FertoCHAR-Commingled food waste derived organic fertilizer prepared by microwave-assisted catalytic pyrolysis

Abstract

ABSTRACT TITLE: FertoCHAR-Commingled food waste derived organic fertilizer prepared by microwave-assisted catalytic pyrolysis The present invention provides for food waste derived soil conditioner and organic fertilizer more particularly pertains to commingled waste-based end-product named FertoCHAR as soil conditioner and organic fertilizer involving microwave-assisted catalytic pyrolysis technique. More specifically, a method for preparation of commingled food waste based nutrient-laden organic fertilizer (termed as FertoCHAR) is provided that serves as a single-step solution for fertilizer applications, capable of substituting a diverse array of chemical fertilizers for different nutrient requirement. This process can be applicable to wide array of commingled waste. Moreover, FertoCHAR enhances the soil organic carbon content, pH, and water holding capacity, all of which are essential for plant growth with production process utilizing microwave-assisted pyrolysis based on select operating conditions like microwave power (600-900 W), temperature (300-600 C), susceptor loading (GAC, SiC, zirconium-based alloy) and residence time (10-30 min) varies based on the feedstock characteristics. Figure 1b

Specification

Description:Field of invention

The present invention pertains to the field of waste management, agricultural chemistry and specifically to the production and application of food waste derived soil conditioner and organic fertilizer more particularly pertains to commingled waste-based end-product named FertoCHAR as soil conditioner and organic fertilizer involving microwave-assisted catalytic pyrolysis technique. More specifically, a method for preparation of commingled food waste based nutrient-laden organic fertilizer (termed as FertoCHAR) is provided, belonging to the field of fertilizer preparation. The method comprises the following steps: (1) drying and shredding commingled food waste; (2) characteristic analysis, microwave-assisted thermo-chemical conversion in inert conditions to obtain the carbon-rich material i.e., FertoCHAR; (3) cooling the FertoCHAR obtained in the step (2) to room temperature, characteristic and elemental analysis; (4) optional intercalation with urea and/or phosphate salts, and constant mixing using starch as binder at 65C to improve required nutrient release capacity of FertoCHAR. FertoCHAR serves as a single-step solution for fertilizer applications, capable of substituting a diverse array of chemical fertilizers for different nutrient requirement. This process can be applicable to wide array of commingled waste. Moreover, FertoCHAR enhances the soil organic carbon content, pH, and water holding capacity, all of which are essential for plant growth. This production process utilizes microwave-assisted pyrolysis, which offers several advantages over conventional pyrolysis technology. It provides volumetric and rapid heating, resulting in improved product yield and quality. The microwave operating conditions like microwave power (600-900 W), temperature (300-600 C), susceptor loading (GAC, SiC, zirconium-based alloy) and residence time (10-30 min) varies based on the feedstock characteristics.



Background Art

Nitrogen and phosphorus are two nutrients that are vital to the structure, processes, and activities of an ecosystem. This is owing to the fact that the availability of these nutrients places a limit on the quantity of plant biomass that can be produced as well as the rate at which plants may develop. In particular, the type and amount of fertilizer used have an effect on the overall crop yield. There are variety of commercial fertilizers in market to enhance crop production yet possess certain disadvantages like low nutrient holding capacity, decrease soil pH thereby making it acidic, increases salinity in some cases, nutrient abundance leading to plant mortality, and blocks water absorption to the soil if applied at higher quantities. Apart from these, they also impregnate certain harmful chemicals in to the soil system, making them non-cultivable in the long run, and also effects nearby water bodies due to nutrient and chemical leaching while erosion. Hence, there is an utmost necessary to introduce better fertilizers to overcome these lacunas, without deteriorating the soil and crop quality.

Recently, biochar has been extensively researched for its applicability in various fields like fossil replacement in energy sector, water and wastewater treatment etc. The utilization of biochar has a multitude of potential for improving soil qualities apart from capturing carbon, thereby mitigating climate change. It is generally prepared by partial carbonization of feedstock like biomass under the absence of oxygen, which results majorly in carbon sequestration, along with the ability to capture and store nutrients and subsequently release them according to the plant requirement to enhance the productivity. Recent study by Danso et al. (2023) demonstrated that the application of biochar lead to an increase in initial cost of crop production, yet reduced the subsequent cropping cost. Different thermo-chemical techniques like torrefaction, hydrothermal carbonization, and pyrolysis etc. have been extensively researched for conversion of biomass into biochar. Certain modifications to the production processes like pre-treatment, post treatment, co-pyrolysis, etc. were also studied to improve the biochar characteristics. However, the pyrolysis process was considered a promising method for converting feedstock into biochar for a variety of applications, where the feedstock is carbonized at elevated temperatures in inert conditions. The major challenges associated with such conventional thermochemical conversion technologies are high input power requirements, greater retention time, low-quality product yield, the requirement for post-treatment technologies, and secondary waste generation which impeded its potential for commercialization. Recently, advanced conversion technologies like microwave-assisted pyrolysis is focused upon, as this technique provides better energy efficiency and consumes lesser time while improving the quality of the required output, in comparison with conventional pyrolysis technique. Different kinds of biochar have various applicability based on the initial characteristics of feedstock like physical and chemical characteristics and operating conditions like pH, temperature, microwave power, time, etc. as they control the composition, surface chemistry, pore and particle size of the resultant biochar. Biochar derived from various wastes like agricultural residues, municipal solid waste (MSW), plastics, etc. are researched for various purposes like adsorbents, soil quality improvement, water and wastewater treatment, replacement of fossils, etc. Different biochar obtained from lower-temperature pyrolysis conditions (300-600 C) are generally viable to be used for soil amendment due to their innate characteristics of better nutrient and water retention capacity combined with porous structure. The composition of the feedstock materials and the pyrolytic conditions also influence the nutritional content of biochar. Biochar made from feedstock like manure and bio-solids, revealed higher nutrient content than the biochar obtained from wood, grass, and straw. However, food waste is one such biomass with significant nutritional values which is often dumped of in LDPE covers leading to their rotting, which can otherwise be a potential organic fertilizer through appropriate treatment.

