FR3036394A1 - DEVICE AND METHOD FOR EVALUATING THE CAPACITY OF A SOLID MATERIAL TO CONSTITUTE A FILTER MEDIUM SUPPORTING A PURIFYING BIOMASS FOR THE PURIFICATION OF WASTEWATER - Google Patents

Abstract

The invention relates to a device for evaluating the capacity of a solid material to form an aerobic purifying biomass support filter medium for the purification of wastewater, which comprises a reactor (20) comprising an upper chamber (21). ) for receiving the solid material and a lower chamber (22), separated from each other by a perforated partition (23), and air circulation means between the atmosphere outside the reactor (20). ) and the lower chamber (22), comprising a hollow tube (25) extending from an upper end (251) opening above the upper chamber (21), to the lower chamber (22), said tube (25) having at least one opening in the lower chamber (22) and being disposed centrally of said reactor (20). The device further comprises influent introduction means in an upper portion of the upper chamber (21) and effluent withdrawal means in the lower chamber (22).

Description

The present invention is in the field of biological purification of wastewater, including so-called domestic wastewater, from buildings or parts of buildings not connected to a public sewage collection network. More particularly, the present invention relates to a device for evaluating the capacity of a solid material to constitute an aerobic purifying biomass support filter medium for the purification of wastewater, as well as a method for such an evaluation, implementing such a device. Homes that do not have access to a public sewage collection system, more commonly referred to as a sewage system, must be equipped with a sewage treatment plant of their own. This is referred to as non-collective sanitation facilities, which are defined by the French regulations as "any sanitation facility ensuring the collection, transport, treatment and disposal of domestic wastewater or similar under the Article R. 214-5 of the Environment Code for buildings or parts of buildings not connected to a public sewage collection network ". It has been developed by the prior art different types of non-collective sanitation facilities. Among these types of installations, in particular filtering masses, also called compact filters, which constitute a biological filtration system using a porous solid medium, especially formed of granular material, called filter media, colonized by a biomass rich in aerobic bacteria purifying, and through which the wastewater to be treated passes. During their journey through the filter, the wastewater is removed by filtration of the suspended matter, and the organic impurities contained therein undergo a biological transformation by the bacteria present in the filter medium. The bacterial development in the filtering medium occurs naturally thanks to the microorganisms, mainly bacteria, present in the wastewater to be purified.

Such non-collective sanitation installations generally comprise a tank containing the filter medium and a system for distributing the effluent in this tank. The wastewater supply is sequential, which allows, after runoff of a body of water on the medium, a phase of natural aeration. Several types of solid materials may be used to form the filter media of non-collective sanitation facilities. Examples of such materials are mineral-type materials such as zeolite or rockwool, synthetic materials such as geotextiles, or organic-type materials such as coconut chips. Organic materials, more specifically plant-based materials, are of particular interest because their implementation is part of a more global strategy for developing renewable resources. Thus, it would be quite advantageous, from an economic as well as an ecological point of view, to be able to use, in order to constitute the filtering media within the non-collective sanitation installations, solid waste resulting from agriculture, and even more so from local agriculture, so as to limit the transport of waste from their place of production to their place of use. However, not all materials of vegetable origin have the appropriate properties to constitute filtering media with a purification capacity satisfying the sanitary and regulatory requirements in force. It is an object of the present invention to provide means for laboratory-wide evaluation of a given solid material, particularly a material of plant origin, whether or not it has the capacity to form a filter medium of adequate properties to ensure the purification of wastewater in a non-collective sanitation installation, ie the ability to form a filter medium with a high level of purification in real conditions of use.

A particular object of the invention is that this evaluation can be performed reliably, easily and at a reduced cost.

For this purpose, according to a first aspect, there is provided by the present invention a device for evaluating, at laboratory scale, the capacity of a solid material capable of forming a porous layer, especially a material plant-based solid, to constitute an aerobic filtering support medium aerobic filter for the purification of wastewater. This device comprises: a reactor, of the downflow type, comprising an upper chamber intended to receive the solid material and a lower chamber, the upper chamber and the lower chamber being separated from each other by a partition wall; perforated separation; means for circulating air between the outside atmosphere of the reactor and the lower chamber, comprising a hollow tube, called a central tube, delimited by a peripheral wall and extending from a first end, said upper end, opening at above the upper chamber, through the upper chamber, to the lower chamber, this tube having at least one opening in the lower chamber and being disposed substantially in the center of the reactor; influent introduction means in an upper part of the upper chamber; And - effluent withdrawal means in the lower chamber. In the expression "solid material", the present description includes both a single material, a mixture of several materials, in bulk or in the form of a set of distinct layers of different materials stacked on each other. others.

