Engineered biochar, manufacturing system, and method for making the engineered biochar

Abstract

An engineered biochar (150) includes plural particles (162), each particle (162) including, hydrogen atoms (152), oxygen atoms (153), carbon atoms (154), and ash (156) including one or more nutrient atoms. The engineered biochar (150) has a pH between 1 and 8.5, an electrical conductivity between 0.01 and 4.95 dS / m measured with a 1:10 engineered biochar to water method, a soluble salt content between 0.01 and 3% of a total dry mass of the engineered biochar, an ash content between 10 and 50% of the total dry mass of the engineered biochar, and a hydrogen to organic carbon molar ratio between 0.1 and 0.7.

Description

ENGINEERED BIOCHAR, MANUFACTURING SYSTEM, AND METHOD FOR MAKING THE ENGINEERED BIOCHARCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 569,824, filed on March 26, 2024, entitled “POST-PROCESSING OF RAW BIOCHAR INTO CARBOSOIL - A SOIL AMENDMENT TECHNOLOGY FOR ALKALINE SANDY SOILS,” the disclosure of which is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTIONTECHNICAL FIELD

[0002] Embodiments of the subject matter disclosed herein generally relate to a composition of the engineered biochar, a system for making the engineered biochar (EB), and a method for making the composition, and more particularly, to making the engineered biochar for alkaline sandy soils.DISCUSSION OF THE BACKGROUND

[0003] Sandy soils dominate much of the Arabian Peninsula, and the Middle East and North Africa (MENA)’s landscape, particularly in the vast deserts. These soils are characterized by their coarse texture, low organic matter, and poor water retention, making them naturally less fertile for agriculture. Due to the extreme arid climate, these soils are also prone to erosion and have limited ability to supporttraditional farming without significant modifications. However, their high permeability allows for rapid drainage, which can be beneficial in preventing waterlogging in areas where irrigation is applied.

[0004] Despite their limitations, sandy soils in some of these regions, for example, in Saudi Arabia, are used for modern agriculture, where advanced irrigation techniques such as drip irrigation and hydroponics enable the cultivation of crops like dates, wheat, and vegetables. Additionally, the sandy areas are utilized for livestock grazing, particularly for camels and sheep, which are well adapted to arid conditions. In urban settings, sandy soils serve as a foundation for construction projects, including roads, buildings, and infrastructure, with engineered solutions in place to mitigate shifting sands.

[0005] In recent years, there has been a growing focus on land reclamation and desert greening projects to combat desertification and improve soil fertility. Techniques such as adding biochar, clay, or organic matter to sandy soils have been tested to enhance water retention and support plant growth. Raw biochars typically have high pH values (above 9, up to 12) and high soluble salt contents (above 3% by mass, potentially reaching 10% or more). These features limit their application in alkaline soils common in arid regions like Saudi Arabia and MENA because they will further increase the pH of the alkaline soil and the salt content, which is undesirable for many plants. Most of the conventional biochars derived from low-density biomass (e.g., chicken manure, cow manure, date palm waste, landscaping waste) exhibit these undesirable properties.

[0006] Efforts to utilize biochar for soil amendment focus on improving soil water retention and nutrient holding capacity. However, the high alkalinity and high soluble salt content, herein referred simply as “salinity,” of the untreated raw biochar hinder plant development when applied to alkaline soils at any concentration above 0.1% by mass (or ~5 tons / ha at 30-cm soil layer). Raw biochar can be especially detrimental to plant development at high-end applications, such as landscaping, gardening, or vegetable growth, where the required dosages can be as high as 30% or even 100%. Moreover, alkaline soils decrease the plant-availability of most nutrients by significantly decreasing their solubility and by volatilization in the case of nitrogen, i.e., ammonia volatilization loss. These issues currently prevent the development of a biochar industry in the regions with alkaline sandy soils.

[0007] Thus, there is a need for an engineered biochar that avoids the above noted problems and can be easily and cheaply manufactured on scale.SUMMARY OF THE INVENTION

[0008] According to an embodiment, there is an engineered biochar that includes plural particles, each particle including hydrogen atoms, oxygen atoms, carbon atoms, and ash including one or more nutrient atoms. The engineered biochar has a pH between 1 and 8.5, an electrical conductivity between 0.01 and 4.95 dS / m measured with a 1 :10 engineered biochar to water method, a soluble salt content between 0.01 and 3% of a total dry mass of the engineered biochar, an ash content between 10 and 50% of the total dry mass of the engineered biochar, and a hydrogen to organic carbon molar ratio between 0.1 and 0.7.

[0009] According to another embodiment, there is a biochar treatment unit configured to remove soluble salts to generate an engineered biochar. The biochar treatment unit includes N stages (i) with N reactors (Ri), where N is a positive integer, the N reactors (Ri) being fluidly connected in series and configured so that a raw biochar enters a first reactor of the N reactors and travels, sequentially, as a slurry (Si), through the remaining reactors to become the engineered biochar when exiting at an Nth reactor of the N reactors, and a fresh water (FW) stream enters the Nth reactor and removes a soluble salt from each remaining reactor, and exits the first reactor as salty water (SW). Each stage (i) includes a conveyor (Ci) configured to remove the slurry (Si) from the reactor (Ri), and a solid-liquid separator (SLSi) configured to receive the slurry (Si) from the conveyor (Ci) and to separate a processed biochar from the slurry (Si) and move the processed biochar to the next reactor (R(i+1 )).

