Patent Application
20220361424
This invention relates to a process and apparatus for producing mycelium biomaterials. More particularly, this invention relates to a process and apparatus for producing mycelium biomaterials in static aerated vessels. Still more particularly, this invention relates to a process and apparatus for the production of mycelium biomaterial, and particularly, for the production of fungal biomaterials.
The growth of materials bound together with the mycelium of filamentous fungus is known art, particularly, as described in U.S. Pat. No. 9,485,917.
As is known, fungi operate primarily on oxygen consuming metabolic pathways. Fungi generate carbon dioxide and heat through the same metabolism, both of which can be toxic to further growth of the mycelium. Fungi are limited in the ability to transport oxygen from an area of high availability to a restricted area, due to not having developed respiratory and circulatory transport systems such as are present in animals. Fungi are also limited in their ability to expel build ups of toxic carbon dioxide and heat, again due to a lack of an organism level effective gas or fluid transport mechanism
In practice, these limitations mean that grown materials bound by mycelium are limited in their overall volume, based on rates of free diffusion of heat and gases. For simple tray based growth, depths of greater than 6″ from an oxygen rich surface are difficult to achieve. Additionally, quantities of material must be separated in such a way as to enable heat removal, such as by filling into 10 lb bags which are spaced apart on racking with air flowing around the grouping of bags, which severely restricts operational efficiency in large scale manufacturing. One successful method of overcoming these limitations in aerobic fermentation methods is to regularly stir the material and fungal colony; however, when the generation of a fully formed bound material is the objective, this method of stirred fermentation is counterproductive.
Accordingly, it is an object of the invention to produce mycelium biomaterials in a relatively simple manner.
It is another object of the invention to be able to grow materials bound by mycelium that are not limited in their overall volume.
It is another object of the invention to provide a process of and apparatus for growing mycelium biomaterials under in non-aseptic open warehouse conditions.
It is another object of the invention to reduce the process cost and complexity of producing mycelium biomaterial.
Briefly, the invention provides a process for producing mycelium biomaterial that provides fresh oxygen to the growing mycelium biomaterial while removing waste heat and waste carbon dioxide by forced aeration through large volumes of material.
The process comprises the steps of mixing a substrate of discrete particles and a fungal inoculum to form a first pourable mixture; and aerating a predetermined height of the mixture in a first phase of fungal expansion for a time and at a temperature sufficient to allow the fungal inoculum to expand and dominate the substrate.
Thereafter, the process comprises the steps of mixing the aerated mixture with added nutrients to form a second pourable mixture; and aerating a predetermined height of the second mixture in a second phase of fungal expansion for a time and at a temperature sufficient to allow the fungal inoculum to bond the discrete particles into a self-supporting biocomposite.
Finally, the process comprises the step of desiccating the biocomposite to form a mycelium biomaterial.
The invention also provides an apparatus for producing mycelium biomaterial. This apparatus includes a blower for generating a steady air stream at a predetermined pressure; an intercooler for regulating the temperature of the air stream; a humidifying unit for humidifying the air stream; a vessel having a cavity for receiving a pourable mixture of discrete particles and a fungal inoculum; and a plurality of nozzles in a base of the vessel in communication with the humidifying unit to deliver humidified air upwardly through the cavity of the vessel and the pourable mixture therein.
The cavity of the vessel may be provided with one or more inserts prior to receiving the pourable mixture so that the inserts may be incorporated in the produced biomaterial.
The cavity of the vessel may be constructed with an internal geometry (void tooling) to make a final product with voids, such as coolers for shipping. A single vessel may incorporate multiple products, such as 48 coolers in one vessel, which would then be cut into final parts after ejection from the vessel.
The invention is a combination of the apparatus required to accomplish aeration as well as the substrate, organism, and process parameters required to successfully achieve controlled reliable growth in the apparatus.
The invention belongs to the category of non-stirred, aerated, solid-state bioreactors, but is unique in the depth of its operation and its ability to operate in a non-aseptic open warehouse conditions, and furthermore in the ability to operate without pasteurization or steam sterilization of the raw materials, dramatically reducing the process cost and complexity. All this is enabled by the specifics of the substrate and process parameters, and in the properties of the materials produced.