The perforations formed in the perforated partition are in particular configured so that they are able to confine the solid material in the upper chamber, preventing its passage in the lower chamber. In another aspect, the present invention relates to a laboratory-wide evaluation method of the capacity of a solid material capable of forming a porous layer, preferably a granular solid material, to form a aerobic purifying biomass filter medium for the purification of wastewater, by means of a device according to the invention. This process comprises: - filling the upper chamber of the reactor with the solid material, - a first supply phase, by the influent introduction means in the upper part of the upper chamber of the reactor, of this chamber higher by a polluting solution, according to a first predetermined batch feed profile, this first phase having a sufficient duration to allow the development of biomass purifier within the solid material and obtaining a steady state, - a second phase feeding, also by the influent introduction means in the upper part of the upper chamber of the reactor, of this upper chamber by a polluting solution, preferably the same polluting solution as that used for the first phase of feeding, according to a second predetermined discontinuous feed profile, preferably substantially identical to the first feed profile, - the sampling of an effluent sample in the lower chamber 20 of the reactor during the second feed phase, by the effluent withdrawal means in said lower chamber, - the analysis of the effluent sample thus taken for the following physicochemical parameters: biological oxygen demand at 5 days (BOD5), suspended matter content (MES), and at least one parameter chosen from the ammonium ion content ( NH4 ±) and the content of nitrate ions (NO3-), preferably the latter two parameters; and comparing, for each of these physico-chemical parameters, the analysis result obtained with a predetermined range of values indicative of a desired level of purification, a result of analysis included in this predetermined range of values being indicative of a solid material capable of constituting a filter medium supporting biomass purifier for the purification of wastewater with respect to said parameter. On the other hand, an analysis result outside the predetermined range of values to be indicative of the desired level of purification is indicative of a solid material lacking, for said parameter, the ability to form a suitable filter medium for a desired level of purification. implemented in a non-collective sanitation installation. According to the invention, a material for which, for at least one of said parameters, the analysis result is not included in the associated predetermined value range, is not likely to constitute a purifying biomass support filter medium. satisfactory aerobic capacity for sewage treatment. Preferably, the analysis steps of the effluent sample and comparison with a predetermined range of values indicative of a desired level of purification are also carried out for at least one, preferably at least two, and preferably together, the following physicochemical parameters: chemical oxygen demand (COD), pH and total nitrogen content (NT). In particular, the evaluation of the total nitrogen content (NT) advantageously makes it possible to check the progress of the nitrification and denitrification reactions occurring in the filter medium. A pH between 5.5 and 8.5 is indicative of a treatment level compatible with the discharge of the effluent into the natural environment. The evaluation of the nitrate content (NO 3 -) makes it possible in particular to verify that the nitrification takes place within the filter medium, which is revealed by an increase in the value measured for the effluent obtained at the outlet. of the reactor, with respect to the known or measured value for the pollutant solution supplying the reactor. The content of ammonium ions (NH 4 +) also makes it possible to verify that the nitrification is carried out correctly, if its value decreases between the known or measured value for the pollutant solution supplying the reactor, and the value measured for the effluent in question. reactor outlet. The method according to the invention may further comprise the analysis of the effluent sample taken at the end of said second feed phase 5 for the following microbiological parameters: concentration of enterococcal microorganisms and concentration of Escherichia coli; and comparing, for each of these microbiological parameters, the result of analysis obtained with a predetermined range of values indicative of a desired level of purification, a result of analysis included in said predetermined range of values being indicative of a solid material capable of constituting a purifying biomass support filter medium for the purification of wastewater with respect to said parameter. The sampling and analysis and comparison steps are also preferably carried out several times over time, so as to allow a follow-up of the evolution of the targeted parameters over time. The device and the method according to the invention advantageously make it possible, on a laboratory scale, to determine whether or not a given solid material has the characteristics which will enable it to form a filtering medium which will present, implemented under real-life conditions. within a non-collective sanitation installation, a satisfactory purification capacity, and in particular in accordance with the regulations in force. In particular, the hollow tube extending into the reactor, substantially in the center of the latter, and having an opening in the lower chamber, allows air to flow from the atmosphere outside the reactor to the reactor. inside the lower chamber, then from the perforations of the perforated partition, to the lower zone of the medium formed by the solid material in the upper chamber. Such an air circulation advantageously ensures good aeration of the solid medium contained in the lower chamber, and thereby increases the reliability of the evaluation of the capacity of the solid material to constitute a filtering medium for sanitation installation. not collective. This reliability is all the more important that the central position of the tube in the reactor further facilitates an even distribution of the solid material throughout the remaining free volume of the upper chamber.

It is the responsibility of a person skilled in the art to determine, depending on the level of purification of the wastewater that he wishes to obtain, this level being in particular dictated by the regulations in force at the time of the implementation of the invention, and by the type of use to which the effluent obtained at the outlet of the reactor is intended, which exact parameters it is relevant to analyze, among those listed above, and for each of these parameters, in which predetermined range of values the value of the result of analysis obtained should be to be indicative of the desired level of purification. These ranges of values may in particular be established, for certain parameters, according to the standards and regulations in force at the time of the test. For other parameters, in particular for the nitrate ion content and for the ammonium ion content, they may otherwise be established by comparison with the known or measured parameter value for the polluting solution introduced into the reactor. The method according to the invention then comprises a step of comparison, for the parameter concerned, of the measured value for the effluent leaving the reactor, to the known or measured value for the polluting solution introduced into the reactor, the latter value constituting the lower or upper limit of the range of values with which the analysis result is compared, to determine whether or not the solid material is capable of providing a satisfactory filtering medium for the purification of wastewater. A predetermined value range may further evolve over time, and be defined by the value obtained for the previous sample, in the case of a process comprising several steps of sampling an effluent sample at different intervals in the weather.

3036394 8 The predetermined value ranges can be defined by two terminals, or a single terminal. With regard to the physicochemical parameters, the process according to the invention preferably also comprises the analysis of at least one, preferably at least two, and more preferably all, of the following parameters: conductivity, - turbidity, - total phosphorus content.

The monitoring of the variations in turbidity makes it particularly advantageous to identify possible problems of operation such as clogging or salting out. As regards the microbiological parameters, the method according to the invention also preferably comprises the analysis of at least one, preferably several, and more preferably all, of the following parameters: the concentration of coliform bacteria, the concentration of microorganisms revivable at 22 ° C and 36 ° C. Each of these parameters, as well as the Escherichia coli concentration and the enterococci concentration, can be analyzed by any conventional method of analysis per se for the skilled person. The polluting solution used is preferably of known composition. Preferably, it is a synthetic solution, representative of a waste water. Here again, it is within the skill of the person skilled in the art to know how to determine the composition of this pollutant synthesis solution as a function of the type of dwelling for which the solid material is intended to be used, within a non-collective sanitation facility. By "first feed phase having a sufficient duration 3036394 9 to allow the development of biomass purifying within the solid material and obtaining a steady state", it is meant in the present description that the duration of the first phase of The feed is sufficient to obtain the stabilization of the evolution of the physico-chemical parameters BOD5 and MES measured for the effluent leaving the reactor. It is within the skills of a person skilled in the art to determine this duration, in particular by experience, by analysis of samples taken on the effluent taken from the lower chamber of the reactor, the stabilization of at least one physico-chemical parameter. among the MESs and BOD5 being indicative of obtaining a steady state. Otherwise, one skilled in the art can determine this duration theoretically, depending on the particular discontinuous feed profile he has chosen. This feed profile is defined in particular by the frequency of introduction of pollutant solution into the reactor and the amount of solution introduced to each tarpaulin. For example, the first feeding phase may have a duration of between four and eight weeks, in particular be equal to about six weeks. At the end of this first feed phase, a quantity of biomass naturally developed within the medium formed in the upper chamber of the reactor. The pollutant solution flowing in the latter, through the filtering medium formed by the solid material, is then subjected to a level of purification more or less high depending on the properties of the solid material. Determining the duration of the second feeding phase is within the skill of the skilled person, depending on the legislation in progress. It can be up to several months. It is preferably greater than or equal to 40 weeks, for example about 40 weeks. The method according to the invention can comprise, during this second feed phase, several steps of sampling an effluent sample in the lower chamber of the reactor, at regular or irregular time intervals, and analysis of these samples. In particular embodiments of the invention, the evaluation method comprises, at the end of the second feed phase, a step of measuring the oxygen content in the solid material contained in the upper chamber of the reactor, at different points of the height of this upper chamber. Obtaining at least a value of less than 15% oxygen, measured by means of an electrochemical sensor, is indicative of the inability of said solid material to constitute a purifying biomass support filter medium for the wastewater purification, because insufficient to ensure the occurrence of nitrification reactions in aerobic medium in the filter medium.

