What is paper recycling?

MSW is 40% Paper

Municipal Solid Waste (MSW) consists of approximately 40% of paper waste, making it the top material that we throw away. That means for every 100 kilogram of trash we throw away, about 40 kilograms of it is paper. Although paper waste is biodegradable but it’s recycling adds more advantage to the municipal solid waste management system.  Paper recycling is a simple process which leads to the recovery of waste paper from MSW and converting it into new paper products. Basically, waste paper can be divided into 3 major categories: mill broke waste, pre-consumer waste, and post-consumer waste. They can be used as feed stocks for making recycled paper. Mill broke paper waste is generated through trimmings and other paper scrap during the manufacturing of paper which is recycled internally in a paper mill. Pre-consumer waste is material which is not generated in pa paper mill. It is a kind of discarded waste before it is ready for consumer use. Post-consumer waste is waste material generated which is discarded after consumer use, such as old corrugated containers (OCC), old magazines, old newspapers (ONP), office paper, old telephone directories, and residential mixed paper (RMP). Paper suitable for recycling is called “scrap paper” and is often used to produce molded pulp packaging.

What types of paper products can be recycled?

Some of the most recognized paper products which can be recycled and can be used by us are: Newspaper, Shredded paper, Phonebooks, Cardboard, Magazines, Computer paper, Envelopes, Junk mail, Construction paper etc. Through recycling of cardboard and other paper products, millions of new paper products are produced such as: Egg cartons, Paper towels, Tissue, Toilet paper, Newspaper, Phonebooks, Paper bags, Notebooks, Stamps, Business cards, Calendars. There are so many other products that are made up of recycled paper. The best thing which is associated with paper recycling is that in the recycling of paper the chemicals and bleaches are used in very less quantity, which is safer for the environment.

What are the benefits of paper recycling?

Waste paper recycling has several advantages. Recycling newspaper saves about 14% of landfill space which can be used to dump other waste materials. It has been estimated that for every ton of newspaper recycled we can save enough energy which can be used to power a television for 31 hours. Through recycling one ton of paper we can save 17 mature trees. Paper recycling reduces sulfur dioxide emissions with eliminating the use of coal which is used in the paper industry to generate power, hence promoting less use of fossil fuel. Most paper have tendency to be recycled up to 8 times to create new products thus it leaves more trees for the sustainability of our environment and saves energy also. When the paper is recycled, it allows more trees to survive and supply us with healthy oxygen to breathe.

Sorting and Transportation of Paper Waste

1.      Sorting

It is necessary to gather clean paper for successful recycling. The paper which is being sent for recycling should not have and should be free from contaminants, such as food, plastic, metal, and other trash, which make paper difficult to recycle due to presence of contaminants. Contaminated paper which cannot be recycled must be composted, burned for energy, or they can be useful in landfills. At the designated recycling centers, paper is generally sorted by its grade or type of paper and sent for recycling.

2.      Collection and Transportation

After the sorting step the paper is taken to a local recycling center or recycling bin. A paper stock dealer or recycling center collects recovered paper from these places at regular intervals. At the recycling center, the collected paper is wrapped in tight bales and transported to a paper mill, where it will be recycled into new paper.

Indian scenario of waste paper recycling

If we look at the data related to the waste paper recycling in India, we can conclude that in India only about 20% waste paper is being currently recovered annually. The low recovery of paper is due to use of paper in wrapping, packing, etc. In India, government bodies and people both are not very much aware of source segregation which results in the contamination of waste and thus becoming unusable. In comparison in developed countries the percentage of recovery of waste paper in India is very low. For instance in Germany it is 73%, Sweden 69%, Japan 60%, Western Europe 56%, USA 49% and Italy 45 %.

By 2010 about half of the global amount of fibers used in papermaking will be recycled fibers; a recent report of Central Pulp & Paper Research Institute (CPPRI) has stated that. However the report admits that recycled fibre sourcing in India is a challenge. Import of waste paper has increased significantly during 1995-2003. Due recognition should be given by the industry as well as the government to this to be an essential secondary raw material because recovered paper has potential to substitute a high-cost and inadequate primary raw material. The average per capita paper use worldwide was 110 pounds. It is estimated that 95% of business information is still stored on paper.

A programme on paper collection called Wealth Out of Waste (WOW) has been launched by ITC Paperboards and Specialty last year in select areas in Hyderabad, Bangalore and Coimbatore and is now expanding it to more areas in South India, including Chennai. In Chennai, it has tied up with 30-40 IT companies including Infosys, IBM and Wipro which would sell their waste paper to ITC for recycling. It also plans to tie up with Residential Welfare Associations (RWAs), NGOs and local bodies to expand the waste paper collection programme.

There is a big problem in India that the mills which depend upon waste paper for recycling are facing a shortage of raw material while the demand is growing as the mills are expanding. Due to non-availability of raw material the cost of waste paper is driving up which has gone up to around Rs 10 a kg, almost double of what it used to cost a year ago.  So the need is to make people and government aware about this programme of paper recycling so as to produce raw material in a huge quantity to help the industries dealing with recycling of paper. This will also improve the sustainability of the environment.

What is Caffeine?

The IUPAC name of caffeine is 1,3,7-trimethylxanthine, and is obtained from tea waste or coffee, or from the dried leaves of Cameelia sinensis. Chemical composition of caffeine suggests that it is an alkaloid which is primarily a class of naturally occurring compounds containing nitrogen. They have the properties of an organic amine base together with nitrogen hence it is an alkaloid.  Some of the typical alkaloids are caffeine, nicotine, morphine, codeine, and cocaine. Caffeine exists as an odorless compound which appears as white powder silky glistening needles. The taste of caffeine is bitter. Caffeine acts on the central nervous system facilitating performance of muscular work and capable of increasing total work which can be performed by muscle. This also acts on cardiac muscle and muscle of kidneys.

Caffeine may be the most widely used and abused drug in the United States.  During the course of the day an average person may unwittingly consume up to a gram of this substance.  The caffeine content of some common foods and drugs is given in table below.

Process of extraction of Caffeine from tea waste

Tea Waste

Caffeine also comes from tea leaves and other tea wastes. The isolation of caffeine from tea leaves is a difficult task and presents the chemist with a major problem. Caffeine does not occur alone in tea leaves, but is accompanied by other natural substances like cellulose, tannins, flavonoid pigments and chlorophyll from which it must be separated. This separation can be very costly due to involvement of many chemicals and sophisticated laboratory is needed. Apart from this caffeine can also be recovered from the waste tea or from the residue left behind after the preparation of the tea.

