problem have been proposed and implemented, among which may be mentioned the incorporation into the liquids to be treated or the discharge into the basins and lagoons of active solutions against odors, as well as misting or spraying techniques. such active solutions over said basins and said lagoons.

 Nevertheless, all these known solutions have the major disadvantage of requiring very large amounts of active solutions and of having a low yield due to the procedures applied.

In fact, to try to obtain a satisfactory result,
The incorporation or the discharge of active solutions results in a treatment in the mass of all the odoriferous liquids, which leads to an excessive consumption of active solutions, which can not be economically supported.

 Misting or spraying techniques, for their part, can not be effectively implemented in the presence of wind, while the latter just increases the perimeter of the areas affected by nuisance by carrying and spreading odors, and present significant yield losses due to the lack of targeting and dispersion of the active molecules in the atmosphere, even in the absence of wind.

 In addition, the known solutions mentioned above are implemented from the edge of ponds and lagoons and are unsuitable for large basins or lagoons (generally several hectares), unless excessive amounts of active solutions are released. .

 Furthermore, the devices and systems for implementing the aforementioned solutions are complex, tedious to use and a high cost, for a limited treated surface.

 Finally, it should be noted that the main vectors of olfactory pollution in the environment are ammonia (NH3), hydrogen sulphide (H2S) and their organic derivatives (amines, mercaptans).

 The propensity of these bodies to exist rather in the gas phase than in a condensed phase, or vice versa, depends on many parameters, such as the temperature, the pH of the liquid phase and the pK values governing the dissociation equilibria.

 The sources of olfactory nuisance involving these two families of compounds are very diverse, as they may be oil refineries, the inorganic or organic chemical industry, the pulp industry (up to 1000 mg / m3 of H2S from "black liquors"), animal by-product processing industries, agro-food industries and also industries involved in waste disposal.

 Many industries are confronted with the nuisance caused by the smelly emanations of wastewater or process water during their treatment by lagooning, settling basin and treatment plant.

Sludge effluent treatment in aerated lagoons can cause intense olfactory nuisances and, from a general point of view, the odorous flows resulting from the treatment of fermentable industrial effluents are much greater than those generated by the treatment stations. urban purifications. Most frequently, there are sulfur compounds (generation of high concentrations of H2S) and mercaptants in the storage and purification of tanneries and for certain industrial activities with high concentrations of amines.

In any case, a masking effect is totally ineffective and can even become dangerous when the concentrations of H2S and
NH3 exceed the toxicity thresholds.

 The present invention is intended to overcome all of the aforementioned drawbacks and to provide a method and a device using the active solutions in a targeted manner and with maximum efficiency, while requiring only simple hardware, easy to install and to use and reduced cost.

 To this end, it relates to a method for treating olfactory nuisances, in particular those generated by the vital processes or the degradation of organic materials, at the level of tanks, settling basins, lagoons or storage containers. similar odoriferous liquid (s) extending over relatively large areas, comprising providing, in a controlled manner, determined amounts of an active liquid composition to one or more immersed injection units (s) in the container (s) concerned and to diffuse, continuously or sequentially, the active liquid composition via ejection openings located under the surface of the liquid (s) odoriferous (s) stored in said container (s) aforementioned (s).

The invention will be better understood, thanks to the following description, which refers to a preferred embodiment, given by way of non-limiting example, and explained with reference to the attached schematic drawings, in which:
FIG. 1 is a schematic representation of a processing device according to the invention, showing only a single diffusion line,
FIG. 2 is a side elevational view partly in section of a feed unit forming part of the treatment device shown in FIG. 1, and
Figure 3 is a schematic top view showing the implementation of a treatment device according to the invention in a lagoon.

 As shown in FIG. 2, the treatment method according to the invention essentially consists of delivering, in a controlled manner, determined quantities of an active liquid composition to one or more immersed injection unit (s) 2. in the container (s) 3 concerned (s) and to diffuse, continuously or sequentially, the active liquid composition via ejection openings 2 'located below the surface 4' of the liquid or ( s) odoriferous (s) 4 stored in said container (s) 3 above (s).