The solid material is a material capable of forming a porous layer. It is preferably a granular material. Preferably, the solid material is a material of plant origin. According to particular embodiments, the device according to the invention also fulfills the following characteristics, implemented separately or in each of their technically operating combinations. In particular embodiments of the invention, the portion of the peripheral wall of the tube disposed in the lower chamber is pierced with at least one through orifice, preferably a plurality of orifices 20 therethrough. Such a configuration of the tube advantageously ensures optimum aeration of the solid material contained in the upper chamber of the reactor. In particular embodiments of the invention, the influent introduction means in the upper part of the upper chamber of the reactor comprises a tilting bucket, providing a sheet feed of the reactor, representative of the type of feed. wastewater from filter media of non-collective sanitation facilities. This bucket is preferably of the bidirectional type, so that it can alternately feed two different reactors.

Preferably, the tilting bucket comprises a plurality of compartments, for example three compartments delimited with respect to one another by walls substantially perpendicular to an axis about which the tipping bucket is able to tilt. Such a characteristic advantageously ensures a more homogeneous distribution of the influent discharged by the tipping bucket into the upper chamber. The influent introduction means in an upper portion of the upper chamber preferably further comprises means for distributing said influent in different areas of the upper surface of the upper chamber. These distribution means may for example comprise a said distribution plate disposed above the upper chamber, and in which are hollowed a plurality of grooves extending substantially in the direction of flow of the influent from the means of distribution. introduction of influent in the upper part of the upper chamber. Each of these grooves is pierced in its bottom by at least one, preferably two, through-holes, to permit flow of the influent into the upper chamber. In particular embodiments of the invention, the reactor is cylindrical, and the tube is preferably also cylindrical, the reactor and the tube then being preferentially substantially concentric.

The device according to the invention, satisfying the above characteristics, is advantageously easy to use, while having a simple constitution, and a cost and limited implementation. In particularly advantageous embodiments of the invention, the device comprises a plurality of reactors and influent introduction means, alternatively, in the upper part of the upper chamber of each of these reactors. In particular, the reactors can be associated two by two to a bi-directional tipping bucket. Such a configuration of the device according to the invention makes it possible simultaneously to evaluate several solid materials for their capacity to form a filter medium for a non-collective sanitation installation, by common material means.