Tea waste can be used at broad level to recover the residual caffeine. For this purpose firstly the source from where the tea waste is generated has to be identified. Regarding this tea waste generated from various tea processing industries has to be collected and brought to the extraction plant for extraction of caffeine. The extraction of caffeine is known to be a multi-stage counter-current extraction technique. The extraction plant is broadly sub-divided into three sections, namely:

• Pre-treatment section.
• Extraction section.
• Post-treatment section.

Extraction of caffeine from tea waste is a three stage process which are described one by one below:

1. Pre Treatment Section

The very first step of extraction is called pre-treatment. For this purpose, in the pre-treatment section, tea waste, lime and water are mixed. The mixing ratio of these three ingredients is pre-fixed and always kept constant. After mixing them in the predefined ratio, the mixture prepared is then cooked at elevated temperature in a mixing device called cooker-cum-mixer. The purpose of the pre-treatment is that by cooking the tissues of the tea waste gets loosen which helps in the efficient extraction of caffeine in the extractor. This is the main reason why pre-treatment is done.

2.  Extraction Section

In this section, a suitable solvent is used to extract caffeine tea waste. In this process, the solvent is recovered subsequently and recycled back to the system. The addition of the solvent leads to the generation of crude caffeine. Complete operation in this section is carried out in a continuous mode other than batch operation. A continuous feed of waste is given to the reactor to maintain the continuity of the reactor system. Inside the extractor, the waste comes in contact with the solvent in counter-current way which leads to the extraction of caffeine in stage-wise manner.  Caffeine is recovered from the miscella, a mixture of lime tea waste and water which is stored in the balancing tank in the form of crude caffeine. During this storage all the solvent is removed from the crude caffeine. The removal of solvent from crude caffeine occurs by a solvent recovery method called evaporation. The solvent recovered in this process is recycled back to the extractor. Before it is recycled back to the extractor it is separated from water in solvent-water separator. Crude caffeine is then subjected to the post-treatment which gives pure caffeine.

The residual decaffeinated tea waste from the extractor moves to the desolventizer where the entrapped solvent in the tea waste is removed by heating. Solvent recovered through this process  is recycled back to the system extractor.

3.  Post Treatment

In the last step, crude caffeine obtained from extraction section which is kept in the storage tank is processed further in order to obtain the final purified caffeine. Here, in this section, crude caffeine is firstly made to dissolve in hot water to separate it from wax. After that, the remaining coloured solution which contains caffeine is treated with activated charcoal and filtered. The activated charcoal being capable of absorbing all impurities absorbs all the impurities and color. The decolorized caffeine solution left behind is then concentrated by means of evaporation and allowed to crystallize. Caffeine crystals are then separated from mother liquor by centrifuging. By centrifuge the small crystals of caffeine tends to agglomerate and thus caffeine is obtained. The caffeine thus obtained is dried further in a drier and pulverized to convert it into powder form before its packing.

The Way Ahead

Extraction of caffeine from tea waste is an environmentally safe practice which leads to the caffeine generation as well as waste management and minimization.

Generally, this type of manure is not as rich in nitrogen as compared to chemical fertilizers; however, the plants may get damaged due to the high ammonia levels when the fresh manure is directly applied. If this raw cow dung is once composted, it can provide numerous benefits to the garden.

Cow dung can be described as the waste product of bovine animal species. These species also include domestic cattle (“cows”), bison (“buffalo”), yak and water buffalo. Cow dung is the undigested residue of plant matter which has passed through the animal’s gut and the elementary canal. The resultant faecal matter produced after digestion is rich in minerals. The color of cow dung ranges from greenish to blackish, often darkening soon after exposure to air.

Composition of Cow Dung

The composition of cow dung manure is basically digested grass and grain. The grass and grain which they eat is not easily digested and remain up to some extent in their residue. The grass has the high cellulose content, although there are some species of microorganisms found in the guts of these animals. They actively work upon the grass and other substrate material to break it into their simpler compounds. The part which is not digested here is forwarded to stomach where in presence digestive juice its gets digested. It has the high roughage content. Cow dung provides high levels of organic materials and rich in nutrients. It contains about 3 percent nitrogen, 2 percent phosphorous, and 1 percent potassium (3-2-1 npk). In addition, one of the other advantages it is very useful for the farmers to use cow dung manure because it contains high levels of ammonia which is potentially dangerous for pathogens. The growth of the pathogens is almost ceased due to its use. For this reason, it’s usually recommended that it be aged or composted prior to its use as cow manure fertilizer.

Composting Cow Manure

Cow Dung is an Excellent Fertiliser

Composted cow manure fertilizer provides an excellent growing medium for agriculture as well as for garden plants. When the cow dung is put for the composting for several days say 3-4 weeks and when turned into compost, it is fed to plants and vegetables. Cow dung manure becomes a nutrient-rich fertilizer because of its satisfactory level of nutrients and fertile efficiency. It can be mixed into the soil or used as top dressing. Most composting bins or piles are located within easy reach of the garden to access them easily.

The processing methodology of cow dung manure is first to collect the animal residue. Heavy manures like that of cows, is mixed with organic substances like vegetable waste, garden debris, hay and straw etc. in addition to the usual organic substances. Small amounts of lime or ash may also be added to promote the carbon content of the manure. The mixed cow dung is then subjected to a pit of predefined dimensions and left for weeks aerobically. Microorganisms or earthworms present in the manure start eating it and converting it into the manure. The process is totally aerobic at the surface but in some cases it is seen that there is there is occurrence of anaerobic environment in the lower levels of the pit and it generates foul smell. To avoid this problem during composting of the manure it should be tossed properly at regular intervals to neglect any possibility of anaerobicity.

There is an important consideration when composting cow manure is the size of bin or pile which has to be used for composting. If the size of the pit would be too small, it would not be able to provide enough heat, which is essential for the composting process. On the contrary if it is too big, the pile may not get enough air. Therefore, frequently tossing the pile is necessary.

