Solid Waste Management

Praveen Kumar SinghM. Sc. Environmental Science

Central University of Rajasthan

What are Wastes?

Waste (also known as rubbish, trash, refuse, garbage, junk, litter, and ort)is unwanted or useless materials. In biology, waste is any of the manyunwanted substances or toxins that are expelled from living organisms,metabolic waste; such as urea and sweat.

Basel Convention Definition of Wastes“substances or objects which are disposed of or are intended to be disposedof or are required to be disposed of by the provisions of the law”

Disposal means“any operation which may lead to resource recovery, recycling, reclamation,direct re-use or alternative uses (Annex IVB of the Basel convention)”

Kinds of WastesSolid wastes

wastes in solid forms, domestic, commercial and industrial wastes

Examples: plastics, Styrofoam containers, bottles, cans, papers, scrap iron, andother trash

Liquid Wastes

wastes in liquid form

Examples: domestic washings, chemicals, oils, waste water from ponds,manufacturing industries and other sources

Classification of Wastes according to their Properties

Bio-degradable

can be degraded (paper, wood, fruits and others)

Non-biodegradable

cannot be degraded (plastics, bottles, old machines, cans, Styrofoam containers and

others)

Classification of Wastes according to their Effects

on Human Health and the Environment

Hazardous wastes

Substances unsafe to use commercially, industrially, agriculturally, oreconomically and have any of the following properties- ignitability,corrosivity, reactivity & toxicity.

Non-hazardous

Substances safe to use commercially, industrially, agriculturally, oreconomically and do not have any of those properties mentioned above.These substances usually create disposal problems.

Classification of wastes according to their origin

and type

Municipal Solid wastes: Solid wastes that include household garbage,

rubbish, construction & demolition debris, sanitation residues, packaging

materials, trade refuges etc. are managed by any municipality.

Bio-medical wastes: Solid or liquid wastes including containers,

intermediate or end products generated during diagnosis, treatment &

research activities of medical sciences.

Industrial wastes: Liquid and solid wastes that are generated by

manufacturing & processing units of various industries like chemical,

petroleum, coal, metal gas, sanitary & paper etc.

Agricultural wastes: Wastes generated from farming activities. These

substances are mostly biodegradable.

Fishery wastes: Wastes generated due to fishery activities. These are

extensively found in coastal & estuarine areas.

Radioactive wastes: Waste containing radioactive materials. Usually these

are byproducts of nuclear processes. Sometimes industries that are not

directly involved in nuclear activities, may also produce some radioactive

wastes, e.g. radio-isotopes, chemical sludge etc.

E-wastes: Electronic wastes generated from any modern establishments.

They may be described as discarded electrical or electronic devices. Some

electronic scrap components, such as CRTs, may contain contaminants such

as Pb, Cd, Be or brominated flame retardants.

Continued….

Sources of Wastes

Households

Commerce and Industry

MAGNITUDE OF PROBLEM: Indian scenario

Per capita waste generation increasing by 1.3% per annum.

With urban population increasing between 3 – 3.5% per annum.

Yearly increase in waste generation is around 5% annually.

India produces more than 42.0 million tons of municipal solid waste

annually.

Per capita generation of waste varies from 200 gm to 600 gm per capita /

day. Average generation rate at 0.4 kg per capita per day in 0.1 million

plus towns.

Affects our health

Affects our socio-economic conditions

Affects our coastal and marine environment

Affects our climate

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.

IMPACTS OF WASTE IF NOT MANAGED WISELY

TECHNOLOGIES AVAILABLE FOR PROCESSING,

TREATMENT AND DISPOSAL OF SOLID WASTE

Composting

Composting is the decomposition of organic matter by microorganism in warm,

moist, aerobic and anaerobic environment.

Composting of MSW is the most simple and cost effective technology for treating

the organic fraction of MSW.

Main advantages of composting include improvement in soil texture and

augmenting of micronutrient deficiencies. It also increases moisture-holding capacity

of the soil and helps in maintaining soil health.

It is simple and straightforward to adopt, for source separated MSW. It does not

require large capital investment, compared to other waste treatment options. The

technology is scale neutral.

Composting is suitable for organic biodegradable fraction of MSW, yard (or

garden) waste/waste containing high proportion of lignocelluloses materials, which

do not readily degrade under anaerobic conditions, waste from slaughterhouse and

dairy waste.

This method, however, is not very suitable for wastes that may be too wet and

during heavy rains open compost plants have to be stopped. Land required for open

compost plants is relatively large. Also, issues of methane emission, odor, and flies

from badly managed open compost plants remain.

At the operational level, if waste segregation at source is not properly carried out

there is possibility of toxic material entering the stream of MSW.

Vermi Composting

Vermi-compost is the natural organic manure produced from the excreta of

earthworms fed on scientifically semi-decomposed organic waste.

Normally, vermi-composting is preferred to microbial composting in small towns

as it requires less mechanization and it is easy to operate. It is, however, to be

ensured that toxic material does not enter the chain which if present could kill the

earthworms.