[0010] According to yet another embodiment, there is a method for making an engineered biochar, and the method includes feeding a raw biochar to a current reactor, feeding a salty water to the current reactor, from a next reactor, removing a washed biochar from the current reactor, and separating the washed biochar from the salty water to obtain the engineered biochar. The engineered biochar has a pH between 1 and 8.5, an electrical conductivity between 0.01 and 4.95 dS / m measured with a 1 :10 engineered biochar to water method, a soluble salt content between 0.01 and 3% of a total dry mass of the engineered biochar, an ash content between 10 and 50% of the total dry mass of the engineered biochar, and a hydrogen to organic carbon molar ratio between 0.1 and 0.7.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0012] FIG. 1 is a schematic diagram of a plant for manufacturing an engineered biochar from biomass waste;

[0013] FIG. 2 schematically illustrates a biochar treatment unit of the plant of FIG. 1 ;

[0014] FIG. 3 is a flow chart of a method for making the engineered biochar based on the biochar treatment unit of FIG. 2;

[0015] FIG. 4 schematically illustrates two reactors of the biochar treatment unit of FIG. 2;

[0016] FIG. 5 schematically illustrates a solid-liquid separator module that is part of a reactor of the biochar treatment unit of FIG. 2;

[0017] FIG. 6 schematically illustrates various other components of the reactor of the biochar treatment unit of FIG. 2;

[0018] FIG. 7 schematically illustrates the biochar treatment unit of FIG. 1 including six reactors operationally connected in series;

[0019] FIG. 8 plots the pH versus salinity for various raw biochars and the engineered biochar manufactured with the biochar treatment unit of FIG. 2;

[0020] FIG. 9 is a graph illustrating the biochar salinity and the water salinity after each stage in the biochar treatment unit of FIG. 2;

[0021] FIG. 10 is a graph illustrating the biochar salinity and pH versus time as an acid is added at one or more stages;

[0022] FIG. 11 A illustrates defining parameters of the engineered biochar manufactured with the biochar treatment unit of FIG. 2;

[0023] FIG. 11 B illustrates secondary parameters of the engineered biochar manufactured with the biochar treatment unit of FIG. 2;

[0024] FIG. 11 C illustrates nutrient atoms of the engineered biochar manufactured with the biochar treatment unit of FIG. 2;

[0025] FIG. 12 illustrates a vertical column process that uses another biochar treatment unit for manufacturing an engineered biochar;

[0026] FIG. 13 illustrates another vertical column process that uses yet another biochar treatment unit for manufacturing an engineered biochar;

[0027] FIG. 14 illustrates the dry tree mass increase for Acacia plants that were treated with the engineered biochar and with other traditional soil amendments;

[0028] FIG. 15 illustrates the increase in the trunk base circumference for Acacia plants that were treated with the engineered biochar and with other traditional soil amendments;

[0029] FIG. 16 illustrates the increase in the trunk base circumference for other plants (Ziziphus spina-christi) that were treated with the engineered biochar and with other traditional soil amendments; and

[0030] FIG. 17 illustrates the increase in the trunk diameter for olive trees that were treated with the engineered biochar and with other traditional soil amendments.DETAILED DESCRIPTION OF THE INVENTION

[0031] The following description of the embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to a biochar treatment unit that includes six reactors. However, the embodiments to be discussed next are not limited to six reactors, but may be applied to a unit having fewer reactors.

[0032] Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

[0033] According to an embodiment, a novel engineered biochar is made with a new multi-stage, water-washing and treatment method that reduces the biochar’s pH to levels below 8.5, and even below 7, and also reduces its salinity to below 3% by mass (and preferably below 1% or below 0.3% for high-end applications). This novel engineered biochar composition enables the use of the biochar in regions where long-term soil enhancers are needed the most, such as the hyper-arid alkalineSaudi Arabian deserts and the MENA region and beyond. In another embodiment, the engineered biochar enables the use of biochar at high concentrations without risk of harming the plants. The engineered biochar has been proved to yield great plant enhancements as demonstrated through several greenhouse and field trials (discussed later). The engineered biochar has the potential to replace the use of the environmentally damaging peat moss in greening projects in Saudi Arabia and MENA region.

[0034] A system (plant) for making the engineered biochar is now discussed with regard to the figures. FIG. 1 schematically illustrates various modules of a biochar processing system 100. Biomass waste 110 is received by the system 100 and carbonized in a carbonization module 120. The biomass waste 110 may include animal manure, plant parts, fruit parts, discarded food, etc. In one embodiment, the carbonization involves a pyrolysis process. The pyrolysis is the thermal decomposition of materials in the absence of oxygen or under very low oxygen conditions. It breaks down complex molecules into simpler gases, liquids, and solid residues by applying heat, typically at 200-900°C, depending on the material and desired products. The low oxygen or no oxygen prevents combustion and allows decomposition of the biomass waste 110 into new chemical compounds. As a result of the pyrolysis process, gases, liquids, and solids are formed. Thus, a separation unit 130 is used to separate these phases. The gas phase may include CO, CO2, H2, CH4, and other hydrocarbons. The liquid phase may include condensable hydrocarbons and tar-like substances. The solid phase may include carbon-rich residue, also called raw biochar. This raw biochar is separated from the otherphases and treated in the biochar treatment unit 140 to generate the engineered biochar 150.

[0035] The engineered biochar 150 manufactured with the biochar treatment unit 140 was found to include hydrogen atoms 152, oxygen atoms 153, carbon atoms 154, ash 156 that includes one or more nutrient atoms (inorganic atoms), trace amounts of soluble salts 158, and non-soluble or low-soluble salts 160. A low- soluble salt is considered in this document to be a salt that has a solubility in water below about 2 g / L. The hydrogen atoms 152, oxygen atoms 153, the carbon atoms 154, the ash 156, and the non-soluble or low-soluble salts 160 may form particles 162, as schematically illustrated in FIG. 1 . Some of these particles may also include the soluble salts 158. In one embodiment, each particle 162 includes trace amounts of the soluble salts 158, for example, below 1% by mass. The soluble salts 158 are mostly removed after the processing performed in the biochar treatment unit 140, as discussed next with regard to FIG. 2. Various characteristics of the engineered biochar 150 are discussed later, and they are illustrated in FIGs. 1 1 A to 11 C. The primary energy for the pyrolysis process may come from the biomass itself through the production of syngas, thus allowing the process of carbonization to be energetically self-sufficient.

