FR2837196A1 - Anaerobic sewage treatment, for small volumes, has a reactor basin for the decanted sewage with an activated sludge bed, followed by a biological filter stage without unpleasant gas emissions - Google Patents

Abstract

To process domestic or agricultural/industrial sewage, it is initially decanted (3) into a tank (5) to precipitate a primary sludge (4). The decanted sewage is injected into a basin (6), containing a bed of activated sludge (2), for anaerobic degrading of any organic matter as an upflow anaerobic sludge blanket (UASB) reactor. In a third phase, after the anaerobic treatment, the sewage is filtered biologically by passing horizontally and/or vertically through at least one bed of macrophytes (15), like a lagoon with evaporation/perspiration and drainage. Odorous gases from the anaerobic stage are filtered through a layer of soil (13) with planted vegetation (14).

Description

vehicle (1)

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  The invention relates to a method and an installation for the purification of domestic or agro-industrial effluents by

  Anaerobic digestion and by biological filtration.

  The present invention relates to the field of processes and installations for the purification of effluents which are particularly suitable for small units, such as, for example, particular wine cellars or other agro-industrial units, just like the communities of the around 200 to 1000 equivalent inhabitants, with permanent, variable or temporary population. For example, the present invention will find its application for the treatment of waste water from holiday villages, campsites,

  sports and leisure complexes, motorway areas, etc.

  The so-called aerobic processes are the most commonly used for the treatment of such effluents. However, they lead to volumes of sludge to be treated which are much more windy.

  important compared to anaerobic digestion.

  Obviously, the facilities for implementing an aerobic treatment process are themselves more expensive and more complex. However, anaerobic effluent treatments generate the production of bio-gas loaded with olfactory compounds

  constitute a nuisance for the environment.

  Also, the installations implementing such anaerobic processes comprise closed reactors allowing a

  recovery of the methane produced and its energy recovery.

  However, in the context of treatment of low volume effluents such as those resulting from a small agro-industrial unit or from communities respecting the proportions indicated above, such recovery turns out to be economically unattractive insofar as the quantity of organic matter to be degraded is not able to supply enough gas justifying the means to

  put into action for its recovery.

  Whether aerobic or anaerobic, the installations currently being implemented also pose the problem of their

integration into the natural environment !.

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  Ultimately, the present invention aims to provide an anaerobic treatment process which, applied to agro-industrial effluents from small units or domestic type and from communities of the order of 200 to 1000 equivalent-inhabitants, proves to be particularly efficient, not only from the point of view of the yield it provides, but also in relation to the quantity of sludge produced, not to mention that the infrastructures correspond to the installations for the installation muvre of this process prove, they, of reduced size, mat, in addition, can be integrated perfectly in the natural environment

  without risk of nuisance whether it is of olfactory or visual type.

  Thus, the invention relates to a process for the purification of domestic or agro-industrial effluents consisting of: a first decantation phase for the elimination of inert and coarse particles in w from their anaerobic digestion; a second phase of injecting the decanted effluent under an active mud bed resulting from bacterial growth linked to the anaerobic degradation of the soluble organic matter contained in this effluent; a third finishing phase consists of a biological type filtration, such as horizontal and / or vertical filtration on at least one bed of macrophytes, that a lagoon, that evapotranspiration with drains; 25. to treat the emanations of olfactory gases resulting at least

  of the second phase through a filtering soil.

  As for the installation for implementing this process, it comprises: at least one first settling tank for removing primary sludge; a digestion reactor UASB (for Upflow Anaerobic Sludge Blanket) comprising means of injection under a bed of active mud and at a controlled rate of rise of the effluents coming from the settling tank;

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  and a biological filter, such as one or more macrophyte fits comprising an inlet and outlet zone for the effluent to be treated; the UASB reactor comprising a biological cover, of the filtering soil type for the treatment of emanations of olfactory gases. According to a feature of the present invention, the decanter

  may also include such biological cover.

  Advantageously, in the event of several fits of mocrophytes, this installation also comprises, between two fits, an internal drainage and filling system, such as sumps and pumps, allowing by tidal range to obtain the conditions for aeration of the medium.

  necessary for a thorough purification.

  Other objects and advantages of the present invention

  will appear during the description which follows relating to

  to exemplary embodiments given by way of indicative example and

not limiting.

  Understanding this description will be facilitated by

  refer to the attached drawing in which: - Figure 1 illustrates, schematically, an installation for implementing the method according to the invention; - Figure 2 is a view similar to Figure 1 illustrating a second embodiment of this installation. - Figure 3 is a schematic representation of a vertical filter planted especially for processing

primary sludge.

