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Note for Municipal Solid Waste Management - MSWM by Md_Shahjada_ Alam

  • Municipal Solid Waste Management - MSWM
  • Note
  • Nuva College of engineering nagpur - RTMNU
  • Civil Engineering
  • B.Tech
  • 1 Topics
  • 1296 Views
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Md Shahjada Alam
Md Shahjada Alam
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M.Tech 2nd Semester Environmental Engineering (C.B.C.S) 2. Type-based classification:Classification of wastes based on types, i.e., physical, chemical, and biological characteristics of wastes. (i)Garbage:  This refers to animal and vegetable wastes resulting from the handling, sale, storage, preparation, cooking and serving of food.  Garbage comprising these wastes contains putrescible (rotting) organic matter, which produces an obnoxious odour and attracts rats and other vermin. It, therefore, requires special attention in storage, handling and disposal. (ii) Ashes and residues:  These are substances remaining 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, as in power-generation plants and factories, these are classified as industrial wastes.  Ashes consist of fine powdery residue, cinders and clinker often mixed with small pieces of metal and glass. Since ashes and residues are almost entirely inorganic, they are valuable in landfills. (iii) Combustible and non-combustible wastes:  These consist of wastes generated from households, institutions, commercial activities, etc., excluding food wastes and other highly putrescible material.  Typically, while combustible material consists of paper, cardboard, textile, rubber, garden trimmings, etc., non-combustible material consists of such items as glass, crockery, tin and aluminium cans, ferrous and non-ferrous material and dirt. (iv) Bulky wastes:  These include large household appliances such as refrigerators, washing machines, furniture, crates, vehicle parts, tyres, wood, trees and branches.  Since these household wastes cannot be accommodated in normal storage containers, they require a special collection mechanism. (v) Street wastes:  These refer to wastes that are collected from streets, walkways, alleys, parks and vacant plots, and include paper, cardboard, plastics, dirt, leaves and other vegetable matter. Page | 9 Municipal Solid Waste Management By SHAH SIR (7888280720)

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M.Tech 2nd Semester Environmental Engineering (C.B.C.S)  Littering in public places is indeed a widespread and acute problem in many countries including India, and a solid waste management system must address this menace appropriately. (vi) Biodegradable and non-biodegradable wastes:  Biodegradable wastes mainly refer to substances consisting of organic matter such as leftover food, vegetable and fruit peels, paper, textile, wood, etc., generated from various household and industrial activities.  Because of the action of micro-organisms, these wastes are degraded from complex to simpler compounds. Nonbiodegradable wastes consist of inorganic and recyclable materials such as plastic, glass, cans, metals, etc. (vii) Dead animals:  With regard to municipal wastes, dead animals are those that die naturally or are accidentally killed on the road. Note that this category does not include carcasses and animal parts from slaughter-houses, which are regarded as industrial wastes.  Dead animals are divided into two groups – large and small. Among the large animals are horses, cows, goats, sheep, pigs, etc., and among the small ones are dogs, cats, rabbits, rats, etc. The reason for this differentiation is that large animals require special equipment for lifting and handling when they are removed. If not collected promptly, dead animals pose a threat to public health since they attract flies and other vermin as they decay. Their presence in public places is particularly offensive from the aesthetic point of view as well. (viii) Abandoned vehicles:  This category includes automobiles, trucks and trailers that are abandoned on streets and other public places.  However, abandoned vehicles have significant scrap value for their metal, and their value to collectors is highly variable. (ix) Construction and demolition wastes:  These are wastes generated as a result of construction, refurbishment, repair and demolition of houses, commercial buildings and other structures.  They consist mainly of earth, stones, concrete, bricks, lumber, roofing and plumbing materials, heating systems and electrical wires and parts of the general municipal waste stream. (x) Farm wastes:  These wastes result from diverse agricultural activities such as planting, harvesting, production of milk, rearing of animals for slaughter and the operation of feedlots. Page | 10 Municipal Solid Waste Management By SHAH SIR (7888280720)