[0036] Details about the biochar treatment unit 140 are discussed with regard to the next figures. FIG. 2 shows one possible implementation of this unit. The biochar treatment unit 140 may include plural (N) individual continuous stirred-tank reactors (CSTR). While FIG. 2 shows N=6 CSTRs, fewer or more reactors may be used. In one application, only two reactors CSTRs are used. In another application,only three reactors CSTRs are used. Each reactor CSTRi in FIG. 2 is associated with a conveyor mechanism Ci and a solid-liquid separator SLSi, where “i” is a positive integer that refers to a specific reactor “i”. In this embodiment, i takes any value between 1 and 6. While FIG. 2 shows the conveyor mechanisms Ci and the separators SLSi being outside the reactors CSTRi, as discussed later, it is possible to place these elements on the reactors, inside or outside, or both inside and outside.

[0037] The operation of the biochar treatment unit 140 is now discussed with regard to the configuration of FIG. 2 and the method 300 illustrated in FIG. 3. In step 302, a mass MB1 of the raw biochar 210, obtained from the carbonization module 120 (see FIG. 1), is fed to a first reactor CSTR1 . This mass includes a given mass of soluble salt MS1 , for example, about 6% of the MB1 (which is the entire mass of the raw biochar 210 to be processed). Salty water SW2 from a second reactor CSTR2 is fed in step 304 to the first reactor CSTR1 for washing the biochar mass MB1 . The salty water SWi from each reactor is provided to a previous reactor for washing the soluble salt from the biochar in the previous reactor. In one embodiment, the salty water SWi may include fresh water and an amount of soluble salt that was removed from one or more of the N reactors. It is noted that the initial freshwater FW is supplied to the last reactor CSTR6. This freshwater FW, after washing some of the soluble salt from the last reactor CSTR6, is supplied to the reactor CSTR5 as salty water SW6, and so on. Thus, the saltiest SWi is the one at the first reactor CSTR1 . The salty water SWi may be recirculated through the reactor CSTRi, with a pump orwith a stirrer, which is discussed later, prior to being discharged for a previous reactor or cleaning.

[0038] A backflow water BFW1 is provided in step 306 to the first reactor CSTR1 . The backflow water BFW1 is generated by a first solid-liquid separator SLS1 , as it separates the washed biochar from the first reactor from the salty water. The first conveyor C1 removes in step 308 the washed biochar from the first reactor CSTR1 and supplies it to the first separator SLS1 in step 310. If the washed biochar has not reached the desired characteristics, the method determines in step 312 to provide the partially washed biochar to the next reactor, and to repeat steps 302 to 310. In one embodiment, each reactor CSTRi has the same structure as the first reactor CSTR1 , i.e. , the reactor CSTRi includes a conveyor Ci, a separator SLSi, etc. For this embodiment, the water-separated washed biochar MB2 is supplied to the second reactor CSTR2 and the process discussed above is repeated for each reactor. However, if the processed biochar has reached the desired characteristic (which results in the engineered biochar 150), the engineered biochar is packed in step 314 and shipped to various clients. The resulting salty water SW1 from the first reactor CSTR1 may then be provided to a water desalination plant for treatment.Note that all other salty water SWi from the next reactors are provided to a previous reactor, i.e., the salty water SW5 from the fifth reactor CSTR5 is provided to the fourth reactor CSTR4, and so on. This means that the salty water SWi flows from the last reactor toward the first reactor (by gravity, as discussed later), while the partially washed biochar (also called the slurry Si in this document) flows from the first reactor toward the last reactor. Note that a slurry is a mixture of denser solids suspended ina liquid, usually water. The slurry is created when the biochar is agitated with water inside the CSTRi. In the SLSi, the slurry gets separated into solid and liquid; the water is drained (BFWi) and the biochar (MBi) goes to the next reactor carrying significant (-60% water) and some salts, but it is in a moist solid form.

[0039] Note that while inside the conveyor (Ci), the mixture is still in slurry form. So, it is correct in the diagram to call those flows inside the conveyor as Si.

[0040] As the slurry Si has less and less soluble salts as it progresses from one stage to another (e.g., from one reactor to another), the salty water becomes more saltier as it travels from the last reactor toward the first reactor.

[0041] The cycle described above (i.e., steps 302 to 310 for the various stages of the unit 140) for the first reactor CSTR1 may include an optional step 316 of injecting an additional substance AS into the reactor for lowering the pH of the partially washed biochar. While FIG. 2 shows no additional substance AS being added to the first reactor in this embodiment, the same figure shows the addition of an acid PA to the second reactor, a further addition of the PA acid to the third reactor, another addition of the PA acid at the fourth reactor, no addition at the fifth reactor, and the addition of an additional substance AS at the sixth reactor. In this embodiment, the PA acid is phosphoric acid, H3PO4. However, in other embodiments, it is possible to use hydrochloric acid, HCI, sulfuric acid, H2SO4, and / or other acids. The PA acid is added to neutralize and solubilize mid-pH low- solubility alkalis, such as calcium and magnesium carbonates, and further lower the pH and soluble salt content in the biochar mass. Note that the output of each reactor CSTRi shows a biochar mass MBi, which decreases with the increase of i. The figurealso shows, at the output of each reactor CSTRi, a salt mass MSi, which is reduced (e.g., halved) with each cycle as the i increases. While FIG. 2 shows the addition of the acid PA at selected reactors and the addition of the additional substance AS at the last reactor, it is possible to add the acid PA to any reactor. The same is true for the addition of the AS.

[0042] The salt increase in the salty water and the salt decrease in the processed biochar is because the freshwater FW is introduced at the last reactor, CSTR6 in this embodiment, and the salty water SW6 from this reactor is provided to the fifth reactor, and the salty water SW5 from the fifth reactor is provided to the fourth reactor, and so on. Thus, the cleanest water FW is provided to the last reactor in the chain and the saltiest water SW1 is extracted to the first reactor. This arrangement works because the biochar at the first reactor has the highest amount of salt and thus, the salty water SW2 received by the first reactor needs to have a salt concentration less than the salt concentration of the biochar MB1 for the first reactor. The same is true for the other reactors, i.e. , the salt concentration of the salty water received by any reactor CSTRi needs to be lower than the salt concentration of the biochar in the reactor CSTRi in order to wash some salt from the biochar MBi.

