FR2811659A1 - PROCESS AND PLANT FOR THE TREATMENT OF INDUSTRIAL, AGRICULTURAL AND URBAN OR HOUSEHOLD LIQUID WASTE, ESPECIALLY PORK SLURRY - Google Patents

Abstract

The invention concerns a method and an installation for treating liquid waste containing water and diluted polluting organic substances, such as pig slurry, or agri-food effluents. The invention is characterised in that it comprises at least: a) a step which consists in thermal evaporation (1) of a substantial proportion of said water; and b) a step (2) which consists in incinerating the concentrate obtained in the preceding step. Preferably, it consists in using a mechanical vapour recompression evaporator (1) combined with an incinerator (2) with fluidised bed and recycling (4) of the heat-exchanging material, in particular sand, and pre-mixing (5) said heat-exchanging material with at least a substantial part of the concentrate (9) obtained in the evaporation step. Said method efficiently destroys the slurry, in particular nitrates, by an inexpensive process, enabling to recuperate its useful elements, among which water with COD < 50, and the phosphates in the form of dry powder reusable as fertiliser, and producing only either useful or non-polluting agents.

Description

Process and installation for treating industrial liquid waste,

agricultural and urban or

  household goods, in particular pig manure.

  Technical sector of the invention: The present invention relates to the technical sector of the treatment of liquid industrial waste, in particular of the food industry, agricultural,

  urban, or household, and in particular pig manure.

  It is known that such waste poses insoluble problems because of their very polluting and / or toxic nature, and their volume. Pig manure is a perfect example of such waste, which is extremely difficult to treat, since it is both very polluting (in terms of chemicals and because of its odor particularly

foul) and very bulky.

  PRIOR ART: 1 5 A technique is known for waste such as pig manure.

  based mainly on spreading.

  We proceed either to direct spreading, which does not call for any particular comment except that it is the most polluting "treatment" mode, or

indirect spreading.

  In the case of indirect spreading, it is possible to very roughly separate the slurry into a so-called dry form (in fact, with roughly reduced humidity) which leaves towards a direct spreading area (we are therefore brought, for this part, to the previous problem), and a liquid form which goes to a lagoon treatment, where it is practically impossible to reduce, in temperate climates, the volume and the polluting load to a level allowing their destruction.

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  Many farms use "spreading plans", that is to say cultivated areas, especially in mays, or cereal crops, oilseeds, legumes, where manure is spread. The problem with this type of "treatment" is that: - odor pollution is obviously not eliminated - nitrogen in the form of nitrates is quickly leachable and progresses rapidly towards surface water and towards the water table; - it has a cost, notably of transport, and represents a significant workload - this cost can be aggravated by losses caused by the fall

world corn prices.

  All the previous modes of "treatment" of liquid manure have in common the serious disadvantages below: - the processes of evaporation have a very important energy cost and give only one concentrated product containing all the initial pollutants - certain drying processes towards a "powder" slurry also have a very high energy cost and does not solve the problem of end use - in none of the cases, the slurry is not destroyed; the previous processes are limited to more or less facilitating the handling of the liquid manure, sometimes avoiding the transport of too large quantities of liquids, etc., but never aim at the destruction of the liquid manure in non or little polluting forms, and in particular never low cost - the form of odor pollution is never eliminated or even reduced, it is sometimes inappropriate at best; the same for other forms of pollution (nitrates in particular)

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  - we do not recover any useful or usable element (except in the case of spreading on corn, but, as we have seen, with in fact significant financial losses: we cannot therefore evoke any "useful" element On the contrary, the farms would like to be freed from the enormous constraint that such "spreading plans" represent for them (hundreds of hectares immobilized and generating a loss, easements for spreading, odor, pollution of soil and yards water, groundwater, etc.). It can be estimated that, as a general rule, one m3 of slurry costs the operator at least 25 francs, with the above drawbacks and without any direct or indirect profit, and without the possibility of expanding the farms, which are

  directly linked to the available spreading areas.

  There is therefore an important and recognized need to solve the problem of the treatment of pig manure, or other waste, examples of which will be given below and which pose comparable problems (pollution, volume). This need has, moreover, been brought to light by news which has been increasingly supplied for at least a decade, such as pollution of surface water and groundwater, and

similar pollution.