According to another aspect, the present invention relates to a granular solid material capable of forming a purifying biomass support filter medium for the purification of waste water used in the constitution of a non-collective sanitation installation. This material has a lower layer based on olive pomace, and a top layer based on hemp, a woody part of hemp that remains after the tow has been removed. Preferably, the thickness ratio between the lower layer and the upper layer is between about 0.3 and 1.5, and preferably between 0.5 and 1. The lower layer advantageously provides good mechanical strength in the middle , while the upper layer confers on the medium formed its good purification capacity. For example, the thickness ratio between the lower layer and the upper layer is substantially equal to 1. The invention also relates to a non-collective sanitation installation comprising a filter medium formed of a bottom layer based on of olive pomace and a top layer of chenevotte. This medium may meet one or more of the above characteristics. The features and advantages of the invention will appear more clearly in the light of the following examples, provided for illustrative purposes only and in no way limiting the invention, with the support of FIGS. 1 to 12, in which: FIG. 1 schematically represents a reactor forming part of a device for evaluating the capacity of a solid material to constitute a filter medium for the purification of wastewater, according to a particular embodiment of the invention. invention; - Figure 2a shows, in section along a transverse plane, a tilting bucket forming part of a device according to a particular embodiment of the invention; - Figure 2b shows, in front view, the tipping bucket of Figure 2a; - Figure 2c shows, in top view, the tipping bucket of Figure 2a; - Figure 3 shows, in top view, a distribution plate of a device according to a particular embodiment of the invention; FIG. 4 represents a pollutant solution preparation system forming part of a device according to one particular embodiment of the invention; FIG. 5 shows a device according to the invention, comprising a plurality of reactors; FIG. 6 shows a cross-sectional view of the upper chamber of the reactor of a device according to the invention, illustrating the zones for measuring the oxygen content in the solid material contained therein; FIG. 7 shows images taken at several points from the height of the upper chamber of a device according to the invention, containing a mixture of chenevotte and olive pomace (CHTGO) as a solid material, after 40 minutes. weeks of second feeding phase of a method according to a particular embodiment of the invention, these images illustrating the colonization of the medium by the biomass along this height; FIG. 8 shows images taken at several points from the height of the upper chamber of a device according to the invention, containing a layer of chenevotte (CHT) superimposed on a layer of olive pomace (GO), in as solid material, after 40 weeks of second feeding phase of a method according to a particular embodiment of the invention, these images illustrating the colonization of the medium by the biomass along this height; FIG. 9 shows a graph illustrating the evolution of the oxygen content (O 2) and of the carbon dioxide (CO 2) content on the height of the upper chamber of a device according to the invention, containing a mixture of chenevotte and olive pomace (CHTGO) as solid material, after 40 weeks of second feeding phase of a method according to a particular embodiment of the invention; FIG. 10 shows a graph illustrating the evolution of the oxygen content (O 2) and the content of carbon dioxide (CO 2) over the height of the upper chamber of a device according to the invention, containing a layer of 5 chènevotte (CHT) superimposed on a layer of olive pomace (GO), as a solid material, after 40 weeks of second feeding phase of a method according to a particular embodiment of the invention; FIG. 11 schematically represents a non-collective sanitation installation containing a filter medium formed of a lower layer based on olive pomace and a top layer based on chenevotte; and FIG. 12 shows images taken at several points from the height of the filter medium of the installation of FIG. 11, these images illustrating the colonization of the medium by the biomass along this height, after 15 weeks of use. for the purification of wastewater from a dwelling. A / Device according to the invention Figures 1 to 5 represent various elements that can be used in the constitution of a device according to the invention, for evaluating the capacity of a solid material to form a filtering medium supporting biomass purifier aerobic, for the purification of wastewater with high purification performance and consistent with a desired level of purification. The device according to the invention comprises a reactor 20, shown in FIG. 1, comprising an upper chamber 21, intended to receive the solid material whose properties are to be evaluated, and a lower chamber 22. The upper chamber 21 and the chamber 22 are separated from each other by a partition wall 23, which is fixed in the reactor by means of a circular seal. This partition 23 is pierced with a plurality of perforations 24, which are of sufficiently small size not to allow the solid material contained in the upper chamber 21 to escape into the lower chamber 22, but large enough to leave a gap. fluid flow freely through the wall 23. The reactor 20 has for example a cylindrical shape. In its interior, extends a central tube 25, preferably of shape 5 also cylindrical and concentric with the reactor 20. This central tube 25 opens at an upper end 251, through an end opening 252, above the upper chamber 21. It extends from this upper end 251, through the upper chamber 21, through the partition wall 23 which is pierced by a window for this purpose, and through the lower chamber 22, to a bottom wall 221 of the latter. The central tube 25 may be open at its lower end, opposite said upper end 251, this opening then being disposed under the lower chamber 22. The central tube 25 is defined by a peripheral wall 253. In its portion disposed in the chamber 22, this peripheral wall 253 is pierced with a plurality of through orifices 254, which ensure a flow of air between the inside of the central tube 25 and the lower chamber 22. As a non-limiting example of the In the invention, the reactor can be made of transparent polyvinyl chloride (PVC), which has the particular advantage of making it possible to visualize the phenomena occurring in its interior. The device further comprises effluent sampling means in the lower chamber 22, having an orifice 222 formed in the bottom wall 221 of the lower chamber 22.

The device also comprises influent introduction means in an upper part of the upper chamber 21. These introduction means may for example comprise a tilting bucket 26, allowing a supply by tarpaulin, an exemplary embodiment of which is shown. in Figure 2a. This bucket 26 is adapted to tilt about a tilting axis 27, between a filling position by the influent and a position of influent spill in the reactor 20. The tipping bucket 26 is preferably of bidirectional type, that is to say it comprises two trays 261, 262 disposed on either side of the tilt axis 27, so that when one of the bins is in the filling position, the other is in the spill position, and vice versa. The tipping bucket 26 is disposed in the device such that each of the tanks 261, 262 is able to feed into influence a reactor 20, 20 'different. The internal volume of influent that each of the tanks 261, 262 is able to discharge into the reactor 20, 20 'associated is adjustable, by means of a set screw 264, 263, which determines the lift height of the tray 261 , 262 opposite, and therefore the influent volume that this tray is able to receive before tipping into the spill position. In order that the volume of influent discharged into the reactor 20 by the tipping bucket 26 is distributed as evenly as possible over the upper surface of the upper chamber 21, each tray 261, 262 is divided into three compartments 265, illustrated in FIGS. FIGS. 2b and 2c, by walls 266 extending substantially perpendicularly to the tilt axis 27 of the trough 26. This configuration advantageously ensures that the influent volume does not concentrate at the center of the trough 26 during the tilting, and instead it is divided into three distinct streams. The device further comprises a plate 28 for distributing the influent discharged by the tipping bucket 26 into different zones of the upper surface of the upper chamber 21. This distribution plate 28, an exemplary embodiment of which is shown in FIG. 3, is disposed at the top of the reactor 20, above the upper chamber 21. The distribution plate 28 is pierced at its center with a central window 281 for passing through the central tube 25. A plurality of grooves 282 are hollowed on its surface, on either side of this central window 281. By way of example, twelve grooves 282 of 4 mm wide each are thus hollowed out.

In order to prevent too much runoff of the water along the central tube 25 and to be able to distribute influent behind this tube, two grooves 283 are arranged so as to follow the central window 281. These two grooves 283 meet behind this central window 281 in a groove 5 284 twice as large, in order to better distribute the influent. Each groove 282, 283, 284 is for example 3 mm deep. Each groove 282, 283, 284 is further pierced in its bottom with a plurality of through orifices 285, for example two through-holes 285. Each of these orifices preferably has a width substantially equal to that of the groove, and, for example, a length of about 1 cm. These grooves 282, 283, 284 and associated through-holes 285 advantageously make it possible to distribute the influent over the entire upper surface of the upper chamber 21, and therefore of the bed of solid material that this chamber is intended to receive. The device may further comprise a pollutant solution preparation system to be poured, as an influent, into the upper chamber 21 of the reactor 20 containing the solid material to be evaluated. An example of such a system is shown in Figure 4.

The polluting solution is preferably an artificial solution, having pollutant concentrations of the same order of magnitude as those found at the outlet of all-water pits on the non-collective sanitation installations. In order to have access to a large quantity and an almost stable quality of pollutant solution, the latter is preferably manufactured in two stages: preparation of a concentrated stock solution, then custom mixing of a volume of this mother solution and city water, to obtain the concentration to be treated. The mixture is carried out by a flushing system with a constant supply, in a tank 29, of tap water 30, supplied by a pipe 301, and mother pollutant solution 31, provided by a The tank 29, called feed tank, is equipped with a level probe. High and low level instructions make it possible to trigger the supply of city water 30 and the supply of mother polluting solution 31.