[0043] A characteristic of the biochar treatment unit 140 illustrated in FIG. 2 and the method illustrated in FIG. 3 is the counter-flow of the biochar slurry Si and the salty water SWi. More specifically, the freshwater FW is injected at the last reactor CSTR6 and the saltiest water SW1 is discharged from the first reactor, i.e., the salty water SWi travels from the last reactor to the first reactor. Opposite to this,the initial mass of biochar (having the high pH and highest soluble salt concentration) is injected first into the first reactor and then travels toward the last reactor.

[0044] Regarding the salt concentration in the biochar material, for the embodiment illustrated in FIG. 2, the initial salt concentration (when entering the first reactor) is about 7% by mass and the final salt concentration (when leaving the sixth reactor) is about 0.12 % by mass. The salt concentration when entering the second reactor is about 3.5% by mass. The salt concentration when entering the third reactor is about 1 .79% by mass. The salt concentration when entering the fourth reactor is about 0.92% by mass. The salt concentration when entering the fifth reactor is about 0.47% by mass. A reaction time Ti in a given reactor CSTRi, between the biochar mass MBi (or slurry Si) and the salty water SW(i+1 ) from a next reactor is about 90 minutes in this embodiment. In another embodiment, the reaction time may be between 30 minutes and 72 hours. In yet another embodiment, the reaction time may vary from one reactor to another reactor (for example, T1 > T2 > T3 > ... > T6). The term “salt” in this embodiment is understood to mean any soluble salt, i.e. , a salt that dissolves in water. Examples of soluble salts include sodium chloride (NaCI), potassium nitrate (KNO3), ammonium sulfate ((NH4)2SC>4), lithium bromide (LiBr). More generically, any salt of group 1 metals, nitrates, acetates, perchlorates, and ammonium salts are considered to be soluble salts. Salts that are not soluble, usually from group 2 metals, include calcium sulfate (CaSC ), calcium carbonate (CaCOa), magnesium carbonate (MgCOa) and silver chloride (AgCI).Thus, the term soluble salt refers in this document to one or more of the above noted salts that are dissolvable in water. As some soluble salts naturally dissolve in water,no additional material is added to the first reactor as one goal is to remove any possible soluble salt just by washing the biochar material with water. However, some salts, usually from group 2 metals, such as calcium carbonate (CaCOa), magnesium carbonate (MgCOa), along with group 2 metal sulphates and phosphates, can become more soluble and consequently washed by reacting with an acid. For this reason, the PA acid is added only at the second and / or third reactor, and not at the first reactor.

[0045] In other words, the method illustrated in FIG. 3 includes a primary stage (i.e., use of the first reactor CSTR1 ) for removal of high-pH soluble alkalis (e.g., potassium carbonate pH 1 1.5, potassium / calcium oxides pH 12.5) using water alone for washing and leaching. Then, the method includes two or more secondary stages (i.e., the use of the second reactor CSTR2 and, optionally, the third reactor CSTR3), which include additional water washing and leaching aided by the application of an acid solution (e.g., hydrochloric acid, sulfuric acid, and / or phosphoric acid, etc.) to neutralize and solubilize mid-pH low-solubility alkalis, such as calcium and magnesium carbonates, and further lower the pH and soluble salt content of the biochar. For an increased quality engineered biochar 150, one or more tertiary stages (e.g., the use of the fourth reactor CSTR4) may be added, for fine- tuning the product specifications with water leaching aided by acid and optional nutrient or chemical enrichment or addition of beneficial microbial cocktails (the additional substance AS).

[0046] The multi-stage process discussed in FIG. 3 and illustrated in FIG. 2 is adopted to maximize the use of acid for the neutralization of the soluble salts, and toreduce the overall amount of water. Each stage removes a fraction of the ash components as the ash components include the soluble salts and have the high pH. The high pH of the biochar is caused by the ash content that is naturally present in raw biochar, especially in those produced from low density biomasses and in industrial processes that inevitably experience partial combustion due to the presence of some air in the reaction zone. The ash is composed of several salts, oxides, and hydroxides that elevate the pH of the biochar. The soluble fraction of the ash also contributes to the salinity of the biochar. Thus, the method of FIG. 3 uses plural stages of water and acid solutions to selectively remove some of those ash components down to the specified pH and salinity ranges.

[0047] The process of FIG. 3 may also be performed in batches, and in several configurations such as suspension, fixed bed, or slurry forms. Additionally, these stages can be combined into fewer or more stages depending on the water to biochar ratios, chemical dosing, mixing inside the reactors, reaction time, flow modes (counter-, cross- or co-flows). Further, the stages illustrated in FIG. 2 are performed in a serial functional manner. However, it is possible to reconfigure the biochar treatment unit 140 to operate in parallel. For this parallel configuration (not shown), two reactors (similar to CSTR1 ) can be added in parallel to increase the overall residence and reaction time for the first stage of removal of high-pH alkalis with water alone. The output of the two reactors could then flow into a single CSTR2, followed by a single or multiple CSTR3. These configurations could be deployed in order to adjust the residence times within each stage without the need of scaling the size of the reactors.

[0048] The speed of the conveyors (Ci) can be adjusted to control the ratio of solid and liquid inside each CSTRi.

[0049] For a batch configuration the biochar is loaded into a tank. A mass ratio of the liquid to solids (water to biochar) may be about 2:1 or higher. The same water is recirculated through the biochar tank a couple of times. Then, the water is drained through filters into auxiliary tanks. Multiple cycles of water or acidic solutions are applied to the same tank, where the water and acid solutions are changed between each cycle. The water solutions from each cycle can be used to treat a biochar in a preliminary stage. A freshwater solution with an acid can be added in order to minimize the number of cycles. The residence times of the biochar in the tank vary from hours to days.