Benefits Cow Manure Compost

There are numerous benefits of composting of cow dung. The manure thus produced from composting has satisfactory NPK content. Moreover it also eliminates harmful ammonia gas and pathogens (like E. coli), as well as weed seeds. The composted cow dung manure adds generous amounts of organic matter to the soil. The moisture-holding capacity of the soil can also be promoted by mixing this compost into soil. This allows sprinkling of water less frequently, because the roots of plants can use the additional water and nutrients from the manure whenever needed. There is one more advantage of using this manure is that it increases the breakup of compacted soils through aeration in the soil.

There are also some beneficial bacteria which are found in the compost which have tendency to convert nutrients into easily accessible forms so they can be slowly released without burning tender plant roots thus it is like protective shell to the delicate roots of the crop. Through composting of cow dung manure is produced and if we see it with environmental health perspective, it also produces about a third less greenhouse gases, making it environmentally friendly.

The Way Ahead

Cattle manure which is derived through composting, adds significant amounts of organic material to the soil. With the addition of cow manure fertilizer, we can improve the overall health of soil and produce a healthy, vigorous plant which is a need of a developing nation, India. In India 65% of the total population still lives in the rural areas. If we plan to do this composting at a large or commercial scale it can have future job openings also for people living in rural areas.

Waste Tyres

A lot of waste is generated from automobiles and one of these wastes is used tyres. The powder of these used tyres can be used as a substitute of raw material for the production of rubber. With the increasing number of cars and trucks all over the world, used tires are also available in large quantities and are extremely cheap for the production of rubber powder. This is a recycling process of vehicles tyres that are no longer suitable for use on vehicles due to wear or irreparable damage such as punctures. Granules of rubber and iron can be obtained in various final grain sizes. This has become meaningful because processed rubber is becoming more and more acceptable on the market due to increasing raw material prices. Waste tyre rubber powder is widely used to build the playground, highway road, etc. It is also material of rubber product. The sales profit depends naturally on the quality of the output material and the pricing structure depends on processing that is as efficient as possible.

The process of manufacturing of rubber powder

Manufacturing of rubber powder from used tyres is a three-stage processing primarily shredding, after that granulation and lastly fine grinding through which high-quality materials for recycling are ultimately produced.

1. Shredding: The very first step involved in the recycling of tyres is shredding. Shredding means separation of wire and mesh from tyre and breaking them into pieces. This can be obtained by a machine with moving parts in which used tyres are put and steel or iron made wires are separated out from the tyre after this tyre is torn to pieces.  The machine is very versatile which can also be used for shredding of all kinds of input materials and is well suited for different industries. The diameter of rotors ranges from 457 mm -850mm to 2000 mm width which are driven by either one or two oversized gearboxes. There is a well integrated hydraulic power pack into the machine housing which is used to save space and protect it from damage but is still easy to access or remove for maintenance. In this machine shredders are usually designed for a wide range of applications and which can also be used in industries such as in-house and general recycling, electronic waste and post consumer waste handling. Apart from the tyre waste input materials can be all types and forms of plastics such as lumps, pipes, film, bales, woven bags, electronic waste like cables and ICBs, paper, wood and other organic materials. In some cases where the raw material or waste is of small size, can be sent directly to the next step granulation.
2. Granulation: The granulators are used in the next step of this recycling process in which pieces of waste tyres are grinded in the large sized granulators to produce large quantity of granules. Granulators are developed as slow-running grinders for applications in the injection and blow molding sector.  The material which has to be granulated is fed via a sound-absorbing feed hopper which is available in a wide range to suit the application.  The slow-speed granulators which are designed of this range are commonly mounted on either low or high level base frames. With these numerous options, the slow speed granulators can be tailored to an extremely wide range of applications. P
3. Pulverizer: The last step involved in the production of rubber powder from tyre waste is to convert the granulated material into the fine powder. This is done by means of pulverizes. Pulverizes are high speed, precision grinders which are used for the processing of medium hard, impact resistant and friable materials. The granulated material is introduced through the centre of a vertically fixed grinding disc which is mounted concentrically with an identical high speed rotating disc to make the fine powder of it. Some typical applications are the pulverizing of plastic products, tube, edge trim materials, film waste. The waste generated from the food, chemical and pharmaceutical industry can also be pulverized in order to make the fine powder.  The material to be pulverized is. Inside the pulverizer the centrifugal force acts on the material to be pulverized and carries the material through the grinding area and the resulting powder is collected with a blower and cyclone system which is fine rubber powder or the other product of which waste material used.

Uses of waste/recycled tyres

Tyre which is not useful for us can be reused in many different ways. Up to some extent it can be used in a steel mill to use the tires as a carbon source which replaces coal or coke in steel manufacturing. This eliminates mining of coal from the ground and then burying tires in landfills, the tires are used directly. Tires can also be used together as different types of barriers such as: collision reduction, erosion control, rainwater runoff, wave action that protects piers and marshes, and sound barriers between roadways and residences. This is practiced through binding of tyres together. In some cases it is seen that entire homes can be built with whole tires by ramming them full of earth and covering them with concrete, known as Earth ships.

Some Artificial reefs are made up of used tires that are bonded together in groups. There is some controversy on the effectiveness of tires as an artificial reef system for which an example is The Osborne Reef Project.

• Tires are used in the process of stamping and cutting some apparel products, such as sandals and as a road sub-base. This is done by connecting together the cut sidewalls to form a flexible net.
• Chipped and shredded tires are used as Tire Derived Fuel (TDF). This can’t be considered as recycling, although TDF helps to eliminate tires from our waste stream and produces a fuel source. These are used in applications of civil engineering such as sub grade fill and embankments, backfill for walls and bridge abutments, sub grade insulation for roads, landfill projects, and septic system drain fields.
• Shredded tires, known as Tire Derived Aggregate (TDA) can also be used in civil engineering applications. TDA can be used as a backfill for retaining walls, fill for landfill gas trench collection wells, backfill for roadway landslide repair projects as well as a vibration damping material for railway lines.
• A size-reduced, recycled rubber which is known as Ground and crumb rubber, can be used in both paving type projects and in moldable products. These types of paving are: Rubber Modified Asphalt (RMA), Rubber Modified Concrete, and as a substitution for an aggregate. Examples of rubber-molded products are carpet padding or underlay, flooring materials, dock bumpers, patio decks, railroad crossing blocks, livestock mats, sidewalks, rubber tiles and bricks, moveable speed bumps, and curbing/edging. The rubber can be molded with plastic for products like pallets and railroad ties. Athletic and recreational areas can also be paved with the shock absorbing rubber-molded material.
• Sometimes rubber from tires is ground into medium-sized chunks which can be used as rubber mulch. Rubber crumb can also be used as an infill, alone or blended with coarse sand, as in infill for grass-like synthetic turf products such as Field Turf.

