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Solid waste management


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Solid waste management

  2. 2. INTRODUCTION: There has been a significant increase in MSW (municipal solid waste) generation in India in the last few decades. This is largely because of rapid population growth and economic development in the country. Solid waste management has become a major environmental issue in India. The per capita of MSW generated daily, in India ranges from about 100 g in small towns to500 g in large towns. Although, there is no national level data for MSW generation, collection and disposal, and increase in solid waste generation, over the years, can be studied for a few urban centers. For example, the population of Mumbai grew from around 8.2 million in 1981 to 12.3 million in 1991, registering a growth of around 49%. On the other hand, MSW generated in the city increased from 3 200 tonnes per day to 5 355 tonnes per day in the same period registering a growth of around 67%. This clearly indicates that the growth in MSW in our urban centers has outpaced the population growth in recent years. This trend can be ascribed to our changing lifestyles, food habits, and change in living standards. MSW in cities is collected by respective municipalities and transported to designated disposal sites, which are normally low lying areas on the outskirts of the city. The limited revenues earmarked for the municipalities make them Ill-equipped to provide for high costs involved in the collection, storage, treatment, and proper disposal of MSW. As a result, a substantial part of the MSW generated remains unattended and grows in the heaps at poorly maintained collection centre. The choice of a disposal site also is more a matter of what is available than what is suitable. The average collection efficiency for MSW in Indian cities is about 72.5% and around 70% of the cities lack adequate waste transport capacities (TERI 1998). The insanitary methods adopted for disposal of solid wastes is, therefore, a serious health concern. The poorly maintained landfill sites are prone to groundwater contamination because of leachate production. Open dumping of garbage facilitates the breeding for disease vectors • Such as flies, mosquitoes, cockroaches, rats, and other pests. The municipalities in India therefore face the challenge of reinforcing their available infrastructure for efficient MSW management and ensuring the scientific disposal of MSW by generating enough revenues either from the generators or by identifying activities that generate resources from waste management. The key issues involved in the solid waste management are growth in population and increasing garbage generation, waste collection system, segregation of waste at source in as many categories as practical, scientific processing of waste material depending on nature, developing infrastructure for solid waste and disposal and processing, decentralize means to process waste to avoid multiple transfer and facilitate disposal etc. IMPORTANCE OF SOLID WASTE MANAGEMENT – Solid waste management not only comes from industrial units. It also comes from various sources. Every man with the operation of daily domestic work creates solid waste for disposal. A study in united state shows that solid waste per person per day in 1920 is 1.2kg. It increases 2.3kg in 1970 and about 3.6kg in 1980. This shows that solid waste per person is mounting due to number of reasons. Solid waste disposal creates a problem primarily in highly populated areas. The more concentrated the population. The greater the problem. City Solid waste generated Mumbai 6000 tones per day. Thane 700 tones per day. Hydrabad 2000
  3. 3. tones per day. Delhi 4000tones per day. In India, generation of municipal solid waste (MSW), industrial, hazardous waste, biomedical waste have been increasing due to• Solid wastes are all the wastes arising from human and animal activities that are normally solid and that are discarded as useless or unwanted. The term refuse, is often used interchangeably with the term solid wastes• Any material that is discarded ,useless or unwanted is considered as a waste• Waste management is the collection, transport , processing, recycling or disposal and monitoring of waste materials• The solid waste management has the following components:• Identification of waste and its minimization at the source• Collection, segregation and storage at the site of collection• . ABSTRACT- Municipal Solid waste management (MSWM) constitutes a serious problem in many third world Cities. Most cities do not collect the totality of wastes generated, and of the wastes collected, only a fraction receives proper disposal. The insufficient collection and inappropriate disposal of solid wastes represent a source of water, land and air pollution, and pose risks to human health and the environment. Over the next several decades, globalization, rapid urbanization and economic growth in the developing world tend to further deteriorate this situation. Items that we no longer need