[0050] Returning to the continuous operation of the biochar treatment unit 140 illustrated in FIG. 2, a more detailed view of the reactors CSTRi is shown in FIG. 4. FIG. 4 shows, for simplicity, only two reactors CSTRi and CSTR(i+1), but the same configuration may be implemented for all N reactors of the unit 140. In one embodiment, the structure of each reactor is the same, i.e., they have the same diameter, height, and include the same functional elements. However, in another embodiment, the structure of one reactor may differ from the next reactor.

[0051] FIG. 4 shows each reactor CSTRi having a tank 400 with an inner chamber 401 that receives a mixer Mi, which is configured to mix the received biochar mass MBi and the received liquid (e.g., salty water SW(i+1 )), to form the slurry Si. The slurry Si partially fills the inner chamber 401 , up to given height Hi. The mixer Mi may include a corresponding motor 402 that rotates a correspondingpaddle 404. The continuous rotation of the paddle 404 maintains the biochar particles in suspension in the salty water SWi. The rotation speed of the paddle 404 is selected to prevent a sedimentation of the biochar particles to the bottom of the tank 400. The rotation speed range for the paddle depends on the size of the biochar particles, the density of the biochar particles, and / or the size of the reactor.

[0052] The process illustrated in FIGs. 2 and 4 allows the counter-current mode, i.e. , the salty water SWi flows in one direction (right to left in FIG. 4), which is opposite to the biochar slurry Si flow (left to right in FIG. 2) between the various reactors. This configuration allows for higher reaction and extraction efficiencies and better resource utilization of water and acid. In this embodiment, to prevent forming a paste inside the reactors, the slurry mixture Si of the biochar and water is obtained by maintain a mass ratio (liquid to solids) of about 4:1 or higher.

[0053] FIG. 4 also shows a distal part of the conveyor Ci being located inside the internal chamber 401 of the reactor CSTRi, in direct contact with the slurry Si. The distal part of the conveyor Ci is configured to receive the slurry Si as input. A rotating part (not visible in the figure, also called a screw) of the conveyor Ci pushes the slurry Si upward a tube 405, until the slurry reaches a top of the tank 400. At this point, the slurry Si is discharged from the tube 405, through a conduit 406, into the separator SLSi. The conveyor Ci includes a motor 408 that rotates the rotating part for moving the slurry Si upwards within the tube 405. One skilled in the art will understand that for this operation to be successful, the slurry Si needs to have a certain consistency. A paste or a very fluid biochar solution would be very difficult to be vertically conveyed to the top of the tank 400 and into the separator SLSi.

[0054] The separator SLSi includes, in this embodiment, a sieve 412, which rotates, due to a motor 512, over a fixed base 502, as better shown in FIG. 5. Inside the sieve 412, there is a screw (or similar element) 510 that is fixed to the sieve and configured to rotate along with the sieve to move the slurry Si along direction A, from the reactor CSTRi toward the reactor CSTR(i+1 ). Salty water from the slurry Si exits the sieve 412 and is collected by a return tray 514, and this water is the backflow water BFWi illustrated in FIG. 2. This water returns back to the tank CSTRi as the return tray 514 is inclined toward this tank 400. This means that the water BFWi returns due to the gravity back to the reactor CSTRi. FIG. 5 shows an intake element 516 which is configured to receive the slurry Si from the conduit 406 of the conveyor Ci and to deliver the slurry to the screw 510, inside the sieve 412.

[0055] Returning to FIG. 4, it also shows a particle sedimentation and backflow PSBi module attached to the reactor CSTRi. While this figure shows the PSBi module being located outside the tank 400, in one embodiment, the PSBi module is located partially inside and partially outside the tank 400. For example, FIG. 6 shows the PSBi module having an inner intake port 610 and an outer output port 620. The intake port 610 may include a plate (e.g., made of metal or plastic) 612 that covers a hole 614 made in the wall of the tank 400. The plate 612 forms a pocket 616 that is sealed at the top and open to the bottom so that the salted water SWi from the tank 400 may enter the pocket 616 only from the bottom, as schematically illustrated by the arrow in FIG. 6. One or more parallel plates 618 may be attached substantially perpendicular to the wall of the tank 400 and also perpendicular to the plate 610, to reduce the turbulence and slow down the flow ofthe salted water SWi, encouraging the sedimentation of the biochar back into the turbulent region of the slurry (i.e. , to avoid the biochar particles to escape the tank 400). The slurry Si is expected to exit the tank 400 through the conveyor Ci and not through the hole 614. Only the salty water SWi is expected to exit through the hole 614 and to enter a chamber 622 formed into the output port 620, as schematically indicated by arrow 624. Note that chamber 622 is open at the top. A removable plate 626 slides inside the chamber 622 for splitting the chamber in two sub-chambers 622A and 622B, for regulating the liquid height inside the chamber 622 and consequently the slurry height in tank 400. The salt water SWi is thus forced to pass over the removable plate 626, from the first sub-chamber 622A into the second subchamber 622B. In other words, the removable plate 626 may have different heights and the operator of the reactor decides which height to use. The presence of the removable plate 622 further prevents the biochar particles from leaving the tank 400. After passing this plate, the salty water SWi exits through pipe 628, located at the bottom of chamber 622, and travels to a previous reactor CSTR(i-1 ) (shown in FIG. 2). In one embodiment, the removable plates 626 have different sizes with the smallest (shortest) being in the CSTR1 and the biggest (highest) in the last CSTR. The size of each plate 626 controls the slurry height in each CSTRi. Thus, having an increment in size of the plates 626 from CSTRi to CSTR(i+1 ) allows the natural gravity driven flow of salty water SW(i+1 ) from CSTR(i+1 ) to CSTRi.