  Despite the obvious magnitude of the problem, no solution capable of solving even a part of the above disadvantages exists to date, and a fortiori not the problem of a definitive treatment at a similar or lower cost. spreading, with solution of all the problems posed and even certain advantages such as the recovery of useful elements; Summary of the invention: The invention no longer aims to displace the problem of pollution by slurry, or to simply reduce somewhat the difficulties of handling by the operator, but to actually treat the slurry by a process: - inexpensive, and very competitive with the cost of spreading,

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  - making it possible to increase the size of farms without additional pollution (and even, by completely reducing pollution) - which destroys the slurry, and eliminates its odor, in particular its release of ammonia making it possible to recover its useful non-polluting elements and in particular phosphates - which only produces useful or non-polluting agents, such as water or nitrogen (or C02 which is obviously less polluting than the effects of spreading)

  - while destroying polluting elements such as nitrates.

  According to the invention, essentially a substantial part of the slurry water is evaporated, combined with an incineration of the concentrate thus obtained. The process or installation according to the invention essentially produces: water of less than 50 COD (chemical oxygen demand), which can be discharged into the natural environment or reused in irrigation or washing of steam , nitrogen, carbon dioxide, and ash mainly composed of phosphates or phosphorus compounds, all with very low energy consumption and cost

  investment and processing acceptable.

  It is doubly surprising to note that it is possible to solve all the problems posed by the slurry, and to recover more elements

  useful, at the cost of very low energy consumption.

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  Detailed description of the invention:

  The invention therefore relates to a method or an installation for treating liquid waste containing water and polluting and / or toxic substances, such as pig manure, characterized in that it comprises at least: e) a step d thermal evaporation 1 of a substantial proportion of said water, and f) an incineration step 2 of the concentrate 9 obtained in step e) above. According to a preferred embodiment, the invention relates to a process of this type, characterized in that it further comprises b) a prior step of separation 3 of the slurry 20 in a so-called phase

  liquid 30 and in a so-called dry phase 11.

  According to a preferred embodiment, the invention relates to a process of this type, characterized in that it further comprises - one or more stages of storage a), c), intermediate products. According to an entirely preferred embodiment, the method or installation according to the invention uses an evaporator 1 of the mechanical recompression type

  vapor, which will be described below.

  The evaporator is preferably multi-stage.

  According to yet another embodiment, the method or installation according to the invention uses an incinerator 2 of the recirculation type (13) of material

  cooler, which will be described below.

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  According to another preferred embodiment, said incinerator 2 is of the fluidized bed and recirculation type (13) of heat-carrying material and premix of this heat-carrying material (5) with at least a substantial part of the concentrate (9) obtained in step evaporation. Such incinerators are described for example in the patent PCT W O

/ 23317.

  Other characteristics and advantages of the invention will be better understood on

  reading of the description which will follow, and with reference to the attached drawing on

  which: FIG. 1 represents the general functional diagram of a mode of

  non-limiting implementation of the process or installation according to the invention.

  - Figure 2 shows a more detailed diagram of implementation and implementation of the method or installation according to the invention, in its form

preferred, but not limiting.

  - Figure 3 shows a detailed diagram of the preferred installation according to the invention. In the appended figures, the same references have the same

  meanings, which are as follows.

  Note: throughout this application, for simplicity, and in order not to multiply the references when this is not useful for understanding, we will designate by a reference X either, depending on the context, either a product or a zone or device . For example, the reference 5 could designate either the recirculating sand, or the premix zone of this

sand with condensate 9.