or don’t have any further use are falling in the category of waste and we tend to throw them away. In early days people were not facing such big problems of disposal because of availability of space and natural material but now a day’s congestion in cities and use of non-biodegradable materials in our day life create many problems. It is directly deals with our hygiene and psychology. So proper management of solid waste• It is a matter for which a specific owner ceases to have use for it. It is also any unwanted or discarded matter. It can be in a solid, liquid or in a gaseous form. A product, material or container is not considered waste until someone throws it away. SOLID WASTE- It is non liquid waste arising from domestic, trade, industrial, agricultural, mining, construction activities and from public services. Or Solid waste may be defined as “unwanted material disposed by man, which can neither flow into streams nor escapes immediately into the atmosphere.” These cause pollution in water, air and soil. Or “Solid waste management is defined as it includes all the activities that seek to minimize the health, environmental and aesthetic impacts of solid waste.” Or “The process of removing the discarded materials from in habited places in a timely manner to prevent the spread of disease, and to dispose the discarded materials in a manner that environmentally acceptable.” Or “The orderly execution of functional elements such as collecting, transporting, processing and disposing of solid waste.” SOURCES OF SOLID WASTE- There are many sources from which the solid waste comes. All living thing creates waste. In natural systems, trees animals and other organisms contribute to waste.Humen creates waste as they alter natural system through extraction, processing and use of natural resources. From
  4. 4. the study of various corporations it is clear that each person creates 44 tons of waste per year. Each person generates 90,000 pounds of waste in a lifetime.• Steam sterilization is also known as autoclaving• The waste is placed in a sealed chamber and exposed to steam at a preset temperature and pressure for a specified time• The wastes have to be prepared by grinding them therefore the chemical disinfectant can penetrate and disinfect the entire mass• Processing temp is about 1210C with processing time of around 12 minutes• There is no volume reduction of waste• Generation of offensive odor and toxic emissions are also possible• For large volumes of wastes continuous sterilization units have been devoloped
  5. 5. Waste- Definition & Classification:Any material which is not needed by the owner,producer or processor: Classification: • Domestic waste • Factory waste • Waste from oil factory • E-waste • Construction waste • Agricultural waste • Food processing waste • Bio-medical waste • Nuclear waste
  6. 6. Solid wastes are generally classified in threegeneral categories:• Municipal Wastes• Industrial Wastes• Hazardous WastesMunicipal Wastes:• Municipal Wastes Include waste from residential, commercial, open areas such as parks, streets, playgrounds etc. and treatment plant waste these include wastes such as, garbage, rubbish, ashes, demolition and construction wastes, special wastes, treatment plant wastes, principally composed of residual sludges
  7. 7. Classification of Material Comprising Municipal :Solid Waste : • Garbage: The animal, fruit or vegetable residues resulting from handling, preparation, cooking, and eating of foods. Because food waste are putrescible, they decompose rapidly, especially in warm weather. • Rubbish: Combustible and noncombustible solid wastes, excluding food wastes or other putrescible material. Typically, combustible rubbish consists of material such as paper, cardboard, plastics, textiles, rubber, leather, wood, furniture, and garden trimmings. Non combustible material consists of glass, crockery, tin cans, aluminum cans, ferrous and non ferrous metals, dirt and construction wastes. • Ashes and Residues: Material remaining from the burning of wood, coal, coke, and other combustible wastes. Ashes and residues are normally composed of fine powdery materials, cinders, clinkers, and small amount of burned and partially burned materials • Demolition and Construction Wastes: Wastes from razed buildings and other structures are classified as demolition wastes. Wastes from the construction, remolding, and repairing of residential, commercial, and
  8. 8. industrial buildings and similar structures are classified as construction wastes. These wastes may include dirt, stones, concrete, bricks. • Special Wastes: Wastes such as street sweepings, roadside litter, catch- basin debris, dead animals, abandoned vehicles are classified as special wastes. • Treatment Plant Wastes: The solid and semisolid wastes from water, wastewater, and industrial-waste treatment facilities are included in the classificationIndustrial Wastes: • Industrial wastes are those wastes arising from industrial activities and typically include rubbish, ashes, demolition and construction wastes, special wastes and hazardous wastes.