Environmental concerns of tyre recyling

Tyre basically consists of heavy metals and other pollutants so there is a potential risk for the (leaching) of toxins into the soil and groundwater when placed in wet soils leading to contamination of ground water and pollution of soil. The solubility of theses toxins varies with the variation in the pH of soil and conditions of local water. Research has proven that very little leaching occurs when shredded tires are used as land fill material. In some cases however, there are limitations on use of this material. For its safe disposal each site should be individually assessed for determining if this product is appropriate for given conditions.

Sometimes eco-toxicity may be a bigger problem than first thought. Studies show that host of vulcanization and rubber chemicals such as zinc, heavy metals leach into water from tires. Shredded tire pieces leach much more, creating a bigger concern, due to the increased surface area on the shredded pieces. Many organisms are sensitive, and without dilution, contaminated tire water has been shown to kill some organisms.

Burning of tyres also produces many harmful gases. In winters, for the purpose of heat poor people burn used tyres which are precursor of air pollution and produces harmful and toxic gases and particulate matters. One can fell seriously ill with the inhalation of these contaminants due to suffocation. So it is better to recycle these tyres to promote secondary raw material for the manufacturing of mew rubber goods. This can also be considered as an efficient drive for the better and safe environment. More economic activity can be obtained from new products derived from waste tires than combustion or other low multiplier production, while reducing waste stream without generating excessive pollution and emissions from recycling operations.

Recycling of Lead Acid Batteries

Recycling of battery is an activity which aims at the safety of the environment by reduction of number of batteries which we dispose off as municipal solid waste dumping sites. Batteries contain a number of heavy metals and toxic chemicals which can hamper the environment and their dumping has raised concern over risks of soil contamination and water pollution.

Lead-acid battery recycling has become the most successful recycling programs in the world today other than recycling of aluminium, glass, paper, plastic etc. In the United States 97% of all battery lead was recycled between 1997 and 2001. For the prevention of lead emissions into the ambient environment it is necessary to adopt an effective pollution control system. Continuous improvements in the technologies of battery recycling plants and furnace designs is required to keep pace with emission standards for lead smelters.

The very first step in process of recycling of lead acid batteries is sorting in which recyclable batteries are sorted into chemistries. During this process it is determined whether the spent battery intact or damaged. There is no effect of this determination one the recycling process because both intact and damaged batteries are recycled separately. Collection centers place lead acid, nickel-cadmium, nickel-metal-hydride and lithium-ion batteries into designated drums, sacks or boxes. It would be profitable for the battery recyclers that if they get steady stream of batteries, sorted by chemistry at no charge.

Image: http://www.batterycouncil.org

The battery is then broken apart in a hammer mill. Hammer mill is a machine that hammers the battery into pieces. The battery gets broken down into pieces which contain plastic, metals and acid. This is kept into a vat, where the lead and heavy materials settles down to the bottom while the plastic rises to the top. At this point, the polypropylene pieces, which make the outer jacket of the batteries, are scooped away and the liquids are drawn off, leaving the lead and heavy metals. From here each of the materials goes into a different “stream.” After this recycling is done for three different materials (plastic, lead and sulphuric acid) that at three different designated places.

Recycling of Plastic

The outer jacket of the batteries is made of polypropylene which is a thermoplastic. For the recycling purpose polypropylene pieces are first washed, then blown dry and sent to a plastic recycler. The purpose of using plastic recyclers is to melt these polypropylene pieces into an almost-liquid state. The molten plastic is then put through an extruder in order to produce small plastic pellets of a uniform size. Recyclers sell these pellets to the manufacturer of battery cases to earn profit, and the process begins again

Recycling of Lead

In the process of recycling of lead, lead grids which are made up of lead oxide and other lead parts are cleaned by washing or any other means, melted together in smelting furnaces powered by coal. Once the lead becomes molten it is then poured into ingot molds. Ingots are the carrying vessels which are made up of metals having different carrying capacities. Large ingots, weighing about 2,000 pounds are called hogs. In the contrast, smaller ingots, weighing 65 pounds, are called pigs. Molten lead is poured into ingots and is allowed to undisturbed. After few minutes, the impurities, which are known as dross, float to the top of the still-molten lead in the ingot molds. The dross is scraped away using scraper and the ingots are left to cool. When these ingots are cooled, they are removed from the molds and sent to battery manufacturers. Battery manufacturers re-melt and reuse these ingots in the production of new lead plates and other parts for new batteries.

Recycling of Sulphuric Acid

There are two possible ways to handle the acid of an old battery:

First method suggests about the neutralization of the acid using an industrial compound which is similar to household baking soda. As soon as it is added to the acid, this turns the acid into water. Once the water is formed, it is treated using municipal water treatment methodologies; disinfected and tested to be sure it meets clean water standards. Then it is released into the municipal sewer system.

Another way to treat acid is to process it using industrial chemicals. After the processing it gets converted into sodium sulfate which is an odorless white powder. This powder has a high demand in laundries as laundry detergent and in the manufacturing of glass and textile also.

Conclusion

The recycling of lead-acid batteries is environmentally safe and sound. The process does not allow the harassment of the nature and stops the acid from spill on the ground and thus prevents the contamination of the soil in the nature. Lead has been recognized as hazardous pollutant which is also ceased at the recycling centre. The most common pollutant plastic, which is a non-biodegradable, is also recycled into useful products. In total, the recycling of the lead-acid batteries has proved itself safe to environment. This is highly regulated and practiced at the state, national and international levels. Through this we can dispose off spent batteries free of cost which sounds very pleasing.

]]> http://www.wealthywaste.com/recycling-of-lead-acid-batteries/feed 0 http://www.wealthywaste.com/ethanol-from-cellulose-waste http://www.wealthywaste.com/ethanol-from-cellulose-waste#comments Mon, 24 Oct 2011 03:42:02 +0000 Atulesh http://www.wealthywaste.com/?p=391 more »]]> Waste can be defined as rubbish, trash, refuse, garbage, junk, litter, and ort which are unwanted or useless materials for us. If we talk about the biological definition of waste then we can say that wastes are unwanted substances, metabolic refuse or toxins which are expelled from living organisms such as urea, sweat or feces. The quantity of waste generation is directly proportional to human development which can be either technological or social.