The apparatus of the invention provides a physical system that consists primarily of an air pre-treatment system and a vessel including air distribution for the production of mycelium biomaterial, and particularly, for the production of fungal biomaterials.
Pre-treatment of the air is critical in order to control temperature, humidity, and gas concentrations. Air is introduced to the system through only a coarse particulate filter for protection of the blower 1—high level filtration for asepsis is not required. The blower used is a rotary lobe blower although other styles including compressors, diaphragm pumps, and regenerative blowers could be used. Critically, the blower is capable of providing air at a range or pressure which enables not only passage through the loose substrate prior to growth, but passage through the fully grown material at the end of the process cycle when pressures are highest.
From the blower, the air is cooled to a programmable temperature (T1) by way of the intercooler or fan ventilator. This allows the system to run in an environment with fluctuating external temperatures, and also controls for the variable amount of heat added by the fan, which may change depending on load. Temperature controlled air can then be split into a plurality of flows via a manifold for the support of multiple vessels. Here flow (v/v/m) is also measured to each vessel to ensure that the desired flow rate is achieved.
Programmable air temperature settings, such as cycles where the air temperature drops or raises over time or fluctuates in a cyclical fashion, can be used to drive certain responses from the mycelium. The programmable air temperature settings can also be used to maintain a stable optimal material temperature while the metabolic activity of the mycelium changes over time.
Air at temperature T1 next enters the humidifying unit wherein the air is bubbled through a column of water. The humidifying unit is constructed with sufficient depth and size to provide sufficient moisture into the air to fully saturate the air. Additionally, as the process of evaporating water into the air stream requires heat, a heater may be implemented to add the energy required to continually fully humidify the air, even at very high flow rates. By varying this energy input it is possible to precisely control the humidity level (RH %) in steady state operation. It is noted that the rate of humidification of the air is much more rapid when the temperature of the water (T2) is maintained at or slightly above the temperature of the air (T1). Intentional lowering of the humidity can also be used as a powerful cooling process step.
The humidifying unit (and all parts of the airflow pretreatment system) must be constructed to handle the pressures which will be sustained at the end of the process, when the material is most completely bound together and has minimum porosity. For this reason, smaller humidification vessels may be used—one for each separate growth vessel—rather than a single much larger humidification vessel which would be costly to build for high pressure operation.
After exiting the humidifying unit, the air is temperature and humidity controlled, and is distributed by insulated hose to the growth vessel.
What has been described is one specific method of generating air with the desired psychrometric properties. It is understood that other methods of temperature control and humidification may be constructed to operate similarly, including but not limited to ultrasonic misting, sling humidifiers, or misting nozzles.
The pre-treated air can be connected to a variety of vessel designs, from custom molded shapes to generic buns for later processing into panels. Construction of the vessel used depends on the nature of the substrate being used, particularly on its porosity, and on other variables such as the metabolic heat generated with the given combination of process parameters.
In its most simple implementation, a single aeration point would be provided at the bottom of a vessel, with air being forced up through the material and exhausting out an open top. As the vessel becomes wider, additional air entry points are needed. In large vessels, an array of nozzles is used, each providing equal flow for generation of uniform materials. It has been found that nozzles which penetrate into the grown material provide better direction of flow and have a greater resistance to side channeling than either a flat bottom with perforations or an air distribution layer (such as loose mulch or gravel).
The nozzles used are specially designed in order to provide uniform back pressure against free flow, therefore maintaining even flow rates through each nozzle and minimizing effects of random porosity variations in the material. In order to maintain this even flow, the pressure drop across the nozzles (PD_N) should be close to or greater than the pressure drop across the loose packed substrate (PD_S). During growth, pressure drop across the substrate will rise by due to the filling in of open gaps in the loose packed substrate with mycelium. Final pressure will equal PD_N+PD_S+PD_G where PD_G is the added pressure drop due to growth.
The process and apparatus of the invention allows for the processing of grown materials bound by mycelium at depths of greater than 6″ and particularly in the range of from 24″ to 28″.