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  1 evaporator 2 incinerator 3 separation stage "dry" phase "liquid phase" TP pneumatic transport 4 smoke filter heat transfer material during recirculation, during the preferred step of premixing with concentrate 9 (also designates the recirculated sand mixture + concentrate and the mixing area) 6 ash (especially phosphates and non-volatile products) 1 o 7 storage tank of the so-called "dry" phase 8 storage tank of the so-called "wet" or "liquid" phase 9 concentrate bottom of evaporator distilled water, high outlet of the evaporator 11 so-called "dry" phase 12 pH adjustment system (by an acid) 13 recirculation of at least a fraction of the heat transfer material from the incinerator (in particular, of sand) 14 possible recycling of the dry phase to the incinerator recirculation pipe of the heat transfer material (especially sand), mixed with concentrate, to the incinerator

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  slurry from farm pits 21 storage and homogenization tank for this slurry nitrogen discharge, water vapor, carbon dioxide 26 high outlet from the incinerator, to the smoke filter 27 combustion air 28 circulation pump 29 pipe from the liquid phase 8 to the evaporator pipe from the liquid phase to the storage tank 8 31 agitator o 32 feed line for the slurry separator 33 submerged feed pump 34 recirculation of the recovered water at the incinerator (zone 5 of premix sand + concentrates) towards the storage tank 8 upper part of the incinerator 36 combustion gases, air, preheating 37 towards spreading 38 possible introduction of concentrates 9 with water 42 recovered from the premix zone 5 with the heat transfer medium, such as sand, for recycling via the pipe 34

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  39 combustion air compressor lower part of the incinerator (creating the fluidized bed) 41 to external incineration 42 washing system, with liquid phase 38, gases from the recycled sand and premixed (5) with the concentrate (9) and water recovery 43, 3 circuit for introducing the concentrate 9 (possibly premixed with the recirculated heat transfer medium 5) 44 recovery by composting (46) or encapsulation (47) O 45 recycling of the gases washed from recycled and premixed sand (5) with the concentrate point of entry of the liquid phase into the evaporator

  The invention will be better understood on reading the description which follows, and

  non-limiting examples below.

  According to the general mode represented in FIG. 1, the treatment method or installation according to the invention is characterized in that it comprises an evaporator 1 combined with an incinerator 2 which treats the concentrate 9 obtained at the bottom of the evaporator, said incinerator 2 having any heating means (not shown as known to those skilled in the art, in particular by the aforementioned WO patent) and destroying said concentrate 9 by

  producing (26) H20, C02, N2 gases and ash.

  Preferably, as shown in FIG. 1, said incinerator 1 contains a charge of inert heat transfer material preheated at start-up by the mixture 36 preferably introduced in the middle or upper part 35 of

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  The incinerator, and preferably driven by a downward movement under the action of the arrival of the charge of concentrate 9 (for example by a

  pneumatic transport system TP or the like).

  In an entirely preferred manner, said incinerator comprises a recirculation circuit (13) of said heat transfer material, at least a fraction of said heat transfer material being taken from an upper zone (35, 45) of said

  incinerator and being reintroduced to the base (40, or 35) of said incinerator.

  According to another option, the charge is introduced to the lower part of the incinerator, and undergoes with the heat transfer material, in particular sand, an upward movement; in this case, the recirculation point of the heat transfer material 13 is located in the zone 35 and conversely the premix 5 is brought to the lower part of the incinerator, where the fluidized bed is formed, by

  example by a worm or the like.

  Preferably, said premix 5 is preheated with thermal energy recovered from the incinerator, either at the burner or at the

  walls, and any similar system within the reach of the skilled person.

  Most preferably, the incinerator operates in a fluidized bed by blowing gas or air into zone 40, the gases possibly being

  combustion used to at least initiate heating of the load.

  More preferably, at least a fraction of said recirculated heat transfer material (13) is premixed, before its reintroduction into said incinerator 2, with at least a fraction of the concentrate 9 coming from the evaporation step 1, in a zone 5, and the assembly is reintroduced into said

incinerator 2.

  Preferably, all or almost all of said heat transfer material (13) is

  premixed with all or almost all of said concentrate 9.

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  According to a preferred embodiment, said premix 5 (and / or said recirculated heat transfer material 13 and / or said concentrate 9) is or are preheated by an auxiliary heating means or by the energy generated

by the incinerator.

  We will use, to heat the incinerator or participate in the heating, and recover a maximum of energy, a compressor 29 supplied with air 27 and

  recirculation 45 coming from the washing means 42.

