Faculty of Agricultural Engineering Assignment Name: Dabeer-UlMulk Reg.No: 2K17AE-42 Topic: Classification of solid waste. Brief on Solid Waste Management in Pakistan Classification of Solid waste Biomass Waste Processing Benefits of utilization energy from Agricultural waste: Course title: Solid Waste Management Course code: EE601 Submitted to: Sir Ghulam Shabir Keerio Solid waste management: Solid waste management is a term that is used to refer to the process of collecting and treating solid wastes. It also offers solutions for recycling items that do not belong to garbage or trash. As long as people have been living in settlements and residential areas, garbage or solid waste has been an issue. Waste management is all about how solid waste can be changed and used as a valuable resource.Solid waste management should be embraced by each and every household, including the business owners across the world. The industrialization has brought a lot of good things and bad things as well. One of the adverse effects of industrialization is the creation of solid waste. Solid-waste management, the collecting, treating, and disposing of solid material that is discarded because it has served its purpose or is no longer useful. Improper disposal of municipal solid waste can create unsanitary conditions, and these conditions in turn can lead to pollution of the environment and to outbreaks of vector-borne disease that is, diseases spread by rodents and insects. Physical Characteristics This includes the determination of percent contents of various ingredients of the solid waste. Specific Weight (Density) Moisture Content Particle Size and Distribution Field Capacity Permeability of Compacted Waste Specific Weight: Specific weight is defined as the weight of a material per unit volume (e.g. kg/m3, lb/ft3) usually it refers to uncompact waste. It varies with geographic location, season of the year, and length of time in storage. Moisture Content: The moisture in a sample is expressed as percentage of the wet weight of the MSW material. The wet- weight method is most commonly used in the field of solid waste management. • Wet- weight Moisture content is expressed as follows: �−� �= ∗ 100 � • Where, M= wet-weight moisture content, % • w= initial mass of sample as delivered, kg (or lb.) • d= mass of sample after drying at 77°C, kg (or lb.) Particle Size and Distribution The size and distribution of the components of wastes are important for the recovery of materials, especially when mechanical means are used, such as trommel screens and magnetic separators. • The size of waste components can be determined using the following equations: • SC = L • SC = (L+w)/2 • SC = (L+w+h)/3 • SC: size of component, mm • L: length, mm • W: width, mm • h: height, mm Field Capacity The total amount of moisture that can be retained in a waste sample subject to the downward pull of gravity. Field capacity is critically important in determining the formation of leachate in landfills. It varies with the degree of applied pressure and the state of decomposition of wastes, but typical values for uncompact commingled wastes from residential and commercial sources are in the range of 50 -60% Permeability of Compacted Waste: The permeability (hydraulic conductivity) of compacted solid waste is an important physical property because it governs the movement of liquids & gases in a landfill. Permeability depends on: • Pore size distribution, Surface area and Porosity Chemical Characteristics: Chemical properties of SW are very important in evaluating the alternative processing and recovery options. Used primarily for combustion and waste to energy (WTE) calculations but can also be used to estimate biological and chemical behaviors. Waste consists of combustible (i.e. paper) and non- combustible materials (i.e. glass). If solid wastes are to be used as fuel, the four most important properties to be known are: Proximate Analysis: Loss of moisture (temp held at 105 C) Volatile Combustible Matter (VCM) (temp increased to 950 C, closed crucible) Fixed Carbon (residue from VCM) Ash (temp = 950C, open crucible) Typical Proximate analysis values Fusing Point of Ash: Clinker (agglomerations of carbon and metals) formation temperature, 2000 to 2200 F (1100-1200 C) Typical data on ultimate analysis of combustible materials found in SW Ultimate Analysis: Molecular composition (C, H, N, O, P, etc.) Energy Content: • Knowledge of the energy content of an organic fraction of solid waste is essential for evaluating its potential for use as a fuel in a combustion system. • Depends on the constituents of a sample • Can be estimated by modified Dulong formula Energy Content (KJ/Kg) = 338.2C+1430 (H-O/8) + 95.4S Inert Residue and energy content of typical MSW Brief on Solid Waste Management in Pakistan Solid waste collection by government owned and operated services in Pakistan's cities currently averages only 50 percent of waste quantities generated; however, for cities to be relatively clean, at least 75 percent of these quantities should be collected Unfortunately, none of the cities in Pakistan has a proper solid waste management system right from collection of solid waste up to its proper disposal. Much of the uncollected waste poses serious risk to public health through clogging of drains, formation of stagnant ponds, and providing breeding ground for mosquitoes and flies with consequent risks of malaria and cholera. In addition, because of the lack of adequate disposal sites, much of the collected waste finds its way in dumping grounds, open pits, ponds, rivers and agricultural land. Urbanization Pattern: According to the 1981 census, of the 5.92 million persons who had migrated within the country, 87.6% moved from rural to urban areas, while only 12.4% moved in the opposite direction. Over 50% of them permanently settled in cities. During the last several decades, migration has occurred from rural to urban areas. The chief factors responsible for