WO2024057333A1

WO2024057333A1 - A process for preparing bio products from biomass for a low carbon economy

Info

Publication number: WO2024057333A1
Application number: PCT/IN2023/050469
Authority: WO
Inventors: Rohit Khaitan; Mamta KHAITAN
Original assignee: Rohit Khaitan
Priority date: 2022-09-16
Filing date: 2023-05-18
Publication date: 2024-03-21

Abstract

The present disclosure relates to a process for preparing bio-products from biomass. The present disclosure relates to ecologically sustainable process for preparation of 2nd generation ethanol by hydrolysis of celluloses of ligno-cellulosic biomass followed by co-fermentation of pentose and hexose sugars along with valorization of lignin to generate heat to produce steam & power and simultaneously produce precipitated silica and gypsum as additional bio-products. The present disclosure provides an efficient, cost-effective, eco-friendly, bio-safe and a circular biochemical process with recovery and reuse of chemicals and which is suitable for industrial preparation and providing a high yield process. There is zero liquid discharge and substantial reduction in carbon dioxide emissions as compared to burning fossil fuels. The main product from the process of this disclosure provides the platform for aviation fuels and preparation of green biodegradable plastics.

Description

A PROCESS FOR PREPARING BIO PRODUCTS FROM BIOMASS FOR A LOW CARBON ECONOMY

TECHNICAL FIELD

[0001] The present disclosure relates to a process for preparing bio-products from biomass. The present disclosure relates to ecologically sustainable process for preparation of 2^nd generation ethanol by hydrolysis of celluloses of ligno-cellulosic biomass followed by co-fermentation of pentose and hexose sugars along with valorization of lignin to generate heat to produce steam & power and simultaneously produce precipitated silica and gypsum as additional products. The process of present disclosure is an efficient, cost-effective, eco-friendly, bio-safe, circular biochemical process with recovery and reuse of chemicals, zero liquid discharge, reduction in carbon dioxide emissions.

BACKGROUND

The need for Biofuels, Present & Future:

[0002] ‘De-carbonization’ refers to the process of reducing ‘carbon intensity’, lowering the amount of greenhouse gas emissions produced by the burning of fossil fuels. De-carbonization is achieved by switching to usage of low carbon energy sources. By replacing fossil fuels with biofuels — fuels produced from renewable organic material — has the potential to reduce the undesirable aspects of fossil fuel production and use, including conventional and greenhouse gas (GHG) pollutant emissions, exhaustible resource depletion, and addressing climate change by contributing to lowering the average temperature increase and achieving net-zero carbon emissions. First generation biofuels are made from sugar crops (sugarcane, sugar-beet) and starch crops (corn, rice, sorghum etc.). Sugar and starch crops are converted through a fermentation process to form bio-alcohols, including ethanol, butanol, and propanol. Second generation biofuels, or cellulosic biofuels, are made from cellulose, which is available from non-food crops such as bamboo and agricultural waste biomass like rice straw, bagasse, corn stover & corncobs. Replacing fossil fuels with biofuels has the potential to generate a number of benefits. In contrast to fossil fuels, which are exhaustible resources, biofuels are produced from renewable feedstocks. Thus, their production and use could, in theory, be sustained indefinitely. Globally, domestic production of ethanol is a prime objective for energy security and reducing dependence of crude oil (fossil fuels).

[0003] Ethanol is the most widely used bio-ethanol fuel. Most vehicles can use gasoline-ethanol blends containing up to 10 percent ethanol (by volume). Flexible fuel vehicles can use E85, a gasoline-ethanol blend containing up to 85 percent ethanol. A recent research by a French public research institution (IFPEN) showed that plug-in flex fuel hybrid vehicles running on E85 were as eco-friendly as pure electric vehicles and have similar greenhouse gas mitigation on the basis of a full life cycle analysis.

[0004] India is the fourth leading consumer of fossil petroleum derived fuel across the world and also the fourth biggest emitter of greenhouse gasses (GHG). The country heavily depends on the import of petroleum products due to the requirement of more than 95% of transportation fuel from petroleum products. Hence it is imperative to replace this major portion of transportation fuel with alternative renewable energy notably through 2G ethanol. Moreover, India generates about 6.50 xlO⁸ MT (metric tons) of agro-residues, so huge quantities of ligno-cellulosic biomass are available although major part of these is utilized for other purposes (Sukumaran et al., 2017).

Current Approaches for production of 2^nd generation ethanol and their limitations:

[0005] For cellulosic ethanol (or 2^nd generation ethanol), commercial size plants have been constructed in Europe, US and Brazil, but regular and reliable production is yet to be proven. Without heavy government support and subsidies, these plants have proven to be commercially unviable. In 2015, Beta Renewables started up operations at the first industrial cellulosic ethanol plant in the world. The 40 million gallons per year (MMgy) plant, located in Crescentino, Italy, was reported to operate on a daily basis, shipping cellulosic ethanol to Europe. However, Beta Renewables was sold in 2018.

[0006] DuPont started producing cellulosic ethanol at its 30-MMgy plant in Nevada, USA. In 2017, DuPont announced that it intends to sell its cellulosic biofuels business and the company found a buyer in VERBIO Vereinigte BioEnergie AG, a German company that produces renewable biogas. In 2015, Abengoa celebrated the opening of a 25 MMgy cellulosic ethanol plant in Hugoton, Kansas, USA. However, in 2016, after experiencing financial difficulties, Abengoa declared its cellulosic bioethanol plant in bankruptcy.

[0007] In 2014, GranBio started up a cellulosic ethanol plant with a capacity of 20 MMgy in Brazil. However, the plant suspended operations in 2016 due to technical difficulties in the pretreatment stage and resumed operations in 2019. In 2017, Enviral (Slovakia) acquired a license to use Clariant’ s sunliquid technology (Switzerland) in a commercial-scale plant for the production of ethanol from agricultural residues. The planned plant will be integrated into the Enviral’ s facility at Leopoldov, Slovakia, and will have an annual production capacity of 50 ktons (15 MMgy).

[0008] In 2014, POET-DSM Advanced Biofuels, a 50/50 joint venture between Royal DSM (Netherlands) and POET, LLC (USA), opened its Project Liberty facility in Emmetsburg, Iowa, USA. The cellulosic ethanol facility was set to produce 20 MMgy of ethanol and then ramp up to 25 MMgy [28]. In 2017, the company achieved a major breakthrough by announcing that Project Liberty was running pre-treatment at 80 percent uptime. However, the plant shut operations in November 2019.

[0009] IOCL’ s 9 mmgy capacity plant has been set-up at Panipat, Haryana India in August 2022 and is based on the enfinity technology patented by PRAJ is estimated to prepare 100 kiloliter of ethanol per day from 667 MT of rice straw. The project will be costing nearly INR 1000 crores as per the press release. The yield of ethanol is barely 150 litres per MT of straw.

[0010] Regardless of all these efforts, the global new investment in 2^nd generation ethanol continues to decline. Several sources mention costs as the main issue for the development of the cellulosic ethanol sector. Cellulosic ethanol production is still facing significant technology challenges and is showing significant capital and operational costs due to the complexity of the conversion processes and low maturity of the technology. The reported ranges of production costs for cellulosic ethanol appear to be substantially higher compared to conventional (or 1st generation) ethanol prices. Overall, the development of both energy and cost effective pretreatment, hydrolysis and fermentation, remain the challenges hindering large-scale deployment of lignocellulosic biomass conversion to ethanol. Challenges encountered in sustainable production of 2^nd generation ethanol: a) An effective separation process for the biomass constituents after pre-treatment remains a challenge. b) Quantity and cost of enzymes also represents a relevant cost component of the operational costs and reducing this cost is key to making cellulosic ethanol economically viable. c) Simultaneous utilization of pentose sugars by highly effective industrial yeast strains is still a challenge in developing continuous fermentation, which is expected to increase the yield and reduce the cost of the final product. Even after remarkable research and developmental activities in the last several decades, production of 2G ethanol from lignocellulosic biomass is still challenging with regard to utilization of pentoses. Saccharomyces cerevisiae is a well-established ethanologen which ferments hexoses to ethanol very efficiently (shown in Figure 1). However, some reports are there showing ability of S. cerevisiae strains to grow on xylose at slow rates owing to the presence of genes related to xylose metabolism (Patino et al., 2019). Lots of research has been directed towards the expression of heterologous genes through recombinant DNA technology to enable it to ferment xylose (Jin and Jeffries, 2004; Ruohonen et al., 2006; Chu and Lee, 2007). However, a significant yield was not obtained using recombinant strains and they do not possess robustness required in context to industry as well as they are specific towards particular type of biomass. d) The Production of value added products other than ethanol from the input biomass is a significant key to unlock the potential of a viable circular bioprocess to produce 2nd generation cellulosic ethanol. Multiple product streams reduce the dependence on ethanol as the main revenue generator, thereby making the technology commercially attractive. e) The fate of lignin and hemicelluloses are one of the important challenges to be overcome. Separated raw material constituents (i.e. lignin and extractives) have to be either further converted into value-added products or utilized economically (Monica Padella et al; Appl. Sci. 2019). f) Amisha Patel et al (Journal of Bio-resources and Bio-products, 2021) reported several challenges which block industrial progress for cost effective and commercial production. Key challenges are related to pre-treatment, enzymatic saccharification, fermentation process, limitations of ethanologens and waste utilization. Integrated lignocellulosic bio-refinery: Gateway for production of second generation ethanol and value added products. Prior arts

[0011] IN270534 discloses a process for the preparation of ethanol by hydrolysis of celluloses of ligno-cellulosic bio-mass which introduces an alkaline pulping stage after the hemi -cellulose hydrolysis & before cellulose hydrolysis to remove lignin. A presoaking step is provided in the various hydrolysis and pulping steps for better and thorough hydrolysis of cellulose under milder conditions.

[0012] IN328578 discloses a transformed microorganism capable of converting an aldopentose to a ketopentose at a higher rate than the equivalent microorganism prior to transformation.

[0013] IN307801 discloses a transformed microorganism capable of one or more of the following:

(a) a higher xylose isomerase activity than the equivalent microorganism prior to transformation;

(b) a higher growth rate in or on a growth medium comprising xylose than the equivalent microorganism prior to transformation; (c) a faster metabolism of xylose than the equivalent microorganism prior to transformation; (d) a higher production of ethanol when grown anaerobically on xylose as the carbon source than the equivalent microorganism prior to transformation.

[0014] WO2016134195 discloses a low-cost process to render lignocellulosic biomass accessible to cellulase enzymes, to produce fermentable sugars. Some variations provide a process to produce ethanol from lignocellulosic biomass (such as sugarcane bagasse or corn stover), comprising introducing a lignocellulosic biomass feedstock to a single-stage digester; exposing the feedstock to a reaction solution comprising steam or liquid hot water (213) within the digester, to solubilize the hemicellulose in a liquid phase and to provide a cellulose -rich solid phase; refining the cellulose-rich solid phase, together with the liquid phase, in a mechanical refiner, thereby providing a mixture of refined cellulose -rich solids and the liquid phase; enzymatically hydrolyzing the mixture in a hydrolysis reactor with cellulase enzymes, to generate fermentable sugars; and fermenting the fermentable sugars to produce ethanol.

[0015] W02009005390 discloses the method is intended to produce bioethanol from lignocellulose materials the plant origin; it is based on the mechanochemical (mechanoenzymatic) treatment of a solid mixture of the lignocellulose substrate and cellulosolytic enzymatic complexes, fermentation of the resulting carbohydrates by ethanologenic microorganisms. The mechanoenzymatic treatment is mechanical treatment of the solid mixture of the lignocellulose substrate and complex enzymes that ensures a high reactive ability of the enzymatic hydrolysis that enables to preserve the activity of the enzymes and equally to save their consumption.