The review of literature reveals that no previous studies were found on fertilizer application of commingled food waste based end-product produced using advanced pyrolysis technique i.e., microwave-assisted pyrolysis. Available literature majorly focused on the application of certain biomass-related biochar as soil conditioner (improve soil properties like water-holding capacity and soil carbon content) or as fertilizer in combination with different other biomass and/or chemical fertilizers that are commercially available. The co-application of biochar and synthetic fertilizers in soil has been the traditional approach utilized to exploit the benefits of their interaction. However, very few studies reported the usage of microwave-assisted pyrolysis technique for biochar production, which is advantageous over conventional pyrolysis techniques in terms of biochar yield, and quality. It significantly improves the properties/characteristics of biochar to be applicable as both soil conditioner and fertilizer. Therefore it is of utmost necessity to differentiate between desired end-product preparation technologies and their corresponding application as soil conditioner and fertilizer.
Food waste (FW) is one of the major biomass components of MSW contributing to around 1.3 billion tonnes per year globally. These wastes when composted retain their organic and nutrient content which deems helpful for plant growth. Nevertheless, the compost quality is affected by certain factors like pH, aeration, humidity, temperature, and space availability, etc. FW co-composted with biochar had better fertilizer applicability compared to compost alone. However, the FW are generally disposed of being wrapped within the plastic bags like LDPE, thus making it difficult for segregation for proper management. Microwave-assisted catalytic pyrolysis of commingled FW (FW+LDPE) proved to be better options for biochar production as per the studies conducted by Neha and Remya 2024 in Environment, Development and Sustainability https://doi.org/10.1007/s10668-024-05413-8. Previous studies contemplated the feasibility of biochar production from mixture of foodwaste and LDPE in particular ratio (87: 13) (50 g of feedstock) using different microwave susceptors like silica gel, fly ash, cement, and GAC through microwave-assisted catalytic pyrolysis as depicted in Neha, Rajput, and Remya 2022 in Environmental Research 210 (2022) 112922. Moreover, Neha, Rajput, and Remya 2022 in Environmental Research 210 (2022) 112922; Neha and Remya 2023 in Biomass Conversion and Biorefnery (2023) 13:9465-9474 explored the applicability of such biochar as adsorbent in wastewater treatment and fuel replacement in energy sector. The techno-economic analysis and corresponding sustainability assessment is done through life-cycle assessment studies of food waste and LDPE biochar production is explored in Neha, Prasanna Kumar Ramesh, and Remya 2022 in Sustainable Energy Technologies and Assessments 52 (2022) 102356, signifying the feasibility of upscaling the microwave-assisted catalytic pyrolysis technology for converting the mixture of food waste and LDPE into valuable biochar. However, much remains to be explored in this field based on the involvement of different susceptors and the biochars and their porosity attained thereof for further modification.
Further literature search revealed the following:

Year Title Technique Operating parameters Product Nutrient Content Remark
2023 Synthesis of tapioca starch/palm oil encapsulated urea-impregnated biochar derived from peppercorn waste as a sustainable controlled-release fertilizer Conventional Pyrolysia (Tubular Furnace), modification by mixing biochar in urea solution Heating rate: 10/min
Biochar:urea:0.6; Pyrolysis Temp: 400 C
Encapsulated Urea-impregnated biochar pellet Nitrogen content: 9.5% The product was synthesized by dipping biochar in starch /PO solution for 10 s. Complete release of nitrogen occurred in 330 min.
2021 A new class of biochar-based slow-release phosphorus fertilizers with high water retention based on integrated co-pyrolysis and co-polymerization Integrated co-pyrolysis and co-polymerization process Temperature: 550 C
Time: 2h
Encapsulated phosphorous enriched biochar Available Phosphorous: 0.69 g/kg Sodium alginate and hydrogel were used for encapsulation
2021 Enhancing Biochar as Scaffolding for Slow Release of Nitrogen Fertilizer Conventional pyrolysis
Temperature: 500 C
H3PO4 activated biochar based slow release fertilizer Nitrogen content: 32.95%
Slow-release nitrogen fertilizers produced using biochar, urea, calcium lignosulfonate, and paraffin wax are characterized and evaluated for efficacy in sustainable agriculture.
2021 Microwave co-pyrolysis of biomass, phosphorus, and magnesium for the preparation of biochar-based fertilizer: Fast synthesis, regulable structure, and graded-release Microwave co-pyrolysis Microwave Power: 700 W
Time: 15 min
Temperature: 260-400 C
CS: K3PO4: MgO= 1: 0.8: 0.4, Biochar based fertilizer (BBF) Precipitated P: 108.76 mg/g organic P: 71.93 mg/g BBFs were prepared through microwave co-pyrolysis by premixing K3PO4 with MgO with cotton stalk (CS).
2021 Coupling anaerobic digestion and pyrolysis processes for maximizing energy recovery and soil preservation according to the circular economy concept Conventional Pyrolysis in steel reactor Temperature: 500 C
Heating Rate: 10 /min
Residence Time: 60 min Biogas plant digestate biochar Nitrogen content: 1.3 %
Phosphorous content: 1.9 % Application of biochar at a rate of 50 t/ha did not produce any detrimental effects on the relative seed germination.
2020 Pyrolysis temperature influences the characteristics of rice straw and husk biochar and sorption/desorption behaviour of their biourea composite Conventional Pyrolysis Temperature : 450 C
CO2 purging: 3L/min
Biourea composites Nitrogen content: 5.8-5.9 % Biourea composites were prepared by adsorption of urea by rice straw/husk biochar for further controlled release of nitrogen
2020 Experimental and feasibility study of spent coffee grounds upscaling via pyrolysis towards proposing an eco-social innovation circular economy solution Conventional Pyrolysis Temperature: 450-750 C
Heating rate: 50 /s Spent coffee ground biochar Nitrogen content: 6.4 % Biochar was applied as soil enhancer
2018 Production of bio-fertilizer from microwave vacuum pyrolysis of palm kernel shell for cultivation of Oyster mushroom (Pleurotusostreatus) Microwave vacuum pyrolysis Microwave Power: 750W
Time: 30 min Palm kernel shell biochar Nitrogen Content: 1% Biochar was mixed with rice bran, calcium carbonate and sawdust and then applied as bio-fertilizer due to its ability to provide a housing for living microorganisms and organic nutrients.


Further the prior art patent search revealed the following:

ID Title Inventor/Author Filling Date Publication Date Remark
IN202411039523 Multi-micronutrients- and carbon nanofiber-modified biochar for enhanced plant growth IIT Kanpur 21.05.2024 28.06.2024 Micro-nano fertilizer was prepared by mixing 2-5 g of bamboo powder with H3BO3, ammonium molybdate and copper nitrate under aqueous phase; dried and pyrolyzed at 400C for 1 h.
Current patent application status reveals to be under examination.
CN114605201A Kitchen waste biomass charcoal-based slow release fertilizer and preparation method and application thereof BianRongjun, Yao Fei, Pan Genxing, Li Wenjian 24.03.2022 10.06.2022 The claimed kitchen waste biomass charcoal-based slow release fertilizer is comprising the following raw materials in parts by mass: 15-30% of kitchen waste, 5-10% of crop straw, 25.5-30.3% of urea, 0.3-2% of dolomite powder, 1-4% of red clay, 0.3-2% of apatite, 0.3-2% of ferric oxide, 5-8% of potassium hydroxide, 3-6% of potassium chloride, 8-13% of 85% phosphoric acid solution, 3-6% of diammonium hydrogen phosphate and 5-10% of bentonite.
CN114230393A Special carbon-based organic-inorganic compound fertilizer for saline-alkali soil and preparation method thereof Wang Hongyan, Zhang Xu, Zhao Wei, Sun Yan 13.12.2021 25.03.2022 A special carbon-based organic-inorganic compound fertilizer for saline-alkali soil comprises 100-200 parts of biochar, 150-250 parts of humic acid, 30-100 parts of pyroligneous, 10-30 parts of medical stone, 50-100 parts of bentonite, 50-100 parts of phosphogypsum, 100-150 parts of nitrogenous fertilizer, 100-150 parts of phosphate fertilizer, 100-150 parts of potash fertilizer and 10-50 parts of trace elements. Biochar is applied for improving water and nutrient retention capacity of soil rather than as a fertilizer.
Current status of patent application is pending
CN113994805A Application method of biochar-based molybdenum fertilizer for improving vegetable quality Huang Yongdong, Wen Dian, Du Ruiying, Deng Tenghaobo, Shi Hanzhi, Jiang Qi, Wang Xu 29.11.2021 01.02.2022 The biochar-based molybdenum fertilizer is prepared from biochar and ammonium molybdate which can effectively replace the nitrogen fertilizer by 10-30%; phosphate fertilizer by 30-50%; and potassium fertilizer by 70-100%. The mass ratio of the biochar to the ammonium molybdate is 1-4: 0.00003 to 0.0003.
Current status of patent application is pending
CN112142537A Biochar compound fertilizer and preparation method and application thereof Du Jun, Yang Huanhuan, Hu Ying and Ailing, Pan Xiuyan, Xu Jidong, Liu Gaoyuan 09.11.2020 29.12.2020 Biochar compound fertilizer comprising 50-60 parts of charcoal, 30-40 parts of livestock and poultry manure, 25-35 parts of bamboo powder, 20-30 parts of peanut shell powder, 5-10 parts of binder, and 0.8-1.5 parts of composite microbial inoculum
Biochar is prepared from plant straws using conventional pyrolysis technique
Binder is at least one of starch, clay and attapulgite
AU2020100065A4 A biochar-based Fertilizer synergist and a preparation method Dianyun CAO, Wenfu Chen, Yuwei Huang, Yu LAN, Jun Meng, Qingyang Wang, Xu Yang 13.01.2020 20.02.2020 Granular biochar prepared from corn cob, peanut hull, rice husk, edible fungi substrate and other agricultural and forestry waste biomass, used as the matrix material comprising a urease inhibitor, a nitrification inhibitor, humic acid and trace elements. This synergist can be applied alone or in combination with other fertilizers at a ratio of 1-5: 100.
The current status of this patent application is ceased
CN107142112B Biochar soil conditioner and preparation method thereof Li Gang, Li Jun, Lai Zhaofei 26.05.2017 08.09.2017 Biochar soil conditioner
Composite consists of 2-10 parts of biochar, 1-5 parts of pyroligneous, 5-10 parts of bacteria, 3-5 parts of binder, and 4-10 parts of organic matter.
Bentonite is used as binder. Microorganisms in biochar help in nutrient release and soil conditioning.
Biochar is prepared through conventional pyrolysis technique
CN105837312A Biochar base fertilizer special for wheat and preparation method thereof Gao Jinhua, Zhao Wen, Zhou Li, Jiang Tingxue 23.03.2016 10.08.2016 The fertilizer is prepared from urea, mono-ammonium phosphate, potassium chloride, potassium dihydrogen phosphate, biochar, EDTA chelated iron, EDTA chelated manganese, EDTA chelated copper, EDTA chelated zinc and other raw materials.
Current status of patent application is pending
AU2014268332B2 Producing fuels and biofertilizers from biomass Mark Allen, Rocco A. Fiato, Yuhan Sun, Quanyu ZHAO 23.05.2014 10.12.2015 Structured biochar was produced by microwave pyrolysis and having an average pore size in the range of 20 to 400 Angstroms.
The biofertilizer having a composition comprising nitrogen fixing cyanobactreia, diazotrophic microorganisms and the structured biochar.
The patent has been granted on 11.07.2019.

While the biochar production is known out of food waste (FW) and co-pyrolysis of FW and polyethylene (FW+PE) is also known, there is still a longfelt need in the art to explore for such biochars and susceptors involved that would be suitable for seed germination and plant health also adaptive to nutrient intercalation to thereby provide for soil conditioner and organic fertilizer formulation out of the same towards applicability of such carbon-rich end product to serve as a potential soil conditioner and organic fertilizer.

OBJECTS OF THE INVENTION

Thus the basic object of the present invention is to provide for food waste derived soil conditioner and organic fertilizer particularly commingled food waste derived organic fertilizer formulation and a process of manufacturing thereof that would promote bulk or large scale utilization of different kinds of commingled wastes (food waste along with plastics) like organic MSW (municipal solid waste), agricultural wastes to address the pressing issue of waste collection, segregation and disposal.

Another object of the present invention is to provide for commingled food waste derived organic fertilizer formulation based on thermochemical conversion technique including microwave-assisted catalytic pyrolysis method and simple modification (if required) to produce FertoCHAR with storage porous structure ranging from 0.5-50 µm and better water and nutrient release ability.

Yet another object of the present invention is to provide for said commingled food waste derived organic fertilizer formulation that would attain out of microwave-assisted catalytic pyrolysis to be advantageous over conventional pyrolysis in involving energy transfer mechanism, that would be rapid, selective, causing volumetric heating so as to produce high quality end-product under less residence time.

Still another object of the present invention is to provide for commingled food waste derived organic fertilizer formulation and methods of preparing the same that would enable other by-products like bio-oil and syngas of high quality.

Yet another object of the present invention is to provide for said production of biochar and commingled food waste derived organic fertilizer formulation attained thereof that would leave no carbon footprint on the environment.

Another object of the present invention is to provide for said biochar and commingled food waste derived organic fertilizer formulation including from municipal solid wastes (MSW) that would on one hand reduce the burden on land acquisition for storage, open dumping, landfilling area and their perpetual maintenance, and on the other hand the biochar would serve as a potential, doable and viable substitute to chemical fertilizers, either fully or partially.

Still another object of the present invention is to provide for said biochar and commingled food waste derived organic fertilizer formulation that would be simple and easy to use and feasible for large scale production free of the requirement of any specific skills and that can be manufactured indigenously at low equipment cost.

SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided food waste derived soil conditioner and organic fertilizer comprising:
co-activated and microwave pyrolyzed comingled food waste based nutrient laden biochar as organic fertilizer having a selective range of comingled food waste feedstock and microwave susceptors including one of the granular activated carbon, silicon carbide and zirconium-based alloy in the weight ratio of 10:1 to 30:1 having pH in the range of 6.58±0.3 and a storage porous structure ranging from 0.5-50 µm for enhanced water holding capacity.

Preferably said food waste derived soil conditioner and organic fertilizer is provided wherein said biochar as pristine biochar is further adaptive to nitrogen based nutrient intercalation/modification having average pore size of 4.98 µm, surface area of 6.89 m2/g, bulk density of 0.48 g/cm3 and water absorbance capacity (WHC) of 41.4%, is least toxic with the inhibition of 0.001%, whereby water holding capacity of soil increases by 62.5% when 8 wt% of said biochar is added in soil as compared to undisturbed soil thereby adapted for soil conditioning.

According to another preferred aspect of the present invention there is provided said food waste derived soil conditioner and organic fertilizer wherein said biochar as P-nutrient based pristine biochar is modified to intercalated N-nutrient laden biochar with improved nitrate release ability and is preferably urea laden/intercalated in the ratio of biochar: urea of 1:1 together with binder material including rice starch in proportions of biochar-urea: rice starch of 5:1 to 15:1.

Preferably said food waste derived soil conditioner and organic fertilizer is provided wherein
said biochar is a microwave assisted/ pyrolysed biochar of said polyethylene (PE) commingled food waste feedstock,
said polyethylene (PE) commingled food waste feedstock includes MSW (municipal solid waste) based food waste along with LDPE (low density polyethylene) suitable as direct feed free of requirement of segregation of plastic from food waste.