 So that it can easily migrate to the surface 4 'and produce the expected effects therein, the diffused active liquid composition advantageously has a lower density than that of the odoriferous liquids 4 stored (in particular less than those of the liquid or liquids constituting the layer extending between the openings 2 'and the surface 4') and does not react or mix with them, especially not with the solvents contained therein.

 The liquids stored for decantation treatment being in most cases charged water, the active liquid composition used is, according to a preferred embodiment of the invention, hydrophobic and has a density of less than 1.

 Advantageously, the active liquid composition spreads, after diffusion, on the surface of the odoriferous liquids 4 stored, especially wastewater, in the form of micelles and contains active agents including aldehydes and reacting in the gaseous state. in a physicochemical manner, with odorophore or odorophore group (s) present on the surface of stored liquids 4, said active agents being diluted in a hydrophobic solvent based on vegetable oil.

 The active liquid composition used contains an effective dose of active agent (s) belonging to the family of perfumery raw materials, chosen not only for their odoriferous properties, but also for their action on sulfur and amine structures as well as for their low vapor pressure, preferably less than 1 mm Hg at 25 ° C. These are molecular complexes selected from saturated or unsaturated aliphatic or branched compounds containing various chemical functions, such as aldehydes, ketones, esters or the like.

By way of illustration, the following shows some of the chemical reactions carried out by the use of the active composition according to the invention.
Reaction of an aldehyde with ammonia

Reaction of an aldehyde with a primary amine

Imine or Schiff Base
Reaction of an aldehyde with sulfur hydride

Thio-aldehyde

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Odorless compound
The active agent is diluted in a hydrophobic solvent. Based on vegetable oil, this solvent contains, inter alia, a surfactant characterized by a sufficiently low hydrophilic-lipophilic balance and fully biodegradable. The mixture (solvent + active agent) is formulated in such a way that the resulting composition has a density of less than 1 and a surface tension such that it ensures perfect spreading on the surface of the water to be treated.

 Thus, going back to the surface after diffusion, the sprays of active liquid composition burst on the surface in the form of dynamic micelles with a very broad spectrum of air / water exchange, leading to a rapid coverage of the liquid surfaces of ponds and lagoons, even large area.

 To do this, the provision of a specific low surface tension for the active liquid compositions results in a perfect spread of the inhibitory complexes on the surface of said stored liquids, allowing to reach the large exchange surface required for the treatment of the nuisances. olfactory as soon as they appear.

 Indeed, the volatile active ingredients contained in the active liquid composition are thus distributed over large areas and come into direct contact with the odorophore molecules during their evaporation at the surface 4 'of the stored liquids 4.

 The removal of the nuisance is therefore obtained by gaseous physicochemical reaction and by compensation and olfactory rectification of the gaseous residual of the reaction with additional substances present in the diffused composition.

 In addition, the provision of a low vapor pressure for the active ingredients contained in said active liquid composition will lead to a slow evaporation thereof and, consequently, a long duration of activity and a yield high olfactory treatment.

 It should be noted that the various bases constituting the active composition used in the context of the present invention is characterized by a very high reactivity on the various molecules responsible for olfactory nuisances. The specific action of the active ingredients on the physicochemical properties of the malodorous molecules makes it possible to reduce the perception of the bad odor.

 Indeed, the invention aims to reduce the perception of the odorant by superimposing a molecule that acts according to an electrostatic process. The malodorous molecule incriminated then arrives on the olfactory receptors in the company of another molecule resulting from the active composition. The binding of this last active molecule, by weak bonds, will have the consequence of modifying the polarity of the malodorous molecule or its hydrophilic or lipophilic property (modification of the partition coefficient) or its stereochemistry, thus limiting the interaction between odoriferous molecules / receptors and the induction of the transmembrane current. In some cases, the phenomenon of hydrogenation of a malodorous molecule, causing the loss of its nucleophilic character, has the consequence of reducing its odor.

 This action combined with a phenomenon of olfactory compensation allows, in defined areas of concentration of product treatment, no longer perceive olfactory nuisances and achieve a reduction of these nuisances often greater than 90%.