[0016] None of the above prior arts disclose a successful design, engineering and demonstration of a continuous hydrolyzer for pre-treatment of cut straw with consistent and repeatable results and efficient breakdown of long chain hemi -cellulose to short chain sugar pentose.. None of the prior arts discloses recovery of silica and gypsum, which are valuable by-products, which make the entire technology proposition commercially viable. Also, none of the prior arts discloses pentose assimilation for ethanol preparation at an industrial scale. Most significantly, none of the prior art discloses an efficient recovery of reusable water through ultra/nano filtration during the processing of sugars generated from cellulosic materials. The complete process flow diagram of the present disclosure is as shown in Figure 3.

[0017] There is an ongoing need for a new and improved process of preparing bio-products from biomass which is efficient, cost-effective, bio-safe, eco-friendly and leads to less generation of waste. It also necessary to obtain the bio product with a higher yield, suitable for industrially relevant and robust process.

OBJECTIVES

[0018] The objective of the present disclosure is to provide a process for preparing bio-products from biomass by hydrolysis of celluloses of ligno -cellulosic biomass followed by co-fermentation of pentose and hexose sugars along with valorization of lignin to generate heat to produce steam & power and simultaneously produce precipitated silica and gypsum as additional products.

[0019] Another object of the present disclosure is to provide a process which is efficient, cost- effective, eco-friendly, bio-safe, circular biochemical process with recovery and reuse of chemicals. The process of present disclosure has zero liquid discharge and reduction in carbon dioxide emissions relative to fossil fuels. The process provides platform for aviation fuels, and for preparation of green biodegradable plastics.

[0020] It is further object of present disclosure is to provide a process provide high yields and suitable for industrial preparation.

SUMMARY

[0021] An aspect of present disclosure provides a process for preparing bio-products from biomass comprising: a) treating the biomass in a fully pressurized vessel (121, 123, 125 & 127) for a vapour phase reaction to obtain a treated biomass (131); b) separating the treated biomass (131) by solid liquid separation to obtain a Cs hydrolysate (145) and a solid form (203); c) neutralizing Cs hydrolysate (145) with a neutralizing agent to obtain an alkaline sugar stream (303) and a byproduct gypsum; d) ultra (305) and nano-filtering (317) the alkaline sugar stream (303) to obtain a first concentrated sugar solution (319) and an alkaline water permeate (323); e) subjecting the solid form with enzymatic cellulose saccharification and separating by solid liquid separation to obtain a Ce hydrolysate (221) and a filter cake (219); f) nano-filtering (317) the Ce hydrolysate (221) to obtain a second concentrated sugar solution (413) and process water; g) co-fermenting the first (319) and second sugar solutions (413) to obtain a fermented solution (629, 703); h) distilling (705 & 707) and dehydrating the fermented solution to obtain a bio-product ethanol; i) drying the filter cake through a dryer to obtain a combustible bio-product; and j) burning the combusted bioproduct to obtain a bio-product precipitated silica (565).

[0022] In an embodiment of the present disclosure provides a process where, the biomass is selected from group consisting of rice straw, paddy straw, corn stover, and sugarcane bagasse or combination thereof, wherein prior to the treating the biomass, it is subjected to a process selected from decontamination from metals, shredding, mechanical size reduction, water settling and recycling or combination thereof. An exemplary embodiment of the present disclosure provides for the biomass to be rice straw or paddy straw (101). [0023] An embodiment of the present disclosure provides a process where, the C5 hydrolysate (145) is obtained in the present process which is rich in pentose sugar, similarly embodiment of the Ce hydrolysate (221) is obtained which is rich in hexose or glucose sugar.

[0024] Further, in an embodiment of the present disclosure provides a process where, the biomass is fed to a fully enclosed and isolated plug flow continuous vapour phase pressurized reactor (121, 123, 125 & 127) isolating all upstream and downstream processes from the severe pre-treatment process conditions of chemical vapours and high temperatures.

[0025] Another embodiment of present disclosure provides a process where, the biomass is subjected to a thermo-chemical exfoliation resulting in breakdown of the fibers and catalysis of hemi-cellulose to C5 hydrolysate (145), with negligible breakdown products which are recalcitrant for further downstream processing.

[0026] Yet another embodiment of the present disclosure provides a process where the biomass coming through the screw feeder (119) is continuously impregnated with an atomized acid (121) and subjected to hydrolysis with steam; which is carried out by a mineral acid selected from the group consisting of nitric acid, oxalic acid and sulfuric acid and under isothermal or constant temperature and constant pressure or isobaric conditions to obtain hydrolyzed biomass.

[0027] Further an embodiment of present disclosure provides a process where, the hydrolyzed biomass is discharged through a cold blow discharger (127) to an agitated blow tank (133), after which the solid liquid separation of treated biomass (131) is carried out by pressurized solid liquid separation system, wherein the slurry is fed (135) at a temperature in the range of 340 to 355 Kelvin and under a pressure in the range of 58 to 72 psi (gauge) to a diaphragm type membrane press (139) and the cake is subjected to hydraulic squeezing at a pressure in the range of 205 to 215 psi (gauge) pressure to increase the solids content to 40-45%.

[0028] Another embodiment of present disclosure provides a process where, the neutralizing agent is selected from the group consisting of ammonia, ground limestone and calcium carbonate, wherein the solution is neutralized to a pH >9 to rid the sugar solution off recalcitrants generated during pre-treatment and generate by-product gypsum.

[0029] Another embodiment of present disclosure provides a process where the after separating gypsum, the alkaline sugar stream (303) is subjected to liquid-liquid separation, wherein the ultrafiltration (305) is carried out to reduce the total suspended solids to below 40 to 50 ppm & turbidity <10 NTU, by pumping the neutralized stream at a pressure in the range of 58 to 72 psi (g) tangentially across a 3000 Dalton membrane and the permeate (323) is then sent for nano filtration (317), the retentate containing suspended solids is taken to a settling tank (313) and recycled for ultra-filtration (305), wherein the permeate (307) comprising alkaline sugar solution is further subjected to nano filtration (317).

[0030] In an another embodiment of present disclosure provides a process where the alkaline sugar stream (303) is subjected to liquid-liquid separation by nano filtration (317), which is carried out by a filtration membrane having porosity in the range of from 100 to 300 Daltons, wherein the alkaline sugar stream is pumped at 405 to 435 psi and through 100 to 300 Dalton porosity filtration membranes and the permeate (323) containing the alkaline water is collected separately, whilst the retentate containing the concentrated sugars (319/ 413) is sent for co-fermentation.

[0031] Yet another embodiment of present disclosure provides a process where the nano filtration (317) provides alkaline water (323) which is recycled for neutralization and dilution of filter cake before enzymatic hydrolysis and for wet washing in turbo washer (107).

[0032] Further, an embodiment of present disclosure provides a process where the enzyme is selected from cellulose-active glycoside hydrolases including cellobiohydrolases, endoglucanases and P-glucosidases and xylanase or combination thereof, wherein the enzyme is having biomass hydrolysis activity (BHU-2-HS/g) value of 2200 to 2253 per gram of enzyme; 117.37 +/- 0.725 FPU/gram FPase activity and the protein content is 95.96 +/- 1.86 mg Psa equivalent per gram enzyme. [0033] In further embodiment of present disclosure provides a process where concentrated sugars (319/413) derived from celluloses are co-fermented using a living modified organism which is modified by insertion and overexpression of three Saccharomyces cerevisiae genes, encoding enzymes involved in the pentose phosphate pathway.

[0034] In a further embodiment of present disclosure provides a process where increase the xylulokinase activity an artificially synthesized gene encoding a xylulokinase as present in the yeast Scheffersomyces stipitis, under the control of an S. cerevisiae promoter and terminator is also inserted, as also two artificially synthesized genes encoding 2 enzymes from Lactococcus lactis resulting in six genes that are all expressed under control of native S. cerevisiae glycolytic promoters. This organism utilizes an efficient xylose metabolic pathway. It efficiently coassimilate or co-ferment the pentose and hexose sugars simultaneously.

[0035] Furthermore embodiment of present disclosure provides a process where filter cake is subject to counter current washing before drying to obtain a dilute acidic Ce sugar solution recyclable wash (215) and lignin and silica (ash) rich retentate.

[0036] Yet another embodiment of present disclosure provides a process where the second concentrated sugar solution (413) is achieved by liquid-liquid separation through nano filtration which is carried out by a filtration membrane having porosity in the range of from 100 to 300 Daltons, wherein the Ce rich hydrolysate is pumped at 405 to 435 psi and through 100 to 300 Dalton porosity filtration membranes for dewatering and the permeate containing the water (409) is collected separately, whilst the retentate (413) containing the Ce rich sugar hydrolysate concentrated sugars is sent for co-fermentation.

[0037] In yet another embodiment present disclosure provides a process where, the cofermentation process is carried in a fermentation vessel having nutrients selected from urea and di-ammonium phosphate.

[0038] Further an embodiment of present disclosure provides a process where the co-fermentation provides carbon dioxide (505, 635) which is passed into the process to obtain bio-product precipitated silica (565). [0039] Yet another embodiment of present disclosure provides a process where the dilute alcohol (617) in the fermented solution (629, 703) is initially dehydrated azeotropically in a distillation column (705 & 707) and then dehydrated using molecular sieves.

[0040] In a further embodiment of present disclosure provides a process where the dryer is selected from group consisting of vibrating fluidized bed dryer, a belt dryer and a spin flash dryer.

[0041] Another embodiment of present disclosure provides a process where the lignin and silica (ash) (219) are dried with a spin flash dryer and burnt in a boiler to obtain a slag (507), wherein the slag (507) is subjected to alkali for ash dissolution (511) and carbonation (523) to obtain silica precipitate and a green liquor, wherein the green liquor is subjected to chemical recovery plant to obtain calcium carbonate and caustic soda.

[0042] Yet another embodiment of present disclosure provides a process where the calcium carbonate is recycled to neutralize acidic sugar solution and caustic soda is recycled for ash dissolution.

[0043] These and other features, aspects, and advantages of the present subject matter will be better to understand with reference to the following description. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the subject matter, nor is it intended to be used to limit the scope of the subject matter.

DETAILED DESCRIPTION OF DRAWINGS:

[0044] The below detailed description of the invention will be better understood when read in conjunction with the appended drawings. For the purpose of assisting in the explanation of the invention, there are shown in the drawings embodiments which are presently preferred and considered illustrative. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown therein. [0045] The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1. Summary of industrial problems and their suggested remedies during 2G ethanol production process.

Figure 2. Mechanism of hydrolysis of Acetyl groups in acidic medium.

Figure 3. Process flow diagram of the process of the present disclosure to obtain bioproducts.

Figure 4. HPLC analysis of assimilation of glucose during fermentation

Figure 5. HPLC analysis of assimilation of xylose during fermentation

Figure 6. HPLC analysis of production of ethanol from assimilation of glucose and xylose

Figure 7. Mass balance of shredded rice straw wet washing and feed to hydrolyzer (Pretreatment section)

Figure 8. Schematic Layout and General Arrangement for Washing & Pre-Treatment which shows Straw(lOl), Straw cutter (103), Inclined Conveyor (105), Turbo Washer (107), Aqua separator (109), DSM screen (111), Recovered straw tank (113), Metering screw (115), Equalizing screw (117), Screw feeder (119), Inlet chamber (121), Hydrolyser Tube 1 (123), Hydrolyser Tube 2 (125), Cold blow discharger (127), Cs Hydrolysate for dilution (129), Hydrolysed biomass from cold blow discharger (131), Agitated Blow Tank (133), Pump (135), Feed to membrane Press (137), Membrane type squeeze press (139), Sugar storage Tank (141), Pump (143) and C5 Hydrolysate to sugar over-liming and dewatering (145).