The substrate may be a highly porous material, such as wood shavings, large wood chips, or wood wool, to allow increased air flow and reduce load on the blower.
The substrate may be selected or supplemented to include certain volatile organic compounds, such as terpenes which inhibit contamination. The aeration may be used to prevent the buildup of these compounds in such a way as to select for only certain desirable organisms such as the fungus which was used.
Choice of a suitable primary substrate, comprising the bulk of the raw material, is key in achieving stable and productive operation. Attributes to consider include density, porosity, nutritional availability, phytochemical composition, and cleanliness.
Density of the material primarily affects the final material properties, although density also modifies the back pressure at which “burping”, as described herein, occurs. Finally, the bulk substrate compressive resistance must be capable of supporting the material density, such that the vessel depth can be achieved without producing an undesirable density gradient from bottom to top of the vessel.
The porosity of the bulk substrate affects the ease of aeration and therefore the size and power of aeration equipment required to maintain aeration throughout the growth period. Porosity also affects the burp pressure drop and the tendency of air to side channel up walls—especially in vessels with a large height to area ratio such as tall cylinder reactors. Porosity is reflected in the loose substrate pressure drop. The porosity also has biological and material property attributes. A more porous material may require more aerial hyphal growth in order to form strongly interconnected particle bonds, and may produce very different acoustic or mechanical properties than a low porous substrate with small gaps between adjacent particles.
The nutritional availability of the substrate is an absolutely critical attribute in proper design and operation of the system. Nutritional availability must be considered both from the perspective of availability to the desired fungal organism or host of organisms, and also from the perspective of availability to commonly present competitive organisms including bacteria and other fungi.
Nutritional availability to the desired organisms should be balanced to produce growth while not being so readily available that the desired organisms overcome the ability of the aeration system to provide replacement oxygen and remove waste carbon dioxide and heat. In this way, an optimized system may actually restrict nutritional availability to the desired organisms as a means of reducing the volume of air flow required or reducing the ultimate delta T between the bottom and top of the vessel (a function of both fluid flow and heat generation rate).
Nutritional availability to non-desirable organisms (contaminants) should be minimized. A substrate which is highly available to a wide array of organisms (such as a substrate high in simple sugars) will require highly aseptic operation, intensive sterilization, and treatment of the air stream to avoid introduction of any contaminants which will compete with and often overtake the desired organisms. Many models for existing mushroom cultivation and other forms of fermentation use widely accessible substrates requiring exclusion of contaminants through other means, or sequences of composting in order to provide biological exclusion. Ideal operation of the invention herein described involves a substrate which is specifically selected to be nutritionally available to as few possible contaminants as can be managed.
Phytochemical composition of the substrate is similarly important as a way to provide selective pressure for the growth of the desired organism and avoidance of contaminants.
Cleanliness of the substrate is a final consideration in the ideal operation of the process. The cleaner the source, the lower the incoming bioburden load which must be overcome by either pre-processing sterilization or by the desired organism during growth. Cleanliness can be affected by the processing methods and storage methods prior to use.
Given all of the above considerations, the current state of the art substrate for the invention is an Aspen microchip produced from Aspen logs using a modified whole tree drum chipper. The chips are 3 mm×3 mm×1 mm in size. Aspen wood is composed of lignocellulose which is well known to be a highly recalcitrant organic molecule, difficult for most organisms to digest.
Additionally, the optimal substrate for the first phase of biomass expansion may be meaningfully different from what can be used for successive phases of further expansion. Once a certain dominance over the substrate has been achieved by the desired organism, additional amounts of more generally available nutrition (Nut %) may be added. These nutrients are quickly dominated by the population of the desirable organism, which outcompetes possible contaminants that would have out competed a less robust population. In this manner, higher metabolic rate growth and rapid development of mycelium can occur. This initial starving of nutrients followed by nutrient addition is described as phase I (TphaseI) and phase II (TphaseII) growth.
The choice of organism involves several considerations including inoculation rate, digestive toolkit, growth temperature dependence, and filamentous cellular morphology.