Continued….

Waste to Energy

Even though the technology of waste to energy (WTE) projects has been proven

worldwide, its viability and sustainability is yet to be to be demonstrated and

established in the country.

The main factors that determine the techno-economic viability of WTE projects are

quantum of investment, scale of operation, availability of quality waste, statutory

requirements and project risks.

Anaerobic Digestion and Biomethanation

Biomethanation is a comparatively well-established technology for disinfections,

deodorization and stabilization of sewage sludge, farmyard manures, animal

slurries, and industrial sludge.

It leads to bio-gas/power generation in addition to production of compost (residual

sludge). This method provides a value addition to the aerobic (composting) process

and also offers certain other clear advantages over composting in terms of energy

production/consumption, compost quality and net environmental gains.

Continued….

This method is suitable for kitchen wastes and, other putrescible wastes, which

may be too wet and lacking in structure for aerobic composting.

This plant is free from bad odor, rodent and fly menace, visible pollution, and

social resistance. It has potential for co-disposal with other organic waste streams

from agro-based industry. The plant can be scaled up depending on the availability

of the waste.

This method is suitable for only the organic biodegradable fraction of MSW; it

does not degrade any complex organics or oils, grease, or ligno-cellulosic materials

such as yard waste.

Incineration

This method, commonly used in developed countries is most suitable for high

calorific value waste with a large component of paper, plastic, packaging material,

pathological wastes, etc.

It can reduce waste volumes by over 90 per cent and convert waste to innocuous

material, with energy recovery. The method is relatively hygienic, noiseless, and

odorless, and land requirements are minimal. The plant can be located within city

limits, reducing the cost of waste transportation.

Continued….

This method, however, is least suitable for disposal of chlorinated waste and

aqueous/high moisture content/low calorific value waste as supplementary fuel may

be needed to sustain combustion, adversely affecting net energy recovery.

The plant requires large capital and entails substantial operation and maintenance

costs. Skilled personnel are required for plant operation and maintenance.

Emission of particulates, SOx, NOx, chlorinated compounds in air and toxic metals

in particulates concentrated in the ash have raised concerns.

Pyrolysis/Gasification, Plasma Pyrolysis Vitrification

(PPV)/Plasma Arc ProcessPyrolysis gasification processes are established for homogenous organic matter

like wood, pulp, etc., while plasma pyrolysis vitrification is a relatively new

technology for disposal of particularly hazardous wastes, radioactive wastes, etc.

Toxic materials get encapsulated in vitreous mass, which is relatively much safer to

handle than incinerator/gasifier ash. These are now being offered as an attractive

option for disposal of MSW also.

In all these processes, besides net energy recovery, proper destruction of the waste

is also ensured. These processes, therefore, have an edge over incineration.

Continued….

This process produces fuel gas/fuel oil, which replace fossil fuels and compared to

incineration, atmospheric pollution can be controlled at the plant level. NO and SO

gas emissions do not occur in normal operations due to the lack of oxygen in the

system.

Sanitary Landfills and Landfill Gas Recovery

Sanitary landfills are the ultimate means of disposal of all types of residual,

residential, commercial and institutional waste as well as unutilized municipal solid

waste from waste processing facilities and other types of inorganic waste and inerts

that cannot be reused or recycled in the foreseeable future.

Its main advantage is that it is the least cost option for waste disposal and has the

potential for the recovery of landfill gas as a source of energy, with net

environmental gains if organic wastes are landfilled. The gas after necessary

cleaning, can be utilized for power generation or as domestic fuel for direct thermal

applications1.

Highly skilled personnel are not required to operate a sanitary landfill.

Major limitation of this method is the costly transportation of MSW to far away

landfill sites.

Continued….

Down gradient surface water can be polluted by surface run-off in the absence of

proper drainage systems and groundwater aquifers may get contaminated by

polluted leacheate in the absence of a proper leacheate collection and treatment

system.

An inefficient gas recovery process emits two major green house gases, carbon

dioxide and methane, into the atmosphere. It requires large land area. At times the

cost of pre-treatment to upgrade the gas quality and leacheate treatment may be

significant.

There is a risk of spontaneous ignition/explosion due to possible build up of

methane concentrations in air within the landfill or surrounding enclosures if proper

gas ventilation is not constructed.

Continued….

Waste hierarchy

Waste hierarchy refers to 3 Rs

Reduce, Reuse, Recycle

WHAT SHOULD BE DONE

Reuse

Reuse corrugated moving boxes internally.

Reuse office furniture and supplies, such as interoffice envelopes, file folders, andpaper.

Use durable towels, tablecloths, napkins, dishes, cups, and glasses.

Use incoming packaging materials for outgoing shipments.

Encourage employees to reuse office materials rather than purchase new ones.

Donate/Exchange

old books

old clothes

old computers

excess building materials

old equipment to local organizations

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Employee Education

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.

education campaign on waste management that includes an extensive internal web site, quarterly newsletters, daily bulletins, promotional signs and helpful reference labels within the campus of an institution.

Continued….

Thank You…