Gasification, Saccharification, Composting 2 PDF

SACCHARIFICATION, GASSIFICATION AND COMPOSTING Saccharification: Breaking a complex carbohydrates to monomeric sugars Plant material containing lignocellulose can be converted into monomeric sugars- fermented to form either ethanol or biogas Increasing energy demand and anticipated...

SACCHARIFICATION, GASSIFICATION AND COMPOSTING Saccharification: Breaking a complex carbohydrates to monomeric sugars Plant material containing lignocellulose can be converted into monomeric sugars- fermented to form either ethanol or biogas Increasing energy demand and anticipated decline in crude oil- led to an immense search for new energy source  Agricultural industries- forestry, paper, foods Bacteria & few fungi- Tricoderma reesei, T. viride, Penecillium piniphilum, Fusarium solani, etc  Lignocellulose Cellulose- 40-60%, upto about 10,000 D- glucose residues, B-1,4- glycosidic bonds hemicellulose- 2nd most abundant non cellulosic, polysaccharides-glucose ,xylan and org. acids, filling voids around fibrils, made up of pentose( D- xylose, D- arabinose) and hexose( D-galactose, D-mannose, etc) lignin and other- lignin is a complex polyphenolic arising through polymerization of p- coumaryl, conifryl, sinapyl alcohol where phenyl propyl as basic unit. 2/3rd phenyl propane units and c- cbonds  Degradation  Physical ( Milling, grinding, radiation, Microwave, Pyrolysis, Gama-radiation treatment, boiling, glycerol heating), Chemical ( NaOH, H2SO4, Ozonolysis, ionic liquids  Biological process (Cellulase, xylanase, ligninase, laccase etc.)  Biological Cellulase is any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis, the decomposition of cellulose and of some related polysaccharides.  Types of cellulase 1. Endocellulases (EC 3.2.1.4) randomly cleave internal bonds at amorphous sites that create new chain ends. 2. Exocellulases or cellobiohydrolases (EC 3.2.1.91) cleave two to four units from the ends of the exposed chains produced by endocellulase, resulting in tetrasaccharides or disaccharides, such as cellobiose. Exocellulases are further classified into type I, that work processively from the reducing end of the cellulose chain, and type II, that work processively from the nonreducing end.  3. Oxidative cellulases depolymerize cellulose by radical reactions, as for instance cellobiose dehydrogenase (acceptor). 4. Cellulose phosphorylases depolymerize cellulose using phosphates instead of water. 5. Cellobiases (EC 3.2.1.21) or beta-glucosidases hydrolyse the exocellulase product into individual monosaccharides.  Xylanase  Responsible for hydrolysis of hemicellulose  Helps in bleaching of kraft pulps debarking, refining pulp fibres and preparing dissolving pulps  Major aim of pulp refining- reduction of energy demand  In enzymatic beating- enzymes are added to bleached pulp fibres to increase ext fibrillation, thus improves paper making properties  1,4-B-xylanase, b-xylosidase, Arabian- furanosidase, glucoronidase, etc. helps to remove side groups from xylan  Ligninases:  C-C bonds, ether bonds needs to be cleaved by oxidative mechanism complex, doesn’t require specific enzymes white rod Basidomycetes- depolymerisation of lignin  Lignin peroxidase (LiP)- Phanerochaete crysoporium, strong oxidizers- oxidation of phenols  Manganese peroxidase( MnP)- mostly in white rod fungi, first reported in P. crysoporium Veratryl ( VA) & Glyoxal oxidase ( GLOX):  components of peroxidase system, VA- fungal metabolism product, lignin degradation  GLOX- extracellular enzymes, produce H2O2 required by other enzyme catalysis Laccase: From basidomycetes, Neurospora, Aspergillus- direct oxidation of phenolic compounds  GASIFICATION: Biomass gasification means incomplete combustion of biomass resulting in production of combustible gases consisting of Carbon monoxide (CO), Hydrogen (H2) and traces of Methane (CH4). This mixture is called producer gas. Producer gas can be used to run internal combustion engines (both compression and spark ignition), can be used as substitute for furnace oil Gasificatio n– Basic Process Chemistry Schematic  Biomass that can be used… Very wide variety of feedstock can be used with simple processing in terms of sizing and moisture reduction to less than 20%, bulk density of above 100 kgs/m3 & free flowing nature. Shells of Agri-residues like Arecanut, Rice husk (as is Cotton / Almond, basis & no need Soyabean / Cashewnut, to briquette) Mustard stalks, Groundnut, Corn Cobs Coconut Waste Wood, Wood chips, Branches & Twigs Bamboo pieces & Plywood & Saw Pine needles mill wastes Greening of Wild bushes and Sugarcane waste lands weeds like Types of Gasifier  What is Biomass Gasification? Basic Process Chemistry Conversion of solid fuels into combustible gas mixture called producer gas (CO + H2 + CH4) Involves partial combustion of biomass Four distinct process in the gasifier viz. Drying Pyrolysis Combustion Reduction  THEORY OF GASIFICATION Carbon monoxide (CO), Hydrogen (H2) and traces of Methane and nonuseful products-tar and dust. The production of these gases is by reaction of water vapor and carbon dioxide through a glowing layer of charcoal. Biomass- charcoal- CO & H2  Drying Drying process process occurs at around 100 °C. Typically the resulting steam is mixed into the gas flow and may be involved with subsequent chemical reactions, notably the water-gas reaction if the temperature is sufficiently  Pyrolysis The pyrolysis process occurs at around 200–300 °C. Volatiles are released and char is produced, resulting in up to 70% weight loss for coal. The process is dependent on the properties of the carbonaceous material and determines the structure and composition of the char, which will then undergo gasification reactions.  