 It is not, in the case of the invention, a masking effect which consists in acting on the sense of smell by transforming the unpleasant odor into a pleasant and more intense odor. The recovery of a strong odor by another masking odor inevitably leads to a new fragrant mixture of olfactory nuisance index exceeding the tolerance threshold of human olfaction. In the case of treatments with the active composition according to the invention, the olfactory values of the active molecules provide an olfactory equilibrium close to neutrality.

 Depending on the operating conditions, the chemical neutralization, combined with the abatement technique, makes it possible to obtain olfactory neutrality. The neutralization by chemical reaction is based on the reactive chemical functions (aldehydes, ketones, saturated or unsaturated, etc.) contained in the active agents of the composition used.

 In general, the reactions balanced with thiol groups or amine functions are neither total nor rapid unless one of the reactants (neutralizing element) is in very large excess and / or the reaction is catalyzed. The result is then a decrease in the concentration of molecules responsible for odor nuisance by the production of odorant molecules whose detection threshold is such that they can not be perceived olfactively, or the most neutral molecule possible olfactory.

 The effectiveness of the active agents is a function of the choice of the formulation of the active composition, depending on the operating conditions (process temperature for example), but also methods for preparing these formulations. Among the manufacturing and preparation techniques, mention may in particular be made of micronization techniques of the active principles and specific incorporation processes, which make it possible to obtain a perfect match and homogeneity between the product to be treated and the inhibiting active ingredients of the active ingredient. 'odour.

 The principles or agents used are mixtures of natural and / or synthetic raw materials. These are essentially aldehydes that act directly on ammonia, hydrogen sulphide and their organic derivatives, or on volatile organic compounds. The active agents used are biodegradable and perfectly ecological and have been subject to compliance corresponding to the intended applications of use.

 By way of example, the active agents used can be of the type described in EP-A-0 247 946.

 The object of the invention is also, as shown in FIGS. 1, 2 and 3 of the appended drawings, a device for treating olfactory nuisances at the level of settling or leaching basins, lagoons, tanks or similar storage containers. of odoriferous liquids, especially for the implementation of the treatment method.

 This device is mainly constituted, on the one hand, by a feed unit 1 housed in a protective container 5 and comprising a reservoir 6 for a liquid composition active against odorophorous molecules or with odorophore group (s) and a module 7 for controlled distribution of active liquid composition, provided with means 8, 8 'of adjustment and control of the operation and, secondly, by at least one line 9 of active liquid composition diffusion fed each by the module of distribution 7, each immersed in a storage container 3 of odoriferous liquids 4 and each constituted by a supply line 9 'on which injection pipes 2 forming injection units are connected bypass, including the ejection openings 2 are located beneath the surface 4 'of the odoriferous liquids 4 stored.

 In order to guarantee a secure positioning of the diffusion lines 9 after installation, each supply line 9 'is sufficiently weighted to rest on the bottom of the storage container 3 concerned (bottom means either the actual bottom of the container 3, or sediment decanted on the latter), the diffusion tubes 2 having a construction such that they are oriented permanently substantially perpendicular to the surface 4 'of the odoriferous liquids 4 stored.

 This latter arrangement avoids any clogging of the diffusion pipes 2 by the sediments and any interference with the active liquid composition, while allowing an adjusted delivery of the latter.

 The length of said diffusion pipes 2 is sufficiently small so that the ejection openings 2 are located under the surface 4 'even when the filling level of the basins or lagoons is at its lowest value (B).

 Keeping the diffusion lines 9 in position, in particular against the movements of the stored liquids 4, can also be reinforced by anchoring one or both ends of said diffusion lines 9 to a corresponding bank of the pool or the concerned lagoon (e), for example by means of a rope forming a line and a peg.

 According to a preferred embodiment of the invention, the diffusion tubes 2, terminated by injection nozzles for example, are connected to the corresponding supply line 9 'via plug connectors T 10, connected in series with the tubular segments forming the pipe 9 'and mounted with the possibility of free rotation around the axis of the latter, at least one float 11 or at least one similar floating element being fixed to each diffusion pipe 2, near the ejection opening 2 'at the free end of the latter, the tubes 2 are therefore always oriented vertically.