  9. 9. Hazardous Wastes:• Wastes that pose a substantial danger immediately or over a period of time to human, plants, or animal life are classified as hazardous wastes. A wastes is classified as hazardous waste if it exhibits any of the following characteristics:• (1) Ignitability (2) Corrosivity (3) Reactivity (4) Toxicity.• In the past, hazardous wastes were often grouped into the following categories:• (1) Radioactive Wastes (2) Chemicals (3) Biological Wastes (4) Flammable wastes (5) Explosives. The chemical category include wastes that are corrosive, reactivity, or toxic. The principal source of hazardous biological wastes are hospitals and biological facilities.
  11. 11. PHYSICAL CHARACTERISTICS:• Density: The knowledge of density is important for the design of all elements of the solid waste management systems like storage, transport and disposal. For example for a known volume of the solid waste its density gives us the idea about the requirement of the truck in tonnage. The density varies significantly from source to the disposal site because of handling, change in moisture content, densification due to vibration of movement, disturbance by animals and birds (scavengers) etc.• Moisture Content: Moisture content of the solid waste is expressed as the weight of moisture per unit weight of wet material. Moisture content varies generally from 20 to 45% depending upon the climatic conditions and level of city (income group) etc. The increase of moisture content increases the weight and thus the cost of transportation and thus the storage section should take care of it. CHEMICAL CHARACTERISTICS: • The chemical characteristics of solid waste are determined for assessing the treatment process. Mainly three chemical characteristics are determined, chemical, bio-chemical and toxicological. Chemical quantities of solid waste in Indian urban centres are pH, nitrogen, phosphorus, and potassium (N-P-K), total carbon, carbon/nitrogen ratio, calorific value. Bio- chemical characteristics include carbohydrate, proteins, natural fiber, and biodegradable factor. Toxic characteristics include heavy metals, pesticides, insecticides etc. • Consideration of lipids (fats, oils and grease) should also be done as they are of a very high calorific value (about 38000 Kcal/kg). These days synthetic organic materials like plastic have become a significant component of solid waste accounting for 5-7%. In India the plastic is non-biodegradable and thus poses a great problem. It chokes the drains and if burnt it produces poisonous gases. The thin plastic sheets and bags are not recycled as the cost of making it dirt & oil free makes the process uneconomical. • All the above considerations of characteristics are required to design, conceive and assess the most appropriate ways of transportation, the requirements of treatment, extraction of energy and the safe, sanitary way of disposal for the protection of environment Thermal deactivation: • Involves raising the temp to such a level that all infectious agents are destroyed • This process is used mainly in treating liquid wastes which is heated to a preset temperature for a specified period and then is destroyed • Irradiation is a process by which ultraviolet or ionizing radiation is used for destroying infectious diseases. The waste is first shredded and sprayed with water • The mass is then heated with microwave radiation under high temperature
  12. 12. E-waste:• E-waste management• Reuse--- repairing or upgrading the used electronic equipment• Donate ---- donating reusable electronic equipments to schools or other non profit organizations• Recycle---- take back programs of electronic goods, heavy metals, plastics, glass etc can be recycled• Dispose --- disposed in secure landfills ---pretreatment is necessary --- size reduction techniques, like crushing ,grinding or mechanical compaction is usedEFFECTS OF WASTE:• GHGs are accumulating in Earth’s atmosphere as a result of human activities, causing global mean surface air temperature and subsurface ocean temperature to rise.• Rising global temperatures are expected to raise sea levels and change precipitation and other local climate conditions.• Changing regional climates could alter forests, crop yields, and water supplies.• This could also affect human health, animals, and many types of ecosystems.• Deserts might expand into existing rangelands, and features of some of our national parks might be permanently altered.• - Some countries are expected to become warmer, although sulfates might limit warming in some areas.• - Scientists are unable to determine which parts of those countries will become wetter or drier, but there is likely to be an overall trend toward increased precipitation and evaporation, more intense rainstorms, and drier soils.• Whether rainfall increases or decreases cannot be reliably projected for specific areas.• Affects our socio-economic conditions• Affects our coastal and marine environment• Affects our climate and health
  13. 13. THE WASTE HIERARCHY:Reduce Waste:- Reduce office paper waste by implementing a formal policy to duplex all draft reports and bymaking training manuals and personnel information available electronically.- Improve product design to use less materials. - Redesign packaging to eliminate excessmaterial while maintaining strength - Work with customers to design and implement a packaging return program. - Switch to reusable transport containers. - Purchase products in bulkReuse:- Reuse corrugated moving boxes internally.- Reuse office furniture and supplies, such as interoffice envelopes, file folders, and paper.- Use durable towels, tablecloths, napkins, dishes, cups, and glasses.
