CHAPTER 4 SUGARCANE ITS BYPRODUCTS AND CO-PRODUCTS, OPPORTUNITIES FOR DIVERSIFICATION: AN OVERVIEW

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1 CHAPTER 4 SUGARCANE ITS BYPRODUCTS AND CO-PRODUCTS, OPPORTUNITIES FOR DIVERSIFICATION: AN OVERVIEW 4.1 Introduction Sugarcane harvesting and processing has the benefits of obtaining multiple products and byproducts which are potential raw materials for the extractive, chemical and bio chemical industry. Practically all products and by-products obtained from sugarcane may become substrates for liquid or solid state fermentation processes using available second and third generation bio-technology a significant number of production process could be developed. The agro-industrial character of sugarcane processing allows for an-industrial development in which all available wastes and resources could be managed profitably. Sugarcane producing countries have a significant advantage in processing a renewable raw material which can be used in human and animal feeding and in the production of basic chemicals with yield not equaled by any other plant. The adjoining Figure provides details of the byproducts of sugarcane industry and their utilization for manufacturing other products and for generation of electricity. 84

2 Chart 4.1 Sugar Factory Functioning and Production of Sugar 85

3 4.2 Bagasse Bagasse is the fibrous matter that remains after sugarcane or sorgum stalks are crushed to extract their juice. For each 10 tonnes of sugarcane crushed, a sugar factory produces nearly 3 tonnes of wet bagasse. Since bagasse obtained as a byproduct of sugarcane processing is composed of fiber, pith, no soluble solids and water. Fiber represents about half of all components and includes cellulose, hemicelluloses and legion of low molecular weight. Bagasse is currently used as bio fuel and in the manufacture of pulp and paper products. The high moister content of bagasse typically 40 to 50% is detrimental to its use as a fuel. For electricity production it is stored under moist conditions and the mild exothermic reaction that results from the degradation of residual sugars dries the bagasse pile slightly. For paper and pulp production it is normally stored wet in order to assist in removal of the short pith fibers which impedes the paper making process as well as to remove any remaining sugar. Pulp and paper, boards, furfural and animal feeds are among the main products obtained from bagasse not used as fuel. The most wide spread use of bagasse around the world is the production of pulp and paper. Every year more than 200 million tonnes of bagasse are obtained together with sugar in all cane producing countries, 95 percent of which is used as fuel in the mills which represent a saving of about 40 million tones of oil. 4.3 Molasses Molasses is sugar byproduct. It is used as a raw material to produce alcohol. Molasses contains about 50% sugar and is being used as a sub-stratum of procedures to produce alcohol, nourishment Yeast or cattle feed, citric acid glutomic (lysine) as well as for admixture in cattle feed. 86

4 Sl.No Table: 4.1: Analytical Details of Molasses 1 Bx % 2 Pol 44.48% 3 Total Sugar in % 48.52% 4 Invert Sugar % 5 PH % 6 Ash 12.14% 7 Density gr/cm Traditionally molasses has been used in India to produce rectified spirit and alcohol of about 95% purity for producing liquor for human consumption and for producing various chemicals. However with technological developments in the recent past molasses has been effectively used to produce bio-ethanol for blending with petrol as fuel. 4.4 Cogeneration of Electricity Sugarcane dry matter when burned produces 4000Keal per Kg(7200Btu/16). One hectare of sugarcane can produce about 100 to 200 million Keal per year equivalent to about 10 to 20 tonnes of oil. Several studies have shown that the sugarcane industry can deliver not only surplus bagasse through efficient generation and use of steam of 60 to 120 KWL electric powers per ton of cane, which can be delivered to the grid. Most cane sugar factories all over the world use 550 to 650 kg of steam per tones of crushed cane. Beet sugar factories with similar process to that in use by cane sugar factories have been known to use about 320 kg per tones of beat. Use of multiple bleeding in evaporation stations for healing and boiling a high number of evaporation stages up to six or seven, the substitution of throtling volves 87

5 by other systems are solutions enhancing energy efficiencies. This has been tried in cane sugar factories and values of the order of 370 kg of steam per tone of cane have been recorded. This decrease in process steam may promote reductions in burned bagasse of about 25 percent. Cogeneration is the cheapest way of delivering surplus electrical power for other industrial uses or to the grid, while also delivering surplus bagasse. Currently most boilers manufactured operate at a ratio of about 2.2 for steam generated to bagasse burnt (bagasse at 50% moisture). An unavoidable condition for economic development of by products is to make use of the available co-generated electric power while having simultaneously surplus bagasse. 4.5 Ethanol Ethanol is generally available as a byproduct of sugar production. It can be used as a bio fuel alternative to gasoline. It is estimated that one hectare of sugarcane yields 4000 liters of ethanol per year (without any additional energy input, because the bagasse produced exceeds the amount needed to distill the final product). This however does not include the energy used in tilling transportation and so on. Thus the solar energy-to-ethanol conversion efficiency is 0.13%. Bio-ethanol blending programme reduce India s dependence on fossil fuel imports. It also ensures that the nation moves towards energy efficiency. Ethanol also has other important advantages of having the best oxidant which helps burn the petrol better when blended with it, their by reducing environmental pollution that fossil fuel are infamous for. With insanity-knocking property it helps improve the Life of engines. At5% blending with petrol the fuel efficiency improves gain with 88