  Preferably, the water from the premix 5 is recovered in the tank 42, and it can be mixed with the liquid phase 30, 8 supplied by 1 o line 38, and this mixture is recirculated through line 34 to the tank

storage 8 of the liquid phase.

  A person skilled in the art will be able to optimize the steps of the process in this way and in a similar manner, and in particular to recover a maximum

of thermal energy.

  According to a preferred embodiment, said evaporator 1 is an evaporator known as "with mechanical vapor recompression", that is to say in which, at the start of the installation, heating is carried out until the "first mist" ( that is to say the first emission of steam), after which at least part of the emitted steam is taken, it is compressed in a compressor, and it is returned to the base of the evaporator, this steam then providing the heating of the charge, here the charge of liquid phase (30, 8,

  29) slurry 20 or other liquid waste.

  The evaporator produced, which is one of the crucial advantages of this

  invention, distilled water (10) COD <50, that is to say non-polluting.

  The evaporator produces approximately 1/10 of the incoming volume of concentrate 9, and

about 9/10 of water.

  According to yet another preferred embodiment, at least part of the thermal energy generated by the incinerator is recovered to heat

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  the evaporator and / or preheat (to around 50 - 70 C) the liquid phase of

  slurry (8, 29) entering (50) in the evaporator.

  According to an entirely preferred embodiment, the method or installation according to the invention further comprises a first step of separation (3) of the incoming slurry 20 (from the pre-pits) into, on the one hand a so-called phase

  "dry" (11) and, on the other hand, a phase called "liquid" (30, 8, 29).

  Preferably, a "FAN TM" type separator known to those skilled in the art is used, supplied via a storage tank 21 comprising a pump.

submerged feed 33.

  O The dry phase 11 is received in a storage tank 7 and is then either recovered (44) by composting (46) or encapsulation (47) (in particular by a superabsorbent polymer), or directed (14) to the incinerator 1 , preferably at the premix zone 5 with the heat transfer material. The liquid phase (30) is directed to the evaporator 1, via possibly

  a storage tank 8 comprising a pH adjustment system 12.

  Part of this liquid phase can be directed at 38 to a tank 42 for recovering the moisture or water contained in the concentrate 9 in zone 5 (evaporation of the water occurs, especially if zone 5 is preheated by a combustion gas, or even without preheating,

  simply because of the heat of the hot heat transfer material recycled in 13).

  The concentrate produced at the bottom of the evaporator is preferably received in a storage tank 9 and can either be preferably directed by a line and pump 28 to the incinerator (or preferably to the premix zone 5), or be directed towards spreading (37) (depending on the needs of the farm, in particular if the farm must use a corn or other crop spreading plan), or towards a type 1 but delocalized incinerator 41 (if the farm

is small for example).

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  Most preferably, the heat transfer material is sand,

analog foundry.

  According to a preferred embodiment, the gas phase 26 exiting at the head of the incinerator 1 passes through a smoke filter 4 which separates the gases H20, N2 and C02 from the ashes 6 (in particular nitrates, phosphates) which are recovered.

EXAMPLES:

  We arrive with the method and the installation according to the invention to be treated approximately.

  600 kg / h of concentrated slurry of pig manure (concentrate 9).

  The water 10 produced returns to 10 F per m3 for an evaporator capable of treating approximately 5 t / h of liquid phase 29, and its cost can be lowered to

  only 3 F per m3 if the evaporator capacity is increased to 150 t / h.

  These values will usefully be compared to the fact that one m3 of slurry currently costs the operator about 25 F per m3, with the disadvantages

current stated above.

  Furthermore, the footprint of an installation according to the invention is approximately 10

  times less than a treatment plant for example.

  In the appended FIG. 2, the operating parameters are, by way of

  non-limiting example, the following.

  Tank 21 1000 m3 Tank 7 20 m3 Tank 8 100 m3 FANTM type separator 10 to 20 m3 / h Material 11 30% DM (dry matter)

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  Liquid phase 30 max 3% DM Concentrates 9 40% DM We can therefore see that the process and installation according to the invention surprisingly provide a solution to all the problems of liquid manure, by completely destroying it, eliminating all pollution, and by producing on the contrary

clean water at low cost.