According to another preferred aspect in said food waste derived soil conditioner and organic fertilizer wherein said modified nutrient laden biochar have average pore size of 4.87 µm translating to negligible interruption in the porous nature of the modified biochar and having surface area of 6.53 m2/g post modification by 5% urea attributed to the deposition of urea particles on the surface of the biochar.

Preferably said food waste derived soil conditioner and organic fertilizer is provided wherein said pristine and modified biochar have atomic ratio of O/C of 0.313 and 0.304 respectively indicative of stability with half-life of 100-1000 years in having O/C ratio in the range of (0.2-0.6), and with the modified biochar having increased nitrogen weight content by ~ 86.2 % is indicative of urea loading/intercalation on surface of the biochar.

According to another preferred aspect of the present invention there is provided said food waste derived soil conditioner and organic fertilizer that attains anyone or more of the following:
wherein said pristine biochar for P release attains equilibrium release condition (312.91 mg/kg) after 900 min, with maximum amount of P leaching of (351 mg/kg) being determined at 40 h, comparable to phosphate release rate of commercial fertilizer named Di-Ammonium Phosphate (DAP) i.e., 280 mg/kg;
said pristine biochar attains equilibrium N release condition of (54.43 mg/kg) after 300 min, with the maximum amount of N leached (55.27 mg/kg) at 48 h, which is comparatively lesser than that of commercial fertilizer (174-225 mg/kg), thereby supporting conditioning of the soil having lesser phosphorous content thereby enhancing the plant yield;
said modified nutrient laden/ intercalated biochar with improved N-release ability based on urea attained equilibrium N release condition of (174.33-180.95 mg/kg) at 24-48 h, and around 181 mg/kg of N leaching after 48 h, which is comparable with commercial fertilizers and without affecting and majorly altering P-release as overall P-release is determined to be 327.05 mg/kg after 48 h with said modified biochar thereby enabled with P-release ability that is 1.2 times improved over commercial fertilizer of DAP and N-release ability that is 3.5% higher than urea.

Preferably said food waste derived soil conditioner and organic fertilizer is provided as 2-7% formulation of biochar in aqueous base aiding seed germination with germination index as high as 93% indicative of non-phytotoxicity.

More preferably said food waste derived soil conditioner and organic fertilizer is provided as 2-7% formulation of biochar in soil base aiding plant growth.

According to another preferred aspect of the present invention there is provided said food waste derived soil conditioner and organic fertilizer wherein said chemical composition of pristine biochar includes

Properties and composition (wt.%) Pristine biochar/FertoCHAR
FC (fixed carbon) > 85.3 ± 7.0
Carbon > 69.0 ± 7.5
Nitrogen >1.2 ± 0.01
Oxygen ≤21.9 ± 4.50
Phosphorous* >92.76 ± 1.55
O/C Ratio# ≤0.31
O/C represents oxygen to carbon ratio (wt/wt %) *Readily available phosphorous (in mg/kg)

Preferably said food waste derived soil conditioner and organic fertilizer is provided wherein said chemical composition of modified biochar includes
Properties and composition (wt.%) Modified biochar/Modified FertoCHAR
FC (fixed carbon) >84.2 ±0.5 %
Carbon >61.6±0.3%
Nitrogen > 11.9±0.01%
Oxygen ≤22.1±3.15%
Phosphorous* >92.76 ± 1.55
O/C Ratio# ≤0.31
pH 6.55±0.4
BD 0.49±0.05
WHC (%) 52
WA (%) 41.1±0.1
Inhibition (%) 0.001
Release Capacity of N (mg/kg) 180.95 mg/kg
Release Capacity of P (mg/kg) 327.05 mg/kg
O/C represents oxygen to carbon ratio (wt/wt %) *Readily available phosphorous (in mg/kg)

According to another aspect of the present invention there is provided a process for manufacturing the food waste derived soil conditioner and organic fertilizer as pristine and modified biochar based formulation comprising the steps of
a. Selecting the suitable waste source as feedstock including commingled food waste comprising food waste and PE followed by drying and shredding such commingled food waste;
b. Providing microwave susceptors selectively including granulated activated carbon (GAC), Silicon carbide (SiC) or Zirconium-based alloy in said feedstock in select feedstock to susceptor ratio of 10:1-30:1 under inert atmospheric conditions and initiating microwave-assisted catalytic pyrolysis in a microwave based pyrolytic system;
c. attaining said biochar as pristine biochar by maintaining stipulated operating parameters including microwave power, temperature and residence time.

Preferably in said process of manufacturing wherein said pristine biochar thus attained is optionally modified with appropriate nutrient preferably urea as per requirement to improve corresponding nutrient release capacity for application as organic fertilizer and soil conditioner.

More preferably on said process for manufacturing wherein said stipulated operating parameters include easily tuneable operating microwave power (600-900 W), temperature (300-600 C), inert gas flow rate of 0.2 L/min and time of 10-30 minutes for said microwave pyrolysis depending on the amount of feedstock (50-250 g) to obtain the biochar, with required time varying inversely with the quantity of feedstock, that is followed by washing to remove surface impurities to be subsequently dried in an oven at 105 C for 1 h.

According to another preferred aspect of the present invention there is provided a process for manufacturing wherein said pristine biochar is modified to improve nitrate release ability by involving urea in the weight ratio of 1:1 whereby 10 g of urea was mixed in 100 mL of hot DI water (90 C) and was continuously stirred until all the urea granules get completely dissolved in water that is followed by adding 10 g of pristine biochar along with 1 g of binder including rice starch that was added to the hot solution and stirring for 30 minutes to obtain therefrom the modified biochar that is nutrient laden after the hot solution was allowed to dry at constant temperature of 65 C.

Preferably in said process for manufacturing wherein said microwave based pyrolytic system includes
inert gas line connected to the microwave control unit based microwave chamber to flush it with inert gas and houses quartz vessel/s to hold the feedstock and susceptor with the mouth of the quartz vessel connected to a condenser that is in turn connected to bio oil collection chamber fitted with an outlet for carrying out the syngas thus generated.

BRIEF DESCRIPTION OF FIGURES
Figure 1. (a) Schematic representation of microwave-assisted catalytic pyrolysis reactor, (b) commingled food waste (Feedstock), FertoCHAR;
Figure 2. Picture of customized microwave reactor;
Figure 3. (a) pHzpc of FertoCHAR, (b) WHC of FertoCHAR added soil;
Figure 41. SEM images of (a) FertoCHAR and (b) FertoCHAR with modification;
Figure 5. EDS images of (a) FertoCHARand (b) FertoCHAR with modification, and (c) comparison of elemental composition of (a), and (b);
Figure 6. FT-IR spectrum of FertoCHAR;
Figure 7.(a) P-release kinetics, (b) N-release kinetics from FertoCHAR and FertoCHAR with modification;
Figure 8. Schematic diagram of N and P release from FertoCHAR and FertoCHAR with modification;
Figure 9. % Germination based on N and P release from FertoCHAR and FertoCHAR with modification;
Figure 10. Plant growth and dry root: shoot ratio under control, 3%, 5%, and 8% FertoCHAR mixed soil conditions;
Figure 11. Root growth and density observed after 15 days under 0%, 3%, 5%, and 8% FertoCHAR conditions.