Figure 9. Schematic Layout and General Arrangement for Enzymatic Hydrolysis which shows Membrane type squeeze press (201), Pre-treated biomass (203), Screw conveyor (205), Stock feed chute (207), Enzymatic hydrolysis reaction vessel (209), Pump (211), Hot water for cake washing (213), Recycled wash water (215), Membrane type press with hot water washing and pressing (squeezing) (217), Lignin & Ash rich retentate to flash dryer & boiler (219), C6 Hydrolysate or Hexose rich sugar solution to nano filtration (221) and Floor level (223).

Figure 10. a) Hexose rich sugar after enzyme hydrolysis and filtration b) Water recovered after nano filtration and c) Concentrated hexose rich sugar after nano filtration. Figure 11. Ultra and nano filtration process flow diagram which shows Feed storage tank (301), Alkaline Sugar Stream (303), UF system (305), UF permeate (Sugars) (307), Clarified sugar tank (309), Settler (313), Slurry to ETP (315), UF Reject (TSS turbidity) (311), NF system (317), NF Reject (Concentrated sugars) (319), Concentrated sugar tank (321), NF permeate (alkaline water recovered) (323) and Clear water tank (325).

Figure 12. Schematic of typical spiral NF membrane which shows Feed (401), Brine seal (403), Filament wound protecting shell (405), Interconnector (407), Permeate (Recovered Water) (409), O ring (411), Concentrated sugars (413) and Flow (415).

Figure 13. Fermentation cycle for cellulosic sugars as analysed by HPLC over Time

Figure 14. Schematic Layout and General Arrangement for Precipitated Silica & Chemical recovery which shows LP Steam (501), Wash water (503), CO2 from Fermentation section (505), Slag or ash from boiler (507), Hopper (509), Ash dissolving & leaching tank (511), Ash dissolving tank agitator (513), Raw Green liquor pump (515), Filter press-1 (517), Dregs cake (50% dryness) (519), CO2 sparger (521), Desilication reactor (523), Desilication agitator (525), Clarified Green liquor supply pump -1 (527), Silica separation clarifier (529), Clarified green liquor storage tank (531), Precipitate silica supply pump-1 (535), Green liquor supply pump-1 (533), Slaker agitator (537), Stationary slaker (539), Screw feeder (541), Lime bin (543) Stationary slaker pump-1 (545), Silica washer (547), Weak silica wash liquor pump-1 (549), Stand-PIPE-1 (551), Precipitate silica dryer feed pump (553), Causticizer agitator- 1 (555), Causticizer agitator-2 (557), Causticizer- 1 (559), Causticizer-2 (561), Spin flash dryer (563), Precipitated silica (565), White liquor clarifier (567), White liquor storage tank (569), Vent (571), Ash dissolving and leaching tank (573), White liquor pump-1 (575), Recausticizer agitator (577), Recausticizer (579), Lime mud washer (581), vent (583), Stand-PIPE-2 (585), Weak wash liquor supply pump-2 (587) Lime mud underflow wash pump-1 (589), To lime mud filter and (591), and White liquor clarifier under flow pump-1 (593).

Figure 15. Schematic Layout and General Arrangement for Sugar Eermentation which shows Cone. C5/C6 sugars after Nano filtration (601), PE or Starter Culture (603), Acid antifoam biocide etc. (605), Mixer-1 (607), Eementer-1 (609), Mixer-2 (611), Fermenter-2 (613), Mixer-3 (615), Beer Well (for Dilute alcohol after fermentation) (617), Circulation Pump-1 (619), Wash cooler-1 (621), Circulation pump-2 (623), Wash cooler-2 (625), Wash feed pump (627), fermented wash to distillation section (629), Cooling water return (631), Cooling water supply (633) and CO2 (635).

Figure 16. Schematic Layout and General Arrangement for Alcohol Distillation which shows Low pressure steam (701), Fermented wash (Dilute alcohol after fermentation from Beer Well) (703), Analyzer column (705), Rectifier column (707), Spent wash pump (709), Reflux pump (711), Solution heater (713), Principal condenser (715), Vent condenser (717), Reflux tank (719), RS cooler (721), Cooling water return (723), Cooling water supply (725), Cooling water return (727), Rectified sprit (729) Cooling water supply (731) Spent lees to ETP (733), and Spent wash (735).

DETAILED DESCRIPTION

DEFINITIONS:

[0046] “Biochemical” refers to use of biological aids or inputs in the process like microorganisms and enzymes as well as inorganic chemicals like acids and bases.

[0047] “Biofuels” are a class of renewable energy derived from living materials. It is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels, such as oil.

[0048] “Biological Safety Levels (BSL)” are a series of protections and individual safeguards designed to protect personnel, as well as the surrounding environment and community. These levels, which are ranked from one to four, are selected based on the agents or organisms that are being researched or worked on in any given setting. A basic setting specializing in the research or working of nonlethal agents that pose a minimal potential threat to workers and the environment are generally considered BSL-1 — the lowest biosafety lab level. It is a defined way of exhibiting specific controls for the containment of microbes and biological agents.

[0049] “Bales” are a large closely pressed bundle of straw bound by a twine or string made from the same material. [0050] “Bath ratio” means the ratio of dry matter (in kilograms) to the volume of wash liquor (in litres).

[0051] “Bauer Mcnett fiber Classification” is used to measure the weighted average fibre length of a pulp using the classification method. Fractionators with 4 tanks with different sieves and integrated vacuum pump.it is a well-accepted testing method.

[0052] “Biomass enzyme activity” by Fluorescence Cellulose Decay (FCD). The method measures the decay of cellulose in a substrate consisting of grinded and sieved pre-treated corn stover (GS-PCS) mixed with a fluorescence enhancer (Calcoflour White, FB28). The cellulose hydrolysis results in a decrease in fluorescence (excitation/emission: 360 nm/460 nm). This is monitored relative to a biomass enzyme standard BHU (2). The method thus measures hydrolysis activity by Fluorescence

[0053] Cellulose Decay (FCD). In the method, the incubation is terminated and monitored after 24 hours at 50 °C.

[0054] “Cs and Ce” refer to 5 and 6 carbon chain sugar monomers respectively or pentose and hexose respectively

[0055] “Circular biochemical process” refers to use of resources by minimizing the extraction of natural resources, maximizing waste prevention, and optimizing the environmental, social, material and economic values throughout the lifecycles of materials, components and products. Naturally grown by-products or damaged products generated in the agricultural production process and materials deemed no longer necessary are recycled and not relegated to “waste” but serve as raw materials and feedstock for a new production cycle.

[0056] “Cellulosic sugars” mean monomeric sugars derived from breaking down polymers of six carbon chain sugars more specifically glucose or hexose which exist naturally as biomass especially in the non-vegetative portion of grains and legumes as well as wild grasses like bamboo, sweet munj cane etc., wood etc. [0057] “Clarifiers” are settling tanks built with mechanical means for continuous removal of solids being deposited by sedimentation. A clarifier is generally used to remove solid particulates or suspended solids from liquid for clarification and (or) thickening.

[0058] “Continuous hydrolyzer” refers to a continuously operated reaction vessel designed to treat low bulk density biomass with uniform rate of feeding and in a vessel that is having a very low volume to the total volume of material treated in a day.

[0059] “Consistency” or “Cy%” refers to the content of solids in a liquid mass containing immiscible or suspended solids.

[0060] “Delignification” refers to the removal of lignin from biomass using an alkaline chemical like caustic soda by formation of sodium lignate as a water soluble compound.

[0061] “De-carbonization” is the reduction of carbon dioxide emissions through the use of low carbon power sources. It refers to lowering the amount of greenhouse gas emissions produced by the burning of fossil fuels by using alternate renewable sources of energy.

[0062] “DSM screen or Dutch State Mines Screen” - a curved concave wedge bar type of stationary screen used for continuous unattended separation of small quantities of fibers in large volumes of fluid.

[0063] “Ecologically sustainable” includes everything that is connected with the Earth's ecosystems. Amongst other things, this includes the stability of climate systems, the quality of air, land and water, land use and soil erosion, biodiversity (diversity of both species and habitats), and ecosystem services (e.g. pollination and photosynthesis). The aim is to safeguard the functioning of natural systems and their capacity for renewal now and in the future. Compliance with the precautionary principle is essential for ecological sustainability.

[0064] “Enzymatic hydrolysis” is a process in which enzymes facilitate the cleavage of bonds in molecules with the addition of the elements of water. The process involves several key steps: (1) transfer of enzymes from the bulk aqueous phase to the surface of the cellulose, (2) adsorption of the enzymes and formation of enzyme-substrate complexes, (3) hydrolysis of the cellulose, (4) transfer of the hydrolysis products from the surface of the cellulosic particles to the bulk aqueous phase, and (5) hydrolysis of the sugar-type products to glucose in the aqueous phase.

[0065] “Enzyme non-productive binding” means adsorption of the enzymes on lignin surface and formation of enzyme-substrate complexes without the formation of any useful breakdown products.

[0066] “Greenhouse gases” (also known as GHGs) are gases in the earth's atmosphere that trap heat. Carbon dioxide and chlorofluorocarbons are examples of greenhouse gases that absorb infrared radiation.

[0067] “Gypsum or calcium sulphate” is used to make plaster of Paris for the building industry and in fertilizers. It the main constituent in many forms of plaster, blackboard or sidewalk chalk, and dry wall.

[0068] “Herschel-Bulkley fluids” are a class of non-Newtonian fluids that require a finite critical stress, known as yield stress, in order to deform. The strain experienced by the fluid is related to the stress in a complicated, non-linear way. Therefore, these materials behave like rigid solids when the local shear is below the yield stress.

[0069] “Lifecycle analysis” is a method of quantifying the environmental impacts associated with a given product. An inventory of resources used and pollutants generated in product production and use is defined. From this an impact assessment estimates the product's ultimate effects on human health, ecosystem function, and natural resource depletion. It has been applied to various biofuels, including corn ethanol, to estimate the net effects of a biofuel on petroleum use, climate change, air and water quality, and other impact categories.

[0070] “Living modified organism (LMO) or genetically modified organism (GMO)” is understood to mean any living organism that possesses a novel combination of genetic material obtained through the use of modern biotechnology. It involves inserting DNA into the genome of an organism.

[0071] “Lorentzen & Wettre Pulp Tester Fibre Morphology” is a fibre analyzer following the latest international standard for fibre length measurements (ISO 16065-2:2007). The fibres are oriented in an image plane in the measurement cell and do not admit spread in the direction perpendicular to this plane. Fibre length, width, shape factor, local deformations, fines, coarseness, vessel cells, shives and fibre blends are measured.

[0072] “Newtonian fluid” is defined as one with constant viscosity, with zero shear rate at zero shear stress, that is, the shear rate is directly proportional to the shear stress, a fluid in which viscosity is independent of the shear rate.

[0073] “Oxygenate” refers to an additive chemical used in Petrol (gasoline) primarily to improve octane and reduce vehicular emissions

[0074] “Precipitated silica” is a form of synthetic amorphous silicon dioxide derived from the naturally occurring silica content in rice straw.

[0075] “Recalcitrant” refers to products that hinder assimilation of sugars by microorganisms.

[0076] “Retentate” is what is retained, for example by a filter or porous membrane.

[0077] “Second generation ethanol” refers to ethanol produced from sugars derived from cellulosic biomass and specifically excludes ethanol from grain, sugarcane and starchy materials.