  The use of this process which eliminates the nuisance of pig manure allows a different approach to this type of farming. In particular, the size of o farms can be significantly increased since the problems of spreading plan will no longer be taken into account. On the other hand, the degradation of the quality of groundwater will be eliminated

  and even, in the coming years, their quality will be improved.

  The invention is therefore of considerable economic importance.

  The applications of the invention relate first of all to the destruction of pig manure, in particular in large-scale intensive livestock operations, but also, with possibly some obvious adaptations: the treatment of waste water, especially urban waste water - the treatment of liquid food waste such as dairy waste, waste such as potato peel sludge, or sweets - some stationery sludge,

  - certain sludges from the chemical industry.

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  The invention also covers industrial products recovered by the process or

installation according to the invention.

  The invention also covers all the embodiments and all the applications which will be directly accessible to those skilled in the art on reading the present application, their own knowledge and

  possibly some routine tests.

Claims (24)

  1 Process for treating liquid waste containing water and polluting and / or toxic substances, such as pig manure, characterized in that it comprises at least: e) a step of thermal evaporation 1 of a proportion substantial of said water, and an incineration step 2 of the concentrate 9 obtained in step e) above. o 2 Method according to claim 1, characterized in that it further comprises b) a prior step of separation 3 of the slurry 20 in a phase called   liquid 30 and in a so-called dry phase 11.   3 Method according to claim 1 or 2, characterized in that I further comprises - one or more stages of storage a), c), intermediate products.   4 Method according to any one of claims 1 to 3 characterized   in that it uses an evaporator 1 of the type with mechanical recompression of steam.   Method according to claim 4, characterized in that the evaporator is multi-story.   6 Method according to any one of claims 1 to 5, characterized   in that it uses an incinerator 2 of the recirculation type (13) of heat transfer material. 7 Method according to claim 6, characterized in that said incinerator 2 is of the type with a fluidized bed and with recirculation (13) of heat transfer material and with a premix of this heat transfer material (5) with the concentrate   (9) obtained in the evaporation step.   8 Method according to any one of claims 4 to 7 characterized   in that it uses an evaporator 1 combined with an incinerator 2 which treats the concentrate 9 obtained at the bottom of the evaporator, said incinerator 2 having any heating means (36, 39) and destroying said concentrate 9   by producing (26) H20, C02, N2 gases and ash.   9 Method according to any one of claims 6 to 8, characterized   in that said incinerator 2 contains a charge of inert coolant material preheated at start-up by the mixture 36 introduced in the middle or upper part 35 of the incinerator, and driven in a downward movement under the action of the arrival of the charge of concentrate 9 (for example by a   pneumatic transport system TP or the like).   Method according to any one of claims 6 to 9 characterized   in that said incinerator includes a recirculation circuit (13) of said heat transfer material, at least a fraction of said heat transfer material being taken from an upper zone (35, 45) of said incinerator and being   reintroduced to the base (40) of said incinerator.   1 1 A method according to claim 9 characterized in that the charge is introduced to the lower part of the incinerator, and undergoes with the heat transfer sand, an upward movement; the recirculation point of the heat transfer material 13 being located in the zone 35 and conversely the premix 5 being brought towards the lower part 40 of the incinerator, where the bed is formed   fluidized, for example by a worm or the like.   12 A method according to claim 7 characterized in that said premix 5 is preheated by thermal energy recovered from the incinerator 2, either at the burner (39 and / or 36) or at the walls.   13 Method according to any one of claims 6 to 12 characterized   in that the incinerator 2 operates in a fluidized bed by blowing gas or air in zone 40, the gases possibly being combustion gases (39) serving for   less initiate heating of the load.   14 Method according to any one of claims 6 to 13 characterized   in that at least a fraction of said recirculated heat transfer material (13) is premixed, before its reintroduction into said incinerator 2, with at least O a fraction of the concentrate 9 coming from the evaporation step 1, in a   zone 5, and the assembly is reintroduced into said incinerator 2.   