DETAILED DESCRIPTION OF THE INVENTION

As discussed hereinbefore, the present invention provides for food waste derived soil conditioner and organic fertilizer more particularly provides for commingled waste-based end-product named FertoCHAR as soil conditioner and organic fertilizer involving microwave-assisted catalytic pyrolysis technique. A method for preparation of commingled food waste based nutrient-laden organic fertilizer (termed as FertoCHAR) is provided that comprises the following steps: (1) drying and shredding commingled food waste; (2) characteristic analysis, microwave-assisted thermo-chemical conversion in inert conditions to obtain the carbon-rich material i.e., FertoCHAR; (3) cooling the FertoCHAR obtained in the step (2) to room temperature, characteristic analysis; (4) optional intercalation with urea and/or phosphate salts, and constant mixing using starch as binder at 65C to improve required nutrient release capacity of FertoCHAR. FertoCHAR serves as a single-step solution for fertilizer applications, capable of substituting a diverse array of chemical fertilizers for different nutrient requirement.
The present invention thus explored the opportunity of involving different susceptors like GAC, silicon carbide (SiC) and zirconium-based alloy for the scaled-up production of FertoCHAR with 50-250 g of feedstock through microwave-assisted catalytic pyrolysis and the porosity attained. The feedstock in current invention is such that the foodwaste is always proportionally higher than LDPE (i.e., foodwaste is > 50% by weight). Moreover, the LDPE proportion impart negligible changes in the biochar characterisitics, since the LDPE majorly influences the biooil yield and quality, where yield reduces with increased LDPE in the feedstock.

The susceptors involved in the current invention gives much improved performance improved than those studied in the inventors own prior published work possibly due to their superior dielectric properties. The greater tanδ value of GAC (0.6), SiC (0.7, in the environment of commingled food waste reaches ~1.7 value at temperature > 150C), and zirconium-based alloy signifies their superior efficacy in conversion of electromagnetic energy into thermal energy. Therefore, these susceptors reduces reaction time and thereby reduces energy burden during FertoCHAR production using microwave-assisted catalytic pyrolysis.


EXAMPLES
FertoCHAR preparation and characterization

FertoCHAR was prepared by microwave-assisted catalytic pyrolysis of commingled waste feedstock (Food waste: LDPE) in a customized batch mode microwave reactor with a maximum output power of 1000W and frequency of 2.45 GHz. Before beginning the pyrolysis process, the inert environment was maintained by purging the nitrogen gas for 20 min at a flow rate of 1 L/min. Pre-determined quantity of granular activated carbon (GAC) or silicon carbide (SiC) or Zirconium-based alloy was used as susceptor to enhance the microwave-assisted catalytic pyrolysis process. More particularly, the FertoCHAR was prepared by maintaining the susceptor: feedstock weight ratio of 1:20, microwave power at 800 W, temperature at 550 C and nitrogen gas flow rate of 0.2 L/min. The obtained FertoCHAR was washed with distilled water up to 3-4 cycles in order to remove the surface impurities and subsequently dried in an oven at 105 C for 1 h.

The FertoCHAR with modification (to improve nitrate release ability) was prepared by mixing FertoCHAR and urea in the weight ratio of 1:1. 10 g of urea was mixed in 100 mL of hot DI water (90 C) and was continuously stirred until all the urea granules are completely dissolved into the water. Later, 10 g of FertoCHAR along with 1 g of binder particularly, rice starch was added to the hot solution and was stirred for 30 minutes. Here, the rice starch acts as a binding material between FertoCHAR and urea. Later, the solution was allowed to dry at constant temperature of 65 C.
The physical and chemical characteristics of FertoCHAR required for studying its applicability as organic fertilizer and soil conditioner are shown in Table 1. The pH of FertoCHAR was found to be 6.58±0.3, which is in the range of effective pH range for plant growth (6.0-7.5). The pHzpc of the FertoCHAR was determined to be 6.85±0.5, providing the ability to resist the excessive (provide controlled) leaching of nutrients present in the soil. The toxicity analysis performed on FertoCHAR proved it to be least toxic with the inhibition of 0.001%, implying its safe for soil applications. Alongside, the bulk density and water absorbance capacity of FertoCHAR was calculated to be 0.48 g/cm3 and 41.4% respectively. Increase in water holding capacity (WHC) of soil was observed due to the presence of FertoCHAR in soil as depicted in Fig 3 (b). The water holding capacity of soil increased by 62.5% when 8 wt% FertoCHAR was added in soil compared to undisturbed soil. This increment in WHC could result in improved water availability for crops, and reduction in water leaching thereby escalating irrigation efficacy by reducing the need for frequent irrigation.
Table 1.Chemical characteristics of feedstock and FertoCHAR
Properties (wt.%) FW LDPE FW-LDPE FertoCHAR
FC (fixed carbon) 11.00 0.60 9.6 ± 0.5 > 85.3 ± 7.0
Carbon 41.17 69.71 44.8 ± 2.5 >69.0 ± 7.5
Nitrogen 2.06 0.12 1.8 ± 0.03 >1.2 ± 0.01
Phosphorous* >92.76 ± 1.55
O/C Ratio# 1.16 0.12 0.95 ≤0.31
O/C represents oxygen to carbon ratio (wt/wt %)
*Readily available phosphorous (in mg/kg)

