FR3145160A1 - Process for valorizing a liquid effluent containing organic matter - Google Patents

Abstract

Process for valorizing a liquid effluent containing organic matter, comprising: A step of supplying the liquid effluent (1); An anaerobic digestion step, producing a digestate and biogas, in which at least part of the organic matter is degraded by contact with microorganisms; A step of producing a sludge enriched with mycelia and/or molecules produced by mycelial strains, in which at least part of the digestate is brought into contact in an aerobic reactor with mycelial strains during a second residence time; dehydration of the enriched sludge producing a cake and a flow of liquid; and in which: - during step (c), the organic matter content and/or the second residence time is controlled to produce a cake comprising a target content of mycelia and/or molecules. Abstract Figure: Figure 1

Description

Process for recovering liquid effluent containing organic matter Field of invention

The invention relates to a process for recovering a liquid effluent containing organic matter.

State of the art

Municipal wastewater treatment plants produce sludge, which is a byproduct of the various treatment processes used to clean the water. This sludge is made up of various organic compounds and contains carbon, nitrogen, phosphorus, and other nutrients and micronutrients.

These sludges are often treated by anaerobic digestion which is a key process to recover the energy initially present in the wastewater in the form of biogas and which allows to reduce the overall mass of the residual sludge to be disposed of. However, the final product (digested sludge) is generally more difficult to dewater because anaerobic digestion alters the amounts of extracellular polymeric substances (EPS) present in addition to increasing the colloid content.

Furthermore, the dewatering of digested sludge generates significant operating costs that will vary depending on the addition of flocculating chemicals in greater or lesser quantities to achieve a desired level of dryness. In addition, the higher the dryness to be achieved, the lower the volume of residual sludge to be evacuated, which reduces transportation costs.

This digested sludge, once dehydrated, can be used for spreading in the fields. However, it must meet a certain quality, particularly with regard to heavy metals and pathogens that may be present. The presence of flocculant-type chemicals that are polymers can also be problematic when the digested sludge is intended for agriculture. Similarly, the presence of micropollutants in the digested and dehydrated sludge can contaminate the fields during spreading, which can be problematic.

It is also known to treat sludge by bringing it into contact with fungal biomass which can decompose and transform the organic matter present in the sludge.

Treatment with fungal biomass improves the dewatering and filterability of treated sludge. Indeed, fungi trap solid particles present in the sludge and compress the sludge with their filamentous mycelia (hyphae) which modify the porosity of biosolids (corresponding to the residue from wastewater treatment that can be recycled). Soluble compounds are thus adsorbed and insoluble solids present in the sludge are trapped by the filamentous body of the fungal biomass, forming grains or granules (“pellets” in English). Fungal granules can increase their biomass by shifting their secondary metabolism using the soluble/insoluble solids of the sludge. As a result, interstitial water is released, which can improve the filterability and therefore the dewatering of sludge treated by fungi.

Thus, document US 7270751 describes a sludge treatment method comprising a step of treating the sludge with micromycetes making it possible to degrade a larger fraction of organic and mineral matter in the sludge and to reduce the volume of the sludge treated accordingly. This step of treatment with micromycetes thus replaces an anaerobic digestion treatment.

Despite the excellent capacity of the anaerobic digestion process to transform organic matter contained in sludge into valuable biogas, to reduce sludge volume, to stabilize sludge and to eliminate pathogens, there are still many emerging pollutants in the treated sludge. The use of certain fungi as a sludge treatment step after anaerobic digestion has demonstrated its ability to eliminate a wide variety of micropollutants. Some fungi produce enzymes that can degrade organic compounds such as pharmaceutical compounds, UV filtering compounds (from sunscreens), and flame retardant compounds. The publication CE Rodriguez- Rodriguez et al. Journal of Hazardous Materials 233-234 (2012) reports the elimination of pharmaceutical compounds, flame retardants and UV filters present in sludge treated by the fungus Trametes versicolor . Digested and sterilized sludge is introduced into an aerated bioreactor in the presence of a solution of macronutrients, micronutrients and glucose before being inoculated with T. versicolor biomass, with glucose being added regularly for biomass growth. The treatment described thus requires the introduction of exogenous carbon, such as glucose, for fungal biomass growth.

The invention aims to overcome all or part of the aforementioned drawbacks. The invention also aims to provide a method for improving the agronomic value of sludge, in particular with a view to spreading it.

1. Une étape de fourniture d’un effluent liquide à traiter contenant de la matière organique ;
2. Une étape de digestion anaérobie de l’effluent liquide, produisant un digestat et du biogaz, dans laquelle une partie au moins de la matière organique contenue dans l’effluent liquide à traiter est dégradée par mise en contact avec des microorganismes pendant un premier temps de séjour ;
3. Une étape de production de biomasse fongique produisant une boue enrichie en mycéliums et/ou en molécules produites par des souches mycéliennes, dans laquelle une partie au moins du digestat est mise en contact dans un réacteur aérobie et en présence de matière organique avec des souches mycéliennes pendant un deuxième temps de séjour ;
4. Une étape de déshydratation de la boue enrichie en mycéliums produisant un gâteau comprenant des mycéliums, et optionnellement les molécules produites par les souches mycéliennes, et un flux de liquide ;
   et dans lequel :

lors de l’étape (c), on contrôle la teneur en matière organique et/ou le deuxième temps de séjour pour produire un gâteau comprenant une teneur cible en mycéliums et/ou une teneur cible en molécules produites par les souches mycéliennes.A first object of the invention concerns a method for recovering a liquid effluent containing organic matter, in particular from a treatment method, comprising:

1. A step of supplying a liquid effluent to be treated containing organic matter;
2. A step of anaerobic digestion of the liquid effluent, producing a digestate and biogas, in which at least part of the organic matter contained in the liquid effluent to be treated is degraded by contact with microorganisms during an initial residence time;
3. A fungal biomass production step producing a sludge enriched with mycelia and/or molecules produced by mycelial strains, in which at least part of the digestate is brought into contact in an aerobic reactor and in the presence of organic matter with mycelial strains during a second residence time;
4. A step of dehydration of the sludge enriched with mycelia producing a cake comprising mycelia, and optionally the molecules produced by the mycelial strains, and a liquid flow;
   and in which:

in step (c), the organic matter content and/or the second residence time are controlled to produce a cake comprising a target mycelial content and/or a target content of molecules produced by the mycelial strains.

This sequence of steps, and in particular the use of an anaerobic digestion step, a fungal biomass production step followed by a dehydration step of the enriched sludge makes it possible to dehydrate the sludge and produce a cake that forms a solid residue whose agronomic value has been improved, and advantageously whose micropollutant content has been reduced. Indeed, the solid residue is enriched by the mycelial strains, and its qualities as a fertilizer are thus improved. In addition, the residue can also be enriched with molecules produced by the mycelial strains, these molecules including hormones, proteins, vitamins, minerals, antibiotics, antimicrobial agents, pesticides and herbicides, further improving the properties of the residue as a fertilizer. Finally, the dehydration step of the process according to the invention can be implemented with the addition of reduced quantities of polymer and/or coagulant type separation aid compounds, or even without the addition of this type of compound. The residue then has a reduced quantity of these chemical compounds, or is even devoid of them, and advantageously, it can have a reduced micropollutant content compared to the liquid effluent entering the process according to the invention.

In addition, the sequence of steps of the invention makes it possible to maximize the energy recovery of the process by producing biogas, to reduce the volume of sludge to be dehydrated due to the succession of anaerobic digestion steps and treatment by mycelial strains, to improve the dehydrability of the sludge and consequently to reduce the volume of dehydrated sludge as well as the costs of transport, evacuation and/or incineration of the treated and dehydrated digestate.