[0078] “Suppressant” is an agent that tends to reduce the intensity of an interaction which would otherwise without the presence of the suppressant happen with a high magnitude. [0079] “Spin flash dryer” is a vertical dryer with rotary pulverizing device, which can simultaneously dry and classify materials. It is a continuous drying device specially designed for drying muddy fibrous materials.

[0080] “Valorization” refers to useful and productive utilization of material or components to produce value added products or energy especially from components not required for the production of the main product.

[0081] “Vapour phase reaction” refers to the process of transferring a substance from a vapour on to a solid phase by passing the vapour through or over a stationary phase. It is a technique to form thin films by chemical reaction on the surface of substrates by using one or more gases and reactants and letting it dissolve in the fluids.

[0082] The present disclosure discloses a method which is a circular biochemical process and recovers water from sugars prior to fermentation for its reuse in process, a first for any sugar fermentation technology. This process step almost eliminates the generation of toxic stillage and concentrated solid residue thereof, generated during evaporation of ethanol when produced from grain or sugarcane juice/ molasses or even when utilizing simultaneous saccharification and fermentation process (SSF) for cellulosic ethanol production. The present disclosure further discloses successful utilization of a modified yeast based on saccharomyces cerevisiae strain also called a living modified organism (LMO) which meets Biosafety level 1 standards and is able to assimilate both pentose and hexose sugars simultaneously with high ethanol efficiency.

[0083] Although, the production of biofuels results in GHG emissions at several stages of the process, studies using economic models have found that biofuels can lead to significant reductions in lifecycle GHG emissions relative to conventional fossil fuels. Second generation biofuels have greater potential to reduce GHG emissions relative to conventional fuels because feedstock is mainly waste products of the main crop. Moreover, in the case of waste biomass, no additional agricultural production is required, and indirect market-mediated GHG emissions can be minimal if the wastes have no other productive uses. Biofuels can be produced domestically, which would lead to lower fossil fuel imports. Biofuels may reduce some pollutant emissions. Ethanol, in particular, can ensure complete combustion, reducing carbon monoxide emissions. The combustion efficiency of the ethanol is higher (15%) than that of gasoline as it contains 34.7% oxygen. Ethanol also keeps down the emission of particulate nitrogen oxides. Hence, ethanol is the first choice as an eco-friendly oxygenate for fuel. The emission of sulfur is also reduced by the use of ethanol as it contains a negligible amount of sulfur as compared with gasoline. Ethanol is a safer substitute to methyl tertiary butyl ether (MTBE) which is an oxygenate and is added to petrol to increase its oxygen content allowing better combustion and, therefore, lesser tailpipe emissions of harmful gases like carbon monoxide but leads to higher emissions of benzene — a carcinogen.

[0084] The present disclosure discloses a technology that gainfully utilizes all the constituents of the cellulosic biomass, namely Celluloses and hemicelluloses for production of short chain sugars and thereafter ethanol, lignin as a source of energy to produce heat (and steam) and siliceous ash to produce precipitated silica (565). Rice straw in particular contains more than 38% of lignin and ash and its productive utilization differentiates this technology from the others. The present disclosure further utilizes a lignin suppressant for efficient enzymatic hydrolysis thereby eliminating a standard process step of delignification using alkali or ammonia and also greatly reducing use of the costly enzymes due to unproductive lignin binding and making the entire process commercially feasible.

[0085] The process waste streams from the fermentation facility are safely disposed with complete deactivation of the LMO using a broad spectrum disinfectant. The entire method and apparatus in the present disclosure is self-contained as it does not rely on import of energy (electricity from the grid or fossil fuels for heat) and regenerates most of the chemicals for reuse. It is an established fact that ethanol production requires very high use of water, nearly 3 to 10 times the volume of ethanol produced; this disclosure requires water mainly for makeup of evaporation losses from cooling towers as most of the process water is recovered and reused. Above all, the present disclosure and technology establishes an ecologically sustainable disposal of rice straw which is presently burned in open fields and is a serious environmental hazard causing severe air pollution. The economics of the process suggest that the ethanol produced is similar in cost to the first generation ethanol produced from Sugarcane juice or rice, thereby making commercial exploitation of this disclosure feasible. [0086] Almost all the technologies proposed for production of cellulosic ethanol rely on ethanol as the only product/source of revenue. Some also propose biogas and compressed biogas from the residual cellulose/hemi-cellulose from processing as also pelletized lignin as a green fuel. This technology produces two additional commercially saleable products other than ethanol namely precipitated silica and gypsum. These are produced from the constituents present in the cellulosic biomass or as a result of the reaction of chemicals used.

PROCESS AND APPARATUS DETAILS:

[0087] Tapping the vast potential of the non-food vegetative part of the agricultural crops for clean and renewable energy is the future for fuels and other energy sources. The ligno-cellulosic agricultural biomass comprising the non-food vegetative residue consists of four major components: cellulose, hemi-cellulose, lignin and inorganic matter. An exemplary embodiment of the present disclosure provides the physical characteristics and proximate analysis of Rice or paddy straw (101), which is used as bio-mass in the process of the present disclosure, which is shown in table 1 below:

Table 1

[0088] Further, an exemplary embodiment of the present disclosure provides the proximate analysis of the rice straw stored in the yard and prior to processing which is shown in table 2 below.

Table 2

[0089] Rice straw which is left after harvesting of the crop using combine harvesters is baled using balers and transported in bales weighing 20 to 22 Kgs to the processing facility.

Storage:

[0090] These are stored in the open on platforms formed using bricks and sand, tightly interlocked. The bales are stacked up to 20 rows high. An embodiment of the present disclosure provides that storage of rice straw in the open resulted in a loss of cellulose and hemi-cellulose content of nearly 5% every 2 months with a consequential increase in extractives and moisture. This reduces considerably when stored away from rain and sunlight. The baled straw so received contains a lot of extraneous matter like rope, glass, iron particles, stuck soil and mud which are detrimental to the apparatus used for processing and need to be removed for consistent operations and results.

Shredding:

[0091] The bales are fed through an inclined belt conveyor with slats to a hopper (509) which is fitted with magnetic separator to pick out any ferrous material and is then fed to a dual pass shredder. An embodiment of the present disclosure provides a process in which at least 80% of the straw is cut to < 20 mm in length and nearly 100% is cut to < 40 mm in length. An exemplary embodiment of the present disclosure provides the average length obtained after shredding of the straw which is shown in table 3 below.

Table 3

The above results were tested using dry sieve analysis.

Wet washing apparatus and method:

[0092] This cut straw (103) is then fed through an inclined belt conveyor (105) to a screw conveyor (205) fitted with pin breakers to detangle entwined straw and is fed directly into a turbo washer (107) wherein it is diluted to 2-3% consistency and beaten with a high agitation twin turbo pulper rotor to loosen and separate the stuck mud and soil. This is then fed into an Aqua separator (109), which is an inclined screw conveyor fitted with slotted sieve at the bottom to separate the excess water along with the loosened mud/soil by gravity. An embodiment of the present disclosure provides that the consistency of the wet washed straw leaving this inclined conveyor (109) is between 15 to 20% implying the biomass has nearly 4 times its weight of water going to the next step of process. The drained water containing fiber along with extraneous matter with ~ 2% consistency is fed to a DSM screen (Dutch State Mines Screen - a curved concave wedge bar type of stationary screen) (111) and thereafter a rotary settler rotating at 5-6 rpm to trigger gravity settling and separate fibers with 14-15% consistency. This fiber so recovered is conveyed to be mixed with the wet washed fiber to minimize fiber loss.

[0093] Further, an embodiment of the process of the present disclosure provides that the water which is separated from the rotary settler is treated in a clarifier and the underflow from the same is recycled for reuse in washing of the cut straw. This washing step may also involve addition of 1 grams per litre (gpl) to 3 gpl strength caustic soda to the water used for wet washing (105) or use alkaline water (323) for better removal of adhered impurities.

The apparatus for continuous hydrolysis (pre-treatment): [0094] The thoroughly washed shredded rice straw is now ready to be fed into the continuous hydrolyzer through a metering screw conveyor (115) followed by an equalizing screw conveyor (117) to ensure smooth feed at constant/uniform rate. As is evident from the physical properties of straw, it has a very low bulk density and if it is to be processed as such, it would occupy a very large volume. It is thus necessary to compress the straw and this is achieved by passing it though a specially designed plug screw feeder (119) which transports biomass from atmospheric conditions to pressure zone. This is achieved through a combination of variable pitch of the screw and a tapered compression housing fitted with anti-rotation bars. Due to extreme compression of the straw, a drain assembly is also provided to collect the water squeezed during the process. An embodiment of the present disclosure provides that the compressed rice straw is passed through a narrow cylindrical feed pipe, into the inlet chamber (121) of the hydrolyser which is fully pressurized with steam. Due to continuous feeding and high compression, a plug is formed in the feed pipe, thereby ensuring no drop in pressure in the pressurized hydrolyser. This effectively isolates upstream equipment from challenging downstream conditions such as chemical vapors, high temperatures and pressure differentials. The inlet is also fitted with a blow back piston to ensure sealing of the hydrolyzer if the plug formed from incoming straw breaks. Before feeding the washed wet rice straw, the entire hydrolyser comprising the inlet and blending chamber (121), the reaction chambers with screw arrangement (123 & 125) to push the material uni-directionally and the cold blow discharger (127) are firstly pressurized with low to medium pressure steam and maintained at a constant pressure to ensure the entire equipment is heated evenly and at a constant temperature.

[0095] Further, an embodiment of the present disclosure provides that the design temperature and pressure of this hydrolyser is 200 degrees Celsius (°C) and 10 Bar g (or 131.4 psi g) respectively and the hydrostatic test pressure is 11.80 Bar g (or 197 psi g). This hydrolyser is a vapour phase reactor wherein the headspace left over the continuously conveying rice straw with the chemicals mixed in (123 & 125) allows for the condensation of the pressurized steam leading to an intense reaction. The entire pressurized vessel is isothermal with near constant temperature maintained throughout the process. The metallurgy for the material of construction is so that it can withstand a pH of 1.

The hydrolysis (pre-treatment) process and key methodology: [0096] The purpose of this pre-treatment is to breakdown the hemi-cellulose to 5 carbon chain xylose or pentose as fermentable sugars and make the cellulose accessible for solubilization. Hemicelluloses are heterogeneous polymers of pentose’s (xylose, arabinose), hexoses (mannose, glucose, galactose), and sugar acids. Unlike cellulose, hemicelluloses are not chemically homogeneous. Ideally, target is to breakdown without the formation of degradation compounds like furfural and acetic acid. An embodiment of the present disclosure provides that the breakdown of hemicellulose is achieved by a catalytic reaction with free hydrogen ion and water to form xylose or pentose and the reaction is characterized as: If the catalysis is uncontrolled, it will lead to formation of furfural as depicted below and/or acetic acid as shown in Figure 2:

PENTOSE FURFURAL

[0097] Further, an embodiment of the present disclosure provides that the key parameters for successful pre-treatment are the quantum of chemicals, the time for the reaction, the temperature at which the reaction occurs and above all the bath ratio. These 4 parameters in correlation are critical for successful pre-treatment as altering any one of these parameters can lead to either formation of breakdown compounds of cellulose and hemi-cellulose or partial breakdown of lignin into phenolics or the vaporization of the breakdown compounds leading to low yields.