this migration are: slow progress in the agriculture sector, low crop yields, lack of alternate employment opportunities and environmental degradation due to water logging/salinity, deforestation and desertification. The large rural influx has, in turn, contributed to the overburdening of urban infrastructure and urban services. There has not only been a rapid decline in the quality and availability of basic urban resources and amenities, such as housing, potable water, transportation, electricity, gas, drainage and sewage but also mushrooming of katchi abadis (squatter settlements), often located on the most marginal land. Today, squatter settlements account for about 25 to 30% of Pakistan’s overall urban population. The municipal institutions do not have sufficient resources and technical capacity to accommodate the needs of increasing urban population. According to a study1, the selected cities are growing at a growth rate from 3.67% to 7.42% which is much higher than the overall growth rate of Pakistan, i.e. 2.8%. Major cities in Pakistan are estimated to double their population in next ten years. These cities are generating high amounts of solid waste which is increasing annually with the respective population growth. Growth in Solid Waste Generation Presently it is estimated that, 54,888 tons per day of solid waste is generated in Pakistan. The Ministry of Environment undertook a study during 1996 on “Data Collection for Preparation of National Study on Privatization of Solid Waste Management in Eight Selected Cities of Pakistan”. The study revealed that the rate of waste generation on average from all type of municipal controlled areas varies from 0.283 kg/capita/day to 0.613 kg/capita/day or from 1.896 kg/house/day to 4.29 kg/house/day in all the selected cities. It shows a particular trend of waste generation wherein increase has been recorded in accordance with city's population besides its social and economic development. Table 2 presents city wise waste generation rate with respective daily and annual estimate of solid waste. Table 2. S. No Waste Generation Estimates Cities Waste Generation Rate Kg/c/day Kg/h/day Generate d Tons/day Tons/ye 1 2 3 4 5 6 7 8 Gujranwala Faisalabad Karachi Hyderabad Peshawar Bannu Quetta Sibi Total 0.469 0.391 0.613 0.563 0.489 0.439 0.378 0.283 3.424 2.737 4.291 3.941 3.423 2.941 2.646 1.896 ar 824.0 924.3 6,450.0 975.7 809.3 36.0 378.0 17 10,414.3 300,760 337,370 2,354,250 356,131 295,395 13,140 137,970 6,205 3,601,22 1 Keeping in view the population growth of 2.61 % per year, an estimate of solid waste generation has been made as presented in table 3. Table 3. Solid waste Generation on the basis of population for 2004 City Urban Areas Karachi Faisalabad Hyderabad Gujranwala Peshawar Quetta Bannu Sibi Remainin g urban areas Rural Areas Sub-Total Add 3 % for hazardo us waste G Total Population (Million) 1998 Census Populatio n (Million) 2004 Solid Waste Waste Generation Generated Tons/day Rate Kg/C/da y Tons/year 9.269 1.977 1.151 1.124 0.988 0.560 0.046 0.082 27.261 10.818 2.307 1.343 1.312 1.153 0.654 0.054 0.095 31.818 0.613 0.391 0.563 0.469 0.489 0.378 0.439 0.283 0.453 6,632 902 756 615 564 247 24 27 14,414 2,420,680 329,230 275,940 224,475 205,860 90,155 8,760 9,855 5,261,110 88.121 102.85 3 152.40 9 0.283 29,108 10,624,420 53,289 19,450,485 1,599 583,635 54,888 20,034,120 130.579 It is important to note there is a big difference in Pakistan between solid waste generation and the amounts reaching final disposal sites. In developed countries, the two figures are usually much the same since most waste arising must be disposed of formally (although) there are moves towards the segregation of some components of waste at the source in a number of countries The situation is made worse in Pakistan as there are no weighing facilities at disposal sites and no tradition of waste sampling and analysis. Furthermore, the types and quantities of wastes arising and reclaimed vary with the locality and, to some extent, with the season; and areas with more traditional lifestyles tend to generate relatively small quantities of waste, and segregation and reclamation practices are more widespread. Solid Waste Management Scenario – Strategic Challenges Solid waste in Pakistan is generally composed of plastic and rubber, metal, paper and cardboard, textile waste, glass, food waste, animal waste, leaves, grass, straws and fodder, bones, wood, stones and fines to various extents. The detailed physical compositions of waste are given in Table 4III. Table 4 Physical Composition of Waste (% weight) in selected Cities Cities Faisalabad Karachi Hyderabad Peshawar Quetta Plastic & Rubber Metals Paper Card board Rags Glass Bones Food Waste 4.80 6.40 3.60 3.70 8.20 0.20 2.10 1.60 5.20 1.30 2.90 17.20 0.75 4.10 2.40 8.40 1.50 3.00 21.00 0.75 2.40 1.50 4.70 1.60 2.00 20.00 0.30 2.10 1.90 4.30 1.30 1.70 13.80 0.20 2.20 1.30 5.10 1.50 2.00 14.30 Animal Waste Leaves, grass etc. Wood Fines 0.80 15.60 3.00 14.00 5.80 13.50 7.50 13.60 1.70 10.20 0.70 43.00 2.25 29.70 2.25 38.90 0.60 42.00 1.50 44.00 Stones 4.60 3.50 3.00 7.30 7.80 The typical composition of municipal solid waste in Pakistan is shown in Table 5 Table 5. Typical Composition of Solid Waste in Pakistani Cities (%) Composition Food Waste % 8.4% to 21 % Leaves, grass, straw, Fodder Fines Recyclables 10.2 % to 15.6 % 29.7 % to 47.5 % 13.6 % to 23.55 % Presently domestic waste in Pakistan has not been carried out in a sufficient and proper manner in collection, transportation and disposal regardless of the size of the city. Solid waste management by municipalities as a whole is quite inefficient as it collects only 5169% of the total waste generated. No weighing facilities are installed at disposal sites. The scavengers play an important role as they separate recyclable at various steps of existing solid waste management. Hazardous hospital and industrial wastes are being simply treated as ordinary waste. Open burning