Finally, an interest of the invention is also to allow the adjustment of the residence time of each of the steps to thus ensure a sufficient carbon supply for the implementation of the step of producing a sludge enriched by the mycelial strains, the production of biogas in the anaerobic digestion step, and a sufficient content of mycelia and/or molecules produced by the mycelial strains in the cake to increase its agronomic value. Thus, advantageously, step (c) of biomass production does not require the addition of exogenous carbon, in particular of the glucose type.

Preferably, during step (c), the organic matter content and/or the second residence time can be controlled as a function of at least one mycelial growth indicator parameter. This parameter can for example be chosen from a variation of a parameter representative of a quantity of dioxygen transferred to the aerobic reactor, a parameter representative of a variation of the chemical dioxygen demand of the sludge during step (c), a parameter representative of a variation of the biological dioxygen demand in the sludge during step (c), a parameter representative of a variation of volatile matter in the sludge during step (c), a mycelial content of the enriched sludge leaving step (c) and/or a content of molecules produced by the mycelial strains of the enriched sludge leaving step (c).

The various parameters presented make it possible to estimate the growth of mycelial strains in the aerobic reactor in order to adapt the control of the second residence time and/or the organic matter content present in step (c) of production of enriched sludge.

Advantageously, in order to further improve the agronomic quality of the solid residue recovered in step (d), the fungal biomass production step can produce a sludge enriched in mycelia and in molecules produced by mycelial strains, said mycelial strains being selected from strains producing molecules chosen from hormones, proteins, vitamins, minerals, antibiotics, antimicrobial agents, pesticides and herbicides.

Advantageously, a portion of the dehydrated and heat-treated digestate may be sent to step (c) and another portion sent to step (d), or the dehydrated and heat-treated digested digestate may be separated, optionally after dilution with water, into a first thickened stream enriched in dry matter and a second stream depleted in dry matter, and the first stream is sent to step (c) and the second stream is sent to step (b) and/or step (c).

Advantageously, at least part of the liquid flow leaving the dehydration step (d) is sent to the anaerobic digestion step (b) and/or the fungal biomass production step (c).

Advantageously, the organic matter content can be controlled:
(i) by controlling the first residence time so that the digestate leaving step (b) has a target organic matter content, and/or
(ii) by adding during step (c) at least a portion of at least one stream chosen from (iia) the liquid effluent to be treated from step (a), (iib) the liquid effluent having undergone pretreatment by hydrolysis, (iic) the digestate leaving step (b) having undergone dehydration and heat treatment, and optionally thickened and/or depleted in dry matter, (iid) the liquid stream leaving step (d) of dehydration.

Controlling the organic matter content makes it possible to control the carbon content in step (b) and in step (c) and thus control the yield of the process and the agronomic value of the liquid effluent to be recovered by this process.

• une conduite de fourniture d’un effluent liquide à traiter contenant de la matière organique ;
• une unité de digestion anaérobie comprenant une conduite d’alimentation raccordée à la conduite de fourniture, une conduite d’évacuation de digestat et une conduite d’évacuation de biogaz ;
• une unité de production de biomasse fongique contenant des souches mycéliennes, comprenant une conduite d’alimentation raccordée à la conduite d’évacuation de digestat et une conduite d’évacuation d’une boue enrichie en mycéliums et/ou en molécules produites par les souches mycéliennes;
• une unité de déshydratation de la boue enrichie en mycéliums et/ou en molécules produites par les souches mycéliennes, comprenant une conduite d’alimentation raccordée à la conduite d’évacuation de la boue enrichie en mycéliums, une conduite d’évacuation d’un gâteau et une conduite d’évacuation d’un flux de liquide;
• un système de contrôle configuré pour contrôler la teneur en matière organique présente dans l’unité de production de biomasse fongique et/ou le deuxième temps de séjour dans cette unité de production de biomasse fongique, en fonction d’une teneur cible du gâteau en mycéliums et/ou d’une teneur cible du gâteau en molécules produites par les souches mycéliennes.

The invention also relates to an installation for recovering a liquid effluent containing organic matter, in particular from a treatment process, comprising:

• a supply line for a liquid effluent to be treated containing organic matter;
• an anaerobic digestion unit comprising a feed line connected to the supply line, a digestate discharge line and a biogas discharge line;
• a fungal biomass production unit containing mycelial strains, comprising a feed pipe connected to the digestate discharge pipe and a discharge pipe for a sludge enriched with mycelia and/or molecules produced by the mycelial strains;
• a unit for dehydrating sludge enriched with mycelia and/or molecules produced by the mycelial strains, comprising a feed pipe connected to the evacuation pipe for the sludge enriched with mycelia, a evacuation pipe for a cake and a evacuation pipe for a liquid flow;
• a control system configured to control the organic matter content present in the fungal biomass production unit and/or the second residence time in this fungal biomass production unit, as a function of a target content of the mycelial cake and/or a target content of the cake in molecules produced by the mycelial strains.

Advantageously, the supply line for the liquid effluent to be treated can be connected to a hydrolysis pretreatment unit comprising a discharge line for a pretreated liquid effluent connected at least to the supply line of the anaerobic digestion unit.

In one embodiment, the digestate discharge line may be connected to a second dehydration unit comprising a discharge line connected to a thermal treatment unit comprising a discharge line for the dehydrated and thermally treated digestate, and the discharge line for the dehydrated and thermally treated digestate may be:
(i) connected to a first discharge line connected to the feed line of the fungal biomass production unit and to a second discharge line connected to the feed line of the dehydration unit, or
(ii) connected to a separation unit, which comprises a first discharge pipe for a first thickened flow enriched in dry matter and a second discharge pipe for a second flow depleted in dry matter, and the first discharge pipe is connected to the feed pipe of the fungal biomass production unit and the second discharge pipe is connected to the feed pipe of the digestion unit and/or to the feed pipe of the fungal biomass production unit, optionally the discharge pipe for the dehydrated and heat-treated digestate is connected to a water feed pipe upstream of the separation unit.

In one embodiment, the liquid flow discharge line from the dehydration unit may be connected to the feed line of the digestion unit and/or to the feed line of the fungal biomass production unit.

Advantageously, the control system may be configured to control the organic matter content in the production unit (i) by controlling the residence time of the liquid effluent in the anaerobic digestion unit such that the digestate leaving this unit has a target organic matter content, and/or
(ii) by controlling the addition to the fungal biomass production unit of at least part of a flow selected from (iia) the liquid effluent to be treated via a feed line connected to the liquid effluent supply line, (iib) the liquid effluent having undergone pretreatment by hydrolysis via a feed line connected to a hydrolysis pretreatment unit, (iic) the dehydrated and heat-treated digestate via the discharge line connected to the discharge line for the dehydrated and heat-treated digestate, and optionally thickened in dry matter via the first discharge line of the separation unit and/or depleted in dry matter via a line connected to the second discharge line of the separation unit, (iid) the liquid flow leaving the dehydration unit via a feed line connected to the dehydration unit.

Advantageously, the installation can further comprise a mycelium culture reactor (180) and the fungal biomass production unit can comprise a mycelium supply line connected to the mycelium culture reactor, and the control system can be configured to discontinuously control over time the supply of mycelium to the production unit from the culture reactor. This culture reactor is thus distinct from the fungal biomass production unit and is not part of it.

Advantageously, the installation comprises a degassing unit between the digestion unit and the fungal biomass production unit, optionally between the digestion unit and the second dehydration unit.

Definitions /abbreviations

By "fungal biomass" we mean biomass consisting of micromycetes, i.e. microorganisms, as opposed to higher fungi.

By "mycelial strains" we mean strains of micromycetes.