Inoculation rate (In %) can affect the operation of the described process in several ways. Higher inoculation can be a means of outcompeting contaminants on a more generally available substrate, of increasing final properties or decreasing growth phases. Lower inoculation most simply saves money but can also be a tool to reduce the metabolic rate and therefore lower the aeration requirements and ultimate delta T between the top and bottom of the vessel.
In concert with careful substrate selection, the desired organism should be selected to be capable of digesting and thriving on a nutrient source which is not generally commonly accessible. This combined restriction allows the system in general to be operated with far less aseptic control than is common in the prior art, allowing open air mixing and no filtration.
The organism selected must also be able to grow at a range of temperatures, and with generally similar growth at the range of temperature between Tbot and Ttop. Selection for this criterion enables a uniform product.
Lastly, the organism must demonstrate the filamentous properties desired for both operation and final product. If the organism generates too much aerial biomass or exudates, the organism might clog the substrate and increase the pressure drop above the burp pressure or above an economically reasonable pressure for operation. Conversely, if the organism does not generate a sufficiently aerial tissue structure, the particles will not be cohesively bound, and material properties will suffer. The relationship between the pressure drop as a result of growth (PD_G) and the mechanical properties is complicated. This relationship can depend on many attributes, such as the individual cell size and strength, the degree of branching between cells, and the adhesion strength of the cells to the substrate. By organism selection and other process parameter control (such as air flow volume and temperature), it is possible to maximize mechanical properties while not producing an excessive pressure drop. The organism used in the herein described process is a white rot fungus, such as Ganoderma lucidum or Trametes versicolor.
The final product may take a variety of forms, including but not limited to a block, flat panels, or a molded shape.
In the case of a block, the vessel would be rectangular and produce a rectangular block or bun. In this instance, humidification might be turned off and air temperature raised while the block is still in the reactor, initiating a drying phase which kills the fungus and stabilizes the material (avoiding the overheating which could occur from removing a biologically active block from the cooling air). Such blocks might be used for civil engineering, or as blanks for carving into architectural components.
In the case of panels, a block (either pre-dried while in the vessel or still fully biologically active) would be removed from the vessel and sliced into a multiplicity of panels. This can be achieved using commonly available sawmill equipment. Panels from 0.25″ up to the full thickness of the block can be produced. Slicing of the block into thin panels allows faster low energy drying and heat treatment than thicker panels. Alternatively, after cutting and before drying, panels can be further incubated to provide surface growth and further strengthening, or to be grown together into larger three dimensional objects.
Potential applications of panels produced in this method include furniture surface and door cores, acoustic panels, insulation panels, rafts for wetland remediation, components for set design, temporary sign panels, and flat sheet packaging material.
The vessel may also be formed as a molded volume for the production of useful shapes, such as a chair or couch substructure or a plurality of shipping cooler volumes. In the case of a chair substructure, additional strengthening and attachment components, such as pieces of wood, may be placed into the vessel prior to filling, and allowed to grow into place. As with the block, some amount of drying while in the vessel can be used to shorten drying time. In the case of shipping coolers, a number of parts might be grown together in a single molded vessel, and then cut apart into individual units for commercial sale either before or after drying.
The mixture may be grown only in phase 1 in the vessel, and then moved into a different vessel for phase 2, after being mixed with nutrients.
The second vessel may be a non-aerated mold or a multiplicity of non-aerated molds, such as a series of thermoformed plastic trays with dimensions of 21″×21″. These molds may be open on top and may include several depressions for filling with the mixture to form shapes, such as, corner blocks for packaging.
The mixture may be grown only in phase 1 in the vessel, and then moved into a different vessel after being mixed with nutrients and not subjected to a phase 2. In this case, after being mixed with nutrients, the mixture is incubated for a time sufficient to allow said fungal inoculum to bond said discrete particles into a self-supporting biocomposite, such as described in U.S. Pat. No. 9,485,917.
The second vessel may also be shaped earth outdoors, for example the bottom of a ditch or depression being prepared for a stream or pond, and where the material will grow in place during a non-aerated phase 2 (at depths <12 inches). The final grown layer may act as an impermeable layer or a load bearing surface, such as a temporary road.