Table 2. Characteristic comparison between soil and FertoCHAR
Characteristics Soil FertoCHAR FertoCHAR with modification
pH 5.78±0.4 6.58±0.3 *NVO
BD 1.41±0.02 0.48±0.04 *NVO
WHC (%) 32 52 *NVO
WA (%) - 41.4±0.07 *NVO
Inhibition (%) - 0.001 -
Release Capacity of N (mg/kg) #nd 55.27 mg/kg 180.95 mg/kg
Release Capacity of P (mg/kg) #nd 351 mg/kg 327.05 mg/kg
#nd: not detected; *NVO: negligible variation observed
As shown in Fig. 4 (a), the average pore size of FertoCHAR (4.98 µm) was determined in the range of storage pores (0.5-50 µm), implying better water and nutrient holding capability to capture and release nutrients in a controlled manner for enhanced plant growth. Similarly, Fig. 4 (b) represents the surface morphology of the FertoCHAR with modification, where the urea particles (flaky substances) were found to be attached/deposited on the FertoCHAR surface, without hampering its native pores. The average pore size of FertoCHAR with modification was determined to be 4.87 µm, which translates to negligible interruption in the porous nature of the FertoCHAR after modification. The surface area of FertoCHAR and FertoCHAR with modification were determined to be 6.89 m2/g and 6.53 m2/g. The slight reduction in the surface area of the FertoCHAR post modification by circa 5% can be attributed to the deposition of urea particles on the surface of the FertoCHAR. The elemental composition of FertoCHARand FertoCHAR with modification was determined using EDS (Fig. 5 (a), (b)) and corresponding comparison is depicted in Fig. 5 (c). The atomic ratio of O/C for both FertoCHAR (pristine and modified) were found to be 0.313 and 0.304 respectively. The lower O/C ratio (0.2-0.6) defines that the current FertoCHAR could remain stable with half-life of 100-1000 years. Alongside, the increase in nitrogen weight content by ~ 86.2 % also suggests that urea was loaded on the surface of FertoCHAR.
FT-IR spectroscopic results (Fig 6) were analysed to understand the presence of different functional groups and their influence on soil applicability of FertoCHAR. The spectral peak around 2923 cm-1 and 2855 cm-1 confirmed the presence of N─H and P─OH functional groups respectively which attribute to the presence of N and P in higher concentrations, in readily-available form for plant uptake. The primary functional groups that comprise FertoCHAR consist of aromatic and heterocyclic carbons, which have been recognised for their chemical recalcitrance, hence promoting stability within soil environments. The strong peaks at 1698 cm-1 confirms the presence of oxygen-rich functional groups like ─COOH, C=O which provides better nutrient exchange opportunities. These sites promotes the microbial activity thereby making it suitable for application in arid soils. The improved N availability after urea-intercalation can be attributed to the spectral band around 1037 cm-1 and 1615 cm-1 denoting C─O and aromatic stretch of C=C functional groups which could facilitate adsorption and subsequently react with ammonia.
Fertilizer potential studies
The fertilizer potential of FertoCHARwas studied using the methodology of nutrient-release kinetics for 2880 min (48 h). Figure 7 (a) and (b) represents the leaching behaviour of phosphate (P) and nitrate (N) respectively. In case of P release study, the equilibrium release condition (312.91 mg/kg) was achieved after 900 min, and similar release rate was observed at later intervals. The maximum amount of P leached (351 mg/kg) was determined at 40 h, which is comparable with the phosphate release rate of commercial fertilizer named Di-Ammonium Phosphate (DAP) i.e., 280 mg/kg. The equilibrium condition (54.43 mg/kg) for N release was achieved after 300 min, however the maximum amount of N leached (55.27 mg/kg) was observed at 48 h, which is comparatively lesser than that of commercial fertilizer (174-225 mg/kg). Thus, it can be inferred that FertoCHAR alone suits to support the soils with lesser phosphorous content thereby enhancing the plant yield. In order to improve N-release ability, the FertoCHAR was upgraded/modified using urea as the additive. The N-leaching study of such obtained FertoCHAR with modification shown promising result of equilibrium condition (174.33 mg/kg) at 24 h, and slightly greater release rate at later intervals. Around 181 mg/kg of N leaching was observed after 48 h, which is in comparable range with commercial fertilizers. This modification of FertoCHAR with urea has not shown any major alteration in P-release, since the overall P-release was determined to be 327.05 mg/kg after 48 h.
Overall, the FertoCHAR with modification was found to provide better nutrient supply (with P and N release of 327.05 mg/kg and 180.95 mg/kg respectively) and improve soil characteristics for the effective plant growth and thereby can be used as a potential organic fertilizer and soil conditioner to enhance crop yield.
FertoCHAR application rate in soil
The nutrient content in the FertoCHAR plays vital role in it application rate in soils alongside other factors viz. plant uptake capacity, soil supply power, etc. The nutrient release capacity of FertoCHAR in terms of nitrate and phosphate were determined to be better than commercial fertilizers. DAP and urea to be the major fertilizers to be used in crop production for phosphate and nitrate supply respectively to the crop. The P-release ability of FertoCHAR post modification was determined to be 1.2 times better than commercial fertilizer like DAP and N-release ability was 3.5% higher than urea.
Reported commercial fertilizer application for wheat production is 75 kg/ha of DAP implying P-requirement of 21 g/ha and 150 kg/ha of urea implying N-requirement of 26.25 g/ha. A total of 225 kg/ha of commercial fertilizer was required to provide required nutrients. The required dosage of FertoCHAR to replace DAP (WFertoCHAR(P)) and urea (WFertoCHAR(N)) was calculated using Eq. 12 and 13 respectively.
The quantity of FertoCHAR required in terms of P-requirement is
(Eq. 12)
The amount of modified CFWB required in terms of N-requirement is
(Eq. 13)
Therefore, applying 145.02 kg/ha of FertoCHARwould replace the net commercial fertilizer dosage of 225 kg/ha.
Seed germination and plant growth studies
VignaRadiata (Green moong) seeds were used for seed germination experiments with distilled water, and aqueous extracts of FertoCHAR and soil separately. The seeds were sterilized by rinsing with 0.1 M NaOCl for 15 min, later washed thrice using distilled water. Three sets of 4 seeds each were used for the experiment aggregating to 12 seeds for each sample (distilled water, aqueous extract of FertoCHAR and aqueous extract of soil). Aqueous extracts of FertoCHAR and soil were obtained by agitating 100 mL of distilled water with 5 g of FertoCHAR and soil respectively. The seeds were placed on the filter paper wetted with 5 mL of sample on the petri dish and kept at 27±2 ℃ for 72 h, maintaining 12 h light - dark photo period throughout. After 72 h, seed germination percentage was calculated as per the Eq. 14 along with the average radicle length for each sample. Further the phytotoxicity of FertoCHAR was assessed by determining the germination index as per Eq. 15.
(Eq. 14)
(Eq. 15)
Where, %G represents seed germination percentage, Le represents mean total radicle length of germinated seeds from FertoCHAR aqueous extract, and Lc represents mean root length of the seeds germinated from distilled water.
The seed germination rate from each sample is represented in Figure 9. Highest seed germination (75%) was observed in FertoCHAR aqueous extract, followed by distilled water (50%) and aqueous extract of soil (33.3%), after 72 h. A total of 9 seeds were generated from 3 sets of FertoCHAR samples after 48 h which remained constant till 72 h, whereas delayed seed generation was observed in distilled water and soil conditions. However, the germination remained constant after 48 h in case of soil conditions whereas the germination rate increased 41.6 - 50% between 48 and 72 h under distilled water conditions. Moreover, the average radicle length of seeds germinated from FertoCHAR extract was measured to be 17.54 ±2.04 mm, followed by 14.12 ± .34 mm (distilled water) and 10.83 ± .68 mm (Soil). It can thus be inferred that the presence of FertoCHAR improved the seed germination rate and radicle length. The germination index (GI) for FertoCHAR application was calculated to be 93.2% suggesting its non-phytotoxic nature, where GI < 50% implies high phytotoxicity, GI between 50-80% implies moderate phytotoxicity and GI > 80% implies no phytotoxicity.
For plant growth studies, FertoCHAR was mixed with soil in 3 different proportions viz. 3%, 5%, and 8% by weight, along with control setup (0%). Custom-made self-watering pots were designed using waste single-use plastic water bottles. 200 g of sample (0%, 3%, 5%, and 8% FertoCHAR) were added in each pot maintained with 100 mL of distilled water. The pots were left undisturbed for 48 h and later the water availability of each sample was determined using Eq. 16. Further, VignaRadiata seeds were sown in each sample and the plant growth was measured daily for 15 days. Later, the plants were up-rooted and cleansed carefully with distilled water to determine the weight and root growth in each sample. Moreover, the dry root to shoot ratio were also calculated.
(Eq. 16)
The available water percentage in each self-watering pots were improved with increase in FertoCHAR content in soil from 27.6% - 38.8%, attributing to the porous structure of FertoCHAR leading to greater water absorption through capillary action. Steady plant growth was observed in control and 3% FertoCHAR conditions from day 1, but no plant growth was observed in 8% FertoCHAR conditions till 5 days. Slower growth was noticed in 5% FertoCHAR conditions compared to control and 3% FertoCHAR, which later overtaken control after 7 days. The final plant length above soil level was found to be 135, 210, 191, and 88 mm for 0, 3, 5, 8% FertoCHARrespectively (Figure 10). The total plant biomass reduced significantly from 495.3 mg to 234.5 mg with increasing FertoCHAR application from 3% to 8%, possibly due to insufficient air supply from pore blockage with excess moisture, supported by the reduced spread of roots with increased FertoCHAR percentage. No particular change was detected in root thickness or color, but the length varied significantly ranging 210 mm-750 mm, with different FertoCHAR proportions. The root length increased ~3 times for 3% FertoCHAR addition compared to control (Figure 11). With the continued increase in FertoCHAR proportions, there was a noticeable decrease in root length, indicating a reduction in the opportunity for root penetration due to pore closure. However, the dry root to shoot ratio reduced (0.4 - 0.2) with FertoCHAR addition (0-8%) suggesting better availability of nutrients post FertoCHAR application. It can be inferred that 3% application of FertoCHAR provided better conditions for enhanced plant growth compared to the control conditions contemplating the applicability of FertoCHAR as an efficient organic fertilizer.