Mycelium is the vegetative apparatus of fungi. It develops by breaking down organic matter and absorbing nutrients and water. In particular, it secretes powerful extracellular enzymes (hydrolase type) that allow it to break down the most resistant organic matter by breaking down polymers into monomers.

Dryness represents the mass percentage of dry matter in a sludge.

The chemical oxygen demand (denoted COD or DCOtot) of a sample is a measure of the totality of oxidizable substances, whether biodegradable or not, of this sample. It is expressed in kg/m ³ of sample. COD can be measured according to the NFT 90-101-February 2001 or ISO 6060-1989 standard.

The biochemical oxygen demand (BOD) of a sample is a measure of the totality of biodegradable oxidizable substances in that sample. It is expressed in kg/m ³ of sample. BOD can be measured according to ISO 5815-1:2019.

Volatile matter (VM), or suspended volatile matter, refers to the part of suspended matter that is likely to be volatilized at 550°C. The determination of the volatile matter content of a sample is carried out by calcination at 550°C of the suspended matter obtained after centrifugation and then drying at 105°C. The volatile matter content, expressed in kg/m ³ of sample, can be determined by gravimetry according to standard NF T90-105-2: 1997.

The reduction rate is defined as the percentage reduction of the values of a parameter measured between the inlet and the outlet of a reactor. The reduction rate is calculated by dividing the difference between the value of the input parameter Pe and the output parameter Ps by the value of the parameter Pe at the inlet of the reactor according to the formula ((Pe-Ps)/Pe) x100.

By "organic matter" we mean matter containing carbon.

Description of figures

Other features and advantages of the invention will emerge from reading the description given below of several particular embodiments of the invention, given for information purposes only but not as a limitation, with reference to the appended drawings in which:

There is a schematic representation of the recovery installation according to a first embodiment of the invention.

There is a schematic representation of the recovery installation according to a second embodiment of the invention.

There is a schematic representation of the recovery installation according to a third embodiment of the invention.

There is a schematic representation of the recovery installation according to a fourth embodiment of the invention.

Detailed description of the invention

The alternative configurations of the different stages of the process presented below can be combined depending on the decided recovery objective.

Step (a) of supply of a liquid effluent to be treated

The recovery process firstly includes a step of supplying a liquid effluent containing organic matter, in particular biodegradable organic matter.

This liquid effluent may be any liquid effluent from a water treatment process and/or organic waste of agricultural, industrial and/or household origin.

This liquid effluent may in particular comprise, or consist of, fresh sludge from a water treatment process, the water optionally being treated in a mixture with organic waste of the aforementioned type.

This water treatment process is typically in three stages: a primary treatment stage, a secondary treatment stage and a tertiary treatment stage. The treated wastewater is municipal and/or industrial wastewater.

The first primary treatment stage generally reduces the solid and/or organic matter content of the wastewater to be treated. This is typically a settling stage, possibly assisted by the prior addition of coagulant and/or flocculant, during which the wastewater is placed in a holding tank or settling basin. The solids contained in the wastewater are thus deposited at the bottom of the tank where they are collected. This stage thus produces so-called primary sludge and an effluent with a reduced solids content. The second stage is typically a biological treatment stage during which the organic matter, nitrogen compounds and/or phosphorus compounds, in the effluent from the first stage are assimilated or decomposed by aerobic and/or anaerobic and/or anoxic microorganisms. This second stage also produces so-called biological sludge. The third stage of tertiary treatment is designed to further clean the water when it is discharged into a sensitive ecosystem or for reuse. This stage may involve the removal of phosphorus and/or micropollutants and/or disinfection and/or filtration. This third stage produces so-called tertiary sludge.

The fresh sludge to be treated is thus all or part of this primary, secondary or tertiary sludge. The fresh sludge, and more generally the liquid effluents treated in the present invention, are made up of various organic compounds and contain carbon, nitrogen, phosphorus as well as other nutrients, micronutrients and micropollutants. The solid matter content of fresh sludge is typically 1 to 40 g/L before thickening and 30 to 100 g/L after thickening and upstream of anaerobic digestion.

Optional hydrolysis step (e)

Optionally, before being sent to step (b), the liquid effluent to be treated from step (a) can be pretreated in a hydrolysis pretreatment step (e).

This pretreatment step (e) makes it possible to increase the yield of the anaerobic digestion step (b) by promoting the degradation of organic matter by microorganisms.

This can be acid or basic hydrolysis, generally carried out at a temperature below 100°C, thermal hydrolysis or biological hydrolysis.

Biological hydrolysis is, for example, a fermentation/hydrolysis step in mesophilic (30 – 42°C) or thermophilic (45 – 70°C) conditions with a residence time of around 1 to 3 days.

Thermal hydrolysis can be a thermal hydrolysis process (THP) which is a process of maintaining sludge, typically having a dry matter content of between 12% and 25%, at a temperature of between 140°C and 165°C with a treatment time of 30 minutes to 60 minutes. The hydrolyzed sludge is then typically cooled in a flash tank before being introduced into the digester.

The aim of hydrolysis is to improve the digestion performance and dehydration of sludge by breaking down the cell walls of microorganisms, the cellular content thus becoming easily degradable anaerobically. It is for example implemented in a dedicated reactor.

After hydrolysis, the liquid effluent is generally diluted to around 10% dry matter before being injected into the digester.

Step (b) anaerobic digestion

The liquid effluent to be treated supplied during step (a) or the pretreated liquid effluent leaving step (e) is then sent, at least in part, generally in its entirety, to an anaerobic digestion step.

Anaerobic digestion or methanization corresponds to a cascade of biochemical reactions allowing methanogenic microbial populations to convert the organic matter present in a digester into biogas corresponding mainly to a mixture of carbon dioxide and methane. The remaining materials are called digestate. Anaerobic digestion can be mesophilic or thermophilic anaerobic digestion. The conditions for implementing this step, in particular the temperature, pH and residence time, can be advantageously chosen in order to maximize biogas production.

Digestion step (b) then produces biogas and a digestate, in which at least part of the organic matter contained in the liquid effluent to be treated is degraded by contact with microorganisms during an initial residence time (hydraulic residence time).

This digestion step is well known and will not be detailed further. It is typically carried out in a bioreactor at a temperature of 35 to 55 °C, generally for an average residence time of 10 to 20 days.

Optional vacuum degassing step of the digestate

In one embodiment, the method according to the invention may comprise a step of vacuum degassing of the digestate leaving step (b) in a degassing unit to recover the methane, and optionally the other gases present (CO2, etc.). This step is preferably implemented upstream of the optional dehydration and heat treatment step.

The digestate is usually degassed in a headspace maintained at a pressure between 5 and 40 kPa lower than the partial pressure of the dissolved gas, which reduces the solubility of the gases and facilitates their evacuation. Degassing can be carried out by means of a vacuum pump or a compressor connected to a gas storage tank.

The advantage of this optional step is to recover more methane and prevent it from being released into the atmosphere during step (c) of fungal biomass production.

In addition, the presence of _CO2 lowers the pH to a range in which recovery of dissolved phosphorus by precipitation in the presence of magnesium in the form of struvite is difficult. By removing _CO2 by degassing, the formation of struvite is promoted. This step also improves the agronomic quality of the cake since, in the presence of magnesium and phosphate, it will be possible to precipitate struvite microcrystals which will end up in the cake. In particular, a compound containing magnesium can be added to the digestate before this degassing step to promote the formation of struvite.

Optional dehydration and heat treatment step

Optionally, the digestate leaving step (b), or the optional degassing step, can be dehydrated and heat treated before being sent to step (c) of fungal biomass production.

Dehydration reduces the water content of the digestate. It can be carried out by filtration (a filter press, a piston press, a screw press) and/or by centrifugation in the usual way. The recovered water can be sent to a treatment unit for reuse or discharge into nature.