of waste especially non- degradable components like plastic bags are adding to air pollution. Municipalities have been reported to spend considerable portion of their budgets on solid waste management but as a return receive nothing (no tax) from the population being served. Institutional, Legal and Management Aspects The Planning & Development Division at the federal level and Planning & Development Departments at the provincial levels are responsible for the preparation of development plans and allocation of resources. At the federal level, the Ministry of Environment is responsible for the development of policies and programmers under the environment theme. The Pakistan Environmental Protection Agency (PEPA) and provincial EPAs are the main regulatory bodies for the implementation of Pakistan Environmental Protection Act, 1997. In Pakistan, municipal governments are usually responsible agency for solid waste collection and disposal, but magnitude of the problem is well beyond the ability of any municipal government. Under the recently devolved local government system, the Town/Tehsil Municipal Administration (TMAs) are responsible for the solid waste collection, transportation and disposal. However, TMAs are unable to cope with continuously increasing volumes of municipal waste due to inadequate funds, lack of rules, regulations and standards, lack of knowhow on the subject, lack of expertise and lack of collection vehicles and equipment. Solid Waste Management Policy The Government of Pakistan enacted the Pakistan Environmental Protection Act (PEPA) in 1997-- which is the most recent and updated legislation on environment. It provides a framework for establishing federal and provincial Environmental Protection Agencies (EPAs). One of the functions of Pak-EPA is to assist the local councils, local authorities, Government Agencies and other persons to implement schemes for the proper disposal of wastes so as to ensure compliance with the standards established by it. Presently the legal rules and regulations dealing with solid waste management in Pakistan are as follows: Current Section 11 of the Pakistan Environmental Protection Act prohibits discharge of waste in an amount or concentration that violates the National Environmental Quality Standards. Draft Hazardous Substances Rules of 1999. Islamabad Capital Territory Bye Laws, 1968 by Capital Development Authority Islamabad “Section 132 of the Cantonment Act 1924 deals with Deposits and disposal of rubbish etc. Provisions contained in the Local Government Ordinance, 2001 Required The rules and guidelines that are yet to be introduced include: Basic Recycling rules Waste Management rules E-Waste Management rules Development of Environmental Performance Indicators (EPI) Eco-Labeling guidelines and its promotion Adoption of Life Cycle Assessment Approaches Guidelines for Environmentally Sound Collection and Disposal Guidelines for model landfill site Classification of Solid waste: Some of the major various classification of solid waste are as follows: 1. Municipal Waste 2. Domestic I Residential Waste 3. Commercial Waste 4. Garbage 5. Rubbish 6. Institutional Waste 7. Ashes 8. Bulky Wastes 9. Street Sweeping 10. Dead Animals 11. Construction and Demolition Wastes 12. Industrial Wastes 13. Hazardous Wastes 14. Sewage Wastes 15. Biomedical/Hospital Waste 16. Plastics. Solid waste is the material generated from various human activities and which is normally disposed as useless and unwanted. 1. Municipal Waste: Municipal waste includes waste resulting from municipal activities and services such as street wastes, dead animals, market wastes and abandoned vehicles. However, the term is commonly applied in a wider sense to incorporate domestic wastes and commercial wastes. 2. Domestic I Residential Waste: This category of waste comprises the solid wastes that originate from single and multi-family house hold units. These wastes are generated as a consequence of house hold activities such as cooking, cleaning, repairs, hobbies, redecoration, empty containers packaging, clothing, old books, paper and old furnishings. 3. Commercial Waste: Included in this category are solid wastes that originate in offices, wholesale and retail stores, restaurants, hotels, markets, warehouses and other commercial establishments. Some of these wastes are further classified as garbage and others as rubbish. 4. Garbage: Garbage is the term applied to animal and vegetable waste resulting from the handling, storage, sale, cooking and serving food. Such wastes contain putrescible organic matter, which produces strong odors and therefore attracts rats, flies and other vermin. It requires immediate attention in its storage, handling and disposal. 5. Rubbish: Rubbish is general term applied to solid wastes originating in households, commercial establishments and institutions, excluding garbage & ashes. 6. Institutional Waste: Institutional wastes are those arising from institutions such as schools, universities, hospitals and research institutes. It includes wastes, which are classified as garbage and rubbish, as well as wastes, which are considered to be hazardous to public health and to the environment. 7. Ashes: Ashes are the residues from the burning of wood, coal, charcoal, coke and other combustible materials for cooking and heating in houses, institutions and small industrial establishments. When produced in large quantities at power generation plants and factories, these wastes are classified as industrial wastes. Ashes consist of a fine powdery residue, cinders and clinker often mixed with small pieces of metal and glass. 