The vessel may take the form of a stationary lane or tunnel where the material is mixed in-vessel between phase 1 and phase 2 and then unloaded by drag conveyor or hoist.
These and other objects and advantages will become more apparent from the following detailed description taken with the accompanying drawings wherein:
Referring to
The process also includes a step of dispensing the mixture into one or more vessels. The vessels may be bins having dimensions of 40″×40″×28″ and are filled to a height of 24″-28″. The mixture may be compacted into a vessel as the vessel is filled.
Thereafter, the mixtures in the vessels are subjected to a step of aeration for a time and at a temperature sufficient to allow the fungal inoculum to expand and dominate the substrate. This step provides a Phase I low nutrient growth. During this step, aeration may be low, e.g. 0.50 v/v/m, since there is little readily available nutrition and thus relatively little heat generation. During this step, the fungal portion of the mixture is able to outcompete any contaminant organisms and expand to cover and dominate the wood chip portion of the mixture. The end result of this step is that the mixture is evenly coated in the fungal tissue; however, it is still easy to break apart and remix.
Next, the mixture is removed from the vessel(s) and mixed with added nutrients.
The mixture with the added nutrients is then poured into a second vessel having a cavity of the final desired shape for the product. Alternatively, the mixture with the added nutrients may be poured back into the first vessel, if that vessel has a cavity of the final desired shape for the product. One advantage of using two vessels is that the vessels can be used in rotation for faster operation.
The addition of nutrients is performed after the fungus has established dominance and is able to outcompete any potential contaminant organisms for access to the easily digestible additional nutrients.
These nutrients are quickly converted into additional fungal tissue biomass, which binds the mixture into its final form. The mixture is then subjected to Phase II aeration, which is higher in velocity and potentially cooler to combat the additional metabolic energy generated by the added nutrients.
During the Phase II aeration, the biomass is aerated for a time and at a temperature sufficient to allow the fungal inoculum to bond the discrete particles into a self-supporting biocomposite.
After solidifying in its final shape, the biocomposite is either desiccated in the vessel or ejected from the vessel while still wet and then dried.
The ejected wet biocomposite may be either dried and further processed, or further processed and then dried. Further processing may include being machined into smaller components such as 1″ panels.
Sheets of the wet biocomposite may be further processed by either a final incubation stage at 100% humidity and 80° F. to form a layer of tissue on the cut surfaces, or by being assembled into a final shape such as a box and being incubated in the same conditions in order to grow together.
Flexible sheets cut from a block may also be pressed into 3D contours by a heated press at 400° F. in a combination drying and forming step.
Final drying of the biocomposite can occur at ambient temperatures over the course of a week or more, or can be expedited to as fast as 24 hours at 180° F. in a wood kiln style dryer. Blocks or panels left covered outdoors for several weeks in a climate with temperatures between 40° F. and 90° F. will continue to harden, producing an aged material.
Referring to
Reactor settings include the air flow rate, the air temperature, the air relativity, and the oxygen percentage. A given recipe might be 0.5 v/v/m for phase I and 1.25 v/v/m for phase II, an air temperature of 75° F., a relative humidity of 100%, and an oxygen percentage equal to atmospheric concentrations.
As further illustrated in
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Referring to
The blower 1 operates to provide a steady air stream at sufficient pressure to flow through the vessel 5, even after tissue growth has occurred.
The intercooler 2 operates to regulate the air temperature out of the blower 1 and to remove heat introduced due to compression.
The manifold 3 operates to separate a pressurized temperature controlled airflow into multiple vessels and includes a means of regulating and measuring the flow to each vessel independently.
The humidifying unit 4 operates as a final temperature control tank for the purpose of raising the humidity of the air stream up to full saturation as well as entraining water mist into the air stream for an additional supply of moisture to the vessel 5. A heater (not shown) is included for the purpose of replacing the heat of vaporization removed by the evaporation of water.
The airflow nozzles 6 operate to distribute the temperature and humidity controlled air stream evenly into the vessel 5 and for the purpose of injecting the air into the growing material 7 in the vessel 5 to prevent side channeling and provide even aeration to all parts of the mixture.