The dehydrated digestate is then thermally treated, for example, with a thermal hydrolysis process as described above or by a hydrothermal carbonization (HTC) process. This HTC process typically operates at temperatures between 180°C and 280°C for a period of a few minutes to several hours in a non-oxidizing atmosphere. The wet dehydrated digestate is treated with pressurized steam and the process produces a solid carbon fraction and a liquid fraction, the latter of which can be returned to the anaerobic digestion step (b) in order to increase the biogas production. The solid carbon fraction is sent to step (c).

Heat treatment sterilizes the digestate and thus promotes the growth of mycelial strains during step (c). The use of heat post-treatment after step (b) of anaerobic digestion, by sterilizing the digestate, reduces the competition between the microorganisms from anaerobic digestion and the mycelial strains, which can reduce the need to add new mycelial strains in step (c).

Once dehydrated and heat-treated, the digestate may be sent directly, in part or in whole, to step (c). The dehydrated and heat-treated digestate contains the initially non-biodegradable organic matter that was not degraded by microorganisms during anaerobic digestion and that was solubilized, and thus made biodegradable, by the heat treatment.

In a first configuration, the dehydrated and heat-treated digestate may be sent in part to step (c) and another part, in particular the remainder, sent to step (d). The proportions between the parts may be chosen according to the quantity of organic matter to be provided in step (c), as described with reference to the control system.

The distribution of the dehydrated and heat-treated digestate between steps (c) and (d) also makes it possible to modulate the impact of the supply of organic matter on the quantity of dioxygen to be provided during step (c) since the latter decreases when this supply is reduced.

In a second configuration, the dehydrated and heat-treated digestate may be separated, optionally after dilution with water, into a first thickened stream enriched in dry matter and a second stream depleted in dry matter, and the first stream may be sent to step (c) and the second stream may be sent to step (b) (enabling further biogas production) and/or to step (c), to supplement the organic matter supply.

The dehydrated and heat-treated digestate can be separated by a liquid/solid separation process such as a gravity or dynamic separation process. Separation can also be aided by the addition of polymer and/or coagulant.

The first thickened flow may have a dryness of 15-45%. Dilution with water prior to separation may facilitate separation.

Anda pe (c) of production of fungal biomass

The digestate provided during step (b) or the dehydrated and heat-treated digestate, optionally thickened and/or depleted in dry matter, is then sent, at least in part, to a step (c) of fungal biomass production producing a sludge enriched in mycelia and/or in molecules produced by the mycelial strains.

During this step (c), at least part of the digestate, optionally dehydrated and heat-treated, or even thickened and/or depleted, is placed in contact in an aerobic reactor and in the presence of organic matter with mycelial strains during a second residence time (hydraulic residence time).

During this stage, the digestate is seeded with fungal biomass (mycelial strains) in the reactor. This reactor is kept aerated in order to provide dioxygen to the mycelial strains and thus allow their development.

The second residence time of the digestate is chosen so as to produce a sludge enriched with mycelia and/or molecules produced by the mycelial strains. This residence time is typically 1 to 10 days, in particular 2 to 5 days. The flows of mycelium and digestate are controlled in the installation accordingly. The development of the mycelial strains is typically carried out at a pH of the order of 5.5 to 9 and at a temperature of 10°C to 30°C. Agitation will advantageously be low, typically with oxygenation making it possible to maintain a dissolved oxygen concentration of the order of 0.1 to 4 mg/l in the reactor.

The process can operate with mesophilic (<38°C) or thermophilic (45 – 65°) mycelial species with low energy consumption. This allows the use of a substrate that is highly stabilized by upstream digestion, requiring low oxygen requirements. The air flow rate to be injected is then low, which minimizes energy consumption for blowing in the air and also to compensate for heat losses due to water evaporation via the blown in air.

In particular, we can choose mycelial strains based on the properties of the molecules they produce.

Mycelial strains are thus advantageously selected from strains producing molecules chosen from hormones, proteins, vitamins, minerals, antibiotics, antimicrobial agents, pesticides and herbicides.

The mycelial strains that can be used can be chosen from the families Trichocomaceae , Hypocreaceae , Mucoraceae , Dipodascaceae , Polyporaceae , Nectriaceae , Incertae sedis , Sclerotiniaceae , Phanerochaetaceae and their mixtures.

The mycelial strains can in particular be chosen from the genera Penicillium Trichoderma , Phoma , Mucor , Fusarium , Galactomyces , Aspergillus , Botrytis , Geomyces , Geotrichum , Akanthomyces , Beauveria , verticillium , Metarhyzium , Ampelomyces , Coniothyrium , Pseudozyma , Trametes , Gliocladiu , Phanerochaete and their mixtures.

For example, mycelial strains can be chosen from among strains of Penicillium spp . species. (e.g. P. roqueforti , P. c amembertii , P. c hrysogenium , P. a tramentosum , P. c orylophilum , P. citrinum , P. waskmanii , P. spinulosum , P. granulatum , P. janczewskii , P. lividum , P. communnae , P. vulpinum , P. juniculo sum , P. brevicompactum , P. corylophilum , P. Cylopium , P. Diversum , P. implicatum , P. lanosum , P. steckii , P. stoloniferium , P. variabile , P. expansum ) , Aspergillus spp . (e.g. A. niger , A. Phoenicis , A. Ficuum , A. terries , A. flavus , A. fumigates , A. ustus , A. brunneo-uniseriatus , A.versicolor , A.parasiticus , A. versicolor ), Trichoderma spp . ( e.g. T. v iride, T. k oningii , T. reese i , T. harzianum , T. atroviride , T. guizhouense ) , Mucor spp . ( e.g. M. hiemalis , M. mucedo , M. racemosus , M. circinelloides , M. fuscus , M. p lumbeus ) , Geotrichum spp ( e.g. G. Candidum , G. Pannorum ) , Fusarium spp ( e.g. F. equisetii , F. solani , F. monoliform , F. oxysporum ), Phoma spp ( e.g. e.g. P homa glomerata , Phoma euyrena ), Botrytis spp ( e.g. Botrytis Cinerea ), Akanthomyces spp ( e.g. Akanthomyces lecanii ), Beauveria spp . ( e.g. Beauveria Bassiana ), Verticillium spp . ( e.g. Verticillium lecanii ) , Metarhizium spp . , Phanerochaete spp . ( e.g. P. c hrysosporium ) , Saprolegniaceae spp ., Cladosporium spp . ( e.g. C. cladosporioides , C. herbarum ), Spicaria spp., Hyloflorae spp. , Galactomyces spp. (G. geotricum ) Ampelomyces Quisqualis , Coniothyrium Nimitans , Gliocladium spp , Purpureocillium Lilacinum , Pseudozyma Flocculosa , Tram e tes Versicolor , Phanerochaete chrysosporium , Geomyces spp . ( e.g. G. pannorum ), Alternaria alternate , Rhinocladiella mansonii , Spotoryx spp . Aureoasidium pullulans, Cephalosporium spp., Epicoccum pupurascens , Stachybotrys atra , Sterile myselium , Asperillius ochraceus , Verticillum spp. Doratomyces stemonitis , Zygorhynchus marrow , Gliocladium spp (e.g. G. Fimbriatum, G. roseum , G. fimbriatum), Gonatobotryum sp., Helminthosporium sp. Isaria cretacea , Paecilomyces spp. (e.g. P.elegans , P. varioti ), Pyrenochaeta terrestris , Rhizopus spp. Scopulariopsis sp. Sepedonium sp. Tryposporium myrtii , Volutella ciliate, Allereschia ( Petriellidium ) crocea , Acremonium sp., Chrysosporium pannorum , Dactylaria sp. Caclyomomyces albus, Dactylomyces albus , Glicadium roseum , Glimastix musicola , Pseuoeurotium zontaurm , Rhizopus arrizus , Sepedonium sp. Sporothrix sp . Talaromyces spiculisoprus , Thamnidium elegans , and mixtures thereof.