8. Bulky Wastes: In this category are bulky household wastes, which can’t be accommodated in the normal storage containers of households. For this reason, they require special collection. In developed countries residential bulky wastes include household furniture and “white goods” appliances such as stoves, washing machines and refrigerators, mattresses and springs, rugs, TV sets, water heaters, tires, lawn mowers, auto parts, tree and brush debris, and so forth. Commercial bulky wastes include packaging and containers in a wide range of sizes, including corrugated cardboard, and wood boxes, fiber, plastic and steel drums usually under 40 gallons (0.15m3), loose and bundled paper (office, printouts), bundles of textiles and plastics, bales of corrugated and paper, furniture and equipment, and flat and wire banding. Industrial bulky waste includes dunnage, including crates, cartons, pallets, skids; large and small steel, fiber, and plastic drums; bales and rolls of paper, plastics, and textiles; miscellaneous metal boxes, tubing, rod, punching’s, and skeleton; wire, rope, and metal banding; and paper, textile, and plastic streamers (William D. Robinson, 1986). 9. Street Sweeping: This term applies to wastes that are collected from streets, walkways, alleys, parks and vacant lots. In the more affluent countries manual street sweeping has virtually disappeared but it still commonly takes place in developing countries, where littering of public places is a far more widespread and acute problem. Street wastes include paper, cardboard, plastic, dirt, dust, leaves and other vegetable matter. 10. Dead Animals: This is term applied to dead animals that die naturally or accidentally killed. This category does not include carcass and animal parts from slaughterhouses, which are regarded as industrial wastes. Dead animals are divided into 2 groups, large and small. Among the large animals are Horses, Cows, Goats, Sheep and the like. Small animals include dogs, cats, rabbits and rats. The reason for this differentiation is that large animals require special equipment for lifting and handling during their removal. If not collected promptly, dead animals are a threat to public health because they attract flies and other vermin as they putrefy. Their presence in public places is particularly offensive and emits foul smell from the aesthetic point of view. 11. Construction and Demolition Wastes: Construction and demolition wastes are the waste materials generated by the construction, refurbishment, repair and demolition of houses, commercial buildings and other structures. It mainly consists of earth, stones, concrete, bricks, lumber, roofing materials, plumbing materials, heating systems and electrical wires and parts of general municipal waste stream, but when generated in large amounts at building and demolition sites, it is generally removed by contractors for filling low lying areas and by urban local bodies for disposal at landfills. While retrievable items such as bricks, wood metal are recycled, the concrete and masonry waste accounting for 50% of the waste from construction and demolition activities, are not been currently recycled in India. Concrete and masonry waste can be recycled by sorting, crushing and sieving into recycled aggregates. These recycled aggregates can be used to make concrete for road construction and building material. This category waste is complex due to the different types of building materials being used but in general may comprise of major components like: Cement concrete, Bricks, Cement plaster, Steel (from RCC, door/ window frames, roofing support etc., Rubble, Stone (marble, granite, sand stone), Timber/wood and a few minor components like Conduits (iron, plastic), Pipes (GI, iron, plastic), Electrical fixtures (copper/ aluminum wiring, wooden baton, Bakelite, wire insulation, plastic switches), Panels (wooden, laminated), Others (Glazed tiles, glass panels). 12. Industrial Wastes: In this category are the discarded solid material of manufacturing processes and industrial operations. They cover a vast range of substances which are unique to each industry. For this reason, they are considered separately from municipal wastes. However, solid wastes from small industrial plants and ash from power plants are frequently disposed of at municipal landfills. The major generators in the industrial solid wastes are the thermal power plants producing coal ash, the integrated Iron and steel mills producing blast furnace slag and steel melting slag, non-ferrous industries like aluminum, zinc, and copper producing red mud and tailings, sugar industries generating press mud, pulp and paper industries producing lime and fertilizer and allied industries producing gypsum. The source and quantum of generation of some major industrial wastes are: 13. Hazardous Wastes: Hazardous wastes may be defined as wastes of industrial, institutional or consumer origin which because of their physical, chemical or biological characteristics are potentially dangerous to human and the environment. In some cases, although the active agents may be liquid or gaseous, they are classified as solid waste because they are confined in solid containers. Typical examples are solvents, paints and pesticides whose spent containers are frequently mixed with municipal wastes and become part of urban waste stream. Table 5.10 lists typical hazardous products found in co-mingled with municipal solid waste. Certain hazardous wastes cause explosions in incinerators and fires at landfill sites. Others, such as pathological wastes from hospitals and radioactive wastes, require special handling at all time. Good management practice should ensure that hazardous wastes are stored, collected, transported and disposed of separately, preferably after suitable treatment to render them innocuous. Hazardous products found in co-mingled with municipal solid waste: Product Concern Household cleaners: Corrosive, Flammable and Irritants Chlorine bleach, Furniture polish, Glass cleaners, Outdated medicines, Shoe polish, Silver polish, Spot remover, Drain openers etc. Personal Care products: Poisonous and Flammable Hair waving lotions, Medicated shampoos, Nail polish remover, Rubbing alcohol Automotive Products: Flammable, Poison and Corrosive Antifreeze, Brake and transmission fluid, Car batteries, Diesel fuel, Kerosene, Gasoline and Waste oil Paint Products: Enamel, Paints and paint solvents and thinners Flammable 14. Sewage Wastes: The solid by-products of sewage treatment are classified as sewage wastes. They are mostly organic and derive from the treatment of organic sludge from both the raw and treated sewage. The inorganic fraction of the raw sewage such as grit is separated at a preliminary stage of treatment, but because it entrains putrescible organic matter which may contain pathogens, must be buried/disposed of without delay. The bulk of treated dewatered sludge is useful as a soil conditioner but invariably its use for this purpose is uneconomical. The solid sludge therefore enters the stream of municipal wastes unless special arrangements are made for its disposal. 