The uniqueness of the present invention:
Existing fertilizers that are commercially in use are chemical driven and impacts negatively to the soil and surrounding environment in the long run. These commercial fertilizers provide specific nutrient required for the plant growth requiring different types of fertilizers to be provided for different nutrient supply for plants. Such high rate of fertilizer application decreases the amount of organic matter in the soil, which can lead to soil acidification. Further, commercial fertilizers do not have soil conditioning abilities rather they negatively impact soil structure, nutrient runoff leading to soil desertification. Different biochar were reported to be used alongside these fertilizers to reduce the above mentioned negative impacts on soil quality. Moreover, biochar were prepared using conventional pyrolysis technique which yielded lower quality biochar and also much time consuming.
The uniqueness of this study lies in preparation of major MSW namely commingled food waste based organic fertilizer (FertoCHAR) using microwave assisted catalytic pyrolysis technology at operating conditions of microwave power (600-900 W), temperature (300-600 C), microwave susceptor (GAC, SiC, zirconium based alloy), feedstock: susceptor ratio (1:10-1:30) under inert atmospheric conditions. Adopting such advanced method produced high quality and nutrient-rich FertoCHAR with better porous structure which improves soil characteristics alongside fertilizer ability. The obtained carbon-based nutrient-rich FertoCHAR having such improved porous structure was modified with urea for improved nitrate release. Such modifications had no adverse effect on other properties of FertoCHAR. The major uniqueness of the present invention is the ability of FertoCHAR being the single step solution for organic fertilizer application instead of multiple fertilizers for different nutrient supply. Another uniqueness of the present invention is that the method and process is not a material specific, instead any commingled waste or by-product is an ideal resource material for manufacturing FertoCHAR simply by adjusting other operating parameters.
The susceptors utilized in this present invention demonstrate enhanced performance giving better porous structures compared to those examined in our previous research, owing to their exceptional dielectric characteristics. The higher tanδ values of GAC (0.6), SiC (0.7, which approaches ~1.7 at temperatures exceeding 150C), and zirconium-based alloy highlight their enhanced effectiveness in transforming electromagnetic energy into thermal energy. However, the susceptors do not affect the quality of biochar, assuming similar operating conditions are maintained. Consequently, these susceptors minimize reaction time and thus lessen the energy demand during the production of FertoCHAR through microwave-assisted catalytic pyrolysis.
The feedstock in the present invention is characterized by a consistent ratio where food waste exceeds LDPE, specifically with food waste comprising more than 50% by weight. Furthermore, the proportion of LDPE results in minimal alterations to the characteristics of biochar, as LDPE primarily affects the yield and quality of biooil, with yield decreasing as the amount of LDPE in the feedstock increases. Since, the biochar quality remains unaffected, the dosage levels as specified shall suit the effective plant growth.
Foodwaste considered in this present invention is focused on Indian context and thereby majorly comprised of rice, breads (or rotis), pulses and fruit and vegetable peels with high nutritional content in terms of N and P. The biochar production was carried out preferably by involving 50-250 g of feedstock with major portion consisting of foodwaste (> 50 wt. %). The variation in LDPE wt. % had insignificant effect on biochar quality, however biooil yield and quality improved with increase in LDPE content in feedstock.
The significant finding of the present invention that cannot be easily envisaged by a person skilled in the art is because the present invention is very special and different from the available methods to produce FertoCHAR also allowing optional upgradation to convert into organic fertilizer with nitrate release ability as:
 It involves advanced thermochemical conversion technique i.e., microwave assisted catalytic pyrolysis technique for conversion of commingled waste into FertoCHAR with a potential for organic fertilizer application.
 This FertoCHAR can act as one-step solution for providing required nutrients for plant growth instead of using multiple fertilizers for each nutrient.
 Apart from fertilizing ability, FertoCHAR also improves corresponding soil properties like pH, water and nutrient holding capacity, and bulk density of soil responsible for improved plant growth.
 In summary, the FertoCHAR developed by way of the present invention has the capacity to serve as an environmentally friendly and stable organic fertiliser, improving crop productivity and minimising nutrient loss by virtue of its superior water and nutrient retention capabilities.
The present invention has the following advantages;
1) The present invention promotes bulk or large scale utilization of different kinds of commingled wastes like organic MSW, agricultural wastes, etc. More particularly, current work utilized commingled food waste (food waste along with plastics), which addressed the pertaining issue of waste collection and segregation.
2) The present invention adopts advanced thermochemical conversion technique namely microwave-assisted catalytic pyrolysis method and simple modification (if required) to produce FertoCHAR with storage porous structure ranging from 0.5-50 µm and better water and nutrient release ability.
3) Microwave-assisted catalytic pyrolysis is advantageous over conventional pyrolysis methods since it involves energy transfer mechanism, rapid, selective, and volumetric heating that produces high quality end-product under less residence time. Moreover the other by-products like bio-oil and syngas of high quality shall also be produced.
4) As the production of FertoCHAR uses commingled waste, there is no carbon footprint on the environment.
5) Use of commingled wastes like MSW reduces the burden on land acquisition for storage, open dumping, landfilling area and their perpetual maintenance.
6) The manufactured FertoCHAR could be a potential, doable and viable substitute to chemical fertilizers, either fully or partially.
7) The proposed methodology is simple and easy to use and feasible for large scale production.
8) No specific skill of a person is required for manufacturing FertoCHAR.
9) Equipment cost is low and can be manufactured indigenously, within India.
, Claims:We Claim:
1. Food waste derived soil conditioner and organic fertilizer comprising: co-activated and microwave pyrolyzed comingled food waste based nutrient laden biochar as organic fertilizer having a selective range of comingled food waste feedstock and microwave susceptors including one of the granular activated carbon, silicon carbide and zirconium-based alloy in the weight ratio of 10:1 to 30:1 having pH in the range of 6.58±0.3 and a storage porous structure ranging from 0.5-50 µm for enhanced water holding capacity.

2. The food waste derived soil conditioner and organic fertilizer as claimed in claims 1 wherein said biochar as pristine biochar is further adaptive to nitrogen based nutrient intercalation/modification having average pore size of 4.98 µm, surface area of 6.89 m2/g, bulk density of 0.48 g/cm3 and water absorbance capacity (WHC) of 41.4%, is least toxic with the inhibition of 0.001%, whereby water holding capacity of soil increases by 62.5% when 8 wt% of said biochar is added in soil as compared to undisturbed soil thereby adapted for soil conditioning.

