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. 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. 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. 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. Solid wastes are generally classified in three
general categories:
• Municipal Wastes
• Industrial Wastes
• Hazardous Wastes
Municipal 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. 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. 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
classification
Industrial 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. 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. 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. 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 used
EFFECTS 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. THE WASTE HIERARCHY:
Reduce Waste:
- Reduce office paper waste by implementing a formal policy to duplex all draft reports and by
making training manuals and personnel information available electronically.
- Improve product design to use less materials. - Redesign packaging to eliminate excess
material while maintaining strength
- Work with customers to design and implement a packaging return program.
- Switch to reusable transport containers.
- Purchase products in bulk
Reuse:
- 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. - 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 new
employees join the institution.
ENERGY RECOVERY:
- old books
- old clothes
- old computers
- excess building materials
- old equipment to local organizations
Municipal 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. • 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. • 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. LANDFILLING:
• Features
• Careful and scientific site selection
• Controlled dumping
• Compaction of waste
• Provision for collecting leachates
Pyrolysis:
• 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. • 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 exploited
Identification 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. 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. 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. 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. 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. • 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 containers
Types of Collection Systems:
• Based on the mode of operation, collection systems are classified into two categories:
Hauled-container systems and
Stationary-container systems
Hauled 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. • 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 sites
Stationary-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
vehicles
Processing 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. 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. 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 method
Deep-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 liquid
Incineration:
• 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. • 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 and
disposal of solid waste are not sufficient to handle the solid waste problems .The methods of
collection or the house collection of solid waste is necessary to change the ugly sight of
overflowing dust on roads.
Present method of solid waste disposal has some limitations so we should use the
new techniques or methods vermicomposting and vermiculture etc..This method should be
adopted for avoiding environmental pollution.
Energy recovery can be done from solid waste.We should adopt the methods ,which
can recover energy from solid waste .Increase awareness in peoples through interesting
programs.