15. Biomedical/Hospital Waste: Hospital waste is generated during the diagnosis, treatment, or immunization of human beings or animals or in research activities in these fields or in the production or testing of biological. It may include wastes like sharps, soiled waste, disposables, anatomical waste, cultures, discarded medicines, chemical wastes, etc. These are in the form of disposable syringes, swabs, bandages, body fluids, human excreta, etc. This waste is highly infectious and can be a serious threat to human health if not managed in a scientific and discriminate manner. It has been roughly estimated that of the 4 kg of waste generated in a hospital at least 1 kg would be infected. These wastes are categorized into 10 different categories as: Human anatomical waste (tissues, organs, body parts etc.) Animal waste Microbiology and biotechnology waste, such as, laboratory cultures, microorganisms, human and animal cell cultures, toxins etc. Waste sharps such as, hypodermic needles, syringes, scalpels, broken glass etc. Discarded medicines and cyto-toxic drugs Soiled waste, such as dressings, bandages, plaster casts, material contaminated with blood etc. Solid waste (disposal items like tubes, catheters etc., excluding sharps) Liquid waste generated from any of the infected areas Incineration ash Chemical waste 16. Plastics: Plastics, due to their versatility in use and impact on environment can be grouped under a different category of solid waste. Plastic with its exclusive qualities of being light yet strong and economical, has invaded every aspect of our day-to-day life. It has many advantages viz., durable, light, easy to mold, and can be adapted to different user requirements. Once hailed as a ‘wonder material’, plastic is now a serious worldwide environmental and health concern, essentially due to its nonbiodegradable nature. Source of generation of waste plastics: Household Carry bags Bottles Containers Trash bags Health and Medicare Disposable syringes Glucose bottles Blood and uro bags Intravenous tubes Catheters ,Surgical gloves Hotel and Catering Packaging items, Mineral water bottles, Plastic plates, glasses, spoons Air/Rail Travel Mineral water bottles Plastic plates, glasses, spoons Plastic bags Biomass: Biomass is used for facility heating, electric power generation, and combined heat and power. The term biomass encompasses a large variety of materials, including wood from various sources, agricultural residues, and animal and human waste. Biomass can be converted into electric power through several methods. The most common is direct combustion of biomass material, such as agricultural waste or woody materials. Other options include gasification, pyrolysis, and anaerobic digestion. Gasification produces a synthesis gas with usable energy content by heatingthe biomass with less oxygen than needed for complete combustion. Pyrolysis yields bio-oil by rapidly heating the biomass in the absence of oxygen. Anaerobic digestion produces a renewable natural gas when organic matter is decomposed by bacteria in the absence of oxygen. Different methods work bet with different types of biomass. Typically, woody biomass such as wood chips, pellets, and sawdust are combusted or gasified to generate electricity. Corn Stover and wheat straw residues are baled for combustion or converted into a gas using an anaerobic digester. Very wet wastes, like animal and human wastes, are converted into a medium-energy content gas in an anaerobic digester. In addition, most other types of biomass can be converted into bio-oil through pyrolysis, which can then be used in boilers and furnaces. Image of a generation station with a large skip of woody materials from the agricultural industry being loaded into it. In Woodland, California, a generation station uses wood from the agricultural industry. This overview focuses on woody biomass used for generating electricity at a commercial-scale facility rather than a utility-scale project. Biomass heat and biogas, including anaerobic digestion and landfill gas, are covered in other technology resource pages in this guide: Biomass Heat Biogas Compared to many other renewable energy options, biomass has the advantage of dispatch ability, meaning it is controllable and available when needed, similar to fossil fuel electric generation systems. The disadvantage of biomass for electricity generation, however, is that the fuel needs to be procured, delivered, stored, and paid for. Also, biomass combustion produces emissions, which must be carefully monitored and controlled to comply with regulations. DESCRIPTION Most bio power plants use direct-fired combustion systems. They burn biomass directly to produce high- pressure steam that drives a turbine generator to make electricity. In some biomass industries, the extracted or spent steam from the power plant is also used for manufacturing processes or to heat buildings. These combined heat and power (CHP) systems greatly increase overall energy efficiency to approximately 80%, from the standard biomass electricity-only systems with efficiencies of approximately 20%. Seasonal heating requirements will impact the CHP system