For a tank 10L of 10 L, the low level of the feed tank is for example set at 2 L filling, and the high level at 8 L. The liquid mixture 32 contained in the tank 29 is constantly stirred by A mechanical stirrer 33. The polluting solution 32 thus obtained in the tank 29 can be conveyed to the tilting bucket (s) 26 by lines 34, by means of peristaltic pumps 35, as shown in FIG. Tilting buckets 26, of bidirectional type, are symbolized by parentheses each associating two reactors 20, 20 'according to the invention. The device comprises a plurality of pairs of reactors 20, 20 ', 15 which can be fed alternately with the same polluting solution 32, from the same feed tank 29. In order to easily vary the pollutant concentration of the solution poured into the the reactors 20, the device according to the invention may furthermore comprise, as shown on the left in FIG. 5, a clear water tank 36 whose contents may also be distributed in the tilting buckets 26, via a pipe 37 and by means of a peristaltic pump 38, so as to dilute the polluting solution 32. Such an embodiment advantageously confers on the device a great adaptability, since it makes it possible to easily vary the degree of dilution of the influent feeding 25 each reactor 20, depending on the specific needs of the experiment. B / Examples of implementation of a method according to the invention A method according to the invention can be implemented in the laboratory as follows, by means of the device described above. By way of illustration, hereinafter described is the implementation of the method for evaluating the purifying capacity of two particular solid materials: a mixture of chenevotte and olive pomace (CHTGO) and a bilayer material (CHT / GO) consisting of a lower layer of olive pomace (GO) and a top layer of chenevot (CHT). Olive pomace is a by-product of the process of extracting olive oil (solid residue), which has been milled as it passes through the pressure mill and then separated from the olive pulp. and dried at 90 ° C. Their average particle size is about 5 mm. The chenevotte used, central and soft part of the hemp stalk, was obtained by mechanical defibration of the hemp stalk.

The total height of material in the reactor is set at 49 cm. In the case of the CHT / GO bilayer material, the two layers, respectively of CHT and GO, are of the same height. The dimensions of the reactor 20 used are as follows. The reactor 20 is a cylinder with a diameter of 20 cm and a height of 60 cm. The central tube 25 has a diameter of 20 mm and a height of 60 cm. It is drilled, at a height of 50 mm from its lower end 255, a plurality of orifices each having a diameter of 3 mm.

The partition wall 23 has a diameter of 20 cm. It is disposed at 50 mm above the bottom wall 221 of the lower chamber 22. It is pierced with a plurality of perforations 24 each having a diameter of 3 mm. The reactor 20 is fed with sheets of 30 ml of influent. For this purpose, each compartment of the bucket has the following dimensions (L x I x h), in cm: 10 x 6 x 2.3. The distribution plate 28 has a diameter of 20 cm. On its surface are dug twelve grooves 282 of 4 mm wide, together forming a rectangle of 10 x 17 cm. The area covered by the grooves 282 then represents 170 cm 2, which results in a distribution of influent spilled into the reactor 20 over 55% of the upper surface of the upper chamber 21. This percentage is substantially equivalent to that obtained in non-collective sewage systems with existing coconut shavings filter.

A volume of 15 L of solid material is placed in the upper chamber 21 of the reactor 20, distributed around the central tube 25. The pilot surface being 311 cm 2, this represents a height of about 49 cm of filter medium formed in the upper chamber 21. The influent is a pollutant solution synthesized from STEP digested sludge and chemical compounds to achieve the desired concentrations of pollutants (Lakel, A., 2005. Non-collective sanitation : instructions for use, CSTB e-notebook, page 6). The characteristics of the pollutant solution are shown in Table 1 below. Parameter Concentration COD (mg.L-1) 400 Chemical Oxygen Demand DB05 (mgr ') 200 Biological Oxygen Demand at 5 days MES (mgr') 90 Materials in Suspension NT (mgN.1 = 1) 65 Total NH4 + Nitrogen ( mgN.1 = 1) Ammonia nitrogen PT (Merl) Total phosphorus Table 1 - Characteristics of the polluting solution The process is carried out over several weeks, more specifically 46 weeks for the material CHTGO (monolayer mixture) and for the material CHT / GO (bilayer). For each of the two materials, firstly, a first phase of supply of the pollutant solution reactor is carried out according to the following discontinuous feed profile: a 30-ml tarpaulin every 12 minutes, ie a daily volume influent to treat 3.4 Lj-1, with no change in feed rate over a day. This first phase extends over a period of 6 weeks, and makes it possible to obtain the steady state in the reactor. This 6-week period corresponds to the period of development of the microbial purifying biomass within the filter medium. A second reactor feed phase is then carried out in the same pollutant solution, according to the same discontinuous feed profile 10 as that described above. This second feeding phase has a duration of 40 weeks for the CHTGO material and for the CHT / GO material. The operation of the reactors is preferably performed in the dark, so as to be as representative as possible of the reality of non-collective sanitation facilities.