As soon as the development occurs, deforestation also takes place. When we cut forests & trees it disturbs the ecological balance in that area and this process leads to the generation of a special type of waste called ‘cellulose waste’. Cellulose is found in outer surface of the plant cell which gives them a tough and rigid structure.

What is cellulose?

Cellulose is the most common organic compound on Earth which is the structural component of the primary cell wall of green plants. It is also found in many forms of algae and oomycetes. It has been observed that some species of bacteria secrete it to form their bio films. Biochemistry says that cellulose is an organic compound having its empirical formula (C₆H₁₀O₅)n which is nothing but a polysaccharide that consists of a linear chain of several hundred to over ten thousand ?(1?4) linked D-glucose units. The structure of the cellulose compound is:

Structure of Cellulose

Cellulose contributes of about 33% of all plant matter. The cotton which we use in our day today practices contains cellulose content of about 90% than that of wood is 40–50%. For paper and pulp industry cellulose is mainly obtained from chips and pulp of wood and cotton. In this industry cellulose is mainly used to produce paperboard and paper. At very small scale it can also be converted into a wide variety of derivative products such as cellophane and rayon. It is the commonly found natural substance which has a rigid structure that is why it has got many applications.

Some animals, particularly ruminants and termites, can digest cellulose with the help of symbiotic micro-organisms that live in their guts. Humans can digest cellulose to some extent; however it is often referred to as “dietary fiber” or “roughage” (e.g. outer shell of maize) and acts as a hydrophilic bulking agent for feces.

How is cellulose waste Generated?

Waste containing cellulose in high concentration is generated from the various industries. In the paper and pulp industry for the production of the paper the raw material is denaturized using the chemicals to make the pulp and to extract the cellulose from the raw material thus making it cellulose free. It is then brought to the paper making section. Waste is also generated in the pulp making section which is recycled to the pulp making plant. Apart from this cellulose waste is also generated from the various sections of textile industry and sugar industry. In sugar industry when sugarcane stalks are pressed in the mills for juice the solid refuse left behind is called Bagasse which contains cellulose fibers in a high concentration. The disposal of this solid waste bagasse is the major problem for the establishment of sugar industry. Nowadays there are technologies which different companies are practicing to convert this bagasse into paper. Some industries which are not aware of this fundamental, they burn this bagaase to convert it into ash or in rural areas they use it as a fuel for making food or in domestic use.

Utilization of Cellulose waste

In present time for the management of cellulose waste technologies are still under development. Some of the ways to dispose of the cellulose waste is incineration. Incineration causes air pollution which can be fatal for the health of human being.

Researchers have found alternative to this problem by making possible the conversion of cellulose waste into ethanol rich biofuels. Cellulosic ethanol is a biofuel produced from wood, grasses, or the non-edible parts of plants. It is a kind of biofuel which is generally produced from lignocellulose which is a structural material and it comprises much of the mass of the plants. The building block units of lignocellulose are cellulose, hemicellulose and lignin. Lignocelluloses have increasingly favoured as most suitable raw material for the next generation of bio-ethanol around the world, as it’s a renewable energy source that, unlike most, is not based on a food crop. By products of lawn and tree maintenance waste, switchgrass, wood chips, miscanthus, solid refuse from paper & pulp industry, sugar industry ant textile industry are some of the cellulosic material for the production of ethanol. Switchgrass and Miscanthus are the major biomass materials being studied today due to their high productivity per acre.  The technology has advantage of diverse and abundant raw materials which are of no use and are easily available but it requires a greater amount of processing to make the monomeric units of sugar for the fermentation of ethanol. These monomeric units of sugar are consumed by the microorganisms in their metabolism as a substrate to convert them into biofuel, ethanol.

Switchgrass and Miscanthus are the major biomass materials being studied today, due to their high productivity per acre. Cellulose, however, is contained in nearly every natural, free-growing plant, tree, and bush, in meadows, forests, and fields all over the world without agricultural effort or cost needed to make it grow.

Production Methodology

Ethanol from cellulose can be produced by two processes:

1. A.    Cellulolysis: This is also called the Biological process. In this process hydrolysis of pretreated lignocellulosic materials is done. Hydrolysis involves use of enzymes to break complex cellulose into simple sugars such as glucose. After hydrolysis fermentation and distillation is done to get pure form of ethanol. Cellulolysis is a step by step process which converts the cellulose waste into ethanol as follows:
2. The very first step which is generally practiced in production of ethanol is the “pretreatment” phase. This step involves making the lignocellulosic material such as wood or straw amenable to hydrolysis.
   1. Once pretreatment is done hydrolysis of cellulose (cellulolysis) is performed in order to break down the molecules into the monomeric units of sugars.
   2. After that sugar solution is separated out from the residual materials.
   3. In the next step microbial fermentation of the sugar solution takes place.
   4. Fermented product contains many impurities which are not suitable for Ideal fuel so these are removed through distillation. Distillation produces roughly 95% pure alcohol.
   5. Then after distillation Dehydration is done by molecular sieves to bring the ethanol concentration to over 99.5%

However, in 2010, a genetically engineered yeast strain has been developed that produces its own cellulose-digesting enzymes. Assuming this technology can be scaled to industrial levels, it would eliminate one or more steps of cellulolysis, reducing both the time required and costs of production.

1. B.     Gasification: In this process the transformation of lignocellulosic raw material takes place to convert them into gaseous carbon monoxide and hydrogen. After that these gases can be converted to ethanol by microbial fermentation or chemical catalysis. This process neither rely on chemical decomposition of the cellulose chain nor any kind of pretreatment is required. In this technique the carbon in the raw material is converted into synthesis gas instead of breaking the cellulose into sugar molecules, by partial combustion. The carbon monoxide, carbon dioxide and hydrogen may then be fed into a special kind of fermenter. Instead of sugar fermentation with yeast, this process uses a microorganism named Clostridium ljungdahlii. In this process microorganism ingests (eat) carbon monoxide, carbon dioxide and hydrogen and produce ethanol and water. The process can thus be broken into three steps:
   1. Gasification — Complex carbon based molecules are broken apart to access the carbon as carbon monoxide, carbon dioxide and hydrogen are produced
   2. Fermentation — Convert the carbon monoxide, carbon dioxide and hydrogen into ethanol using the Clostridium ljungdahlii organism
   3. Distillation — Ethanol is separated from water

A recent study has found another Clostridium bacterium that seems to be twice as efficient in making ethanol from carbon monoxide as the one mentioned above.