[0098] The pre-treatment is achieved by adding a mineral acid like nitric acid or oxalic acid but preferably sulfuric acid in a ratio between 3 to 5% by weight of the bone dry mass of rice straw so as to achieve an initial bath ratio of between 2 to 5. An exemplary embodiment of the present disclosure provides that the quantity of sulfuric acid should be 4% of the dry matter and the starting bath ratio to be 2.5. An embodiment of the present disclosure provides that the a solution of sulfuric acid having a strength of 0.255 M to 0.510 M is atomized to fine droplets in the inlet chamber (121) so as to impregnate the continuously fed compressed rice straw by matching the flow rate of rice straw with the volume of diluted sulfuric acid targeting the requisite bath ratio. An embodiment of the present disclosure provides that the sudden expansion of straw when it enters the chamber allows the sulfuric acid to penetrate it homogeneously. An exemplary embodiment of the present disclosure provides that a 0.357 M solution of industrial grade sulfuric acid is pumped into the inlet chamber (121) to react with the wet straw. An embodiment of the present disclosure provides that mixture falls onto a slow moving screw in the 1^st Reaction chamber (123) which pushes the mass uni-directionally allowing vapour phase reaction with condensing steam and sulfuric acid impregnated rice straw. This leads to thermo-chemical exfoliation and solubilizes the hemi-cellulose by breaking down long chain polysaccharides of pentose sugars to monomeric xylose sugars which forms a highly acidic sugar solution. An embodiment of the present disclosure provides that the residence time in the hydrolyser tubes (123 and 125) is between 10 to 30 minutes and an exemplary embodiment of the present disclosure provides that it is 22 minutes. Further, an embodiment of the present disclosure provides that the condensed steam during the reaction increases the bath ratio to 2.75 to 4.5 and the temperature of the reaction vessel is maintained between 110 °C to 145 °C. An exemplary embodiment of the present disclosure provides that the bath ratio is 3.5 and the temperature of reaction is 130 °C. The solubilization of polysaccharides and other components of rice straw leads to residual fiber content of 60 to 70% more preferably 65%. An exemplary embodiment of the present disclosure provides the mean values of expected results which is shown in table 4 below. Table 4

[0099] In an exemplary embodiment, nearly 14% cellulose, 65% hemi-cellulose, 25% of lignin and ash and almost all of the extractives are solubilized during the pretreatment. Another exemplary embodiment of the present disclosure provides that the mean values of the breakdown and solubilized products recovered are: 5% Glucose as 2.9 GPL; 30% Xylose as 12.50 GPL; 6% Arabinose as 2.9 GPL; Acetic acid 0.80 GPL; Hydroxy methyl furfural (HMF) 0.10 GPL and Furfural: 0.75 GPL. An embodiment of the present disclosure provides that the loss during processing is 8 to 10% cellulose and 28 to 32% Hemi-cellulose. Another exemplary embodiment of the present disclosure provides that loss during processing is 9% cellulose and 30% Hemicellulose.

[0100] An embodiment of the present disclosure provides that to achieve an optimum overall yield of fermentable sugars, it is essential that the fiber yield after the pre-treatment is nearer to 70% but not lower than 60%. Otherwise, the sugar and thus ethanol yield will be below par and uneconomical resulting in unsustainable operations. The residual fiber along with the solubilized sugars collects in the discharger chamber (127), and an embodiment of the present disclosure provides that the bath ratio in this chamber is 5 to 7. The solids content or consistency is 13 to 16%. An exemplary embodiment of the present disclosure provides that in the discharger chamber (127), the bath ratio is 6 and the solids content is 14.50%. This is too high to be discharged through pipes as these display a HerscheLBulkley fluid character and needs to be diluted to make it flow properly through the discharge pipes. An embodiment of the present disclosure provides that this sugar and fibers solution in the discharger chamber (127) is diluted to 6 to 9% more preferably 8% so that it can be blown using the inherent pressure available in the hydrolyser and to a blow tank. Another embodiment of the present disclosure provides that this dilution is done using the sugar solution (129) recovered after separating the fibers from the hydrolyser. Another embodiment of the present disclosure provides that this sugar solution with fibers (hydrolysed biomass after pretreatment) is pumped to a suitable pressurized solid liquid separation system from the blow tank using pumps (135) that can handle medium consistency Non-Newtonian fluids. This separation module can be a vertical stacked recessed plates with diaphragm automated filter, or a screw press or similar pressurized separation equipment.

[0101] An embodiment of the present disclosure provides that the separation module is an automated membrane filter press (139) with automatic discharge as well as squeezing operation to reduce occluded sugar solution carryover in the fiber with water washing. An embodiment of the present disclosure provides that the sugar solution retained in the fiber is 2 to 3 times by weight of the biomass more preferably 2.5 times. Another embodiment of the present disclosure provides that the separated sugar solution is stored in a Polypropylene or fiber reinforced plastic lined CI or mild steel tanks (141), suitable to handle acidic medium. An exemplary embodiment of the present disclosure provides the fiber generated after pre-treatment undergoes a major transformation and the physical attributes which is shown in table 5 below.

Table 5

[0102] The above characteristics are important in ascertaining the appropriate filtration media specifications for plant operations. In an embodiment of the present disclosure provides that, the fiber length has reduced from an average 20 mm length of the shredded rice straw to an average length of ~ 0.75 mm, a clear confirmation of the disentanglement of the ligno-cellulosic structure and making the cellulose accessible for saccharification. The schematic diagram for washing and hydrolysis (pre-treatment) and solid liquid separation is shown in Figure 8.

Apparatus for enzymatic cellulose saccharification:

[0103] The industrial design for a suitable equipment for saccharification of cellulose using enzymes is extremely challenging. This is because the cellulose rich fibers with nearly 60% moisture is like a damp solid mass. The process of agitating some slurries, especially those formed during pulping and their mixing to make paper is to a large extent understood as also the empirical rules applicable for the same. For most paper stock slurries, the maximum solids concentration (aka consistency) is 12-15%; the practical limit is 6-8%. This is because the required torque is almost proportional to the cube of the solids content when it is between 2-8%, but increases disproportionately thereafter with every % increase in consistency. Slurries containing ligno - cellulosic biomass is an entirely different proposition. They cannot be mixed with equipment designed to agitate liquids, so solids mixers must be used. Unfortunately, such mixers are very expensive on a volumetric basis, and are therefore not practical to use for the complete saccharification reactions which require substantial time. However, one can take advantage of the fact that the saccharification process ultimately converts the stiff, fibrous structure into soluble sugars, leading the final solution to be a low viscosity liquid. High-solids fibrous slurries can form a pile with a finite angle of repose also known as shear thickening. This phenomenon is associated with yield (shear) stress, and that certain shear stress must be exceeded before motion will occur. Above that shear stress, the material is often shear-thinning.

[0104] Fluids exhibiting a combination of yield stress and shear-thinning behavior are known as Herschel-Bulkley fluids. Fibrous slurries are two-phase systems: a liquid carrier phase and a solid, fibrous phase. The carrier is typically a low-viscosity liquid such as water. The sometimes high apparent viscosity results from the mechanical interactions among fibers as shear stress is imposed on the system in an attempt to make it flow. In bulk flow, such as in a pipe or an agitated tank, the apparent viscosity depends on the shear rate distribution. An embodiment of the present disclosure provides that the rheology starts out as Herschel Bulkley (shear thinning with a yield stress), then follows the power law, and sometimes ends up nearly Newtonian fluid. Solids mixers which are designed to mix high viscosity materials, rely on high shear mixer designs which are highly power intensive. With the multitude of variables, it is necessary to test each feedstock in each process at each major stage of hydrolysis to obtain sufficient data for agitator design.

[0105] An embodiment of the present disclosure provides that the high shear agitator lifts the material inside the cylindrical reaction vessel (209) along the sides and drops it in the center around the shaft of the agitator forcing it to the bottom. The damp solid fibrous mass from pre-treatment and after dewatering, is conveyed using belt conveyors and/or screw conveyors (205) to either of the reaction vessel (209) as above.

The saccharification of cellulose and separation of lignin and siliceous ash:

[0106] An embodiment of the present disclosure provides that the cellulose rich biomass after pretreatment is highly acidic and this acidity is detrimental to enzymes as the most conducive range for these enzymes to react effectively is 4 to 5 pH, preferably 4.5. An exemplary embodiment of the present disclosure provides that alkaline water (323) recovered after nano filtration (317) of pentose rich sugar solution is added to raise the pH to the desired level. Once the desired pH of 4.5 is reached, a lignin suppressant agent is added, so that it prevents the adsorption (or binding) of enzymes (cellulose’s) to lignin. This non-productive binding of enzymes to lignin is the singular cause for excessive consumption of enzymes and which has resulted in this process being hitherto uneconomical and thus resulting in the 2^nd generation ethanol industrial scale plants to fail commercially. It is observed that the interaction between enzyme and lignin is founded upon a combination of hydrophobic interaction, electrostatic interaction, and hydrogen bonding, all of which are related to the properties of lignin surfaces. To relieve this enzyme non-productive binding to lignin, it can be hypothecated that altering the properties of lignin surfaces is an effective strategy in achieving an increased yield (or reduced consumption of enzymes) for better economic viability.

[0107] The mechanism of action by which these chemicals improve enzymatic hydrolysis is by adsorbing/binding them to the lignin surfaces through a combination of hydrophobic interaction and hydrogen bonding, which imparts a physical barriers between lignin sites and enzymes and thus prevented enzyme adsorption on lignin. These lignin suppressant chemicals do not provide the requisite hydrophobic/electrostatic/ hydrogen bonding to the enzymes to attach, thereby redirecting the enzymes to cellulose and hemi-cellulose, thus avoiding unproductive lignin binding and usage. This chemical treatment is done prior to enzymes being applied to the biomass. An embodiment of the present disclosure provides that this reaction is carried out under ambient conditions i.e. 40°C to 55°C, preferably 45°C, thereby eliminating any chance of formation of volatiles and degradation products from cellulose. Importantly, this chemical is neutral to xylose which is carried over as occluded dissolved solids in the retentate and does not degrade these sugars.

[0108] An embodiment of the present disclosure provides that the cellulose rich biomass of pH 4.5 is mixed with a non-ionic detergent like sodium lauryl sulphate, Tween 60 but more preferably polyethylene glycol (peg, having molecular formula C2nH4n+20n+i) which is a synthetic, hydrophilic, biocompatible polymer. PEG is synthesized using a ring-opening polymerization of ethylene oxide to produce a broad range of average molecular weights ranging from 100, 200, 600, 1000, 1500, 3000, and 7000 going to 20,000. An exemplary embodiment of the present disclosure provides that PEG of average molecular weight 4000 is made into a solution using process water to make a solution having 0.0071 Molarity. An embodiment of the present disclosure provides that the quantity of PEG 4000 to be used is 10-15% of the lignin present in the biomass. An exemplary embodiment of the present disclosure provides that PEG 4000 equal to 13.50% by weight of the lignin content is used and this solution is thoroughly mixed with the cellulose rich biomass of pH 4.5 under ambient conditions i.e. 40 °C to 55 °C, preferably 45 °C to ensure adequate binding to the lignin surface. Another exemplary embodiment of the present disclosure provides that at this stage the biomass is fully prepared for receiving the enzymatic treatment and having a solids content of 17-19%, preferably 18%.

[0109] Further, an embodiment of the present disclosure provides that the temperature of the biomass and the added reactants is maintained in the enzymatic saccharification vessel (209). Commercially available Cellic Ctec3 enzyme cocktail from Novozymes was used for the biological degradation of cellulose and xylan. This enzyme cocktail comprises of both cellulase enzyme and xylanase enzyme. This exhibited high Carboxymethyl Cellulase assay for endo-13-1, 4-glucanase (CMCase assay), Filter Paper Assay for saccharifying cellulase (FPase assay) and beta glucosidase (B-glucosidase) activity in converting cellulose to glucose and xylanase activity resulted in conversion of hemi-cellulose to xylose. The vendor claimed a Biomass hydrolysis activity (BHU-2-HS/g) value of 2253 per gram of enzyme. Further, the active enzyme protein content of the enzyme cocktail is approximately 20-30% cellulose and 1-5 % xylanase (endo-1,4-). We further had the enzyme analysed for FPase activity (filter paper activity) and an embodiment of the present disclosure provides that this was 117.37 +/- 0.725 FPU/gram and the protein content (Bradford method) was 95.96 +/- 1.86 mg Psa equivalent per gram enzyme.