efficiency. A simple biomass electric generation system is made up of several key components. For a steam cycle, this includes some combination of the following items: Fuel storage and handling equipment Combustor / furnace Boiler Pumps Fans Steam turbine Generator Condenser Cooling tower Exhaust / emissions controls System controls (automated). Direct combustion systems feed a biomass feedstock into a combustor or furnace, where the biomass is burned with excess air to heat water in a boiler to create steam. Instead of direct combustion, some developing technologies gasify the biomass to produce a combustible gas, and others produce pyrolysis oils that can be used to replace liquid fuels. Boiler fuel can include wood chips, pellets, sawdust, or bio- oil. Steam from the boiler is then expanded through a steam turbine, which spins to run a generator and produce electricity. In general, all biomass systems require fuel storage space and some type of fuel handling equipment and controls. A system using wood chips, sawdust, or pellets typically use a bunker or silo for short-term storage and an outside fuel yard for larger storage. An automated control system conveys the fuel from the outside storage area using some combination of cranes, stackers, re-claimers, front-end loaders, belts, augers, and pneumatic transport. Manual equipment, like front loaders, can be used to transfer biomass from the piles to the bunkers, but this method will incur significant cost in labor and equipment operations and maintenance (O&M). A less labor-intensive option is to use automated stackers to build the piles and re- claimers to move chips from the piles to the chip bunker or silo. Wood chip-fired electric power systems typically use one dry ton per megawatt-hour of electricity production. This approximation is typical of wet wood systems and is useful for a first approximation of fuel use and storage requirements but the actual value will vary with Most wood chips produced from green lumber will have a moisture content of 40% to 55%, wet basis, which means that a ton of green fuel will contain 800 to 1,100 pounds of water. This water will reduce the recoverable energy content of the material, and reduce the efficiency of the boiler, as the water must be evaporated in the first stages of combustion. System efficiency. For comparison, this is equivalent to 20% HHV efficiency with 17 MMBtu/ton wood. The biggest problems with biomass-fired plants are in handling and pre-processing the fuel. This is the case with both small grate-fired plants and large suspension-fired plants. Drying the biomass before combusting or gasifying it improves the overall process efficiency, but may not be economically viable in many cases. Exhaust systems are used to vent combustion by-products to the environment. Emission controls might include a cyclone or multi-cyclone, a baghouse, or an electrostatic precipitator. The primary function of all of the equipment listed is particulate matter control, and is listed in order of increasing capital cost and effectiveness. Cyclones and multi-cyclones can be used as pre-collectors to remove larger particles upstream of a baghouse (fabric filter) or electrostatic precipitator.In addition, emission controls for unburned hydrocarbons, oxides of nitrogen, and sulfur might be required, depending on fuel properties and local, state, and Federal regulations. How Does It Work? In a direct combustion system, biomass is burned in a combustor or furnace to generate hot gas, which is fed into a boiler to generate steam, which is expanded through a steam turbine or steam engine to produce mechanical or electrical energy. Illustration of how a direct combustion/steam turbine system operates. The biomass first goes into storage, then preparation and processing, and on to simultaneously create ash and exhaust. From there, the biomass becomes boiler fuel that produces steam to operate a steam turbine and generator to make electricity. In a direct combustion system, processed biomass is the boiler fuel that produces steam to operate a steam turbine and generator to make electricity. Types and Costs of Technology There are numerous companies, primarily in Europe, that sell small-scale engines and combined heat and power systems that can run on biogas, natural gas, or propane. Some of these systems are available in the United States, with outputs from about 2 kilowatts (kW), and approximately 20,000 British thermal units (Btu) per hour of heat, to several megawatts (MW). In addition, small-scale (100 to 1,500 kW) steam engine/gen-sets and steam turbines (100 to 5,000 kW) that are fueled by solid biomass are currently available in Europe. In the United States, direct combustion is the most common method of producing heat from biomass. Small-scale biomass electric plants have installed costs of $3,000 to $4,000 per kW, and a leveled cost of energy of $0.8 to $0.15 per kilowatt hour (kWh). The two principal types of chip-fired direct combustion systems are stationary- and travelinggrate combustors, otherwise known as fixed-bed stokers and atmospheric fluidized-bed combustors. FIXED-BED SYSTEMS There are various configurations of fixed-bed systems, but the common characteristic is that fuel is delivered in some manner onto a grate where it reacts with oxygen in the air. This is an exothermic reaction that produces very hot gases and generates steam in the heat exchanger section of the boiler. FLUIDIZED-BED SYSTEMS In either a circulating fluidized-bed or bubbling fluidized-bed system, the biomass is burned in a hot bed of suspended, incombustible particles, such as sand. Compared to grate combustors, fluidized-bed systems generally produce more complete carbon conversion, resulting in reduced emissions and improved system efficiency. In addition, fluidized-bed boilers can use a wider range of feedstock’s. Furthermore, fluidized-bed systems have a higher parasitic electric load than fixed-bed systems due to increased