Combustion The combustion process occurs as the volatile products and some of the char react with oxygen to primarily form carbon dioxide and small amounts of carbon monoxide, which provides heat for the subsequent gasification reactions. The basic reaction here is C +O2 = CO2  Gasification The gasification process occurs as the char reacts with steam to produce carbon monoxide and hydrogen. C +H2O = H2 + CO  Applications Power Thermal Generation Applications o Irrigation Pumping o Hot Air Generators o Village Electrification o Dryers o Captive Power o Boilers (Industries) o Thermic Fluid o Grid-fed Power from Heaters Energy o Ovens Plantations on Wastelands o Furnaces & Kilns o Simultaneous Charcoal COMPOSTING:  It is the transformation or Controlled decomposition of Organic material( plant matter)  Invertebrates (insects and earthworms) microorganisms- bacteria and fungi on leaves, grass, food scraps,etc  soil texture, structure WHY:  Nature ( environmentally) associated-- keeps biodegradable waste out of landfills & sewage plants, alternative to burning, important ingredient in the garden for plant growth ( fertilizers)  75% N, 60-70% Potassium, 100% Phosphorus to soil loosens soil, increase moisture holding capacity  check on wasteland  saves money – buying of manure  Not affect public health, high temp pathogenic microbes killed  acts as pesticides Material and factors:  Any organic materials as piles, proper ratio of Carbon-rich or browns and Nitrogen-rich or greens  Cooked food leftovers, meat or meat associated cooked foods, cheese, coal, etc can be use Effective- chlorophenols, petroleum hydrocarbons, polychlorinated biphenyls, etc 30 parts brown: 1 part green.. If not balanced odour formation or other problems  Water- not to dry not too wet, 40- 60% preferable squeeze handful of material to see water content  Air- absence of it leads to take over of anaerobic microbes, putrefying garbage  Size- 3feet wide depend tall  Temperature- efficient at 104 to 131°F, if same temp with outside environment, need to add more Nitrogen Types:  Bin composting  Yard trimming composting  Mixed MSW composting  Anaerobic composting  Vermicomposting 1. Backyard/ bin composting  Convenient way to reduce volume of trash by household  Yard waste, Kitchen scraps  Newspaper, Cardboard 2. Yard Trimmings Composting  large scale by the private sector firms or PWD, material taken at central location processed in aerated windrows where organic form in rows/piles  compost used for local landscaping projects 3. Mixed msw composting: Another treatment option, done in medium- to- large scale facility private firms receive at the site of location  Recyclable materials- aluminium, glass, etc. aerated windrows In-vessel composting- left to decompose  alternative- temperature and moisture control 4. vermicomposting:  Used of red worms to produce compost, easy  Basics needs to be followed enclosed bin- indoor & outdoor bins Challenge to find source of worm. 2 species- Eisenia foetida ( red worm), Lumbricus rubellus  idea to provide cool, moist bedding for worms to live in  Vermi-compost  Vermicomposting is a process that relies on earthworms and microorganisms to help stabilize active organic materials and convert them to a valuable soil amendment and source of plant nutrients.  Earthworms will consume most organic materials, including food preparation residuals and leftovers, scrap paper, animal manure, agricultural crop residues, organic byproducts from industries, and yard trimmings.  Importance of vermicomposting  Instead of disposing of food scraps, yard wastes, and other organics, the materials can be vermicomposted.  This method of recycling converts organic materials that have traditionally been viewed as waste into a valuable soil amendment for plants and crops.  When vermicompost is added to soil, it boosts the nutrients available to plants and enhances soil structure and drainage.  Vermicompost has also been shown to increase plant growth and suppress plant disease and insect pest attacks.  Advantages of vermicompost  Vermicompost is rich in all essential plant nutrients.  Provides excellent effect on overall plant growth, encourages the growth of new Shoots / leaves and improves the quality and shelf life of the produce.  Vermicompost is free flowing, easy to apply, handle and store and does not have bad odour.  It improves soil structure, texture, aeration, and water holding capacity and prevents soil erosion.  Vermicompost is rich in beneficial micro flora such as , P- solubilizers, cellulose decomposing micro-flora etc in addition to improve soil environment.  Vermicompost contains earthworm cocoons and increases the population and activity of earthworm in the soil.  Vermicompost minimizes the incidence of pest and diseases.  It enhances the decomposition of organic matter in soil.  Nutritive value of vermicompost Organic carbon 9.5 – 17.98% Nitrogen 0.5 – 1.50% Phosphorous 0.1 – 0.30% Potassium 0.15 – 0.56% Sodium 0.06 – 0.30% Calcium and Magnesium 22.67 to 47.60 meq/100g Copper 2 – 9.50 mg kg-1 Iron 2 – 9.30 mg kg-1 Zinc 5.70 – 11.50 mg kg-1 Sulphur 128 – 548 mg kg-1 Suitable species of worms for vermi- composting Eisenia foetida Eudrilus euginae Perionyx excavatus Bimastos parvus Basic characters of suitable species  Should be tolerant to disease  Culturing technique should be simple enough to adopt  Should be efficient convertor of plant or animal bio-mass  Wider adaptability  Growth rate-fast  Compatibility with other worms  Worms should produce large number of cocoons that should not have long hatching time, so that multiplication and organic matter conversion is fast  Requirements for vermicomposting  Container :- In a container of 2.23x 2.23 m, about 10 kg of earthworms can convert approximately 1t per month  Bedding material:-This is the lower most layer of earthworm feed substrate that is required to be composted-banana stem peels, coir pith, coconut leaves, grasses etc..  Moisture content:- 30-40%  Temperature:- 20-300 is optimum