  - Figure 4 is a schematic representation of two horizontal plant filters equipped with a drainage and filling system allowing extensive purification. Thus, the invention relates to a method and an installation 1

  for the purification of domestic and / or agro-industrial effluents.

  The process consists of a first decantation phase intended to make the effluent compatible with the rest of the process.

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  treatment. This decantation, preferably in an anaerobic atmosphere, aims to eliminate inert and coarse particles. The sludge collected through this wind settling

quote the primary sludge.

  It should be noted that during this phase, part of the organic pollution is also retained, which undergoes anaerobic degradation liberating metabolites which will be digested in the following phases. Precisely, in a second phase, the effluent from this settling is injected under a bed of active mud resulting from bacterial growth linked to the anaerobic degradation of the material.

  organic, soluble contained in this effluent.

  Finally, as part of a third phase, it is proceeded

has biological filtration.

  This can borrow different forms of realization. By way of example, a horizontal filter 16 has been shown in FIGS. 1 and 2 of the attached drawing in the form of a bed of macrophytes 15 which the effluent from the second phase passes through. In FIG. 4, several of these horizontal filters 16, 16 ′ are illustrated, consisting of such a bed of macrophytes that the effluent can pass through for a more advanced purification. In fact, this filtration can consist, again, in the lagooning of these effluents, in making them pass through coppices with rotational travel, or in making them undergo an evapotranspiration with drains under trees or

shrubs ...

  It should be observed that, in accordance with the method according to the invention, the emanations of olfactory gases resulting from the different phases and in particular from the second, or even also from decantation, wind treated through a cover.

biological filtering.

  To return to the installation allowing the implementation of this process, it comprises a decanter 3 for the elimination of primary sludge 4. This decanter 3 can be in the form of an independent tank as illustrated in FIG. 1 or associated with the UASB reactor 6. In this case and as illustrated in FIG. 2, there is one and the same tank 7 subdivided into two s 2837196 compartments 8, 9 one of which defines the decanter 3 and the other this

UASB reactor 6.

  In this regard, the latter, recovering the effluent from the settling tank, is equipped with 1O means making it possible to take this effluent from its upper part to inject it under a bed of

  active mud 2 allowing the degradation of organic matter.

  The design bases of this 6 wind reactor calculated, as the case may be, starting from the load when this is high, for example in the case of agrifood effluents, ie from the residence times in the case of weakly effluents charges

such as urban effluents.

  Furthermore, said injection means 10, which comprise at the bottom of the reactor several injection ramps connected to a supply line 12 taking the effluent in the upper part, it is associated with means for controlling the flow of injected effluent. in order to keep the mud bed 2 expanding, taking into account that it is looking for a speed

  upward usually between 0.5 and 0.9 m / in.

  For the dimensioning of this UASB 6 reactor, account is taken in the event of a highly charged effluent of 4 to 12 kg of COD / m3 of reactor and a residence time of 6 to 18 hours in weakly charged effluent. The tank 7 defining, as the case may be, either exclusively the UASB reactor 6, or, in combination, the latter and the settling tank 3,

  is advantageously in the form of a buried pit.

  Furthermore, with regard to anaerobic treatment, it is pre w, according to the invention, to treat the emanations of olfactory gases through a biological filtering cover surmounting said tank 7. This cover is defined in the form of a filtering soil allowing to block and oxidize the compounds causing an odor nuisance. Preferably, this filtering soil is made from peat, iron compounds and plant plants 14. However, other inert or biological materials can be used, such as compost, plant waste, plastics ... Note, again, that this biological cover 13 can rest on a floating or fixed structure in

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  depending on the size and shape of the structure, in this case

of the tank 7.

  In addition, it can extend widely above this tank 7 so as to provide a sufficient exchange volume for the treatment of emanations of olfactory gases. As indicated above, the effluents leaving the reactor

  UASB 6 undergo a biological filtration phase.

  Preferably but not limitatively, this filtration takes place on at least horizontal filter 16 in the form of a bed of

macrophytes 15.

  Insofar as this filtration is horizontal flow, the filter 16 corresponds to the installation 1 comprises an inlet zone 17 for the effluent and another for discharge 18, these zones 17, 18 being made up of coarse rocky blocks. Between these rears the filter 16 comprises a filtering mass made of small and medium-sized gravels therefore constitute

bed 15.

  This can be intermittently supplied with effluent leaving the UASB reactor 6. for better efficiency, it can also be associated with this filter 16 recirculation means 19 allowing a part of the effluent lt to be taken out of the filter 16, therefore from evacuation zone 18, to reinject it into the

level of the intake area 17.