fan power requirements. BIOMASS GASIFICATION SYSTEMS Photo of a small, modular bio power system. Small, modular bio power system by Community Power Corporation Although less common, biomass gasification systems are similar to combustion systems, except that the quantity of air is limited, and thus produce a clean fuel gas with a usable heating value in contrast to combustion, in which the off gas does not have a usable heating value. Clean fuel gas provides the ability to power many different kinds of gas-based prime movers, such as internal combustion engines, Stirling engines, thermos electric generators, solid oxide fuel cells, and micro-turbines. The efficiency of a direct combustion or biomass gasification system is influenced by a number of factors, including biomass moisture content, combustion air distribution and amounts (excess air), operating temperature and pressure, and flue gas (exhaust) temperature. APPLICATION The type of system best suited to a particular application depends on many factors, including availability and cost of each type of biomass (e.g. chip, pellet, or logs), competing fuel cost (e.g. fuel oil and natural gas), peak and annual electrical loads and costs, building size and type, space availability, operation and maintenance staff availability, and local emissions regulations. Projects that can make use of both electricity production and thermal energy from biomass energy systems are often the most cost effective. If a location has predictable access to year-round, affordable biomass resources, then some combination of biomass heat and electricity production may be a good option. Transportation of fuel accounts for a significant amount of its cost, so resources should ideally be available from local sources. In addition, a facility will typically need to store biomass feedstock on-site, so site access and storage are factors to consider. As with any on-site electricity technology, the electricity generating system will need to be interconnected to the utility grid. The rules for interconnection may be different if the system is a combined heat and power system instead of only for electricity production. The ability to take advantage of net metering may also be crucial to system economics. Waste Processing: Waste processing means the physical alteration in waste to make it best suited for technology adopted for its treatment. The processing of wastes helps in achieving the best possible benefit from every functional element of the solid waste management (SWM) system. It requires proper selection of techniques and equipment for every element to derive maximum economical value. Various methods used in waste processing are baling, shredding, compaction, drying, metal segregation etc. Objectives of processing techniques: Three major objectives of any processing done on waste are: Improving efficiency of SWM system: the technology should always help in making the waste transport and storage effective. Example – waste paper is baled to reduce transporting and storage volume requirements, compaction and shredding of waste is done to improve the efficiency of the transportation and disposal. Recovery of resources: materials with high market value and in sufficient quantity are recovered from mixed waste by various segregation techniques Example - paper, cardboard, plastic, glass, ferrous metal, aluminum and other residual metals Recovering conversion products and energy: Combustible organic materials can be converted to intermediate products and ultimately to usable energy. Incineration, pyrolysis, composting or bio- digestion. Shredding and drying is necessary before the waste material can be used for power generation to reduce moisture content. At the stage of storage and transportation, it is very important to store maximum waste in one truck and small storage area. This reduces the fright of trucks and storage space thus reduces the investment. Various methods are used to reduce the volume of waste. The most widely used techniques are mechanical, chemical and thermal techniques of volume reduction. Manure: Manure is organic matter that is used as organic fertilizer in agriculture. Most manure consists of animal feces; other sources include compost and green manure. Manures contribute to the fertility of soil by adding organic matter and nutrients, such as nitrogen, that are utilized by bacteria, fungi and other organisms in the soil. Higher organisms then feed on the fungi and bacteria in a chain of life that comprises the soil food web. History According to a Byzantine tradition attributed to Cassian’s Bassus pig dung was generally not usable as fertilizer, except for almond trees. Similar views recorded by Columella were unrelated to the Islamic taboos of later centuries, though the medieval Andalusian writer Ibn Bassal and some later writers from Yemen also recorded negative effects of pig dung "burning" plants. Ibn Bassal described a sort of mixed manure with straw or sweeping mixed in as mudaf, implying that was not composed of only manure. The sweepings from hot baths included urine and human wastes, which Ibn Bassal describes as dry and salty, unsuitable for use as fertilizer unless mixed with manure. Ibn Bassal gives two recipes for composting pigeon (hamam) and possibly donkey (himar) manure, though the translation is uncertain. Bassal says the excessive heat and moist qualities of pigeon dung worked well for weaker and less hardy plants, especially those effected by cold temperatures. Types Skatole is the source of the foul smelling odor of manure. There are in the 21st century three main classes of manures used in soil management: 1. Animal manure 2. Compost 3. Green manure Animal manure: Concrete reservoirs, one new, and one containing cow manure mixed with water. This is common in rural Hainan Province, China. Most animal manure consists of feces. Common forms of animal manure include farmyard manure (FYM) or farm slurry (liquid manure).FYM also contains plant material (often straw), which has been used as bedding for animals and has absorbed the feces and urine. Agricultural manure in liquid form, known as slurry, is produced by more intensive livestock rearing systems where concrete or slats are used, instead of straw bedding. Manure from different animals has different qualities and requires different application rates when used as fertilizer. For example horses, cattle, pigs, sheep, chickens, turkeys, rabbits, and guano from seabirds and bats all have different properties. For instance, sheep manure is high in nitrogen and potash, while pig manure is relatively low in both. Horses mainly eat grass and a few weeds so horse manure can contain grass and weed seeds, as horses do not digest seeds the way that cattle do. Cattle manure is a good source of nitrogen as well as organic carbon.