Analysis of Physico-Chemical and Microbiological Parameters During this second phase, samples are taken from the influents at the inlet of the reactors and the effluents leaving the reactors, in order to evaluate the purification capacities of the solid materials tested. For this purpose, the effluents leaving the reactors are sampled weekly to evaluate their physicochemical and microbiological characteristics. This weekly sampling begins after about 6 weeks of operation in the second feeding phase. The effluents at the outlet of the reactor are collected for 48 hours in buckets placed under the reactors, in order to collect a sufficient volume to carry out a suitable sampling for analyzes. Buckets and drain pipes are washed and wiped beforehand. The effluents are homogenized before being placed in flasks. The physicochemical parameters evaluated are the chemical oxygen demand (COD), the biological oxygen demand at 5 days (BOD5), the pH, the conductivity, the turbidity, the total phosphorus content (PT), the nitrogen total 3036394 22 (NT), nitrate content, ammonium ion content and suspended solids content (MES). These analyzes are carried out in a conventional manner in itself for the skilled person. Table 2 below indicates, for each parameter, the analysis method used, with reference to the associated standard. Parameter Unit Method Reference standard pH pH-meter NFT 90-008 Conductivity (Cond.) 1 .. 1S.cm-1 Conductivity meter NF EN 27888 (T 90-031) Turbidity (Turb.) NTU Turbidimeter NF EN ISO 7027 (T 90-033) Chemical demand in mg.L-1 Rapid test ISO 15705 Oxygen (COD) Biological demand in mg.L-1 Inoculation NF EN 1899 Oxygen (DB05) - Incubation (T 90-103) Total nitrogen (NT) mgN.L-1 Rapid test NF EN ISO 11905-1 Ammonium (NH4 +) mgN.L-1 Test rapid NF EN ISO 90015-2 Nitrates (NO3) mgN.L-1 Rapid Test Total Phosphorus (PT) mgP.L-1 Rapid Test NF EN ISO 6878 (T90-023) Suspended Substances (MES) mg.L-1 Filtration bench NF EN 872 drying at 105 ° C. (T 90-105) Table 2 - Methods of analysis used According to the invention, the values to be respected are fixed as follows: DB05 <35 mg / L; MES <35 mg / L; COD <125 mg / L. The NH 4 + ammonium ion concentration should decrease between inlet and outlet if the nitrification is performed properly and therefore be well below 35 mg / L. It must be correlated with an increase in NO3- nitrate concentration. The pH must be between 5.5 and 8.5, which advantageously makes it possible to ensure that the effluent can be discharged into the natural medium.

3036394 23 The monitoring of turbidity variations makes it possible to identify operating problems such as clogging or salting out. The average removal efficiencies for the various physicochemical parameters studied throughout the study are calculated according to the following equation: - v, 7: 1 (Ce-Ci) Lit-1 This x 100 n where This; is the reactor inlet concentration for sampling i; n is the number of samples and Ci is the reactor outlet concentration for sampling. For the evaluation of the microbiological parameters, the influent at the reactor inlet and the effluent at the outlet of the reactor are sampled monthly. Samples are collected in 250 mL high density polyethylene (HDPE) bottles. Monthly withdrawals begin after 12 weeks of operation in the second phase. On the day of sampling, 15 drilled tubes and stoppers adapted to the sample bottles are disinfected with ethanol. The pipes and plugs are then placed under the reactors and at the outlet of the feed tank. The pipes are rinsed with the effluent for 15 minutes, then they are connected to the sampling bottle. The duration of the sampling depends on the output rate of the effluent 20 and lasts about 1 hour, to collect between 70 and 100 mL required for microbiological analyzes. Table 3 below presents the microbiological parameters analyzed, as well as the reference of the standard by describing the analysis protocol. Parameter Standard Escherichia Coli NF EN ISO 9308-3 Enterococci NF EN ISO 7899-1 Coliform bacteria NFT-90 413 Microorganisms revivable at 22 ° C and 36 ° C NF ENISO 6222 Table 3 - microbiological parameters studied 3036394 24 The values to be respected for each of these parameters depends on the use for which the effluent is intended, for example for irrigating crops or green spaces, for a simple discharge into the soil, etc. The results obtained for the two solid materials tested, at the end of the test, are shown in Table 4 below. PH material Cond. Turb. COD DB05 NT PT NH4 + NO3 MES μS / cm NUT mg / L mg / L mg / L mg / L mg / L mg / L mg / L CHT / GO 5.7 558 0.82 18 <3 50 13.0 15 , 0 26.5 5.80 CHTGO 7.8 7.35 7.40 88 10 53 12.5 48.5 <0.6 21.12 Table 4 - Analysis results obtained for the two solid materials tested The material CHT / GO appears to meet the predetermined criteria to demonstrate adequate sanitation capacity. The CHTGO medium does not meet the criteria set, particularly with regard to the ammonium ion and nitrate ion contents. The high turbidity for this material also indicates possible problems of clogging / salting out. Observation of the colonization of the filtering medium An observation of the colonization of the filter media is carried out using an endoscope allowing access to the core of the filter medium. For this purpose, a metal rod 50 cm long, perforated with 10 cm opening windows separated by full 1 cm windows, is immersed in the filter medium 39, successively at several observation points. This rod allows to direct the camera of the endoscope during the observation. An engine for delaying the rise time of the camera is installed at the top of the metal rod. The miniature camera is then introduced into the engine, then into the metal rod to be driven to the bottom of the filter bed. The camera then rises the entire filter medium by taking pictures at regular length intervals, thus allowing colonization to be observed over the entire height of the medium at a given point. The camera takes a photo every 4 mm. For each medium, three observation points are made 3036394 25 making it possible to apprehend the homogeneity of the colonization. An example of distribution of these observation points 40 is shown in FIG. 6. The observation points are uniformly distributed around the central tube 25.

Figure 7 presents the observations made for the CHTGO medium. The different viewing heights are, from the top of the filter media, 5.7 cm (a), 12.7 cm (b), 16.7 cm (c), 20.2 cm (d), 27, 1 cm (e), 31.0 cm (f), 39.5 cm (g) and 44.9 cm (h). It is observed in this figure that the CHTGO medium is colonized over its entire height. The upper 20 cm of the medium (a to 10 d) show a more pronounced colonization. These observations concerning the degree of colonization can be put in correspondence with the profile of the oxygen content in the filter medium described below, and are consistent with the effluent analysis results at the outlet of the reactor. Figure 8 presents the observations made for the CHT / GO medium.

The different viewing heights are, from the top of the filter medium, 1.2 cm (a), 6.1 cm (b), 10.1 cm (c), 14.2 cm (d), 21 cm. 6 cm (e), 26.1 cm (f), 33.1 cm (g) and 38.6 cm (h). In this figure, the dotted line indicated the line of separation of CHT and GO layers. It is observed that the medium CHT / GO is totally colonized on all its height. Very intense colonization is observed on the first 20 cm (a to e). The chènevotte is no longer identifiable in the purifying biomass and accumulated matter. Again, these observations on the degree of colonization can be mapped to the profile of the oxygen content in the filter media described hereinafter, and are consistent with the results of analysis of the effluent leaving the reactor. Gas Analysis An evaluation of the gas content (O 2 and CO 2) in the filter media was performed at the same points as those used for the observation described above. For this purpose, a measurement rod is introduced into the medium. This cane is equipped with a retractable tip. The tip allows easier penetration into the medium: the tip is then closed and no measurement is made. When the depth is reached, the cane is raised which releases the tip and the measurement is then performed. The gases present in the medium are sucked into a DRÂGER XAM® 7000 analyzer via an integrated pump. The measurement of 02 is done with the aid of an electrochemical sensor, the measured value is expressed in% O2. The saturation value is 20.9%. The CO2 measurement is based on infrared radiation, the value is expressed in% CO2. A measurement of the quantity of gas is carried out every 5 cm approximately to the bottom of the filter medium.