 In order to be able to process several storage containers 3 or a very large storage container 3 with a single power unit I situated on a bank or on a corresponding central location, each diffusion line 9 is connected to the distribution module 7 of the feed unit 1 by a main transfer pipe 12, possibly extended by a network of secondary pipes 12 'connected in parallel to said main transfer pipe 12, the non-immersed portions of said pipes 12, 12' being covered with a thermal insulation coating.

 The evacuation circuit may further comprise a pressure-maintaining valve 17 and a pressure gauge 18 and have, connected bypass, a discharge valve 19 connected to a return pipe opening into the reservoir 6.

 According to another characteristic of the invention, the dispensing module may comprise a metering pump 13 whose suction circuit terminates in a suction strainer 14 located near the bottom of the tank 6 and whose evacuation circuit feeds, by means of an injection head 15, the diffusion line or lines 9, if necessary via a main transfer pipe 12 and secondary pipes 12 'extending it, the operation of said pump metering device 13 which can be preset and / or preprogrammed by means of members 8 'adapted to an automatic control module 8.

 The automatic control module 8 advantageously allows the preselection of the diffusion parameters such as, for example, the quantities of active liquid composition diffused, the nature of the diffusion (continuous or sequential), the time slots of effective diffusion (for example adjustable from 5 seconds to 3 minutes in increments of one second), intervals between diffusion slots (e.g. adjustable from 10 minutes to 4 hours in 5 minute increments) or the like.

 In order to obtain maximum efficiency of the device with minimal material resources, it may advantageously be provided that the diffusion lines 9 are located in particular along at least a portion of the edges or banks of the storage containers 3 concerned, their provision and their extension depending on the configuration of the surrounding area 21, including inhabited, to protect.

 As shown in Figure 3 of the accompanying drawings, the diffusion lines 9 are arranged to be located along the edges of the storage containers 3, opposite to those adjacent to the surrounding area to be protected 21 and to cover accordingly, under the action of the wind V, substantially the entire surface 4 'of the stored liquids 4.

 In order to optimally use the active liquid composition, the diffusion lines 9, or portions 9a and 9b of these diffusion lines, are fed according to certain factors and air-flow parameters at the surface 4 'of the liquids. storage containers 3, in particular the wind direction V.

 The determination of these parameters or factors may be effected by means of suitable devices (wind vane, anemometer or the like) and evaluated by the automatic control module 8.

 Thus, referring to the situation shown in FIG. 3 of the appended drawings and taking into account the direction of the wind V indicated, a supply of the single portion of the diffusion line 9a will be sufficient to effectively protect the zone 21.

 According to a further characteristic of the invention, also represented in FIG. 1 of the appended drawings, the protective container comprises a removable and lockable lid 5 'allowing access to the dispensing module 5 and to the filling opening 6' of the tank 6, the protective container 5 being furthermore thermally insulated and containing a heating means 16 of its internal volume, connected to a temperature sensor and avoiding the freezing of the solution present in the tank 6.

 In addition, it may also be provided a visual and / or audible alarm 20 warning the operator in case of malfunction or exceeding a low level in the tank 6.

 Thanks to the invention, it is therefore possible to provide a device for treating olfactory nuisances of settling ponds and lagoons, having a simple structure, adaptable to ponds or lagoons of various shapes and sizes, flexible to use ( modification of the number of diffusion units, programming of the diffusion), making it possible to precisely control the treated zones, using the active composition with an optimal yield, not influenced by the wind and protected from the frost in its greater part, because of his immersion.

 Of course, the invention is not limited to the embodiment described and shown in the accompanying drawings. Modifications are possible, particularly from the point of view of the constitution of the various elements or by substitution of technical equivalents, without departing from the scope of protection of the invention.