[0110] The biological degradation of cellulose (cellulolysis) in an enzymatically controlled synergistic process involves three types of glycoside hydrolases (GH): endo-[3-l,4-glucanases, exo-P-l,4-cellobiohydrolases, and [3-glucosidases for cellulose hydrolysis. To decrease the level of polymerization of the cellulose chain, [3- 1 ,4glycosidic bonds of the cellulose strands are randomly broken down by endo-P-l,4-glucanases. Further, exo-P-l,4-cellobiohydrolases releases cellobiose or glucose by removing subunits at both reducing and non-reducing ends of the cellulose chain. To complete the bio-degradation of cellulose, glucose is produced through hydrolysis P- glucosidases from cellobiose or water soluble cellodextrin.

[0111] The breakdown of xylan is relatively more complex due to its heterogeneous nature and xylanases capable of cleaving the heterogeneous P- 1 ,4-glycoside linkage effectively degrade xylan to produce xylose. Hence the prior need for acid hydrolysis. An embodiment of the present disclosure provides that the enzyme is dosed at the rate of 75 +/- 5 BHU-2-HS/g of Cellulose (or glucan) or alternately 3.75 to 4.00 FPU/gram Cellulose (or glucan) resulting in saccharification of cellulose > 85% to hexose and residual hemicellulose > 85% to xylose. Without lignin suppressant the enzyme consumption on the pre-treated biomass (203) (as also cited in other research papers available in public domain) shows a dosage of 15 - 20 FPU/gram and that too yielding a maximum saccharification of 77-80% of cellulose, which renders the enzymatic hydrolysis uneconomical. An embodiment of the present disclosure provides that use of lignin suppressant PEG 4000 resulted in reduction in enzyme usage by 65 to 80%. The reaction of enzymes with cellulose is given hereunder:

Enzymatic hydrolysis of cellulose

[0112] Post the addition of the enzyme, the solids content reaches 14-18% more preferably 16%. The shear resistance to the agitator blades drops slowly initially and then sharply as the time of reaction proceeds. At this juncture the fiber loses its entire shear strength and the mass is like a Newtonian fluid. A combination of high shear mixers which can mix this fluid intensely is now activated in addition to the agitator so that near homogeneity of this mass with the reactants and enzymes is achieved. This accelerates the solubilization of cellulose to glucose and near complete dissolution occurs in 48 to 60 hours more preferably 52 hours. Considering the economics of the operation, the quantity of enzymes may be changed to reduce the time taken for solubilization of cellulose.

[0113] A higher quantity of enzymes can reduce the time required for the complete process, but makes the entire process uneconomical. The liquefied mass is subject to membrane filtration followed by hot water (213) washing. The washing of the cake displaces the sugars and the cake has minimal residual carried over sugars. The washing is done twice following the counter current principles, wherein the last wash is done using fresh hot process water and the filtrate is stored separately and used for the first wash of the next cycle. The first wash is done using the filtrate of the last wash, after it is heated to 80 C (215). The filtrate from the first filtering of the hydrolyzed substrate is rich in sugars and is taken for dewatering and fermentation (221). An exemplary embodiment of the present disclosure provides the mean values of expected results for the residual biomass/ retentate which is shown in table 6 below.

Table 6

[0114] In an exemplary embodiment nearly 80% of available cellulose and 85% of available hemicellulose is solubilized to sugars during enzymatic hydrolysis and the mean values of the dissolved sugars recovered are: Glucose as 65 GPL and Xylose as 15 GPL. An exemplary embodiment of the present disclosure provides the overall recoveries from rice straw components starting as bone dry input and after enzymatic hydrolysis which is shown in table 7 below.

Table 7

[0115] The schematic layout and general arrangement for enzymatic hydrolysis is shown in Figure 9.

[0116] After completion of this step, there are 2 streams of product available for further processing: Glucose (Hexose) sugars free of suspended particulate matter (221) and a lignin/silica rich residue (219) containing 45-55% solids content.

Apparatus & method for sugar neutralization & dewatering:

[0117] In an exemplary embodiment the Cs hydrolysate recovered after pre-treatment are highly acidic and also very dilute. For better ferment-ability, these are subjected to neutralization and/or over-liming. Thereafter, the sugar solution is to be acidified to 5.5 to 6 pH prior to fermentation. Over-liming can be achieved using ammonia or a basic salt. Preferably ground limestone or calcium carbonate is added to the acidic Cs hydrolysate in an agitated reaction vessel and a sufficient quantity of calcium carbonate is added to raise the pH to 9 to 10, preferably 10. This is called over-liming and results in removal of recalcitrants to fermentation. An embodiment of the present disclosure provides that the sulfuric acid in the sugar solution reacts with calcium carbonate to form Calcium Sulfate (gypsum) and release of water and carbon dioxide as gas. An embodiment of the present disclosure provides that the sugar solution after neutralization is filtered through a high pressure membrane press operating at 142 to 215 psi g pressure so that the cake comprising of gypsum discharged from the press has less than 30% occluded moisture. The gypsum recovered as filter cake is washed and dried and packed for the market. [0118] Liquid-Liquid separation of molecules with sub- Angstrom scale precision is the basis of nano-filtration (NF) technology. In an embodiment of the present disclosure, after gypsum separation, the alkaline sugar stream is subjected to ultrafiltration (UF) (305) to reduce total suspended solids to less than 40-50 ppm and turbidity to <10 NTU. In another embodiment of the present disclosure, UF is done by pumping the alkaline sugar stream tangentially across a 3000 Dalton membrane at pressures ranging from 58 to 72 psi (g) and then sending the permeate (307) to nano filtration (NF) (317), which is carried out by a filtration membrane having porosity in the range of from 100 to 300 Daltons, wherein the alkaline sugar stream is pumped at 405 to 435 psi and through 100 to 300 Dalton porosity filtration membranes and the permeate containing the alkaline water (323) is collected separately, whilst the retentate which is the first concentrated sugars is sent for co-fermentation. The retentate from UF (305) containing suspended solids is sent to the settling tank and returned to ultrafiltration (305), and the permeate containing the alkaline sugar solution is subjected to further nano filtration (317). In an embodiment of the present disclosure the water so recovered would be recycled for reuse in processing for dilution of biomass after pre-treatment. The high pH of the water (~10 pH) would neutralize the acidic biomass leading to eliminating the use of alkaline salts for this step.

[0119] Similarly, C6 hydrolysate (221) obtained after enzymatic cellulose saccharification, is subjected to nanofiltration (NF), which is accomplished by a filtration membrane with porosity in the range of 100 to 300 Daltons and a dewatering efficiency of 50%. The C6 rich hydrolysate is pumped at 405 to 435 psi and through 100 to 300 Dalton porosity filtration membranes and the permeate containing the alkaline water is collected separately, whilst the retentate containing the second concentrated sugars (413) is sent for co-fermentation, wherein the second concentrated sugar solution (413) is achieved by liquid-liquid separation through nano filtration, whilst the retentate containing the Ce rich sugar hydrolysate concentrated sugars is sent for co-fermentation. Further, an embodiment of the present disclosure provides that the sugar solution is passed through a battery of (NF) membranes with a dewatering efficiency of 83%. An exemplary embodiment of the present disclosure provides that for every 100 litres of sugar solution fed into the NF module, 83 litres of pure water or permeate (409) would be separated and 17 litres of concentrated sugar (413) solution would be recovered. The sugar solution so produced is concentrated to 110 to 130 gpl more preferably 120 gpl of hexose rich sugars. The water so recovered is either mixed with mild sodium hydroxide to raise the pH to neutral or slightly basic ~ 7 to 7.2 pH and sent for reuse as process water or alternately, directly used in cold blow discharger (127) during pre-treatment.

[0120] An exemplary embodiment of the present disclosure provides the hexose rich and pentose rich sugar solutions have a ratio of 2: 1 volume by volume and results expected from NF of hexose sugars which is shown in table 8 below.

Table 8

[0121] The UF membrane used is a hollow fiber type. This is a very rugged membrane that has a thin film layer on a polyethersulphone backing. It gives the membrane a characteristic high flux and a tight pore structure making it a low cut off UF. An embodiment of the present disclosure provides UF membranes of 04Kda to 06Kda porosity and an exemplary embodiment of the present disclosure provides UF membrane of 5000 Dalton (da) porosity. An embodiment of the present disclosure provides NF membranes made of thin film composite polyamide with porosity of 100- 150 da to 200-300 da, and an exemplary embodiment of the present disclosure provides NF membrane of 100-150 da. The pictures of the substrate and water generated from UF/NF is shown in Figure 10. The schematic for the process flow for UF & NF and of a typical spiral NF membrane is shown in Figure 11 and Figure 12 respectively. Sugar fermentation to ethanol:

[0122] The sugars after concentration are cellulosic monomeric sugars comprising both pentose and hexose sugars. Whereas, Saccharomyces cerevisiae is the microorganism of choice to assimilate hexose sugars, unfortunately, by itself, it does not assimilate C5 sugars. The Saccharomyces cerevisiae strain needs to be modified with the purpose of providing the organism with the ability to metabolize the pentose sugar D-xylose, and thus to convert D-xylose into ethanol at a high rate in addition to the natural ability of the strain to convert glucose into ethanol. The resultant yeast strain is not capable of producing any compound that is new to the organism, or to produce in high amounts any compounds that it could not produce in such amounts prior to the modifications. The sole effect of the modifications is that the resultant strain can use D-xylose as carbon source in addition to glucose and other hexose sugars.

[0123] The organism has been genetically modified by insertion and overexpression of three Saccharomyces cerevisiae genes, encoding enzymes involved in the pentose phosphate pathway. Those three genes have been cloned from the recipient S. cerevisiae strain itself. To increase the xylulokinase activity an artificially synthesized gene encoding a xylulokinase as present in the yeast Scheffersomyces stipitis, under the control of an S. cerevisiae promoter and terminator was also inserted. Further, two artificially synthesized genes encoding 2 enzymes from Lactococcus lactis has been inserted, under the control of S. cerevisiae promoters and terminators. Those six genes are thus all expressed under control of native S. cerevisiae glycolytic promoters and the produced enzymes retained intracellularly. The two Lactococcus lactis genes enable the yeast to convert D-xylose into D-xylulose, and the remainder overexpressed genes cause an increased flux through the existing Pentose Phosphate Pathway. In conjunction, these modifications provides the yeast with the ability to perform high rate conversion of D-xylose into ethanol. By up-regulation of the pentose phosphate pathway, and expression of a bacterial xylose isomerase, as well as a xylose 1 -epimerase, the strain utilizes an efficient xylose metabolic pathway. This organism is already patented which is granted to Terranol a/s of Denmark and has been duly disclosed under prior art IN328578 and IN307801. The balance between ethanol yield and ethanol productivity - ethanol production and yeast growth - has to be well understood and tuned to sugars sourced from different cellulosic sources. [0124] The living modified organism (LMO) or genetically modified organism as above, which is categorized under Biosafety Level 1 , is to be propagated from its lyophilized state to appropriate concentration and quantity which is also called a pre-ferment (PF) to enable it to co-assimilate or co-ferment the pentose and hexose sugars simultaneously.