The results obtained are shown in Figure 9 and Figure 10 for the CHTGO material and the CHT / GO material, respectively. Regarding the CHTGO material, it is observed that the percentage of oxygen O 2 present in the medium decreases when the probe is immersed in the medium, while the percentage of carbon dioxide CO2 increases. The percentage decreases from 19% to 5 cm to a value as low as 11% to 30 cm. The important colonization of the first centimeters of medium seems to make difficult the passage of the oxygen towards the bottom of the medium. A slope of decrease of the oxygen within the mass of -0.32% 02.cm-1 is obtained.

With regard to the CHT / GO material, it is observed that the O 2 content is substantially constant, at a value of about 18%, over the entire height of the filter medium, which is indicative of a material capable of constituting a filtering medium. for the purification of wastewater in a non-collective sanitation installation.

The tests carried out using the device according to the invention, in accordance with the process according to the invention, thus make it possible to identify that the bilayer material CHT / G0 has the appropriate properties to allow the purification of domestic wastewater. The CHTGO monolayer medium is not suitable. It exhibits poor oxygenation, poor durability over time, as well as lower purification efficiencies.

3036394 27 C / Validation under real conditions of the evaluation result In order to validate this result, the CHT / GO bilayer solid material, described above, has been tested in a pilot site in situ a house. The in situ pilot was installed on a single house. The site is occupied by a family of five. The house is composed of five main rooms. The land is flat and of the boulbène type. It is a clay soil that does not allow the infiltration of water. The waters are therefore released into the natural environment via a ditch. The complete system installed comprises, in a conventional manner in itself, a buffer tank upstream of the all-water tank; an all-water pit of 4000 L (sEBico, concrete tank); a pre-treated sewage lifting station (MR PUMPS, post: SK4 / 10, 2 pumps: Vortex F); the pilot treatment plant, based on CHT / GO material as a filter media; and a treated wastewater lifting station (MR PUMPS, station: SK4 / 15, 2 pumps: Vortex F). The pilot plant 50 is shown schematically in FIG. 11. It comprises a tank 51, for example of fiber-reinforced concrete with polyethylene (PE) fibers. The distribution of the pretreated waste water in the tank is carried out via a feed system, illustrated at 52 in the figure, in particular a system known as a sprinkler, fed under pressure, and arranged in the upper part of the tank. 51. The filtering medium is disposed inside the tank and consists of a lower layer 53 of olive pomace and a top layer 54 of hemp. The thicknesses of these two layers are substantially identical. The lower layer 53 rests on an intermediate floor 55 composed of a grating (Diamond, fiberglass reinforced polyester), for example installed at 0.15 m from the bottom 56 of the tank. On this floor 55 is preferably placed a mesh geogrid of less than 3 mm, which goes up to the top of the filter medium so as to prevent it from falling to the bottom of the pilot.

Under the intermediate floor 55, the totality of the effluents is directed towards an outlet 57 so as to avoid the presence of dead volume in the tank 51. Inspection pads 58, conventional in themselves, are installed in the wall upper 59 of the tank 51. A ventilation system is also installed in the tank 51. This system is composed of four perforated pipes 60 arranged at the four corners of the tank 51. These pipes 60 extend substantially from the bottom 56 of the tank 51, up to the top of the filter medium, without however reaching the upper wall 59 of the tank 51. They are for example drilled on their height with twelve staggered holes. In order to aerate the central part of the filter medium, perforated drains 61, for example four in number, are further placed between the lower layer 53 and the upper layer 54 of the filter medium. These drains 61 are connected to chimneys, not visible in the figures, giving onto the outside of the tank 51. In this example, the installation is sized to process 6 equivalent inhabitants (EH). The tank 51 has dimensions (L x I x h) of 3.20 x 2.40 x 1.40 m, for a useful volume of 6 m3. The height of the filter medium in the tank 51 is set at 0.70 m (ie 0.35 m per layer of filter media). This represents a volume of filter medium of 4.2 m3. Each layer 53, 54 occupies a volume of 2.1 m3, which represents a mass of about 1.5 tons of olive cake and about 300 kg of hemp seed. The pipes 60 of the ventilation system have a height of 0.90 m.

25 This in situ pilot plant was regularly monitored for 1 year from the date of commissioning to confirm experimental laboratory results under actual conditions of use. A characterization of the wastewater entering the sector was carried out at the start of the study. The collection of all the wastewater 30 leaving the dwelling was carried out every 24 hours for 7 consecutive days.