  14. 14. - Use incoming packaging materials for outgoing shipments.- Encourage employees to reuse office materials rather than purchase new ones.RECYCLE:- Develop an “office recycling procedures” packet.- Send out recycling reminders to all employees including environmental articles.- Train employees on recycling practices prior to implementing recycling programs.- Conduct an ongoing training process as new technologies are introduced and newemployees join the institution.ENERGY RECOVERY:- old books- old clothes- old computers- excess building materials- old equipment to local organizationsMunicipal solid waste disposal methods: • Composting • Sanitary landfill • Incineration and pyrolysis • Reuse, recovery and recycle COMPOSTING: • Aerobic decomposition of organic matter by bacteria and fungi • To ensure a reasonable composting rate following parameters are to be maintained
  15. 15. • Temp-25- 50 0 C• pH – 5- 8• Moisture -50 -70%• The material to be composted has to be segregated to remove non bio-degradable materials like glass , plastics ,metals and alloys
  16. 16. • A proper mix of nutrients like animal waste, sewage sludge is necessary to ensure proper growth of bacteria and fungi• Excess compaction may be avoided• Porous structure should be maintained to ensure free circulation of air• This mixture is arranged in windrows of about 2.5 m width• Turned twice a week• Composting process takes about 4 to 6 weeks• Color of mass becomes dark and organic matter in the solid waste transforms to a stable humus• Continuous aeration and mixing• Composted solid waste is a good nutrient and can be used as a manure after addition of certain conditioners
  17. 17. LANDFILLING: • Features • Careful and scientific site selection • Controlled dumping • Compaction of waste • Provision for collecting leachatesPyrolysis: • It is defined as heating the solid waste at very high temperature in absence of air. • Pyrolysis is carried out at a temperature between 500 0 C to 1000 0C to produce three component streams. • Gas: It is a mixture of combustible gases such as hydrogen, carbon dioxide, methane, carbon mono-oxide and some hydrocarbons.
  18. 18. • Liquid: It contains tar, pitch, light oil, and low boiling organic chemicals like acetic acid, acetone, methanol etc. • Char: It consists of elemental carbon along with inert material in the waste feed. • The char liquid and gases have high calorific values. • It has been observed that even after supplying the heat necessary for pyrolysis, certain amount of excess heat still remains which can be commercially exploitedIdentification of Waste and its Minimization at the Source • The minimization of the waste production is the best strategy. For this, first of all the process should be such that there is a least production of waste. • Then the next step is to reuse the remaining waste in the same process. This reduces the cost of transportation etc. • The above mentioned methods can be adopted on a large scale also, but for that the waste is firstly collected, transported and than utilized. This incurs a large cost. So it is always preferable that if the waste production is minimized or the waste is reused, recycled at the source itself. The self motivated willing reduction of waste is generally not possible, so strict enforcement of the law should be there. The waste reduction and reuse, recycling should be given incentives from the government in the form of tax reduction and loans
  19. 19. Collection, Segregation and Storage at the Site of Collection: • The main problem of solid waste management is the collection of solid waste. The household waste consists of all types of general waste. At present there is no scientific, clean, hygienic, efficient practice of waste collection in most of the cities of India including the metro cities. • The industrial waste is also handled in the same way. The collection and storage of waste is the most neglected operation in any industry • The best way would have been the segregation of waste at the generation point. Segregation means collecting it in different bins, or plastic bags. The domestic waste can be broadly separated as reusable (paper, plastic, metal etc.), and non reusable. The non reusable may have organic matter like kitchen waste or inorganic matter like dust, dirt etc. The organic matter is liable to decomposition (putrescible) and thus requires immediate attention. • This separated waste should be regularly collected by the worker directly from the houses at some well defined time. Then it should be transported in (covered vehicles)to some waste collection depots for utilization/transportation to different sites. The organic waste can be used for the production of biogas or for the extraction of energy, incineration (controlled burning or making organic compost, and vermi- composting
  20. 20. CLASSIFICATION OF BINS:Transportation of Solid Waste: • The waste is transported from the storage depots to the disposal sites in tractor trollies or ill designed open trucks. • Though it has been instructed by the law that the transportation must be done in closed containers only. The industrial waste must be transported separately and must be disposed in a safe way after suitable treatment. • Any type of the Hazardous waste should be labeled and coded so that in case of an accident the emergency services know how to handle a spillage.