[0125] An embodiment of the present disclosure provides that the desired volume of PF or starter culture (603) is prepared equivalent to 15 to 25% of the total volume of the sugars being fermented preferably 20% with a cell concentration of 5-8 gpl preferably 6.5 gpl. Another embodiment of the present disclosure provides that the starter culture broth or PF (603) is pitched into the fermenter vessel (609 & 613). Another embodiment of the present disclosure provides that thereafter the sugar slurry of 110-130 gpl concentration preferably 120 gpl comprising of Cs and Ce streams is fed to the fermenter using the fed-batch method. Another embodiment of the present disclosure provides that initially 10% of the total volume of sugar substrate to be fermented is fed to the fermenter along with nutrients like urea and di-ammonium phosphate and anaerobic fermentation wherein the yeast is allowed to assimilate the same. Another embodiment of the present disclosure provides that Hexose is fully assimilated while xylose to the extent of 35% is assimilated before the time to add the next batch of substrate is reached.

[0126] Another embodiment of the present disclosure provides that the time taken for the above is about 4-6 hours preferably 5 hours. Thereafter, the sugar substrate is fed in equal batches as per the standard fed batch fermentation procedure. Anaerobic fermentation is an exothermic reaction and the entire substrate during the process is maintained at 30 to 32 °C by circulating cooling water in the limped coils on the outer surface of the fermenter as also circulating the sugar solution in the fermenter through an external plate & frame type heat exchanger. Samples are drawn at intervals of 4 hours and tested for Specific Gravity at the plant. Microscopic analysis for cell viability, contamination, HPLC analysis for sugar consumption and ethanol content, cell concentration by biomass analysis is conducted.

[0127] An embodiment of the present disclosure provides that the fermentation process continues for 37 to 39 hours till the hexose sugars are fully exhausted and the residual xylose sugars remain constant over a 4 hour period. An exemplary embodiment of the present disclosure provides that approximately 5-6% of initial xylose remains unexhausted in the fermented wash (629, 703) and the ethanol efficiency achieved is 87 to 89%. Another embodiment of the present disclosure provides that the entire fermentation section is fully enclosed with restricted access for authorized personnel only to meet the BSL-1 norms. Another embodiment of the present disclosure provides that the carbon dioxide (635) vented from the fermenters is bubbled through a suitable disinfectant and then taken to a floating bell storage and thereafter compressed for pressurized storage. The entire process water from pump seals etc. is passed through a disinfection treatment tank and then discharged for further treatment/recycling.

[0128] Whole fermented wash (629, 703) is transferred to common beer well tank (617). It is then pumped continuously to the analyzer column (705) and thereafter to the rectifier column (707) to achieve rectified spirit of 94% to 95% concentration. The ethanol at this stage is also known as extra neutral alcohol or ENA. For fuel grade ethanol, ENA is dehydrated by the Molecular Sieve Dehydration System (MSDS) to a final concentration of 99.50% to 99.70%. An exemplary embodiment of the present disclosure is that the ethanol produced is free from alkalinity, fully miscible in water and has a density of 0.7972 at 15.6 °C. Acidity as (Acetic acid) as tested is nil. The residue on evaporation as tested as nil. An exemplary embodiment of the present disclosure provides the analysis of the spent wash generated from the analyzer column (705) which is shown in table 9. The schematic layout and general arrangement for alcohol distillation is shown in Figure 16.

Table 9

[0129] The above analysis shows that the quality of spent wash generated is far less toxic compared to the wash generally generated in molasses or grain based distillery or other cellulosic ethanol processes. The spent wash (735) is evaporated and the condensate recovered is nearly neutral to smell and albeit acidic. It is recycled after treating with an alkaline solution and after passing it through a reverse osmosis membrane. The schematic layout and general arrangement for silica & chemicals and process flow diagram for fermentation is shown in Figure 14 and Figure 15 respectively.

Lignin burning/ steam generation, silica precipitation & chemical recovery:

[0130] An embodiment of the present disclosure provides that the retentate (219) recovered from membrane filtration of enzymatically hydrolyzed substrate and after counter current washing contains nearly 35% lignin and 40% silica rich ash in the solid cake. The cake also has nearly 45 to 55% moisture. An exemplary embodiment of the present disclosure provides that the calorific value of the dried cake obtained is 2900 +/- 100 Kcal/kg. The key takeaway is that having undergone so many stages of acidic reaction and washing, the ash leftover is relatively pure save for the lignin and residual cellulose/ hemi-cellulose content and some extractives. These are easily burned, having some heat value.

[0131] Another embodiment of the present disclosure provides that the residue is dried in a suitable dryer like a vibrating fluidized bed dryer or a belt dryer or a spin flash dryer. An exemplary embodiment of the present disclosure provides that a spin flash dryer with hot air from the flue gases from the boiler having 170 to 180 °C temperature is fed with the wet residual biomass with 45 to 55% moisture and is dried to <5% moisture and recovered in bag filters. Another embodiment of the present disclosure provides that this dried residue is then burnt in a specially designed boiler with bed temperature maintained between 500 to 600 °C to generate medium pressure steam for process use mainly during pre-treatment and rectification/distillation of ethanol.

[0132] The slag from the boiler (507) contains nil or negligible organic matter (unburnts) and is composed of mainly inorganics of which silica constitutes >75%. An embodiment of the present disclosure provides that this ash is dissolved with caustic soda which is added in the ratio of 10 tol5% of the total dry ash content, preferably 11.50% as a IM solution. Another embodiment of the present disclosure provides that dissolution takes place by mixing ash and hot water at > 90 °C to which caustic lye is added to achieve 1 Molarity. Another embodiment of the present disclosure provides that the reaction is allowed to continue till sodium silicate is formed and nearly all the alkali is exhausted and pH of 9 to 9.5 is reached and 75% of the ash dissolves. This is filtered through filter press (517) and the filtrate which is pure sodium silicate is again treated in an agitated jacketed vessel (523) and heated to > 90 °C preferably 95 °C. Another embodiment of the present disclosure provides that pure carbon dioxide (505) (from fermentation section) is bubbled in a controlled manner resulting in silica precipitation. Another embodiment of the present disclosure provides that this entire mass of sodium carbonate solution and silica is passed through a clarifier (529) and silica is recovered from the under-flow.

[0133] An embodiment of the present disclosure provides that the silica is washed on drum and sieve washer (547) and then dried in spin flash dyer (563) to produce pure precipitated silica. Another embodiment of the present disclosure provides that Precipitated silica produced is nearly 6 to 10% by weight of the input bone dry weight of rice straw. An embodiment of the present disclosure provides that the overflow from the clarifier called green liquor is subjected to reaction with quick lime or calcium oxide (CaO) at > 90 °C preferably 95 °C. CaO is added through a slaker (539) to remove impurities like sand, grit, etc. and mixed with green liquor in reaction vessels and maintained at elevated temperature till NaOH is formed along with precipitated CaCCh. This entire mass of dissolved NaOH and CaCCh as suspended solids is passed through a clarifier and the over flow called white liquor or NaOH is recovered for reuse and the underflow is passed through lime mud washers (drum and sieve washer) to recover relatively pure CaCOa.

[0134] Silica finds use as an anti-caking agent as well as an adjunct for pesticides, insecticides fungicides; it also finds use as a rubber strengthening agent and as an additive, it is used to improve rubber tear strength, flex fatigue resistance, abrasion resistance, heat buildup, hardness, modulus, resilience, and adhesion. Silicone rubber (hydroxy terminated silicones) and silicone fluid (polydimethylsiloxane) are high value added products finding ever increasing use globally. Silicone rubbers are widely used in industry, and there are multiple formulations. Silicone rubbers are often one- or two-part polymers, and may contain fillers to improve properties or reduce cost. Silicone rubber is generally non-reactive, stable, and resistant to extreme environments and temperatures from -55 to 300 °C (-70 to 570 °F) while still maintaining its useful properties. Due to these properties and its ease of manufacturing and shaping, silicone rubber can be found in a wide variety of products, including voltage line insulators; automotive applications; cooking, baking, and food storage products; apparel such as undergarments, sportswear, and footwear; electronics; medical devices and implants; and in home repair and hardware, in products such as silicone sealants. Silicon atoms derived from precipitated silica is combined with methyl chloride and heated. It is then distilled into a polymerized siloxane known as polydimethylsiloxane.

[0135] Production of ethanol combined with gypsum and silica establishes a viable process for a 2^nd generation ligno-cellulosic ethanol bio-refinery. The complete process flow diagram of the entire processes is shown in Figure 3.

WORKING EXAMPLES:

Example 1: Wet washing apparatus and method:

[0136] Cut and Shredded rice straw containing 15% moisture is conveyed from the shredder (103) using an inclined belt conveyor (105) to a screw conveyor equipped with a pin breaker to loosen the tangled straw and is then fed directly into the turbo washer (107). In this example, 10 Metric Tonnes of as is straw is conveyed and 330 MT’s of water is added simultaneously to dilute the straw and the resultant colloidal solution of 2.50% consistency (Cy) is agitated vigorously to loosen all the mud and extraneous matter stuck to it. This solution is discharged from the top of the turbo washer (107) to an Aqua separator (109), which comprises of an inclined screw conveyor fitted with a slotted screen. Nearly 96% of the solution or 326 MT’s containing 8.40 MT’s of straw when conveyed through this aqua separator (109), gets dewatered and about 284 MT’s of separated water is recycled for dilution of the straw. About 4% rejects from the turbo washer (107) are discharged from the bottom onto a DSM screen (111) and fiber (cut straw) is separated and put back into the turbo washer. The water from the DSM screen is taken to the clarifier.

[0137] The wet straw of 20% Cy from Aqua separator (109) is fed to the second turbo washer (107) and again 295 MT’s of water is added to dilute the colloidal solution to 2.5% Cy. Again 324 MT’s or 96% of the material is dropped into an aqua separator (109) which is longer than the first one and dewaters 303 MTs of water (or 92% of total water in the colloidal solution) which along with the water from the second DSM screen (111) is sent to clarifier for settling. Nearly 248 MT’s of water from the clarifier is recovered and recycled for dilution of straw before turbo washing, 46 MT’s to the first turbo washer and 203 MT’s to the second one. About 54.5 MT’s of water rejected from the clarifier is taken for reverse osmosis and is recycled as process water. 21 MT’s of washed straw having 40% Cy is taken for the next process step of pre -treatment. Of the 625 MT’s of water required for the process, only 52 MT’s or 8% water from other sources is required. It is a complete process with counter current washing and recycling to yield clean biomass for further processing. This exemplary process is shown with a flow chart in Figure 7.

[0138] The present disclosure provides an efficient, cost-effective, eco-friendly, bio-safe, circular biochemical process, recovery and reuse of chemicals, zero liquid discharge, reduction in carbon dioxide emissions relative to fossil fuels, provide platform for aviation fuels, provide platform for preparation of green biodegradable plastics and suitable for industrial preparation and providing a high yield process.