3. The food waste derived soil conditioner and organic fertilizer as claimed in claims 1 or 2 wherein said biochar as P-nutrient based pristine biochar is modified to intercalated N-nutrient laden biochar with improved nitrate release ability and is preferably urea laden/intercalated in the ratio of biochar: urea of 1:1 together with binder material including rice starch in proportions of biochar-urea: rice starch of 5:1 to 15:1.

4. The food waste derived soil conditioner and organic fertilizer as claimed in claims 1-3 wherein
said biochar is a microwave assisted/ pyrolysed biochar of said polyethylene (PE) commingled food waste feedstock,
said polyethylene (PE) commingled food waste feedstock includes MSW (municipal solid waste) based food waste along with LDPE (low density polyethylene) suitable as direct feed free of requirement of segregation of plastic from food waste.

5. The food waste derived soil conditioner and organic fertilizer as claimed in claims 3-4 wherein said modified nutrient laden biochar have average pore size of 4.87 µm translating to negligible interruption in the porous nature of the modified biochar and having surface area of 6.53 m2/g post modification by 5% urea attributed to the deposition of urea particles on the surface of the biochar.

6. The food waste derived soil conditioner and organic fertilizer as claimed in claims 1-5 wherein said pristine and modified biochar have atomic ratio of O/C of 0.313 and 0.304 respectively indicative of stability with half-life of 100-1000 years in having O/C ratio in the range of (0.2-0.6), and with the modified biochar having increased nitrogen weight content by ~ 86.2 % is indicative of urea loading/intercalation on surface of the biochar.

7. The food waste derived soil conditioner and organic fertilizer as claimed in claims 1-6 attains anyone or more of the following wherein
said pristine biochar for P release attains equilibrium release condition (312.91 mg/kg) after 900 min, with maximum amount of P leaching of (351 mg/kg) being determined at 40 h, comparable to phosphate release rate of commercial fertilizer named Di-Ammonium Phosphate (DAP) i.e., 280 mg/kg;
said pristine biochar attains equilibrium N release condition of (54.43 mg/kg) after 300 min, with the maximum amount of N leached (55.27 mg/kg) at 48 h, which is comparatively lesser than that of commercial fertilizer (174-225 mg/kg), thereby supporting conditioning of the soil having lesser phosphorous content thereby enhancing the plant yield;
said modified nutrient laden/ intercalated biochar with improved N-release ability based on urea attained equilibrium N release condition of (174.33-180.95 mg/kg) at 24-48 h, and around 181 mg/kg of N leaching after 48 h, which is comparable with commercial fertilizers and without affecting and majorly altering P-release as overall P-release is determined to be 327.05 mg/kg after 48 h with said modified biochar thereby enabled with P-release ability that is 1.2 times improved over commercial fertilizer of DAP and N-release ability that is 3.5% higher than urea.

8. The food waste derived soil conditioner and organic fertilizer as claimed in claims 1-7 as 2-7% formulation of biochar in aqueous base aiding seed germination with germination index as high as 93% indicative of non-phytotoxicity.

9. The food waste derived soil conditioner and organic fertilizer as claimed in claims 1-7 as 2-7% formulation of biochar in soil base aiding plant growth.

10. The food waste derived soil conditioner and organic fertilizer as claimed in claims 1-9 wherein said chemical composition of pristine biochar includes
Properties and composition (wt.%) Pristine biochar/FertoCHAR
FC (fixed carbon) > 85.3 ± 7.0
Carbon > 69.0 ± 7.5
Nitrogen >1.2 ± 0.01
Oxygen ≤21.9 ± 4.50
Phosphorous* >92.76 ± 1.55
O/C Ratio# ≤0.31
O/C represents oxygen to carbon ratio (wt/wt %) *Readily available phosphorous (in mg/kg)

11. The food waste derived soil conditioner and organic fertilizer as claimed in claims 1-10 wherein said chemical composition of modified biochar includes
Properties and composition (wt.%) Modified biochar/Modified FertoCHAR
FC (fixed carbon) >84.2 ±0.5 %
Carbon >61.6±0.3%
Nitrogen > 11.9±0.01%
Oxygen ≤22.1±3.15%
Phosphorous* >92.76 ± 1.55
O/C Ratio# ≤0.31
pH 6.55±0.4
BD 0.49±0.05
WHC (%) 52
WA (%) 41.1±0.1
Inhibition (%) 0.001
Release Capacity of N (mg/kg) 180.95 mg/kg
Release Capacity of P (mg/kg) 327.05 mg/kg
O/C represents oxygen to carbon ratio (wt/wt %) *Readily available phosphorous (in mg/kg)
12. A process for manufacturing the food waste derived soil conditioner and organic fertilizer as claimed in claims 1-11 as pristine and modified biochar based formulation comprising the steps of
a. Selecting the suitable waste source as feedstock including commingled food waste comprising food waste and PE followed by drying and shredding such commingled food waste;
b. Providing microwave susceptors selectively including granulated activated carbon (GAC), Silicon carbide (SiC) or Zirconium-based alloy in said feedstock in select feedstock to susceptor ratio of 10:1-30:1 under inert atmospheric conditions and initiating microwave-assisted catalytic pyrolysis in a microwave based pyrolytic system;
c. attaining said biochar as pristine biochar by maintaining stipulated operating parameters including microwave power, temperature and residence time.

13. The process for manufacturing as claimed in claims 12 wherein said pristine biochar thus attained is optionally modified with appropriate nutrient preferably urea as per requirement to improve corresponding nutrient release capacity for application as organic fertilizer and soil conditioner.

14. The process for manufacturing as claimed in claims 12 or 13 wherein said stipulated operating parameters include easily tuneable operating microwave power (600-900 W), temperature (300-600 C), inert gas flow rate of 0.2 L/min and time of 10-30 minutes for said microwave pyrolysis depending on the amount of feedstock (50-250 g) to obtain the biochar, with required time varying inversely with the quantity of feedstock, that is followed by washing to remove surface impurities to be subsequently dried in an oven at 105 C for 1 h.

15. The process for manufacturing as claimed in claims 12-14 wherein said pristine biochar is modified to improve nitrate release ability by involving urea in the weight ratio of 1:1 whereby 10 g of urea was mixed in 100 mL of hot DI water (90 C) and was continuously stirred until all the urea granules get completely dissolved in water that is followed by adding 10 g of pristine biochar along with 1 g of binder including rice starch that was added to the hot solution and stirring for 30 minutes to obtain therefrom the modified biochar that is nutrient laden after the hot solution was allowed to dry at constant temperature of 65 C.

16. The process for manufacturing as claimed in claims 12-15 wherein said microwave based pyrolytic system includes
inert gas line connected to the microwave control unit based microwave chamber to flush it with inert gas and houses quartz vessel/s to hold the feedstock and susceptor with the mouth of the quartz vessel connected to a condenser that is in turn connected to bio oil collection chamber fitted with an outlet for carrying out the syngas thus generated.




Dated this the 30th day of October, 2024 Anjan Sen
Applicants Agent
IN/PA-199

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