3036394 29 This campaign validated the representative nature of the selected family. The treated wastewater was sampled with one sampling campaign per month. Samples were taken on seven consecutive days, with one sampling every 24 hours. The treated wastewater was taken from the lifting station at the outlet of the treatment system using a HYDREKA refrigerated automatic sampler (HACH SIGMA 900 SD sampling head) which was programmed to collect 210 mL every 18 min, which represents a sample of 80 samples over 24 hours for a total collected volume of about 17 L. The waters were then homogenized using a plastic rod, before to be transferred to the sampling bottles. The sampling flasks were completed three times with a mixture of the water contained in the sample tank between each fill. The physico-chemical parameters MES, COD, BOD5, NT and pH were measured on the water samples taken from the pilot in situ. A summary of the results obtained is presented in Table 5 below for each Camp campaign. Camp. Volume MES DCO DB05 NT pH (L) (mg / L) (mg / L) (mg / L) (mg / L) Preparation 1 369 ± 148 73 ± 10 751 ± 81 150 ± 20 85 ± 11 7.3 ± 0.3 steady state 2 322 ± 196 62 ± 19 448 ± 52 110 ± 33 81 ± 10 7.2 ± 0.5 3 353 ± 139 114 ± 25 523 ± 51 84 ± 20 97 ± 13 7.7 ± 0 , 6 Speed 4 364 ± 104 42 ± 10 250 ± 41 26 ± 10 67 ± 5 7.4 ± 0.2 permanent 5 370 ± 150 34 ± 8 211 ± 32 22 ± 22 72 ± 14 7.3 ± 0.3 6 301 ± 128 37 ± 4 218 ± 32 17 ± 7 64 ± 5 7.4 ± 0.1 7 376 ± 98 51 ± 17 209 ± 17 19 ± 7 104 ± 14 7.1 ± 0.1 Table 5 - Results of analysis of the physicochemical parameters, expressed on average ± standard deviation over seven consecutive days 3036394 Endoscope observations were also performed at the end of the 35th week of experimentation, in order to follow the development of biomass within the filter medium. Figure 12 shows the observations made. The different viewing heights are, from the top of the filter medium, 2.6 cm (a), 12.0 cm (b), 19.9 cm (c), 27.0 cm (d), 36 cm. 4 cm (e), 46.2 cm (f), 51.2 cm (g) and 59.5 cm (h). In this figure, the dotted line indicated the line of separation of the layers GO and CHT. It is observed that the medium CHT / GO is totally colonized on all its height. An analysis of the gases was also carried out so as to know the oxygenation of the medium. All of these tests in real-life conditions made it possible to validate the good purification performance of the CHT / GO filter medium, and to validate the reliability of the method according to the invention for evaluating a solid material to constitute a filtering medium for the filtration medium. treatment of wastewater in a non-collective sanitation installation. This method, associated with the device according to the invention, advantageously makes it possible to easily test, at a limited cost, materials of plant origin, in particular the waste of local agriculture, so as to provide a particularly advantageous method of recovery. from the economic point of view, those of these wastes having adequate capacity for sewage treatment.

Claims (10)

REVENDICATIONS1. Device for evaluating the capacity of a solid material to constitute an aerobic purification biomass carrier filter medium for the purification of wastewater, characterized in that it comprises: a reactor (20) comprising an upper chamber (21) for receiving said solid material and a lower chamber (22), said upper chamber (21) and said lower chamber (22) being separated from each other by a perforated partition wall (23), - air circulation means between the outside atmosphere of the reactor (20) and said lower chamber (22), comprising a hollow tube (25) delimited by a peripheral wall (253) extending from a first end , said upper end (251), opening above the upper chamber (21), through said upper chamber (21), to said lower chamber (22), said tube (25) having at least one opening in said lower chamber re (22) and being disposed at the center of said reactor (20), influent introduction means in an upper part of said upper chamber (21), and effluent removal means (222) in said lower chamber (22). 2. Device according to claim 1, wherein the portion of the peripheral wall (253) of the tube (25) disposed in the lower chamber (22) is pierced with at least one through hole (254). 3. Device according to any one of claims 1 to 2, wherein the influent introduction means in the upper part of the upper chamber (21) comprise a tilting bucket (26). 3036394 32 4. Device according to claim 3, wherein the tipping bucket (26) comprises a plurality of compartments (265) defined relative to each other by walls (266) perpendicular to an axis (27) around which said tilting bucket (26) is able to rock. 5 5. Device according to any one of claims 1 to 4, wherein the influent introduction means in an upper portion of the upper chamber (21) comprise means for distributing said influent in different areas of the upper surface of the upper chamber (21). 6. Device according to claim 5, wherein the means of distributing said influent in different zones of said upper part of the upper chamber (21) comprise a said distribution plate (28) disposed above said upper chamber (21). ), in which a plurality of grooves (282, 283, 284) extending in the direction of flow of the influent from said influent introduction means into the upper part of said upper chamber (21) is hollowed out. ), each of said grooves (282, 283, 284) being pierced in its bottom with at least one through hole (285). 7. A method of evaluating the ability of a solid material to form an aerobic scavenger biomass support filter medium for the purification of wastewater by means of a device according to any one of claims 1 to 6. , characterized in that it comprises: - filling the upper chamber (21) of the reactor (20) with said solid material, - a first supply phase of said upper chamber (21) with a polluting solution (32). ), according to a first predetermined discontinuous feed profile, said first phase having a sufficient duration to allow the development of purifying biomass within said solid material and obtaining a steady state, - a second feed phase of said upper chamber 3036394 33 (21) by a polluting solution (32), according to a second predetermined discontinuous feed profile, - the sampling of an effluent sample in the lower chamber e (22) of the reactor (20) at the end of said second feed phase, 5 - the analysis of the effluent sample thus taken for the physicochemical parameters: biological oxygen demand at 5 days, content of suspended matter, and at least one parameter selected from ammonium ion content and nitrate ion content, and comparing, for each of said parameters, the result of analysis obtained with a predetermined range of values indicative of a desired level of purification, a result of analysis included in said predetermined range of values being indicative of a solid material capable of constituting a purifying biomass support filter medium for the purification of wastewater with regard to said parameter. 15 8. Process according to claim 7, comprising: the analysis of the effluent sample taken at the end of said second feed phase for the microbiological parameters: concentration of enterococcal microorganisms and concentration of Escherichia coll; and comparing, for each of said parameters, the result of analysis obtained with a predetermined range of values indicative of a desired level of purification, a result of analysis included in said predetermined range of values being indicative of a solid material capable of constituting a purifying biomass support filter medium for the purification of wastewater with regard to said parameter. 9. A method according to any one of claims 7 to 8, comprising, at the end of the second phase, a step of measuring the oxygen content in the solid material contained in the upper chamber (21) of the reactor ( 20), at different points of the height of said upper chamber (21), obtaining at least a value of less than 15% of oxygen being indicative of the inability of said solid material to constitute a medium filtering support of biomass purifier for sewage treatment. 10. A process according to any one of claims 7 to 9, wherein said solid material is a material of plant origin.