Advantages & Environmental Effects

According to U.S. Department of Energy studies conducted by Argonne National Laboratory of the University of Chicago, one of the benefits of cellulosic ethanol is that it reduces greenhouse gas emissions (GHG) by 85% over reformulated gasoline. By contrast, starch ethanol (e.g., from corn), which most frequently uses natural gas to provide energy for the process, may not reduce GHG emissions at all depending on how the starch-based feedstock is produced. In comparison to gasoline, ethanol burns cleaner, thus produces less carbon dioxide and overall pollution in the air. Additionally, only low levels of smog are produced from combustion. Carbon dioxide gas emissions are shown to be 85% lower than those from gasoline. Cellulosic ethanol contributes little to the greenhouse effect and has a five times better net energy balance than corn-based ethanol. When used as a fuel, cellulosic ethanol releases less sulfur, carbon monoxide, particulates, and greenhouse gases. Cellulosic ethanol should earn producers carbon reduction credits, higher than those given to producers who grow corn for ethanol, which is about 3 to 20 cents per gallon.

Air pollution is one of the major concerned problems today. Fresh air is getting polluted day by day mainly due to the uncontrolled emissions from industrial stacks, vehicular exhausts, construction activities, forest fires, and other man made sources of air pollution. For the economic development of any nation energy is the prerequisite. Electrical energy is being generated all over the world from thermal power plants in quantities varying from few to thousand megawatts. More than half of the electricity we consume in a day is produced through the power plants fueled by coal. Thermal power plants produce electricity but in addition to electricity these plants also produce a material that is of our major concern and fast becoming a vital ingredient for improving the performance of a wide range of concrete products. The material is called fly ash.

What is Flyash

Fly ash is non-combustible mineral portion of coal which is generated in combustion, and  it primarily comprises of fine particles that rise with the flue gases. It is necessary for thermal power plants to grind the coal into the fineness of powder for its efficient burning. When coal is burnt its carbon part is consumed and molten particles rich in silica, alumina and calcium are left behind. With the help of air pollution control devices these particles are captured and solidified later as microscopic, glassy spheres that are collected from the power plant’s exhaust before they can “fly” away hence the product’s name is Fly Ash. Ash which does not rise is termed as bottom ash. In a simple context, fly ash usually refers to the ash produced during combustion of coal.

From time to time practices have been involved for management of fly ash and conversion of this ash into bricks is one of them. Fly ash brick (FAB) are specifically masonry units which are used as building material. These bricks are made up of Class C fly ash and water, compressed at high temperature and pressure and toughened with an air entrainment agent. Due to the presence of high concentration of calcium oxide in class C fly ash, the brick can be described as “self-cementing” because when it is mixed with lime it combines to form cementitious compounds.

Manufacturing Process of Flyash Bricks

The manufacturing of fly ash bricks is quite easy and it is said to save energy because the process involves very little consumption of energy. This also reduces mercury pollution and costs 20% less than traditional clay brick manufacturing system. Raw material required for production are fly ash, gypsum, alum and stone crushing dust. For manufacturing of fly ash bricks, these raw materials have to be mixed as per the ratio specified by the individual industrial establishments. Most of the machine manufacturers suggest the following TWO mixing ratios which are

1. Normal Mixing ratio and
2. Profitable mixing ratio

The composition of raw materials in the normal mixing ratio is fly ash 62%, sand 25%, lime 8% and gypsum 5% while in case of profitable mixing ratio this ratio becomes 20%, 60%, 15% and 5% respectively. Fly ash manufacturers use profitable mixing ratio to survive in the market if they are facing low availability of fly ash. If a manufacturer is using the profitable mixing ratio for the production of fly ash then at the same he should maintain the quality too.

For the production of fly ash bricks firstly fly ash, gypsum, sand and hydrated limes are fed into a pan mixer manually where water is added in the required proportion for intimate mixing. The proportion of the raw material is generally in the ratio depending upon its quality and availability. Once raw materials are mixed, the mixture is shifted to the hydraulic Brick Making machines. The bricks are carried on wooden pellets to the open area where they are dried and water cured for 14 days. The bricks are tested and sorted before dispatch.

Quality Control and Standards

The Bureau of Indian Standards has formulated and published the following specifications for maintaining quality of the Fly ash Brick and testing purpose.

Quality and Standards: IS 12894:1990 Specification for Fly ash Lime bricks

Types of Flyash Bricks

Fly ash bricks are generally classified into four major groups:

1. Clay Fly ash Bricks
2. Fly ash – Sand Lime Bricks
3. Cold Bonded Lightweight Fly ash Bricks, Blocks and Tiles
4. Flux Bonded Fly ash Bricks Blocks and Tiles

Indian conditions offer wide range of potential among the non-conventional forms of energy like agricultural/industrial waste and municipal solid waste. It becomes possible due to the occurrence of the different Agro-climatic regions all over the country and availability of wide spectrum of residues. It is estimated that presently around 500 millions tones of agricultural and forest residues are generated annually and about 50 million tonnes of industrial waste consisting of Press mud, food & fruit processing waste, willow dust DGDS, spent wash and others.

Previously most of these used to be dumped as waste or burnt inefficiently causing air pollution. Due to their low bulk density and irregular sizes, handling and transportation of these materials was also difficult. But nowadays, these agricultural and municipal biodegradable wastes are converted into high density fuel pellets/briquettes through management of agricultural waste. These briquettes are efficiently being used to replace firewood, coal, liquid fuel and gas in domestic as well as in industrial uses across the world.

What is Biocoal?

Bio Coal as a Better Energy Alternative

‘Biocoals’ are solid fuels mainly non-conventional/renewable source of energy, having higher energy efficiency, low moisture and ash content and having zero potential of elimination of harmful gases like SO₂ & NO₂ other than conventional sources of energy. Pellets/briquettes of biocoal are made from processed agricultural refuse and process of converting agricultural waste to solid fuel is also non polluting. The agricultural solid waste is converted into high density and energy concentrated fuel briquettes and this is termed as Biocoal Briquetting. Biocoal Briquetting plants can be of various sizes which in which conversion of agricultural waste into solid fuels takes place. The application of coal, wood, furnace oil and other conventional fuels in industrial as well as in domestic practices can be readily substituted with the use of biocoals.