[0056] FIG. 6 also shows an intake port 640 that is configured to receive the salty water SW(i+1 ) from the next reactor CSTR(i+1 ). The intake port 640 may include a pipe 642, a hole 644 formed in the wall of the tank 400, and a cover 646,for directing the intake salty water SW(i+1 ) toward the bottom of the tank 400. The cover 646 also prevents the slurry to flow into the port 640, reducing the risk of clogging. In one embodiment, a height of the location of the hole 644 relative to the bottom of the tank 400 is smaller than a height of the location of the hole 614 of the PSBi. The structure of the reactor CSTRi illustrated in FIGs. 4 to 6 may be shared by all other reactors in the biochar treatment unit 140.

[0057] The reactors discussed above with regard to FIGs. 2 to 6 are illustrated in FIG. 7 being attached to a common frame 702. This figure shows a combination of 6 CSTRs in series, separated by 6 rotary sieve separators SLSi, and with particle sedimentation and backflow PSBi units attached inside each tank 400 of each reactor CSTRi. The slurry Si is pumped into the rotary sieve separator SLSi via an Archimedes screw of the conveyor Ci. The liquid BFWi passing through the sieve 412 goes back into the same tank since it might carry particles with it. The salty water SWi from the particle sedimentation and backflow PSBi unit and the biochar slurry Si flow in counter current. The unit 140 shown in FIG. 7 also includes at least one acid dispensing module ADMi, which is configured to dispense a given amount of an acid PA stored in a tank 710. The ADMi may include a pump or valve 712 for dispensing the acid PA to the corresponding tank 400. In one embodiment, a processor 720 may be connected in a wired or wireless manner to the various motors, pumps, valves, and other elements for controlling the flow of the slurry, the salty water, and the dispensing of the acid. An additional substance dispensing module 740 may also be present for dispensing the AS. The additional substance dispensing module 740 may have a similar structure as the ADMi.

[0058] Based on the process illustrated in FIG. 3 and the biochar treatment unit 140 illustrated in FIGs. 2 and 4 to 7, the inventors have obtained an engineered biochar composition 150 that has a pH and salinity (where salinity refers to soluble salt contents, as previously discussed) as illustrated in FIG. 8. FIG. 8 also shows the pH and salinity of the raw biochar 210 (i.e., biochar that was not treated based on the method of FIG. 3 and the unit 140). The raw biochar’s pH and salinity appear to show a linear relationship 800 for a pH between 9 and 12.2. This correlates with the ash content and ash type present in the raw biochar and with the negative quality of the biochar both due to the high salinity and high pH. FIG. 8 also shows the properties achieved by the engineered biochar 150 (obtained with the biochar treatment unit 140), i.e., pH < 8.5 and salinity below 1%.

[0059] FIG. 9 shows that a total of 3 stages are preferred to bring the biochar’s salinity (soluble salt by mass, illustrated as curve 910) below 1%. Curve 912 illustrates the salinity of the salted water SWi after each stage. However, if the engineered biochar 150 is desired to have a lower salinity, more stages may be used. Note that a stage refers to the use of a single CSTRi as illustrated in FIG. 2 or 6.

[0060] FIG. 10 illustrates the results of two experiments. For the first experiment (see curves B3 1010 (for slurry pH) and 1012 (for biochar BC pH)), the acid PA was added in a single step (i.e., the PA injection for the CSTR2 in FIG. 2). BC pH stands for the pH of the biochar or solids after removing them from the solution (slurry Si) and performing the standard pH measurement for the biochar(e.g., 1 g of biochar to 10mL of deionized water). The slurry pH is measured in-situ while the slurry is being mixed inside the tank 400.

[0061] For the second experiment (see curves B4 1020 (for BC pH) and 1022 (for slurry pH)), the acid PA was added in two steps (e.g., the PA injection at CSTR2 and the PA injection at CSTR3 in FIG. 2). For the first step, the PA added was 1 .75% by mass and for the second step, the added PA was 1 .75% by mass. It can be seen that the 3.5% acid (experiment B3) addition by mass was sufficient to bring the pH of the slurry Si down to the required level below 8.5. The overall residence time of 1 .5 hour per stage was sufficient for the neutralization reactions and the leaching of salts. The split addition of acid (experiment B4) had only a localized effect and did not affect the final pH. The inventors observed a residual pH rise, possibly due to calcium carbonate present deep inside the pores of the biochar particles that equilibrated with the outer pores active sites as the slurry kept in water. A similar reaction is expected to happen for the biochar particle even if it is directly applied to a moist soil. Therefore, it should be desirable to neutralize the pH to levels slightly below the target, in order to avoid the pH to bounce back to values above the desired limit.

[0062] The characteristics of the engineered biochar 150 obtained based on the biochar treatment unit 140 illustrated in FIG. 2 or 7 are illustrated in the table of FIG. 11 A. Note that five different parameters 11 10 to 1 118 characterize the engineered biochar 150 in this embodiment. These parameters are the pH 1110, the electrical conductivity 11 12, the soluble salt content 1 114, the ash content after the combustion 11 16, and the hydrogen to organic carbon molar ratio (H / Corg) 1118.The H / Corg 1118 relates to the stability of the engineered biochar 150. FIG. 11A shows a first engineered biochar (column 1120) having a first quality standard (e.g., using three stages out of the six stages illustrated in FIGs. 2 and 7) and a second engineered biochar (column 1122) having a second quality standard (e.g., using only two stages of the six stages). The last column 1124 of the table in FIG. 11 A illustrates an example of the engineered biochar 150 when obtained from chicken manure. In another embodiment, the engineered biochar may be defined by any four of the above five parameters. In yet another embodiment, the engineered biochar may be defined by any three of the above five parameters. Note that the ranges and / or specific values shown in the table of FIG. 11 A for the engineered biochar 150 are obtained due to the specific use of the unit 140 discussed above.