Mycelial strains need organic matter, especially carbon, to grow. This organic matter advantageously comes from only one of the process streams. Thus, the amount of organic matter needed for the growth of mycelial strains can come from:

- digestate by controlling the residence time of the liquid effluent in step (b) so that the digestate contains sufficient carbon for the development of mycelial strains, and/or

- dehydrated and heat-treated digestate, or even thickened and/or depleted in dry matter, and/or

- hydrolyzed liquid effluent obtained during the optional hydrolysis step: this effluent has the advantage of containing much more organic matter than the digestate, and/or

- from the liquid flow from dehydration step (d), in particular when part of the dehydrated and heat-treated digestate is sent directly to dehydration step (d): this liquid flow then still contains undegraded carbon which can be used either by the microorganisms during step (b) or by the mycelial strains during step (c).

It should be noted that the reduction in the residence time of step (c), when implemented downstream of a thermal post-treatment, makes it possible to return a fraction of the biodegradable carbon to digestion, for example via the liquid flow from the dehydration step or via a pipe returning part of the enriched digestate leaving step (c) to digestion step (b), and to ensure overproduction of biogas.

Optionally, during step (c), mycelial strains are added punctually and discontinuously over time, these mycelial strains coming from a culture reactor, for example installed and operated on the same site as the process or on a remote site (this reactor can then be shared with other installations), in which mycelial strains are developed. The added mycelial strains are thus produced in a dedicated reactor separate from the reactor used during step (c), via a direct connection between the reactors, or not. In particular, this culture reactor is supplied with nutrients containing carbon, nitrogen, phosphorus, etc.

Indeed, a depletion of the concentration and/or diversity of mycelial strains may occur inside the aerobic reactor. Thus, it is sometimes necessary to add mycelial strains punctually for the proper functioning of the process. However, it is not necessary to provide a continuous supply of mycelial strains to step (c) by a culture reactor located upstream of step (c).

The mixture between the mycelial strains and the digestate, optionally dehydrated and heat-treated, or even thickened and/or depleted, allows for better dispersion of the mycelia in the sludge to obtain a homogeneous mixture.

At the end of step (c), a sludge enriched with mycelia and/or molecules produced by the mycelial strains is thus recovered, having for example a target content of mycelia and/or molecules produced by the mycelial strains. Step (c) is in particular controlled so that the cake produced during step (d) has a target content of mycelia and/or molecules produced by the mycelial strains. Since the content of mycelia and/or molecules in the cake depends on the content of these components in the sludge leaving step c), this control can be carried out by controlling the sludge leaving step c) in mycelia and/or molecules produced by the mycelial strains, and/or by controlling the cake. These target contents can be chosen according to the desired application and the mycelial strains used.

Step (d) dehydration of treated sludge

The sludge enriched with mycelia and/or molecules produced by the mycelial strains, produced during step (c) is then sent to a dehydration step producing a solid residue forming a cake and a liquid flow called filtrate or centrate depending on the dehydration technique used (filtration or centrifugation respectively).

During step (d), a first cake rich in mycelia and/or molecules produced by the mycelial strains is produced.

When the optional dehydration and heat treatment step is implemented, this dehydration step (d) can be carried out without added chemical compound such as flocculant and/or coagulant. Otherwise, dehydration step (d) can be implemented with a reduced quantity of chemical product.

Dehydration reduces the water content of the sludge enriched with mycelia and/or molecules to achieve a dryness of approximately 20% to 65%. Dehydration can be carried out by filtration (a filter press, a piston press, a screw press) and/or by centrifugation in the usual manner.

Optionally, at least part of the liquid flow leaving the dehydration step (d) can be sent to the anaerobic digestion step (b) and/or to the fungal biomass production step (c). This makes it possible to increase the efficiency of the biogas plant and also to treat a maximum of carbon included in particular in the organic matter present. This can also make it possible to supplement the supply of organic matter necessary for step (c).

Process control

The process is also controlled by adjusting the organic matter content present in the reactor of step (c) and/or the second residence time of step (c) to achieve a target mycelial content and/or a target content of molecules produced by the mycelial strains in the cake exiting step (c). This control can be implemented by a control system as described below.

The organic matter content can be determined by measuring the COD, BOD or MV of the sludge entering and leaving step (c). These measurements are typically carried out once a day in the laboratory.

The organic matter content and/or the second residence time may be controlled as a function of at least one mycelial growth indicator parameter chosen from a variation in a parameter representative of the quantity of dioxygen transferred to the aerobic reactor, a parameter representative of a variation in the chemical dioxygen demand of the sludge during step (c), a parameter representative of a variation in the biological dioxygen demand in the sludge during step (c), a parameter representative of a variation in volatile matter in the sludge during step (c), a mycelial content of the enriched sludge leaving step (c) and/or a content of molecules generated by the mycelial strains of the enriched sludge leaving step (c).

These different parameters can be measured and calculated using sensors and/or measurements taken on samples taken at specific times at the inlet and outlet of the aerobic reactor.

BOD, COD and MV, as well as the mycelium and molecule contents of the enriched sludge leaving step c) are measured in the laboratory on samples taken. These parameters can be determined one to several times per day or per week depending on requirements. The mycelium content can be determined by standard techniques such as analysis of the cultivable mycological flora or real-time PCR (Polymerase Chain Reaction), also called quantitative PCR or qPCR. The content of molecules produced can be determined by any appropriate assay method.

The flow of oxygen transferred to the aerobic reactor (corresponding to the oxygen actually consumed by the biological activity of the mycelial strains) can be used as the main indicator of mycelial biological activity. It has the advantage of being able to be measured continuously. This flow, denoted F, is for example determined by a continuous measurement of the gas flow (Q), typically air, blown into the aerobic reactor, and by a continuous measurement of the concentration Cs of oxygen in the gas escaping from the aerobic reactor. The flow F of oxygen transferred to the aerobic reactor can then be expressed by the formula F = Q x (Ce – Cs), Ce being the concentration of oxygen in the gas blown into the reactor.

The parameter representing a COD, BOD and/or MV variation can be a reduction or a quantity destroyed (measured in mass per unit of time). The quantities of COD, BOD and/or MV destroyed in the reactor, or the reductions, are also good indicators of mycelial biological activity. To determine these indicators, it is necessary to carry out measurements of COD, BOD and/or MV in the sludge and/or liquid effluent flows entering and leaving the reactor, then to calculate the corresponding reductions or to carry out mass balances in order to calculate the quantities of COD, BOD and/or MV destroyed in the aerobic reactor. The contents of the sludge from step c) in mycelia and/or molecules produced by the mycelial strains can also be used. These indicators can be used to control the process, with the limitation that they do not provide continuous information due to their determination techniques.

In an advantageous embodiment, the flow F may be used as the main indicator, and the reductions or quantities destroyed in COD, BOD and/or MV, and/or the contents of mycelia and/or molecules produced may be used as redundancy for the control based on the flow F of transferred dioxygen (as described above), for example to adjust an applied F setpoint value.

Once the indicator parameter has been determined and depending on its value, the organic matter content can then be adjusted (controlled) in several ways. It can be adjusted by controlling the first residence time so that the digestate leaving step (b) has a target organic matter content. For this purpose, it may be possible to measure the COD of the digestate (or the BOD or the MV) and control the residence time accordingly, or to use pre-established data tables indicating the organic matter content as a function of the residence time of the liquid effluent in the digester.