1 5 A method according to any one of claims 6 to 14, characterized   in that all or almost all of said heat transfer material (13) is   premixed with concentrate 9.   16 Method according to any one of claims 7 to 15, characterized   in that said premix 5 (and / or said recirculated heat transfer material 13 and / or said concentrate 9) is or are preheated by a heating means   annex or by the energy generated by the incinerator.   17 Method according to any one of claims 6 to 16 characterized   in that to heat the incinerator or participate in the heating, and recover a maximum of energy, a compressor 29 is used supplied with air 27 and recirculation gas 45.   18 Method according to any one of claims 11 to 17,   characterized in that the water from the premix 5 is recovered in the tank 42, and it is mixed with the liquid phase 30, 8 brought in via line 38, and this mixture is recirculated through line 34 towards the tank of storage 8 of the liquid phase.   19 A method according to any one of claims 4 to 18 characterized   in that said evaporator 1 is a so-called "mechanical vapor recompression" evaporator, that is to say in which, at the start of the installation, heating takes place until the "first mist" (this is i.e. the first vapor emission), after which at least part of the emitted vapor is taken, it is compressed in a compressor, and it is returned to the base of the evaporator, this vapor then ensuring the heating of the load, here the liquid phase load (30, 8, 29) of the slurry 20 or other liquid waste.   Method according to any one of claims 4 to 19 characterized   in that the evaporator produces distilled water (10) of COD <50, and the evaporator produces approximately 1/10 of the incoming volume of concentrate 9, and about 9/10 of water.   21 Method according to any one of claims 6 to 20 characterized   in that at least part of the thermal energy generated is recovered   by the incinerator to heat the evaporator and / or preheat (to around 50 -   70 OC) the liquid slurry phase (8, 29) entering (50) in the evaporator.   22 Method according to any one of claims 1 to 21, characterized   in that it further comprises a first step of separation (3) of the incoming slurry 20 (from the pre-pits) into, on the one hand a so-called phase   "dry" (11) and, on the other hand, a phase called "liquid" (30, 8, 29).   23 Method according to claim 22, characterized in that the dry phase 11 is received in a storage tank 7 and is then either recovered (44) by composting (46) or encapsulation (47) (in particular by a superabsorbent polymer), is directed (14) to the incinerator 2, at the level   of the premix zone 5 with the heat transfer material.   24 Method according to any one of claims 22 or 23   characterized in that the liquid phase (30) is directed to the evaporator 1, optionally via a storage tank 8 comprising a system of pH adjustment 12.   A method according to any of claims 22 to 24   characterized in that part of this liquid phase is directed at 38 to a tank 42 for recovering the moisture or water contained in the concentrate 9 in the zone 5 (evaporation of the water occurs, especially if the zone is preheated by a combustion gas, or even without preheating, simply by the heat of the hot heat-transfer material recycled in 13).   26 Method according to any one of claims 4 to 25 characterized   in that the concentrate produced at the bottom of the evaporator 1 is preferably received in a storage tank 9 and is either directed by a line and pump 28 towards the incinerator (or towards the premix zone 5), or towards   a type 2 but relocated incinerator 41.   1 o 27 A method according to any one of claims 6 to 26, characterized   in that the heat transfer material is sand, foundry sand to the analog.   28 Method according to any one of claims 6 to 27 characterized   in that the gas phase 26 leaving the incinerator 2 passes through a smoke filter 4 which separates the gases H20, N2 and 002 from the ashes 6   (in particular nitrates, phosphates) which are recovered.   29 Installation for processing industrial or agrifood liquid waste, in particular pig manure, characterized in that it comprises an evaporator 1 of the mechanical vapor recompression type, an incinerator 2 of the fluidized bed type and with recirculation (13) of heat transfer material and premix of this heat transfer material (5) with the concentrate   (9) obtained in the evaporation step.   Applications of the method according to any one of claims 1   to 28 or from the installation according to claim 29 to the destruction of pig manure, in particular in large capacity intensive livestock farms, and in the following operations: the treatment of waste water, especially urban waste - the treatment of liquid waste food products such as dairy waste, waste such as potato peel sludge, or sugar confectionery stationery sludge, - sludge from the chemical industry. 31 Industrial waste recovered by the process or installation according to one   any one of claims 1 to 29, in particular water (10) with COD <50,   phosphates and nitrates and other ashes (6).