[0063] FIG. 11 B illustrates secondary parameters that may characterize the engineered biochar 150. These secondary parameters include a bulk density, water holding capacity (WHC), both as mass fraction and volumetric fraction, cation exchange capacity (CEC), material stability, moisture content, typical bulk density, specific surface area, total organic carbon, total organic matter, and biochar particle size. Note that the material stability parameter is calculated based on a linear formula, where the independent variable is the H / Corg discussed above. Note that the Typical values column 1130 shows ranges of the values of these parameters obtained from various experiments performed with biochar from various sources and with various stages of the treatment unit 140 while the column Engineered Biochar 1132 shows the actual values obtained from a run with chicken manure biochar for the unit 140. Further note that any of these secondary parameters may be combinedwith the parameters illustrated in the table of FIG. 11 A for defining the characteristics of the engineered biochar 150. In other words, any three or more parameters of the table in FIG. 11 A may be optionally combined with one or more of the secondary parameters of the table in FIG. 11 B for defining the final engineered biochar 150.

[0064] FIG. 11 C illustrates the possible nutrient atoms of the engineered biochar 150 when made from chicken manure. When the engineered biochar 150 is made from another material, its composition may vary with about + / - 20% relative to the composition illustrated in FIG. 11C. One or more of the nutrient atoms illustrated in this figure may characterize the engineered biochar 150, in addition to the three or more parameters of FIG. 11A. In one embodiment, the engineered biochar 150 may be characterized by the three or more parameters of FIG. 11 A, the one or more parameters illustrated in FIG. 11 B, and the one or more nutrients illustrated in FIG. 11C. Note that the Total column 1140 in FIG. 11C indicates a percentage range of a weight of each nutrient versus the weight of the entire engineered biochar, e.g., 3- 5% w / w for N. The same column 1142 also indicates a specific value, e.g., 4.08 % for the N, which corresponds to a single measurement. The “readily available” column 1142 in FIG. 11 C indicates the actual mass of the nutrient in mg for one kg of the engineered biochar 150 (e.g., 802 mg of N per 1 kg of biochar) that can be more easily extracted by plant roots.

[0065] The engineered biochar 150 may also be obtained by using a vertical column process, with a modified biochar treatment unit 1200, as illustrated in FIG.12. For this embodiment, there are N plug flow reactors (PFRi). FIG. 12 shows two reactors PFRi and PFR(i+1 ). Each reactor PFRi has a conveyor Ci, which may besimilar or different from the conveyor Ci illustrated in FIGs. 4 and 7. The conveyor Ci takes the slurry Si from a bottom of the tank 400 and transfers it to the next tank, without any or minimum solid-liquid separation. Salty water SW(i+1) from the next reactor PFR(i+1) flows, due to the gravity or pump (not shown), to the current reactor PFRi. Instead of the PSBi module illustrated in FIG. 6, a mesh filter 1210 may be used for preventing the biochar to move along piping 1220, to the previous reactor. This vertical process utilizes sedimentation (for removing the biochar from the bottom of the tank to the next tank) and gravity separation, or pumps and valves, for moving the salty water SWi from one tank to the previous tank. FIG. 13 shows an embodiment in which the reactor PFRi is replaced with a CSTRi reactor to achieve another modified biochar treatment unit 1300. The CSTRi reactor is shown having a mixer Mi. A biochar bed sediment 1310 is shown at the bottom of each tank 400 and the conveyor Ci moves the biochar sediment to the next reactor.

[0066] Valid for all embodiments, the final wastewater (see SW1 in FIG. 2) may undergo reverse osmosis or evaporation. The recovered salts (rich in K, Mg, and / or Ca) may be used as fertilizers. The sodium content remains low due to the biomass origin.

[0067] Experiments performed by the inventors for growing various plants in the desert with the engineered biochar 150 have shown a significant enhancement in biomass growth (above 60% in some cases) sustained over multiple years, as illustrated in FIG. 14 for an acacia field (the engineered biochar 150 was made from date palm biochar; 1 kg of the biochar was applied in a pit of 60 cm depth). FIG. 15 illustrates the trunk base circumference of the plants grown with engineered biochar150 incorporated in the top 30 cm of the soil at varying does from 5 to 100 ton / ha rate (5CS to 100CS) for acacia farnesiana. FIG. 16 shows the same conditions for Ziziphus spina-chisti. Both experiments illustrate a substantial increase in the trunk base circumference when 100CS of biochar is supplied versus the control soil. FIG. 17 illustrates an experiment with olive trees in which the engineered biochar 150 was incorporated in the top 60 cm of the soil at 5.3 kg / plant (CBS) compared with equally fertilized and irrigated controls and beneficial microbial cocktail (Bact).

[0068] The inventors have found that the soil properties are improved when the engineered biochar 150 is added, e.g., enhanced water retention and nutrient holding capacity. At 1 % mass ratio (~5% volumetric) the water holding capacity of sandy soils increases by about 1 1% while the nutrient retention capacity (CEC) increases by about 53%. It was also found that the engineered biochar 150 may be applied not only in agriculture, but also in landscaping, and regreening projects, especially in arid and alkaline soil environments. Its ability to improve soil properties at high application rates without negative side effects along with its environmental aspect of carbon sequestration, provides a significant advancement over existing soil amendments such as raw biochar, compost, or peat moss. In this regard, note that the engineered biochar 150 experiences negligible mass (or material) loss after one year while a peat moss or compost based products can experience more than 81% material loss, i.e., due to microbial decomposition.

[0069] The term “about” is used in this application to mean a variation of up to20% of the parameter characterized by this term.

[0070] Since water or moisture content is always present in the biochar, the term “total mass,” when related to the concentration of elements or properties of the engineered biochar, refers to the total dry mass of the engineered biochar without accounting for the water or moisture content.

[0071] It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first object or step could be termed a second object or step, and, similarly, a second object or step could be termed a first object or step, without departing from the scope of the present disclosure. The first object or step, and the second object or step, are both, objects or steps, respectively, but they are not to be considered the same object or step.

[0072] The terminology used in the description herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used in this description and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and / or" as used herein refers to and encompasses any possible combinations of one or more of the associated listed items. It will be further understood that the terms "includes," "including," "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Further, as used herein,the term "if" may be construed to mean "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context.