Alternatively or in combination, the organic matter content can be adjusted (controlled) by adding in step (c):

- part of the liquid effluent from step (a), which consequently contains a lot of organic matter, and/or

- at least part of the hydrolyzed liquid effluent, optionally obtained during the hydrolysis step (e), which also contains a lot of undegraded organic matter, and/or,

- at least part of the digestate having undergone the optional dehydration and heat treatment step, and/or,

- at least part of the digestate having undergone the optional dehydration and heat treatment step and after thickening and/or reduction in solid matter, and/or

- at least part of the liquid flow which comes from dehydration step (d), in particular when the sludge dehydrated in this step comes partly from a sample located downstream of step (b) but upstream of step (c), in particular from a sample located downstream of the heat treatment described above.

The quantities of the various added flows and/or the second residence time can be determined based on the organic matter content of these flows, the latter being either measured, for example via COD, BOD or MV, or estimated from data tables, for example constructed from tests.

In particular, a reduction in COD, BOD and/or MV (or a quantity of COD, BOD and/or MV destroyed) greater than a threshold value, an increase in the quantity of oxygen transferred F, in particular beyond a threshold, an increase in the content of mycelia and/or molecules produced by the sludge leaving step c) above a threshold are indicators of excess biological activity and require a reduction in the organic matter supplied to the aerobic reactor and/or a reduction in the residence time in the aerobic reactor. Conversely, a reduction in COD, BOD and/or MV (or a quantity of COD, BOD and/or MV destroyed) below a threshold value, a reduction in the quantity of oxygen transferred F, in particular below a threshold, a drop in the content of mycelia and/or molecules produced by the sludge leaving step c) below a threshold, are indicators of insufficient biological activity and require an increase in the organic matter supplied to the aerobic reactor and/or an increase in the residence time in the aerobic reactor. The above threshold values as well as the amplitudes of the decreases and/or increases triggering an input/reduction of organic matter and an increase/reduction of the second residence time, as well as the inputs/reductions in organic matter and the increase/reduction of the second residence time, can be previously determined by tests in order to obtain a target content of mycelia and/or molecules produced by the mycelial strains in the cake.

The target mycelium content of the cake can be determined by the usual techniques previously described after dilution of the cake, and set according to the desired content. The content of the cake in molecules produced can be determined by any suitable assay method after dilution of the cake, and set according to the desired content.

The second residence time can be adjusted (controlled) according to a setpoint or a setpoint interval previously determined by testing. The second residence time can typically be controlled by changing the liquid level in the fungal biomass production unit or the flow rate of the incoming stream to this reactor by adding dilution water. If the second residence time is greater than a setpoint and needs to be reduced, then the liquid level can be reduced or dilution water can be added to the incoming stream, while if the second residence time is less than the setpoint and needs to be increased, then the liquid level can be increased or the dilution water can be reduced if dilution water was added so far.

Once the organic matter content present in the aerobic reactor and/or the second residence time have been adjusted, a quantity of dioxygen necessary for the mycelial strains to grow and consume at least part of the organic matter supplied is supplied to the reactor of step (c). This supply of quantity of dioxygen is usually done so as to maintain a target concentration of dissolved dioxygen inside the reactor, typically of the order of 0.1 to 4 mg/l.

Description of the i Installation

In reference to the , according to a first embodiment of the invention, an installation 100 is described for recovering a liquid effluent from a treatment process, in particular water treatment. The installation 100 comprises a supply line 1 for a liquid effluent to be treated containing organic matter, an anaerobic digestion unit 110 capable of implementing step (b), a fungal biomass production unit 120 capable of implementing step (c) and a dehydration unit 130 for the sludge enriched with mycelia leaving the production unit 120, capable of implementing step (d).

The anaerobic digestion unit 110 comprises a feed line 2 connected to the supply line 1, a digestate discharge line 3 and a biogas discharge line 4. This unit can be a continuous stirred-tank reactor (also called in English “continuous stirred-tank reactor” or CSTR) or a reactor with a fixed culture.

The fungal biomass production unit 120 comprises, or consists of, an aerobic reactor, and comprises a feed line 5 connected to the digestate discharge line 3 and a discharge line 6 for the enriched sludge. This unit may also be a continuous stirred tank reactor (CSTR) or a reactor with a fixed culture. The fungal biomass production unit 120 also comprises an air injection line connected to an air compressor not shown. .

The dehydration unit 130 comprises a feed line 7 connected to the discharge line 6 of the fungal biomass production unit 120, a discharge line 8 for a liquid flow and a recovery line 8' for the solid residue (cake). This unit can be chosen from a centrifugation unit, a filtration unit and a combination of these units to produce a cake rich in mycelium having a dryness of between 20% and 65%. The discharge line 8 can be connected to the feed line 2 of the digestion unit 110 (not shown in the ).

The recovery installation 100 further comprises a process control system 140 for, during step (c), adjusting the content of organic matter present and/or the second residence time and producing a digestate enriched with mycelia and/or molecules produced by the mycelial strains and a cake comprising a target content of mycelia and/or molecules produced by the mycelial strains. This adjustment of the organic matter can be achieved by controlling the organic matter content entering the fungal biomass production unit 120 via the pipe 5 by controlling the hydraulic residence time of the digestion unit 110, and/or by supplying to the fungal biomass production unit 120 liquid flows containing organic matter, such as the liquid effluent to be treated via a pipe 18 and/or the liquid flow leaving the fungal biomass production unit 120 via a pipe 23. Other liquid flows can be used alternatively or in combination as described with reference to FIGS. 2 to 4.

There presents a second embodiment of a recovery installation 200 according to the invention, described by differences with respect to the installation of the first embodiment. The same elements are designated by the same references. The fungal biomass production unit 120 comprises an air injection pipe 121 connected to an air compressor 122 for aerating the reactor. Of course, any aeration system can be envisaged.

In the embodiment of the , the recovery installation 200 comprises a hydrolysis pretreatment unit 150.

The hydrolysis pretreatment unit 150, capable of implementing step (e) of the method, is connected to the supply line 1 of the liquid effluent to be treated, either directly (not shown) or via a fluid distributor R1. This fluid distributor R1 is connected on the one hand to the supply line 1 and on the other hand to a first line 1a connected to the unit 150 and a second line 1b. The pretreatment unit 150 comprises a discharge line 9 for pretreated liquid effluent connected to the supply line 2 of the anaerobic digestion unit 110, either directly (not shown) or via another fluid distributor R2. This fluid distributor R2 is connected on the one hand to the discharge line 9 and on the other hand to a first line 9a connected to the supply line 2 and to a second line 9b. The lines 1b and 9b of the fluid distributors R1 and R2 are here connected to the supply line 5 of the fungal biomass production unit 120 to supply it with liquid effluent and hydrolyzed liquid effluent respectively. The fluid distributors, for example of the solenoid valve type, can be controlled by the control system to send specific quantities of liquid effluent and/or hydrolyzed liquid effluent into the production unit 120.

This pretreatment unit 150 can be a biological hydrolysis reactor with a hydraulic residence time of 1 to 3 days or a thermal hydrolysis reactor with a hydraulic residence time of 20 to 60 minutes.

Optionally, the installation 200 comprises a reactor 180 for culturing mycelial strains. The fungal biomass production unit 120 comprises a supply line 12 for mycelial strains connected to the reactor 180 for culturing mycelial strains. The supply of mycelial strains from the culture reactor is controlled by the control system 140 in a discontinuous manner, for example via a valve 181 of the fungal biomass production unit 120 fluidically connected to the supply line 12.

Optionally, the installation comprises a degassing unit 210 between the digestion unit 110 and the fungal biomass production unit 120, comprising for example an inlet connected to the digestate evacuation pipe 3 and an outlet connected to the supply pipe 5 of the fungal biomass production unit.