[4]Chicken litter, coming from a bird, is very concentrated in nitrogen and phosphate and is prized for both properties. Animal manures may be adulterated or contaminated with other animal products, such as wool (shoddy and other hair), feathers, blood, and bone. Livestock feed can be mixed with the manure due to spillage. For example, chickens are often fed meat and bone meal, an animal product, which can end up becoming mixed with chicken litter. Compost Compost containing turkey manure and wood chips from bedding material is dried and then applied to pastures for fertilizer. Compost is the decomposed remnants of organic materials. It is usually of plant origin, but often includes some animal dung or bedding. Green manure Green manures are crops grown for the express purpose of plowing them in, thus increasing fertility through the incorporation of nutrients and organic matter into the soil. Leguminous plants such as clover are often used for this, as they fix nitrogen using Rhizobia bacteria in specialized nodes in the root structure. Other types of plant matter used as manure include the contents of the rumens of slaughtered ruminants, spent grain (left over from brewing beer) and seaweed. Benefits of utilization energy from agricultural waste: Energy utilization of agricultural waste is among the most effective methods for disposing of agricultural waste. It refers to the conversion of agricultural waste into clean energy. This includes the use of crop field residues such as crop straw, crop process residues such as rice husk and corncob, livestock breeding waste such as farm bedding and manure, and slaughterhouse waste such as carcasses and wastewater. Over the last decades, remarkable improvements have been made in technology for energy utilization of agricultural wastes, including agricultural wastes gasification technologies such as straw thermal cracking gas and biogas, agricultural wastes liquefaction technologies such as hydrolysis, enzymolysis, Fischer–Tropic synthesis, and water phase catalysis, agricultural wastes solidification technologies such as biomass briquette technology and steam explosion pretreatment technologies, and power generation technologies from agricultural wastes, such as straw directly burning, straw–coal co-firing and biogas generate electric technologies. In addition, with the advancing energy utilization technology of agricultural waste, the forms of energy utilization of agricultural waste have become more and more diversified, and the major types include pyrolysis gas, biogas, biomass molding fuel, fuel ethanol, bio- gasoline, bio-kerosene, bio-diesel, and electricity, and so forth. Accordingly, a great variety of by-products are generated during the process of energy utilization of agricultural waste, such as biogas residue. Of late, with the deepening of research on energy utilization of agricultural waste, scholars started to devote themselves in the study of biogas residue disposal, in order to prevent secondary pollution. In recent years, the importance of energy utilization of agricultural waste has been widely recognized by all sectors of the community. First, large-scale farming creates a huge amount of agricultural waste that aggravates environmental problems, widely existing in developing and developed countries Energy utilization of agricultural waste is helpful to the release of fossil fuel shortage. Researchers have found that agricultural wastes, including crop straw and livestock manure, will be the most perspective energy source as an alternative of nonrenewable energy in the near future [Energy utilization of agricultural waste is conducive to relieve the issues of global resource waste. Great efforts have been done in resources utilization of agricultural waste in some countries, and the comprehensive utilization ratio of agricultural waste has been significantly increased. Energy utilization of agricultural waste contributes to environmental improvement. With rapid economic development, energy consumption has gradually increased, which causes a series of serious environmental problems. At present, environmental issues have gradually become one of the biggest obstacles to economic development. Sustainable development of the economy and environment is one of the most important issues for modern society. The shortage of fossil energy has restricted the sustainable development of the economy and environment. The combustion of fossil fuel (a nonrenewable resource) has been seen as a major cause of global climate change. Energy utilization of agricultural waste in rural areas has obvious advantages. A study on farm anaerobic digestion of agricultural waste shows that, with anaerobic digestion, the Greenhouse Gas (GHG) emission reduction effect can be strengthened by the increased CH4 production potential. Therefore, encouraging energy utilization of agricultural wastes has been recognized as an important factor for environmental problem improvement. Energy utilization of agricultural waste could not only conduce to solving resource and environmental problems, but also bring great economicbenefits.