6 better mileage per liter at 5% ethanol blends, lower environmental pollution and longer life of engine. India has an indigenous installed capacity to produce over 400 crore liters of rectified spirit/alcohol and over 150 crore liters of fuel ethanol which is sufficient to meet requirement for 7-8% ethanol blending with petrol. The national bio-fuel policy approved by the Government has plans for 20% ethanol blending programme by Government of India should seriously follow its approved 5% mandatory ethanol blending with petrol programme which will be essential for the energy security of the nation and which will help reduce pollution from fossil fuel and improve our use of renewable energy in the form of fuel ethanol. 4.6 Press Mud Press mud or Filter mud is a residue left over from sugarcane after extraction of juice. Depending on the quality of cane press mud is about 3.5% to 4.5% of total cane crushed. Raw press mud composes of carbon, nitrogen, phosphorous, potash, calcium, magnesium, copper, zinc, manganese, iron, silicon and wax. The composition varies significantly on the soil conditions, cane varieties, period of supply of cane and geographical variations. The content of nitrogen, phosphorous and potash in press mud is about 2.5%, 1.5% and 3% respectively. Sugar mills use spent wash which is an affluent with press mud to produce bio compost as manure. This is an approved method of disposal of distillery effluents. It is found from experience that the productivity of not only sugarcane but other crops also is much better with the use of this manure. It is in the interest of farmers and the agriculture sector to use press mud and spent wash to produce this manure. 89

7 All the sugar mills in India produce manure by using press mud which besides being soil friendly manure also substitutes potash, a large quantity of which is imported in the country and thus saving foreign exchange. The sugar factories have invested hugely for production of manure the process of which is duly approved by Central Pollution Control Board. as manure. Press mud is used for animal feel and as cane wax in addition to it being used Chart: 4.2: Graphical Representation of Co-generation & Sugar Plant 4.7 Diversification Opportunities of sugar industry. Opportunities for diversification of sugar industry include. 1. Production of raw sugar, plantation white sugar, amorphous sugar and glucose and fructose syrup. 2. Alcohol production 3. Production of animal feed 90

8 4. Production of pulp and feed 5. Production of agglomerated products 6. Production fuels 7. Generation of electrical power and steam for raw sugar production and 8. The use of steam in raw sugar production. 4.8 Sugar Cane as a Raw Material Sugarcane has one of the most efficient photosynthetic mechanisms among commercial crops. This allows it to fix energy and transform it into green biomass. From cane harvest 8 products and by products which are potential raw material for the extractive, chemical and biochemical industry. Various sugar producing countries currently produce more than fifty commercial products. The dry matter content of sugarcane produce on one hectare has a fuel equivalent of about 10 to 20 tonnes of oil. As a metabolic energy carrier for animal feeding each cultivated hectare delivers million calories each year equivalent to more than 8 times the yield of other fodder crops. Sugarcane processed using chemical biotechnologies, can produce a high number of products and is surpassed only by those obtained from petro chemistry. Practically all products and by products obtained from sugarcane may become substrates for liquid or solid state fermentation processes using available second and third generation biotechnology a significant number of production processes could be developed. 91

9 Sugarcane producing countries have a significant advantage in possessing a renewable raw material which can be used in human and animal feeding and in the production of basic chemicals with a yield not equaled by any other plants (O.Almazan etal 1998). 4.9 Technological Changes and the Impact on Sugarcane Related Products Production based on bio-chemical process could be applied to the sugarcane byproducts for diversification. Biotechnologies of second and third generation have made available conventional and new technologies for the production of amino acids, vitamins, organic acids, solvents, microbial polymers proteins for human and animal consumption enzymes for industrial use, alcohol and co-products industry and such microbiological processes as: silage, biologic treatments of lignocelluloses residues, bio pulping and bio bleaching processes, anaerobic digestion of waste streams and other alternatives. In addition more sophisticated technologies are available for their application in the pharmaceutical industry. It may be considered that all sugarcane byproducts could be used as substrates for liquid or solid state fermentation opening a wide range of possibilities for production based on bio-chemical processes. Byproducts Ethanol based Chemical Industry and Diversification of Sugarcane Related The developments of chemical industry from ethanol as an alternative or compliment to petro-chemistry allow the production of basic products in all industry branches. The two most developed alternatives are those following the ethylene and acetaldehyde paths. The first one produces a great variety of plastic materials and the second one develops acetate compounds, which are the basis of paint and varnish industries. 92

10 Based on sugarcane by-products some alternatives for herbicides production could be undertaken Diversification as a Component of Sugar Production In the last decade a better integration of by products production with sugar processing has started in order to benefit from potential advantages in energy use, waste disposal and market penetration. The cultivation of new varieties showing higher yields of green matter for by-products production has also been explored. The Cuban experience in by-product development in the fields of raw material, finishing complexity of processes and added value can be divided in four phases of which boundaries and extensions are arbitrarily established Diversification Phases The first phase covers the direct use of raw materials at low processing level. The second phase integrates those productions using by-products as raw materials and intermediate products of sugar processing, in processes of little complexity leading end products of special characteristics. The third phase involves products made by chemical and biochemical changes using second generation byproducts and sugar as materials. Properties of products are quite different to those of raw materials from which they were prepared; technologies show medium to high complexity. The fourth phase generates products obtained from by-products of second and third phase. They are promoters or intermediaries of other processes. Complex chemical and bio-chemical technologies are involved, the end products showing high added value. 93

11 These technological alternatives show that sugar producing countries can broad in widen the horizon for sugarcane exploitation when following diversification approach Premises in Alterative Selection Selection of those showing attractive economical results Integral layout of involved technologies Efficient use of energy Flexible economy of scale Priority to animal feeding Non polluting of the environment 94