There presents a third embodiment of a recovery installation 300 according to the invention, described by differences with respect to the installation 200 of the second embodiment. The same elements are designated by the same references.

Unlike the installation of the second embodiment, the installation 300 does not include the hydrolysis pretreatment unit 150, the fluid distributors R1 and R2 and the associated pipes.

The installation 300 comprises a second dehydration unit 160 and a heat treatment unit 170.

The second dehydration unit 160 is connected to the digestate discharge pipe 3 and it comprises a dehydrated digestate discharge pipe 10. It also comprises a discharge pipe 10' for a second water flow which can be sent to a treatment unit before reuse or discharge into nature.

The heat treatment unit 170 is connected to the dehydrated digestate discharge line 10 and it comprises a dehydrated and heat-treated digestate discharge line 11.

The discharge line 11 is connected to a fluid distributor R3 itself connected to a discharge line 13 connected to the feed line 5 of the fungal biomass production unit 120 and to a discharge line 14 connected to the feed line 7 of the dehydration unit 130. It is thus possible to send a portion of the dehydrated and heat-treated digestate leaving the heat treatment unit 170 directly to the dehydration unit 130. The liquid flow leaving the latter via the line 8 contains organic matter, which can be returned either to the digestion unit 110 or to the production unit 120 or both. For this purpose, the discharge line 8 can be connected to a fluid distributor R4 which is connected to two lines 8a, 8b, as shown in the . Line 8a is here connected to feed line 5 of production unit 120, line 8b being connected to feed line 2 of digestion unit 110. Fluid distributors R3, R4, for example of solenoid valve type, can be controlled by the control system to send specific quantities of dehydrated and heat-treated digestate and/or liquid streams into fungal biomass production unit 120, the distributors sending the remainder of the streams they receive to dehydration unit 130 and digestion unit 110, respectively.

Optionally, the installation 300 comprises a degassing unit 210 between the digestion unit 110 and the second dehydration unit 160, comprising for example an inlet connected to the digestate evacuation pipe 3 and an outlet connected to the second dehydration unit 160.

Finally, the presents a fourth embodiment of a recovery installation 400 according to the invention, described by differences with respect to the installation 300 of the third embodiment. The same elements are designated by the same references.

The installation 400 comprises a separation unit 190 connected to the discharge pipe 11 of dehydrated and heat-treated digestate from the heat treatment unit 170.

The separation unit 190 is for example a separation unit by sieving, by decantation optionally with injection of reagents (of the coagulant and/or flocculant type), or by centrifugation optionally with injection of reagents (of the coagulant and/or flocculant type). For example, a draining table, a sieve, a vibrating sieve, a grid, a belt filter, a filter, a vibrating filter may be used. It may also be chosen from a membrane filtration unit and a cloth filtration unit.

The separation unit 190 comprises a first discharge pipe 15 for a first thickened flow enriched in dry matter connected to the feed pipe 5 of the fungal biomass production unit 120 and a second discharge pipe 16 for a second flow depleted in dry matter connected to the feed pipe 2 of the digestion unit 110 via a pipe 16b and/or to the feed pipe 5 of the production unit 120 via a pipe 16a, here via a fluid distributor R5. The fluid distributor R5, for example of the solenoid valve type, can be controlled by the control system to send specific quantities of dehydrated and heat-treated digestate, thickened or depleted, into the production unit 120.

Optionally, the discharge pipe 11 for dehydrated and heat-treated digestate is connected to a water supply pipe 17 upstream of the separation unit 190 in order to allow the dilution of the digestate before it enters the separation unit 190.

In this embodiment, the production unit 120 further comprises a recirculation pipe 6’ returning a portion of the mycelium-enriched digestate exiting the fungal biomass production unit 120 to the inlet thereof. This recirculation pipe 6’ may be equipped with a heat exchanger to maintain the temperature or heat the reactor of the unit 120 because, depending on the heat losses and the dilution, the temperature may vary in the reactor. This variant may of course be present in the other embodiments described.

The various embodiments described and their variants can be combined. In particular, the installations 100, 300 and 400 could be equipped with a hydrolysis pretreatment unit 150, fluid distributors R1 and R2 and associated pipes, as described with reference to the . Installations 200, 300 or 400 could be equipped with the lines 18 and 23 described with reference to the . Further, in each of the described embodiments or combinations thereof, the facility may include a degassing unit 210 between the digestion unit 110 and the fungal biomass production unit 120 as described with reference to the , or between the digestion unit 110 and the second dehydration unit 160 as described with reference to the .

Whatever the method of implementing the installation, the control system 140 may in particular comprise:

- first means for adjusting the residence time of the digestate in the fungal biomass production unit 120 implementing step (c),

- optionally second means for adjusting the residence time of the digestate in the anaerobic digestion unit implementing step (b),

- third means of adjusting the quantity of organic matter present in the fungal biomass production unit,

- optionally means for determining at least one mycelial growth indicator parameter chosen from a variation in a parameter representative of a quantity of dioxygen transferred to the aerobic reactor, a parameter representative of a variation in the chemical dioxygen demand of the sludge during step (c), a parameter representative of a variation in the biological dioxygen demand in the sludge during step (c), a parameter representative of a variation in volatile matter in the sludge during step (c), a mycelial content of the enriched sludge leaving step (c), and a content of molecules produced by the mycelial strains of the enriched sludge leaving step (c),

- calculation and transmission means connected to determination means and adjustment means.

The first and second means for adjusting the residence time may comprise valves for regulating the flow rates entering and leaving the units to be controlled and/or pumps for circulating the flows in the units to be controlled, these units being able to be equipped, for example, with a variator for controlling the flow rates supplied.

The third adjustment means may comprise valves for regulating the flow rates of one or more of the flows supplying the fungal biomass production unit implementing step (c). These flows are those previously described with reference to the figures or to the method. For example, these are regulating valves and/or distributors controlling the flow rates circulating in one or more of the following pipes connected to the fungal biomass production unit 120: the liquid effluent circulation pipe 1b, the hydrolyzed liquid effluent circulation pipe 9b, the liquid flow circulation pipe 8a from the dehydration unit 130, the dehydrated and heat-treated digestate circulation pipe 13, the thickened first flow circulation pipe 15, the depleted second flow circulation pipe 16a.

The determination means may include one or more sensors, for example, and without limitation, a flow meter for measuring the quantity of air entering the aerobic reactor, a tensiometer or ammeter for measuring the quantity of current transferred to an aerator of the aerobic reactor. The determination of the MV, BOD or COD or the contents is generally carried out in a laboratory.

The calculation and transmission means may comprise one or more processors, for example microprocessors or microcontrollers. Communication means, optionally bidirectional, may be provided between the calculation and transmission means and the first and second adjustment means and/or between the different determination means described.

Advantageously, the calculation and transmission means of the control system according to the invention can be programmed to determine the quantity or flow rate of one of the aforementioned flows and/or the second residence time, in particular as a function of at least one mycelial growth indicator parameter received from the determination means (and in particular entered manually or automatically), in particular by implementing a feedback loop.

The control system 140 may also include a system for regulating the aerobic reactor of step (c) comprising a dissolved oxygen sensor, a temperature sensor, means for controlling the temperature of the aerobic reactor (for example comprising the heat exchanger on the recirculation line 6' previously described), a system for aerating the reactor, and controlling the aeration and the temperature in order to maintain a constant dissolved oxygen concentration inside the reactor.

The different embodiments presented with reference to figures 1 to 4 can be combined depending on the decided valuation objective.