The apparatus serves to produce a finished block of grown material 8 that is ejected from the vessel 5 and subsequently sliced into panels 9. As indicated, the panels 9 may be stacked in vertically spaced apart manner for the purpose of either final curing or more efficient drying by convection.
Referring to
In addition, the cavity 10 of the vessel 5′ may be provided with one or more inserts 11 (
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The flat panels 19 may be cut thin enough for the final product to be flexible for use in products, such as conformable landscape mats (
A plurality of flat panels 19 may also be assembled into a final shape (not shown) and finish grown to make a final product such as coolers for shipping.
Referring to
Also, a mesh screen 25 is disposed on the cylindrical body 21 over the expansion chamber 22 and a cylindrical cover 26 is slidably mounted over the cylindrical body 21 and the mesh screen 25. The cover 26 has an opening 27 coaxial with the expansion chamber 22 to deliver air therethrough.
The cross sectional areas of the screen 25 and expansion chamber 22 are selected such that even with partial blockage due to substrate chips lying against the screen 25, the remaining cross sectional area is still greater than the cross sectional area of the flow restriction area. This minimizes flow variation between nozzles due to the random orientation of chips on the screens. Without this feature, one nozzle might be blocked by chips while another might have free flowing air. Additionally, each nozzle 5 extends into the material to decrease air channeling across the vessel wall.
It is important to note here that if PD_S+PD_G exceeds force of gravity on the substrate, the growing material will lift, opening low resistance air-flow channels that will bypass the material and reduce aeration effectiveness. This is colloquially termed “burping” and whether it occurs in operation is a combined function of the porosity of the substrate, the density of tissue growth, the air flow rate required, and the density of substrate—which all combine to dictate the burping back pressure (Pburp).
One critical dimension is the height (h) of the vessel 5 (
By the same reasoning, there will always be a temperature difference between the bottom and top of the vessel, so long as the material is generating heat and being cooled by aeration. It is important that the air flow rate, the metabolic conditions, the energy availability of the substrate, the organism selected for growth, and the height of the vessel all be selected in concert in order to provide that the delta T between top and bottom is small enough that final properties compared from the top and bottom of the material are both within desired specifications.
The final parameter for the vessel is the top surface treatment. Aeration can be used as a means to reduce the settling of contaminant spores on the material; however, for additional exclusion of surface contamination, a lid may be desired. This lid may take the form of a physical barrier, with features allowing for escape of the aeration air, but such lids can trap condensation, heat, and moisture. As described herein use is made of a permeable top layer of material specifically selected to prohibit the growth of any contamination, such as wood ash. This allows for the free flow of aeration air without formation of condensation or trapping of hot exhaust gases. Once an inhibitory priority effect has been established, the permeable top layer may be removed.
The vessel should be one which can be filled, moved around, and dumped. The same ventilation system may be applied to much larger lanes, as are used in commercial composting. Here, substrate is loaded in, mixed in place when needed, and might be extracted by way of a drag net conveyor, again as is used in composting.
Lanes are vessels which are fixed construction cement structures of substantially large size. A lane would be on the order of 100-400 feet long and 6-10 feet wide vs. a 4′×4′ vessel.
Whereas the vessels, such as a 4′×4′ vessel, are portable and can be flipped upside-down to extract the product, lanes are not movable, and finished product must be pulled out of the lane. Also, for the mixing step where added nutrients are mixed in, portable vessels are small enough that the contents can be dumped into a mixing machine, and then dispensed back into the small vessel. For lanes, the nutrients are added directly into the lane, and then a piece of mixing equipment (such as an auger on a gantry system) must mix the mixture within the lane.
Thus, the invention provides a process and apparatus for producing mycelium biomaterials in a relatively simple manner and mycelium biomaterials that are not limited in their overall volume.
The invention also provides a process and apparatus for growing mycelium biomaterials under non-aseptic open warehouse conditions thereby reducing the process cost and complexity of producing mycelium biomaterial.
This application claims the benefit of U.S. Provisional Patent Application 62/675,922, filed May 24, 2018.
| Number | Date | Country | |
|---|---|---|---|
| 62675922 | May 2018 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16419868 | May 2019 | US |
| Child | 17825937 | US |