[0073] The disclosed embodiments provide an engineered biochar that is appropriate for alkaline desertic soils. It should be understood that this description is not intended to limit the invention. On the contrary, the embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.

[0074] Although the features and elements of the present embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein.

[0075] This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.

Claims

WHAT IS CLAIMED IS:1 . An engineered biochar (150) comprising: plural particles (162), each particle (162) including, hydrogen atoms (152), oxygen atoms (153), carbon atoms (154), and ash (156) including one or more nutrient atoms, wherein the engineered biochar (150) has: a pH between 1 and 8.5, an electrical conductivity between 0.01 and 4.95 dS / m measured with a 1 :10 engineered biochar to water method, a soluble salt content between 0.01 and 3% of a total dry mass of the engineered biochar, an ash content between 10 and 50% of the total dry mass of the engineered biochar, and a hydrogen to organic carbon molar ratio between 0.1 and 0.7.

2. The engineered biochar of Claim 1 , wherein the pH is about 7, the electrical conductivity is about 1 .5 dS / m, the soluble salt content is about 0.58%, which are dissolvable in water, the ash content is about 45%, the hydrogen to organic carbon molar ratio is about 0.5, and an individual size of the plural particles is smaller than3. The engineered biochar of Claim 1 , wherein the one or more nutrients atoms is at least one of: potassium with a weight percentage between 0.7 and 2 of the total mass, calcium with a weight percentage between 5 and 10 of the total mass, or copper with a weight percentage between 0.001 and 0.2 of the total mass.

4. The engineered biochar of Claim 1 , wherein the soluble salt content is due to soluble salts, which are salts dissolvable in water.

5. A biochar treatment unit (140) configured to remove soluble salts to generate an engineered biochar (150), the biochar treatment unit (140) comprising:N stages (i) with N reactors (Ri), where N is a positive integer, the N reactors (Ri) being fluidly connected in series and configured so that, a raw biochar (210) enters a first reactor of the N reactors and travels, sequentially, as a slurry (Si), through the remaining reactors to become the engineered biochar (150) when exiting at an Nth reactor of the N reactors, and a fresh water (FW) stream enters the Nth reactor and removes a soluble salt (158) from each remaining reactor, and exits the first reactor as salty water (SW), each stage (i) including: a conveyor (Ci) configured to remove the slurry (Si) from the reactor (Ri), and a solid-liquid separator (SLSi) configured to receive the slurry (Si) from the conveyor (Ci) and to separate a processed biochar from the slurry (Si) and move the processed biochar to the next reactor (R(i+1 )).

6. The biochar treatment unit of Claim 5, wherein the reactor (Ri) is one of a continuous stirred-tank reactor (CSTRi), a plug flow reactor (PFRi), or a reactor having an intermediary configuration.

7. The biochar treatment unit of Claim 5, wherein the reactor (Ri) is configured as a continuous stirred-tank reactor (CSTRi) and includes a mixer (Mi) configured to mix the slurry (Si) to prevent particle sedimentation.

8. The biochar treatment unit of Claim 5, wherein the solid-liquid separator (SLSi) includes a sieve and a screw that are simultaneously rotated by a motor to separate the slurry and advance the biochar to the next reactor, wherein the solid-liquid separator (SLSi) is configured to discharge a separated biochar (MBi) to a next reactor (CSTR(i+1 )) and return the back flow water (BFWi) to the current reactor (CSTRi).

9. The biochar treatment unit of Claim 5, wherein the reactor (Ri) includes a sedimentation zone to separate biochar from the slurry.

10. The biochar treatment unit of Claim 5, wherein the conveyor (Ci) includes a screw rotated by a motor for lifting the slurry to the solid-liquid separator (SLSi).1 1 . The biochar treatment unit of Claim 5, wherein each reactor further comprises: a particle sedimentation and backflow (PSBi) module configured to separate salty water from the slurry (Si) of the current reactor and move to a previous reactor (R(i-1 )).

12. The biochar treatment unit of Claim 11 , wherein the particle sedimentation and backflow (PSBi) module includes: an inner part located inside a tank of the current reactor, the inner part comprising an intake port with one or more parallel plates attached to the port for receiving the slurry and reducing a turbulent flow allowing particles in the slurry to settle back into the turbulent region; and an outer part located outside the tank and comprising a box with a plate of adjustable length for regulating a liquid height inside the tank.

13. The biochar treatment unit of Claim 5, wherein N is 1 , 2, 3, 4 or 5.

14. The biochar treatment unit of Claim 5, further comprising: an acid dispensing module (ADMi) configured to dispense a given amount of an acid to one or more reactors or stages.

15. The biochar treatment unit of Claim 5, further comprising: an additional substance dispensing module (AS) configured to dispense to one or more reactors or stages a given amount of a chemical, and / or a micronutrient and / or a microbial cocktail.

16. A method (300) for making an engineered biochar (150), the method comprising: feeding (302) a raw biochar (210) to a current reactor; feeding (304) a salty water to the current reactor, from a next reactor; removing (308) a washed biochar from the current reactor; and separating (310) the washed biochar from the salty water to obtain the engineered biochar (150), wherein the engineered biochar (150) has: a pH between 1 and 8.5, an electrical conductivity between 0.01 and 4.95 dS / m measured with a 1 :10 engineered biochar to water method, a soluble salt content between 0.01 and 3% of a total dry mass of the engineered biochar, an ash content between 10 and 50% of the total dry mass of the engineered biochar, and a hydrogen to organic carbon molar ratio between 0.1 and 0.7.

17. The method of Claim 16, wherein a reaction time is between 1 minute and96 hours.

18. The method of Claim 16, further comprising: providing the engineered biochar to a next reactor for further washing.

19. The method of Claim 16, further comprising: adding an acid to the engineered biochar, in the next reactor or stage, for reducing a pH of the engineered biochar.

20. The method of Claim 16, further comprising: adding an additional substance, in a reactor or stage, comprised of a chemical, and / or a micronutrient and / or a microbial cocktail.

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