Biocoal is 100% natural due to existence of solid form lignin in the agro waste which acts as a natural binder there is no need to add chemicals or any other foreign substance to the process. This form of briquetting came to be known as Binderless Technology. Loose Biocoal has very low specific density of just 60 to 180 Kg/m3 but in the briquette form has high specific density (1200 Kg/m3) and bulk density (800 Kg/m3). Thus briquettes are 65% more energy efficient than that of loose biocoal. Costs for transportation of biocoal and loading/unloading are much lesser and storage requirement is also substantially reduced.

Manufacturing of Biocoal

The manufacturing process of biocoal involves various stages. In the very first step waste material is tested for their chemical composition in order to decide their suitability. Once waste has passed this test, it is dried in the sun until the moisture content falls down to 10-15% and this range of moisture content is ideal for briquetting. However if material has higher moisture content it needs to be dried before use. After ensuring the desired moisture content of the waste it is screened, chopped and ground to get the desired size and bulk density of the waste and is transported into huge bins. This brings uniformity and equal moisture content to the waste and through screening havier and metallic parts is segregated out. In the manufacturing process air used can be hot or wet as the case may be, for control of moisture. Now, Material which was stored into bin is discharged to the briquetting machine through extraction and conditioning screw. Here binder and steam may be added depending upon the binding capacity of the proper mix. By the time briquettes are achieved at very low speed of briquetting. These briquettes are now cooled by briquette\pellet cooler or ambient air and packed in bags.

Briquettes are ideally available in the size 8-25 mm in diameter and 25 to 50 mm in length. The size of these briquettes may vary from industry to industry depending upon their product specifications and their needs. These briquettes have got high calorific value which ranges from 3500 to 5000 kcal/kg depending on the raw material or the type of the waste used. Finely processed briquettes have low ash content of 10-15 % as compared to 20-40 % in coal. The machine can be set to produce the processed waste materials either in pellet form or into briquettes.

Calorific value of Biocoals

Burning of biocoal briquettes produces considerable amount of energy which is used in the different applications in the industries. It has been observed that the calorific value of biocoal is between 3500-5000 kcal/kg depending on the raw material or the type of the waste used. The table shown below depicts the typical values of energy and ash content in the biocoals produced from different agricultural wastes:

Environmental advantages of Biocoal Briquettes

Energy specialists all over the world are interested now in finding an alternative source of energy to fossil fuels and to reduce Greenhouse Gas emissionswhich are primarily responsible for global warming.Developed from Seed Shells, Biocoal Briquettes are the ready substitute for use in heating applications.With this development we can significantly reduce greenhouse gases and heating costs and the development of rural communities can also be sustainably assisted.

Heavy consumers can avail CARBON CREDIT benefits also as the burning of these briquettes does not produce any carbon (fly ash) content so it’s pretty good to earn some Standard Units of carbon Credit which is sold at Rs. 1200 approx. for 1 Carbon credit in International market. Briquettes produced from agricultural waste offer numerous advantages over fossil fuels, they are listed below:

• Bio Coal Briquettes are cheaper than other traditional fuels used for the heating applications.
• Oil and coal, when burnt, produces high content of sulphur and pollute the environment. In the case of biocoals this problem is practically not seen.
• Bio Coal briquettes have a higher practical thermal value and much lower ash content (2-10% as compared to 20-40% in coal).
• There is no emission of fly ash content when biocoals briquettes are burnt.
• Due to their ideal size they posses for their complete combustion, biocoal briquettes have high burning efficiency.
• In the case of biocoal briquettes combustion is more uniform compared to coal and boiler response to changes in steam requirements is faster due to higher quantity of volatile matter in biocoal Briquettes.
• Usually production of biocoal briquettes takes place in the nearby area of their consumption centers and supplies do not depend on erratic transport from long distances.
• In order to save nations foreign exchange biocoal offer industries to make maximum use of them.
• Biocoals possess high density which provides easy handling, preservation and wastage during transportation is also minimised against conventional fuels which are added advantage.

Economy of Biocoals

Biocoals have proven their applicability to be very economical fuel in the industries and have replaced conventional fuels widely. This goes very clear with this graph. In this graph we are discussing about an industry which is involved in the production of steam. The cost of steam generation in rupees can be calculated in terms of furnace oil consumption in litres per day. With the increased demand of steam generation more quantity of oil is consumed and the cost also increases exponentially. If we compare between the cost of furnace oil and biocoal we can easily conclude that the cost of operating an industry is just doubled with the use of furnace oil for steam generation than that of biocoal. One can run the industry at approximately 50% less cost if biocoal is used as a fuel. Suppose that for steam generation in boiler, 1,000 litre of furnace oil is used and it costs around 50,000 rupees but for the generation of the same quantity of the steam, biocoal briquettes cost less than around 20,000 rupees.

Biomass Briquettes are available in the market at very attractive cost that is around Rs. 4.5/ Kg and Furnace Oil is available at Rs. 26/ litre. It is also very beneficial to the domestic customers to use the biocoal briquettes at very cheaper price. Hence we can say that the economy in the case of biocoal is more beneficial & acceptable to the owner of the industry.

Applications

Industries with thermal applications installed are using Groundnut Shell Bio Coal Briquettes for steam generation in boilers, heating purpose etc. and thus saving their nations foreign exchange, which is used to purchase conventional fuels. Promising results are shown with the use of Bio Coal as a fuel for energy & has got potential to replace the fuel even in coal based gas producing systems and oil firing in furnaces permanently. Few applicable industries that are in practice of using Bio Coal as a Fuel Source are – Ceramic and refectory Industries, Spinning mill, Solvent extraction plant, Lamination industries, Chemical units, Dyeing plants, Leather industries, Brick making units, Milk plants, Other industries having thermal applications, Food processing industries, Vegetable plant, textile industries, Gastifier system in thermal power plants. They are using biocoal with the hope that it is present in the abundance in our environment and economical too.

Present Scenario

Briquettes/white coal has been world widely accepted and demand for the briquetting plants is growing day by day. In modern time most advanced and developed nations are adapting the concepts of preservation and also concerned how to retain their natural resources. Energy plays the key factor in economic development in most countries today. Today governments and concerned agencies worldwide are also encouraging other developing countries to make use of this theory to meet the energy crisis in the coming future because the demand for fuel and energy is increasing day by day. They are practising this approach because most of the developing nations lack knowledge and technology but have an abundant supply of agro waste. Introduction of the briquetting industry would be a potentially profitable project with the lots of possibilities of conservation of our natural resources. Thus we can conclude that adoption of briquetting technology will be contributing towards a better environment and this will not only create a safe and hygienic way of disposing the waste, but turn it into a cash rich venture by converting waste into energy.