  21. 21. Treatment of Solid Waste: • The waste has to be treated before disposal for the protection of environment. • In the treatment the biodegradable waste can be processed by composting, vermi- composting, anaerobic digestion or any other appropriate biological processing for stabilization of waste. • In any case the solid waste should be reduced in quantity at the source, segregated, then carefully transported and the economically treated before the final disposal. • In the treatment the biodegradable waste can be processed by composting, vermi- composting, anaerobic digestion or any other appropriate biological processing for stabilization of waste. • The waste has to be treated before disposal for the protection of environment.
  22. 22. Energy Recovery and Disposal: • The most common methods of energy recovery and disposal for non hazardous solid waste are incineration, composting and landfill. The final disposal of waste should be done in such a way that it remains a waste in actual sense, i.e. nothing can be recovered out of it and it could not be used any where Collection Services For Solid Wastes: Municipal Collection Service: • Although a variety of collection services are available the three most common are curb, alley and backyard collection. Curb collection has gained popularity because labour costs for collection can be minimized. In the future, it appears that the use of large container which can be emptied mechanically with an articulated container pickup mechanism will be the most common method used for the collection of municipal wastes. • Curb Service: The house owner is responsible for placing the solid waste containers at the curb on the scheduled day. The workmen come, collect and empty the container and put back at the curb. The house owner is required to take back the empty containers from the curb to his house.
  23. 23. • Alley Service: The containers are placed at the alley line from where they are picked up by workmen from refuse vehicle who deposit back the empty container • Set out Set Back Service: Set out man go to the house collect containers and empty them in the refuse vehicle. Another group of persons return them to the house owner’s yard • Backyard Service: The workers with the vehicles carry a bin, wheel-barrow or sack or cloth to the yard and empty the solid waste container in it. The wheel barrow or bin is then taken to solid waste vehicle where it is emptied.Commercial-Industrial Collection Services: • The collection service provided to large apartment buildings, residential complexes, and commercial and industrial activities typically is centered around the use of large movable and stationary containers and large stationary compactors. Compactors are of type that can be used to compress material directly into large container or to form bale that are then placed in large containersTypes of Collection Systems: • Based on the mode of operation, collection systems are classified into two categories:  Hauled-container systems and  Stationary-container systemsHauled Container Systems: • Collection system in which the containers used for the storage of waste are hauled to the processing, transfer, or disposal site, emptied, and returned to either their original location or some other location are defined as hauled-container system. • There are two main types of container Tilt-frame Container, and Trash-Trailer. The collector is responsible for driving the vehicles, loading full container and unloading empty containers, and emptying the contents of the container at the disposal site. In some cases, for safety reasons, both a driver and helper are used. • Systems that use tilt-frame-loaded vehicles and large containers, often called drop boxes, are ideally suited for collection of all types of solid wastes and rubbish from locations where the generation rate warrants the use of large containers. Open-top containers are used routinely at warehouses and construction sites. Large Containers used in conjunction with stationary compactors are common at commercial and industrial services and at transfer stations. Because of the large volume that can be hauled, the use of tilt-frame hauled container systems has become widespread, especially among private collectors servicing industrial accounts.