Claims (17)

Process for recovering a liquid effluent containing organic matter, comprising:

1. A step of supplying a liquid effluent to be treated containing organic matter;
2. A step of anaerobic digestion of the liquid effluent, producing a digestate and biogas, in which at least part of the organic matter contained in the liquid effluent to be treated is degraded by contact with microorganisms during an initial residence time;
3. A fungal biomass production step producing a sludge enriched with mycelia and/or molecules produced by mycelial strains, in which at least part of the digestate is brought into contact in an aerobic reactor and in the presence of organic matter with mycelial strains during a second residence time;
4. A dehydration step of the sludge enriched with mycelium producing a cake comprising mycelia, and optionally the molecules produced by the mycelial strains, and a liquid flow;
   and in which:
   in step (c), the organic matter content and/or the second residence time are controlled to produce a cake comprising a target mycelial content and/or a target content of molecules produced by the mycelial strains.

Recovery method according to claim 1, characterized in that, during step (c), the organic matter content and/or the second residence time are controlled as a function of at least one mycelial growth indicator parameter chosen from a variation in a parameter representative of a quantity of dioxygen transferred to the aerobic reactor, a parameter representative of a variation in the chemical dioxygen demand of the sludge during step (c), a parameter representative of a variation in the biological dioxygen demand in the sludge during step (c), a parameter representative of a variation in volatile matter in the sludge during step (c), a mycelial content of the enriched sludge leaving step (c) and/or a content of molecules produced by the mycelial strains of the enriched sludge leaving step (c). Recovery method according to claim 1 or 2, characterized in that the fungal biomass production step produces a sludge enriched in mycelia and in molecules produced by mycelial strains, said mycelial strains being selected from strains producing molecules chosen from hormones, proteins, vitamins, minerals, antibiotics, antimicrobial agents, pesticides and herbicides. Recovery process according to any one of claims 1 to 3, characterized in that the liquid effluent to be treated during step (b) is previously pretreated in a step (e) of pretreatment by hydrolysis. Recovery method according to any one of claims 1 to 4, characterized in that it comprises a step of vacuum degassing of the digestate leaving step (b) in a degassing unit to recover methane, and optionally the other gases present. Recovery method according to any one of claims 1 to 5, characterized in that the digestate leaving step (b), optionally from the degassing step, is dehydrated and heat treated before being at least partly sent to step (c). Recovery method according to claim 6, characterized in that a portion of the dehydrated and heat-treated digestate is sent to step (c) and another portion is sent to step (d), or in that the dehydrated and heat-treated digestate is separated, optionally after dilution with water, into a first thickened stream enriched in dry matter and a second stream depleted in dry matter, and the first stream is sent to step (c) and the second stream is sent to step (b) and/or step (c). Recovery method according to any one of claims 1 to 7, characterized in that at least part of the liquid flow leaving the dehydration step (d) is sent to the anaerobic digestion step (b) and/or the fungal biomass production step (c). Recovery method according to any one of claims 1 to 8, characterized in that, during step (c), the organic matter content is controlled:
(i) by controlling the first residence time so that the digestate leaving step (b) has a target organic matter content, and/or
(ii) by adding during step (c) at least a portion of at least one stream chosen from (iia) the liquid effluent to be treated from step (a), (iib) the liquid effluent having undergone pretreatment by hydrolysis, (iic) the digestate leaving step (b) having undergone dehydration and heat treatment, and optionally thickened and/or depleted in dry matter, (iid) the liquid stream leaving step (d) of dehydration. Recovery method according to any one of claims 1 to 9, characterized in that during step (c) mycelial strains are added punctually and discontinuously over time, the mycelial strains coming from a dedicated culture reactor. Installation (100, 200, 300, 400) for the recovery of a liquid effluent containing organic matter, comprising:

• a supply line (1) of a liquid effluent to be treated containing organic matter;
• an anaerobic digestion unit (110) comprising a feed line (2) connected to the supply line (1), a digestate discharge line (3) and a biogas discharge line (4);
• a unit (120) for producing fungal biomass containing mycelial strains, comprising a feed pipe (5) connected to the digestate discharge pipe (3) and a discharge pipe (6) for a sludge enriched with mycelia and/or molecules produced by the mycelial strains;
• a dehydration unit (130, 230, 330, 430) for dehydrating the sludge enriched with mycelia and/or molecules produced by the mycelial strains, comprising a feed pipe (7) connected to the discharge pipe (6) of the fungal biomass production unit, a cake discharge pipe and a liquid flow discharge pipe (8);
• a control system (140) configured to control the content of organic matter present in the fungal biomass production unit (120) and/or the second residence time in this fungal biomass production unit (120), as a function of a target content of the mycelium cake and/or a target content of the cake in molecules produced by the mycelial strains.

Recovery installation (200) according to claim 11, characterized in that the supply pipe (1) for the liquid effluent to be treated is connected to a hydrolysis pretreatment unit (150) comprising a discharge pipe (9) for a pretreated effluent connected at least to the supply pipe (2) of the anaerobic digestion unit (110). Recovery installation (300, 400) according to claim 11 or 12, characterized in that the digestate discharge pipe (3) is connected to a second dehydration unit (160) comprising a discharge pipe (10) connected to a heat treatment unit (170) comprising a discharge pipe (11) for the dehydrated and heat-treated digestate, and in that the discharge pipe (11) for the dehydrated and heat-treated digestate is:
(i) connected to a first discharge line (13) connected to the supply line (5) of the fungal biomass production unit (120) and to a second discharge line (14) connected to the supply line (7) of the dehydration unit (130), or
(ii) connected to a separation unit (190), which comprises a first discharge line (15) for a first thickened flow enriched in dry matter and a second discharge line (16) for a second flow depleted in dry matter, and the first discharge line (15) is connected to the feed line (5) of the fungal biomass production unit (120) and the second discharge line (16) is connected to the feed line (2) of the digestion unit (110) and/or to the feed line (5) of the fungal biomass production unit (120), optionally the discharge line (11) for the dehydrated and heat-treated digestate is connected to a water feed line (17) upstream of the separation unit (190). Recovery installation (200) according to any one of claims 11 to 13, characterized in that the discharge pipe (8) of the liquid flow from the dehydration unit is connected to the supply pipe (2) of the digestion unit and/or to the supply pipe (5) of the fungal biomass production unit. Recovery plant (100, 200, 400) according to any one of claims 11 to 14, characterized in that the control system (140) is configured to adjust the organic matter content in the fungal biomass production unit (120) (i) by controlling the residence time of the liquid effluent in the anaerobic digestion unit so that the digestate leaving this unit has a target organic matter content, and/or
(ii) by controlling the addition to the fungal biomass production unit (120) of at least a portion of a flow selected from (iia) the liquid effluent to be treated via a feed line (18) connected to the liquid effluent supply line (1), (iib) the liquid effluent having undergone pretreatment by hydrolysis via a feed line (19) connected to a hydrolysis pretreatment unit (250), (iic) the dehydrated and heat-treated digestate via the discharge line (13) connected to the discharge line (11) of the dehydrated and heat-treated digestate, and optionally thickened in dry matter via the first discharge line (15) of the separation unit (190) and/or depleted in dry matter via a line (16a) connected to the second discharge line (16) of the separation unit (190), (4) the liquid flow leaving the dehydration unit (130) via a supply line (23) connected to the dehydration unit (130) Recovery installation (200) according to any one of claims 11 to 15, further comprising a mycelium culture reactor (180), characterized in that the fungal biomass production unit (120) comprises a mycelium supply line (12) connected to the mycelium culture reactor (180), and in that the control system (140) is configured to control discontinuously over time the supply of mycelium from the culture reactor to the production unit (120). Recovery installation (100, 200, 300, 400) according to any one of claims 11 to 16, characterized in that it comprises a degassing unit (210) between the digestion unit (110) and the fungal biomass production unit (120), optionally between the digestion unit (110) and the second dehydration unit (160).