The present disposal of plastics (Non PVC) is either by recycling land filling or by incineration. Land filling and incineration have negative impacts on the environment.

Thinner polythene/polypropylene carry bags are the most abundantly disposed of wastes, which may not be collected by ragpickers for onward recycling because of lower returns. These polythene/polypropylene bags are easily compatible with bitumen at specified conditions and a blend can be prepared and used for road laying.

Almost 90% of the polymeric materials are made up of either polyethylene or polypropylene or polystyrene, which being heated at around  130-140⁰c gets softened without releasing any gaseous products, while,        when PVC is incinerated (>700⁰c), it  may produce toxic gases like Dioxins.

Homopolymers, like high and low density polyethylene and polypropylene, as well as  random and block copolymers, like ethylene-vinyl acetate, ethylene/propylene, styrene-b-butadiene-b-styrene and styrene-b-ethyl-ene-co butylene-b-styrene, have been used as bitumen modifiers. Polymer blended bitumen has better properties regarding softening point, penetration point, ductility, stripping value and marshall stability value. Hence the blend can be used for laying flexible pavement.

In the process of the preparation of polymer-bitumen aggregate mix, the temperature used is only-170⁰C and no chlorine or copper is present in the system. The polymer materials used are polyethylene, polypropylene and polystyrene only and polyvinyl chloride is not used to avoid the possibility of presence of chlorine in the system because of which Dioxin does not form.

The whole process is very simple and economical and needs no new machinery.

The technology is also very simple and the waste plastics available in the surrounding area can be used then and there.

Crumb rubber requires a temperature of 180⁰C whereas 60/70 grade bitumen needs 160⁰C only. This accounts for fuel conservation.

Roads have been laid at different places at Tamil Nadu using different surface area and different composition are performing well.

A scheme for laying waste plastics-Tar road in rural area for 1000 km was launched on 16^th July, 2003 at Namakkal by the Honourable Chief Minister of Tamil Nadu Dr. J. Jayalalitha.

Waste Utilisation in Tanneries

It is being increasingly recognized that end of pipe solutions are not the ultimate strategy for waste management. Economic instruments have a major role to play. These also include cost cuttings through  recovery, reuse and recycle of waste materials as also a more prudent use of resources and a reduction in the quantity of effluents discharged. The ideal being achieving zero or near zero discharge. The use of clean process technologies to achieve these ends is of great advantage to tanners. It has been demonstrated that a Tannery with a production capacity of 2000 kg. of hides /skin per day might potentially save Rs. 1.4 million per month by adopting clean process technologies. A number of clean technology options for tanners have emerged.

Reduction in raw material consumption:
Salt consumption could be reduced by lowering the time between slaughtering and further treatment and by cooling the hides preferably below 4 degrees Celsius for good preservation up to 3 weeks. Fleshing and trimming could be practiced in the slaughter house. Dry salting can also minimize the use of salt for preservation of hides. Low environmental impact antiseptics have also been tried as a substitute for salt as a preservative. Preservatives like TCMTB, Isothiazolone products, potassium dimethyl dithiocarbamate, Sodium Chlorite, benzalkonium chloride, sodium fluoride and boric acid have also been used. Some of these have also been found to be useful for soaking, pickling and wet blue preservation.

In the beam house, a significant reduction in water consumption can be achieved by the use of new drums and processors to facilitate efficient draining and washing and the recycle of low floats.
As a part of clean process initiatives in the soaking process, the use of low polluting antiseptics has been tried. Fleshing of green hides after soaking is a cleaner alternative over fleshing after liming.
Upto 40% of sodium sulphide and 50% of lime can be saved by the direct recycling of the liming float. In order to maintain the quality of leather, unhairing and opening up processes should be done in separate stages. When tanning and pickling floats are separated they result in a saving of about 80% of salt and 20-25% of either formic or sulphuric acid. Salt concentrations in pickling floats can also be reduced by using non swelling agents.
Splitting on the lime is a cleaner technology than chromium tanned splitting as it reduces the amount of chromium used and gives off waste that can be easily used for the production of Gelatine.

Reduction of Pollutants at source:
Mechanical desalting by hand shaking, mechanical brushes or a drum type shaker can remove up to 10 % of salt added to the hides for processing. This can be reused for pickling after dissolution and removal of solids. Desalting of raw hides has resulted in a reduction of up to 15% salt loads at the salt pans in some tanneries at Tamil Nadu. A reduction of up to 15% of T.D.S. has also been observed due to use of enzyme based unhairing processes and better quality lime in tanneries. Segregating and reusing pickle and chrome tanning liquors also has the capacity to reduce the T.D.S by 10% in composite tannery waste waters. Clean processes have resulted in reduction of emission loads in composite waste waters from about 600 to 400 Kg. /ton of raw material.
Solvent recovery, extraction of brines and commercial reuse of recovered grease has been advocated as a clean process technology for degreasing.

Reduction of B.O.D. and C.O.D at source:
Mechanical desalting, use of enzyme assisted sulfide-reduced dehairing and cleaner chrome tanning have resulted in at least 30-40% reduction in the B.O.D. and C.O.D. loads per tonne of leather produced. Recovery of hair either when it is separated during the liming or at the end of the hair saving process and reutilization as a nitrogen source may in itself  bring down the C.O.D. loads by about 15-20% in the mixed effluents and a reduction of 25-30% in total nitrogen.

Reduction of Sulphide Loads:
A 50-60% reduction in the Sodium Sulphide loads required for dehairing has been observed by using enzyme based technologies. This has also demonstrated a net gain of 2% increase in the area of leather and could compensate for the increased cost of using enzymes. The reduction in sulphides has also demonstrated a potential ability to save atleast 8-10% of the cost of end of pipe treatment.

Reduction of Nitrogen Salts:
The use of ammonium salts in deliming is responsible for the generation of about 40% ammoniacal nitrogen.Various Nitrogen free deliming technologies are now available. The use of Carbon Dioxide is one such. The insertion of Hydrogen Peroxide before Carbon Dioxide reduces the creation of Hydrogen Sulphide.