  24. 24. • The application of trash-trailer is similar to that of tilt-frame container systems. Trash- trailer are better for the collection of especially heavy rubbish, such as sand, timber, and metal scrap, and often are used for the collection of demolition wastes at construction sitesStationary-Container System (SCS): • Collection systems in which the containers used for the storage of wastes remain at the point of waste generation, except when moved for collection are defined as stationary-container systems. There are two main types of stationary-container system: (1) Those in which self-loading compactors are used and (2) Those in which manual loaded vehicles are used. • Container size and utilization are not as critical in stationary-container systems using self-loading collection vehicles equipped with a compaction mechanism as they are in the hauled-container system. Trips to the disposal site, transfer and loading methods is in the collection of residential wastes and litter. Manual methods are used for the collection of industrial wastes where pickup points are inaccessible to the collection vehiclesProcessing of Solid Waste: • Processing techniques are used in solid waste management systems to (1) improve the efficiency of solid-Waste disposal systems (2) To recover Resources and (3) To prepare materials for the recovery of conversion products and energy. • Mechanical Volume Reduction • Mechanical Volume Reduction is perhaps the most important factor in development and operation of solid-waste management systems. Vehicles equipped with compaction mechanisms are used for the collection of most municipal solid wastes. To increase the life of landfills, wastes are compacted. Paper for recycling is baled for shipping to processing centres.Thermal Volume Reduction: • The volume of municipal wastes can be reduced by more than 90 % by incineration. In the past, incineration was quite common. However, with more restrictive air- pollution control requirement necessitating the use of expensive cleanup equipment only a limited number of municipal incinerators are currently in operation. More recently, increased haul distances to available landfill sites and increased fuel costs
  25. 25. Manual Component Separation:• The manual separation of solid waste components can be accomplished at source where solid waste are generated, at a transfer station, at a centralized processing station or at the disposal site. Manual sorting at the source of generation is the most positive way to achieve the recovery and reuse of materials. The number and types of components salvaged or sorted depend on the location, and the resale market
  26. 26. Disposal:• Disposal on or in the earth’s mantle is, at present the only viable method for long-term handling:• (1) Solid Wastes that are collected and are of no further use,• (2) The residual matter remaining after solid wastes have been processed,• (3) The residual matter remaining after the recovery of conversion products and energy has been accomplished.• Landfilling is the method of disposal used most commonly for municipal wastes; land farming and deep-well injection have been used for industrial wastes. Although incineration is often considered a disposal method, it is in reality, a processing methodDeep-Well Injection:• Deep-Well Injection for the disposal of liquid solid waste involves injecting the wastes deep in the ground into permeable rock formations or underground caverns. The installation of deep wells for the injection of wastes closely follow the practices used for the drilling and completion of oil and gas wells. To isolate and protect potential water supply aquifer, the surface casing must be set well below such aquifers, and cemented to the surface of the well. The drilling fluid should not be allowed to penetrate the formation that is To be used for waste disposal. To prevent clogging of the formation, the drilling fluid is replaced with a compatible solution.• Deep well injections has been used principally for liquid wastes that are difficult to treat and dispose of by more conventional methods and for hazardous wastes. The waste may be liquid, gases, or solids. The gases and solids are either dissolved in the liquid or are carried along with the liquidIncineration:• Incineration can be defined as a controlled combustion process for burning solid, liquid and gaseous combustible wastes to gases and residue containing non combustible material.• Incinerators are used for the process of incineration. Following important points should be observed carefully during incineration.• Charging of solid waste should be continuous
  27. 27. • Each batch of waste should be well mixed and proportion of fuel should be such that complete combustion takes places and the proper temperature is maintained. • Auxiliary burners are usually installed above the refuse to ignite it and to establish the draft at the beginning of the cycle. This is required when moisture content of solid waste is high. • The minimum temperature in the chamber should be not less than 670 0C so that all organic matter is incinerated and foul smelling gases are oxidized Advantages of Incineration: • Most hygienic method • Complete destruction of pathogens • No odour trouble • Heat generated may be used for raising steam power. • Clinkers produced may be used for road construction. • Less space Required • Adverse weather condition has no effect. CONCLUSION: From the above discussion we can conclude that the present methods of collection anddisposal of solid waste are not sufficient to handle the solid waste problems .The methods ofcollection or the house collection of solid waste is necessary to change the ugly sight ofoverflowing dust on roads. Present method of solid waste disposal has some limitations so we should use thenew techniques or methods vermicomposting and vermiculture etc..This method should beadopted for avoiding environmental pollution. Energy recovery can be done from solid waste.We should adopt the methods ,whichcan recover energy from solid waste .Increase awareness in peoples through interestingprograms.