Advantages:

1. The process of present disclosure provides a successful design, engineering and demonstration of a continuous hydrolyzer for pre-treatment of cut straw with a throughput rate of 500 - 600 Kilograms/hour with consistent and repeatable results and efficient breakdown of long chain hemi-cellulose to short chain sugar pentose. Minimal formation of known recalcitrant like furfural, 5 -hydroxymethyl furfural, formic acid and acetic acid is the key design feature established. These compounds are normally observed to be formed during acid catalyzed hydrolysis and are inhibitors and known to hinder fermentation leading to lower yields and higher processing times. Most importantly, the process does not require either shredding of the biomass to a very fine size i.e. below 1 mm in size and also no presoaking of the biomass in acid prior to hydrolysis (this was considered important for removal of acetyl and uronic acid groups from hemi-cellulose). The process of present disclosure provides feeding shredded and washed biomass to the continuous hydrolyser at a relatively high 40% solids content and achieving pre-treatment end point through continuous processing without having to further dilute the substrate. Cut straw has a very low bulk density 110 Kgs/cubic meter and would require a vessel nearly 10 times its volume to process in a batch process. It is to overcome this challenge that a hydrolyzer which can compress the straw and process it continuously was designed and optimized for commercial scale operations. The process of present disclosure further provides for the elimination of the process step of delignification prior to enzymatic hydrolysis of the cellulose recovered after pre-treatment. The delignification step leads to loss of cellulose/hemicellulose and thus lowering of yield of sugars for fermentation. It is well established that the interaction between enzyme and lignin is founded upon a combination of hydrophobic interaction, electrostatic interaction, and hydrogen bonding, all of which are related to the properties of lignin surfaces. To relieve this enzyme non-productive binding to lignin, the present process demonstrates that altering the properties of lignin surfaces is an effective strategy in achieving an increased yield (or reduced consumption of enzymes) for better economic viability. Addition of lignin suppressants improve enzymatic hydrolysis by adsorbing/binding them to the lignin surfaces. These suppressants do not provide the requisite hydrophobic/electrostatic/ hydrogen bonding to the enzymes to attach, thereby redirecting the enzymes to cellulose and hemi -cellulose, thus avoiding unproductive lignin binding and usage. The process of present disclosure further provides for the successful recovery of water for reuse from the dilute sugars recovered from pre-treatment and enzymatic hydrolysis prior to these being subjected to fermentation. This is achieved using ultra/nano filtration processes which are highly energy efficient and economical to operate, besides ensuring separation of all high molecular weight impurities from sugar stream. This method significantly reduces the consumption of water for the production of ethanol thereby making the technology ecologically sustainable and environmentally friendly. Corn ethanol requires 3 times water to ethanol produced whereas rice ethanol plants require 10 times water to ethanol produced. Commercial cellulosic ethanol pants have reported water consumption 11 times the ethanol production. Moreover, concentrated pure sugar streams are produced for fermentation, a first for commercial ethanol production. The process of present disclosure further provides for the simultaneous utilization of pentose sugars by highly effective industrial modified yeast strains which leads to a significant increase in ethanol yields. Whereas, saccharomyces cerevisiae is the microorganism of choice to assimilate hexose sugars, unfortunately, by itself, it does not assimilate pentose sugars. The saccharomyces cerevisiae strain needs to be modified with the purpose of providing the organism with the ability to metabolize the pentose sugar D-xylose, and thus to convert D- xylose into ethanol at a high rate in addition to the natural ability of the strain to convert glucose into ethanol. The resultant (modified) yeast strain is not capable of producing any compound that is new to the organism, or to produce in high amounts any compounds that it could not produce in such amounts prior to the modifications. The sole effect of the modifications is that the resultant strain can use D-xylose as carbon source in addition to glucose and other hexose sugars. By up-regulation of the pentose phosphate pathway, and expression of a bacterial xylose isomerase, as well as a xylose 1 -epimerase, the strain utilizes an efficient xylose metabolic pathway. By assimilating relatively pure sugars, ethanol efficiency of 87 to 89% has been achieved with the said modified yeast culture within reasonable time period for fermentation as compared to the time taken for complete fermentation observed during of sugars from grain/ molasses.

5. The process of present disclosure further provides for the production of precipitated silica as a valuable product stream in significant quantities thereby establishing an alternate revenue stream to ethanol.

6. The process of present disclosure is a process whereby all the chemicals are recovered and recycled during the entire process leading to negligible solid discharge and insignificant liquid discharge.

7. The process of present disclosure further provides for production of ethanol with potential to reduce 78% carbon and greenhouse gas emissions versus fossil fuels. These are based on lifecycle analysis of the process from field to pump. Life cycle GHG emissions from ethanol are 292 kg CO2 eq./ton straw. Ethanol blending with petrol (or gasoline) to the extent of 5% or E5, would reduce GHG emissions by 4.3% whereas an E20 blend would lead to a reduction of 17.4%. Thus cellulosic ethanol is a potent source for de-carbonization. [0139] Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. As such, the spirit and scope of the subject matter should not be limited to the description of the preferred embodiment contained therein.

Claims

I CLAIM:

1. A process for preparing bio-products from biomass comprising: a) treating the biomass in a fully pressurized vessel (121, 123, 125 & 127) for a vapour phase reaction to obtain a treated biomass (131) ; b) separating the treated biomass ( 131 ) by solid liquid separation to obtain a Cs hydrolysate (145) and a solid form; c) neutralizing Cs hydrolysate (145) with a neutralizing agent to obtain an alkaline sugar stream (303) and a by-product gypsum; d) ultra (305) and nano-filtering (317) the alkaline sugar stream (303) to obtain a first concentrated sugar solution (319) and an alkaline water permeate (323); e) subjecting the solid form (203) with enzymatic cellulose saccharification and separating by solid liquid separation to obtain a Ce hydrolysate (221) and a filter cake (219); f) nano-filtering the Ce hydrolysate (221) to obtain a second concentrated sugar solution (413) and process water (409); g) co-fermenting the first (319) and second sugar solutions (413) to obtain a fermented solution (629/703); h) distilling (705 & 707) and dehydrating the fermented solution to obtain a bio-product ethanol; i) drying the filter cake through a dryer to obtain a combustible bio-product; and j) burning the combusted bio-product to obtain a bio-product precipitated silica (565).

2. The process as claimed in claim 1 , wherein the biomass is selected from group consisting of rice straw (101), paddy straw (101), corn stover, and sugarcane bagasse or combination thereof.

3. The process as claimed in claim 1, wherein prior to the treating the biomass, it is subjected to a process selected from decontamination from metals, shredding, mechanical size reduction, water settling and recycling or combination thereof.

4. The process as claimed in claim 1, wherein the C5 hydrolysate (145) is a sugar solution rich in pentose.

5. The process as claimed in claim 1, wherein the C6 hydrolysate (221) is a sugar solution rich in hexose or glucose.

6. The process as claimed in claim 1 , wherein the biomass is fed to a fully enclosed and isolated plug flow continuous vapour phase pressurized reactor (121, 123, 125, & 127) isolating all upstream and downstream processes from the severe pre-treatment process conditions of chemical vapours and high temperatures.

7. The process as claimed in claim 1, wherein the biomass is subjected to a thermo-chemical exfoliation resulting in breakdown of the fibers and catalysis of hemi-cellulose to Cs hydrolysate (145).

8. The process as claimed in claim 6, wherein the biomass coming through the screw feeder (119) is continuously impregnated with an atomized acid and subjected to hydrolysis with steam; which is carried out by a mineral acid selected from the group consisting of nitric acid, oxalic acid and sulfuric acid and under isothermal or constant temperature and constant pressure or isobaric conditions to obtain hydrolyzed biomass.

9. The process as claimed in claim 8, wherein the hydrolyzed biomass is discharged through a cold blow discharger (127) to an agitated blow tank (133).

10. The process as claimed in claim 1, wherein the solid liquid separation of treated biomass (131) is carried out by pressurized solid liquid separation system, wherein the slurry is fed (135) at a temperature in the range of 340 to 355 Kelvin and under a pressure in the range of 58 to 72 psi (gauge) to a diaphragm type membrane press (139) and the cake is subjected to hydraulic squeezing at a pressure in the range of 205 to 215 psi (gauge) pressure to increase the solids content to 40-45%.

11. The process as claimed in claim 1 , wherein the neutralizing agent is selected from the group consisting of ammonia, ground limestone and calcium carbonate.

12. The process as claimed in claim 1, wherein the solution is neutralized to a pH >9 to rid the sugar solution off recalcitrant generated during pre-treatment and generate gypsum as by-product.

13. The process as claimed in claim 1, wherein after separating gypsum, the alkaline sugar stream (303) is subjected to liquid-liquid separation, wherein the ultra-filtration (305) is carried out to reduce the total suspended solids to below 40 to 50 ppm & turbidity <10 NTU, by pumping the alkaline stream at a pressure in the range of 58 to 72 psi (g) tangentially across a 3000 Dalton membrane and the permeate (307) is then sent for nano filtration (317), the retentate (311) containing suspended solids is taken to a settling tank (313) and recycled for ultra-filtration (303), wherein the permeate (307) comprising alkaline sugar solution is further subjected to nano filtration (317).

14. The process as claimed in claim 13, wherein the alkaline sugar stream (303) is subjected to liquid- liquid separation by nano filtration (317), which is carried out by a filtration membrane having porosity in the range of from 100 to 300 Daltons, wherein the alkaline sugar stream (303) is pumped at 405 to 435 psi and through 100 to 300 Dalton porosity filtration membranes and the permeate (323) containing the alkaline water is collected separately, whilst the retentate containing the concentrated sugars (319, 413) is sent for co-fermentation.

15. The process as claimed in claim 1, wherein the nano filtration (317) provides alkaline water which is recycled for neutralization and dilution of filter cake before enzymatic hydrolysis and for wet washing in turbo washer (107).

16. The process as claimed in claim 1, wherein the enzyme is selected from cellulose-active glycoside hydrolases including cellobiohydrolases, endoglucanases and P-glucosidases and xylanase or combination thereof.

17. The process as claimed in claim 15, wherein the enzyme is having biomass hydrolysis activity (BHU-2-HS/g) value of between 2100 to 2275 per gram of enzyme; 117.37 +/- 0.725 FPU/gram FPase activity and the protein content is 95.96 +/- 1.86 mg Psa equivalent per gram enzyme.

18. The process as claimed in claim 1, wherein the concentrated sugars (319, 413) are co-fermented using a living modified organism which is modified by insertion and overexpression of three Saccharomyces cerevisiae genes, encoding enzymes involved in the pentose phosphate pathway.

19. The process as claimed in claim 1, wherein the filter cake is subject to counter current washing before drying to obtain dilute acidic Ce sugar solution recyclable wash (215) and residual lignin and silica (ash) rich retentate.

20. The process as claimed in claim 1, wherein the second concentrated sugar solution (413) is achieved by liquid-liquid separation through nano filtration which is carried out by a filtration membrane having porosity in the range of from 100 to 300 Daltons, wherein the Ce rich hydrolysate (221/401) is pumped at 405 to 435 psi and through 100 to 300 Dalton porosity filtration membranes for dewatering and the permeate containing the water (409) is collected separately, whilst the retentate (413) containing the Ce rich sugar hydrolysate concentrated sugars is sent for co-fermentation.

21. The process as claimed in claim 1, wherein the co-fermentation process is carried in a fermentation vessel having nutrients selected from urea and di-ammonium phosphate.

22. The process as claimed in claim 1, wherein the co-fermentation provides carbon dioxide (505/635) which is passed into the process to obtain bio-product precipitated silica (565).

23. The process as claimed in in claim 1, wherein the dilute alcohol (617) in the fermented solution (629/703) is initially dehydrated azeotropically in a distillation column (705 & 707) and then dehydrated using molecular sieves.

24. The process as claimed in claim 1, wherein the dryer is selected from group consisting of vibrating fluidized bed dryer, a belt dryer and a spin flash dryer

25. The process as claimed in claim 18, wherein the lignin and silica (ash) (219) are dried with a spin flash dryer and burnt in a boiler to obtain a slag (507), wherein the slag (507) is subjected to alkali for ash dissolution (511) and carbonation (523) to obtain silica precipitate and a green liquor.

26. The process as claimed in claim 1, wherein the green liquor is subjected to chemical recovery plant to obtain calcium carbonate and caustic soda.

27. The process as claimed in claim 1, wherein the calcium carbonate is recycled to neutralize acidic sugar solution and caustic soda is recycled for ash dissolution.