  It will be noted that for further purification, this filtration can be ensured through several of these horizontal plant filters 16, 16 '. The installation can then be provided with an internal drainage and filling system 16 '', such as sumps and pumps, allowing by marnage to obtain the conditions

  of aeration of medium necessary for a thorough purification.

  Plants, preferably planted on filtering soils, have wetland plants which have already been shown to be effective in terms of compound oxidation.

  smell of a biological gas from anaerobic digestion.

  The process according to the invention ends with a phase of treatment of the primary sludge 4 extracted from the settling and of the secondary sludge from the UASB reactor 6. This consists of a

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  filtration on a vertical plant filter 20, more particularly

shown in figure 3.

  This one will also be able to receive the products of crushed mowing, as well as those of the fits of macrophytes 15. The development of a detritivorous flora and fauna allows the

formation of a recoverable compost.

  Finally, this vertical filter 20 made of gravel, is provided with a water recovery drain 21 which will be recycled as part of the filtration on the bed of macrophytes 15. As part of the purification of effluents from activities agro-industrial in urban or peri-urban zone, it can be envisaged to subject these effluents only to the first two phases of anaerobic treatment, that is to say the phase of decantation 1S and digestion on a bed of active mud, so as to make them

  compatible with urban sanitation systems.

  Finally, lton notes that the process according to the invention and the installation for its implementation allow the recovery of water and composts resulting from the treated effluents, as well as a landscaping integration that enhances the structure of the structure. In addition, given the low energy demand, the electromechanical supply can be ensured thanks to the use of renewable energy allowing installation in deviations and

significant savings.

  Although the invention has been described in connection with a particular embodiment, it is understood that it is in no way limited thereto and that various modifications of shapes, materials and combinations of these can be made to it. various elements without

  for that to move away from the framework and the spirit of the invention.

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Claims (10)

claims   1. Process for the purification of domestic or agro-industrial effluents consist of: - a first decantation phase for the elimination of inert and coarse particles with a view to their anaerobic digestion; - a second phase of injection of the decanting effluent under an active mud bed (2) resulting from the bacterial growth linked to the anaerobic degradation of the organic matter contained in this effluent; - A third finishing phase consists of a biological type filtration, such as horizontal and / or vertical filtration on at least one bed of macrophytes (15), that lagooning, that evapotranspiration with drains; - to treat the emanations of olfactory gases resulting in   less of the second phase through filtering soil.   2. Method according to claim 1, characterized in that the emanations of olfactory gases resulting from the   decantation phase through a filtering soil (13).   3. Method according to claim 1, characterized in that one proceeds to a recirculation of the effluents during the biological filtration.   4. Installation for implementing the method according to one   any of the preceding claims, characterized by the fact   that it comprises: - at least a first settling tank (3) for removing the primary sludge (4); - a UASB digestion reactor (6) recovering the effluent from the decanter (3) and comprising injection means (10) making it possible to withdraw this effluent from its upper part to inject it under a bed of active mud (2 ) and at controlled rate of climb; - and a biological filter (16), such as at least one horizontal filter (16,16 ') in the form of a bed of macrophytes (15), 9 2837196   comprising an inlet (17) and outlet (18) zone for the effluent to be treated; - the UASB reactor (6) comprising a biological cover, of the filtering soil type (13) for the treatment of emanations of olfactory gases. 5. Installation according to claim 4, characterized in that the decanter (3) comprises a biological cover of type filtering soil.   6. Installation according to claim 4 or 5, characterized in that the UASB reactor (6) is in the form of a buried pit surmounted by the biological filtering cover (13) defined by a filtering soil resting on a floating structure or fixed.   7. Installation according to one of claims 4 to 6,   characterized by the fact that the settling tank (3) and the UASB reactor (6) are defined by a block and even tank (7) subdivided into two compartments (8, 9).   8. Installation according to any one of claims 4   7, characterized in that the biological filter (15) is constituted by a horizontal flow filtration bed comprising a filtering mass made of small and medium-sized gravels, while the intake zones (17) and evacuation   (18) of the wind effluent made up of coarse boulders.   9. Installation according to any one of claims   above, characterized by the fact that it comprises recirculation means (19) with a view to withdrawing at least from the discharge zone (18) part of the effluent for the   reinject at the intake area (17).   10. Installation according to any one of the claims   previous, characterized by the fact that the biological filter consists of at least two horizontal plant filters (16, 16 '), such as fits of mocrophytes (15), equipped with an internal drainage and filling system (16 '') in order to obtain, by tidal range, the conditions of aeration of the environment necessary for a purification