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M.Tech 2nd Semester Environmental Engineering (C.B.C.S)  In many areas, the disposal of animal waste has become a critical problem, especially from feedlots, poultry farms and dairies. (xi) Hazardous wastes:  Hazardous wastes are those defined as wastes of industrial, institutional or consumer origin that are potentially dangerous either immediately or over a period of time to human beings and the environment. This is due to their physical, chemical and biological or radioactive characteristics like ignitability, corrosivity, reactivity and toxicity.  Note that in some cases, the active agents may be liquid or gaseous hazardous wastes. These are, nevertheless, classified as solid wastes as they are confined in solid containers. Typical examples of hazardous wastes are empty containers of solvents, paints and pesticides, which are frequently mixed with municipal wastes and become part of the urban waste stream. Certain hazardous wastes may cause explosions in incinerators and fires at landfill sites. Others such as pathological wastes from hospitals and radioactive wastes also require special handling. Effective management practices should ensure that hazardous wastes are stored, collected, transported and disposed of separately, preferably after suitable treatment to render them harmless. (xii) Sewage wastes:  The solid by-products of sewage treatment are classified as sewage wastes. They are mostly organic and derived from the treatment of organic sludge separated from both raw and treated sewages.  The inorganic fraction of raw sewage such as grit and eggshells is separated at the preliminary stage of treatment, as it may entrain putrescible organic matter with pathogens and must be buried without delay. The bulk of treated, dewatered sludge is useful as a soil conditioner but is invariably uneconomical. Solid sludge, therefore, enters the stream of municipal wastes, unless special arrangements are made for its disposal. Ques No.02:- Explain various physical, chemical & biological characterisation of solid waste. (Compulsory For 7 Marks) Ans:- Various physical, chemical & biological characterisation of solid waste:1.Physical Propeties of MSW: (a) Specific Weight (Density) (b)Moisture Content (c) Particle Size and Distribution (d) Field Capacity (e) Permeability of Compacted Waste Page | 11 Municipal Solid Waste Management By SHAH SIR (7888280720)

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M.Tech 2nd Semester Environmental Engineering (C.B.C.S) (a) Specific Weight (Density) : Specific weight is defined as the weight of a material per unit volume (e.g. kg/m3 , lb/ft3 )  Usually it refers to uncompacted waste.  It varies with geographic location, season of the year, and length of time in storage.  Density of waste, i.e., its mass per unit volume (kg/m3 ), is a critical factor in the design of a SWM system, e.g., the design of sanitary landfills, storage, types of collection and transport vehicles, etc. To explain, an efficient operation of a landfill demands compaction of wastes to optimum density.  Any normal compaction equipment can achieve reduction in volume of wastes by 75%, which increases an initial density of 100 kg/m3 to 400 kg/m3 . In other words, a waste collection vehicle can haul four times the weight of waste in its compacted state than when it is uncompacted. A high initial density of waste precludes the achievement of a high compaction ratio and the compaction ratio achieved is no greater than.  Significant changes in density occur spontaneously as the waste moves from source to disposal, due to scavenging, handling, wetting and drying by the weather, vibration in the collection vehicle and decomposition. (b)Moisture Content : Moisture content is defined as the ratio of the weight of water (wet weight - dry weight) to the total weight of the wet waste. Moisture increases the weight of solid wastes, and thereby, the cost of collection and transport. In addition, moisture content is a critical determinant in the economic feasibility of waste treatment by incineration, because wet waste consumes energy for evaporation of water and in raising the temperature of water vapour. In the main, wastes should be insulated from rainfall or other extraneous water.  We can calculate the moisture percentage, using the formula given below:  Moisture content (%) =( Wet weight - Dry weight)÷ Wet weight ×100  A typical range of moisture content is 20 to 40%, representing the extremes of wastes in an arid climate and in the wet season of a region of high precipitation. However, values greater than 40% are not uncommon. (c) 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.For example, ferrous items which are of a large size may be too heavy to be separated by a magnetic belt or drum system.  The size of waste components can be determined using the following equations: Sc = L Sc = (L+w)/2 Sc = (L+w+h)/3 Page | 12 Municipal Solid Waste Management By SHAH SIR (7888280720)

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