Claims (12)

 1. A method for the treatment of olfactory nuisances, especially those generated by the vital processes or the degradation of organic matter, at the level of tanks, settling ponds, lagoons or odoriferous liquid storage containers (s) ) similar (s) extending over relatively large areas, characterized in that it consists essentially of delivering, in a controlled manner, determined amounts of a liquid active composition to one or more injection unit (s) (2) immersed in the container (s) (3) concerned and to diffuse, continuously or sequentially, the active liquid composition via ejection openings (2 ') located beneath the surface (4 ') of the odiferous liquid (s) (4) stored in said container (s) (3) above.  2. Method according to claim 1, characterized in that the diffused active liquid composition has a density lower than that of the odoriferous liquids (4) stored and does not react or mix with them.  3. Method according to claim 1, characterized in that the active liquid composition is hydrophobic and has a density of less than 1.  4. Method according to any one of claims 1 to 3, characterized in that the active liquid composition spread, after diffusion, on the surface of the odoriferous liquids (4) stored, including wastewater, in the form of micelles and contains active agents comprising especially aldehydes and reacting in gaseous state, physico-chemically, with the odorophore or odorophore group (s) present on the surface of the stored liquids (4), said agents active ingredients being diluted in a hydrophobic solvent based on vegetable oil.  5. Odor nuisance treatment device at settling or leaching tanks, lagoons, tanks or similar storage containers of odoriferous liquids, in particular for carrying out the treatment method according to any one of the claims. 1 to 4, characterized in that it consists mainly of, on the one hand, a power unit (1) housed in a protective container (5) and comprising a reservoir (6) for a liquid composition active against the odorophore or odorophore group (s) and a module (7) for controlled distribution of active liquid composition, provided with means (8, 8 ') for controlling and controlling the operation and, secondly, by at least one active liquid composition diffusion line (9) each supplied by the dispensing module (7), each immersed in a storage container (3) of odoriferous liquids (4) and each constituted by a pipe supply nozzle (9 ') on which diffusion pipes (2) forming injection units are branched off, the ejection openings (2') of which are situated under the surface (4 ') of the odoriferous liquids (4) ) stored.  6. Device according to claim 5, characterized in that each supply line (9 ') is sufficiently weighted to rest on the bottom of the storage container (3) concerned and in that the diffusion tubes (2) are oriented continuously substantially perpendicular to the surface (4 ') of the odoriferous liquids (4) stored.  7. Device according to claim 6, characterized in that the diffusion tubes (2) are connected to the corresponding supply line (9 ') via T-connectors (10), connected in series with the segments. tubular forming the pipe (9 ') and mounted with free rotation around the axis of the latter, and in that at least one float (11) or at least one similar floating element is attached to each pipe of diffusion (2), close to the ejection opening (2 ') at the free end thereof.  8. Device according to any one of claims 5 to 7, characterized in that each diffusion line (9) is connected to the distribution module (7) of the supply unit (1) by a main transfer pipe (12), optionally extended by a network of secondary pipes (12 ') connected in parallel to said main transfer pipe (12), the non-immersed portions of said pipes (12, 12') being covered with an insulation coating thermal.  9. Device according to any one of claims 5 to 8, characterized in that the diffusion lines (9) are located in particular along at least part of the edges or banks of the storage containers (3) concerned, their arrangement and their extension being a function of the configuration of the surrounding area (21), particularly inhabited, to be protected.  10. Device according to any one of claims 5 to 9, characterized in that the diffusion lines (9), or portions (9a and 9b) of these diffusion lines, are fed according to certain factors and aeraulic parameters. at the surface (4 ') of the liquid storage containers (3), including the wind direction (V).  11. Device according to any one of claims 5 to 10, characterized in that the dispensing module (7) comprises a metering pump (13) whose suction circuit ends with a suction strainer (14) located in the vicinity of the bottom of the tank (6) and whose evacuation circuit supplies, by means of an injection head (15), or the diffusion lines (9), where appropriate via a main transfer pipe (12) and secondary pipes (12 ') extending it, the operation of said metering pump (13) being preset and / or preprogrammed by means of members (8') adapted from a automatic control (8).  12. Device according to any one of claims 5 to 11, characterized in that the protective container comprises a lid (5 ') lockable, allowing access to the dispensing module (5) and to the filling opening ( 6 ') of the container (6), the protective container (5) being further thermally insulated and containing a heating means (16) of its internal volume.