environmental engineeringzxzbx z,n zjhcgjzhgkj sgsdjhf ksfhjs kjsgfsjhgfkj s

7/30/2019 Environmental Engineeringzxzbx z,n zjhcgjzhgkj sgsdjhf ksfhjs kjsgfsjhgfkj s

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Presented to:

Sir Uman Ahmed

Environmental

Engineering

Assignment: Disposal of

solid waste

Faisal latif---BSME-01093039 (Section B)
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Introduction

The disposal of solid waste is a problem. This problem continues to grow with the growth of

population and development of industries. Disposal of waste in open pits has become routine in

majority of places. Landfill

Semisolid or solid matter that are created by human or animal activities, and which are

disposed because they are hazardous or useless are known as solid waste. Most of the solid

wastes, like paper, plastic containers, bottles, cans, and even used cars and electronic goods are

not biodegradable, which means they do not get broken down through inorganic or organic

processes. Thus, when they accumulate they pose a health threat to people, plus, decaying

wastes also attract household pests and result in urban areas becoming unhealthy, dirty, and

unsightly places to reside in. Moreover, it also causes damage to terrestrial organisms, while

also reducing the uses of the land for other, more useful purposes.

Classification of Solid waste

Garbage: decomposable wastes from food Rubbish: non-decomposable wastes, either combustible (such as paper,

wood, and cloth) or noncombustible (such as metal, glass, and

ceramics)

Ashes: residues of the combustion of solid fuels


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Large wastes: demolition and construction debris and trees Dead animals Sewage-treatment solids: material retained on sewage-treatment screens, settled

solids, and biomass sludge

Industrial wastes: such materials as chemicals, paints, and sand

Mining wastes: slag heaps and coals refuse piles Agricultural wastes: farm animal manure and crop residues

Method of solid waste disposal

Methods for disposal are as below:

Open burning

Dumping into the sea

Sanitary Landfills

Incineration

Composting

Ploughing in fields

Hog feeding

Grinding and discharging into sewers

Salvaging

Fermentation and biological digestion

Open burning

Not an ideal method in the present day context

Dumping into Sea

Possible only in coastal cities Refuse shall be taken in barges sufficiently far away from the coast (15-30 km) and dumped

there


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Very costly Not environment friendly

Sanitary Landfilling

Simple, cheap, and effective A deep trench (3 to 5 m) is excavated and refuse is laid in layers Layers are compacted with some mechanical equipment and covered with earth, leveled and

compacted. With time, the fill would settle

Microorganisms act on the organic matter and degrade them Moisture content not less than 60% for good biodegradation Refuse depth is generally limited to 2m Temperature in the initial stages of decomposition as high as 70 degree C then drops Reclaimed areas may be used for other uses

Engineered Landfills

Bottom of the trench is lined with impervious material to prevent the leachate fromcontaminating groundwaters

A well designed and laid out leachate collection mechanism is to be provided where theLeachate so collected is treated and then disposed off.

Figure: A Typical Sanitary

Landfill


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Incineration

A method suited for combustible refuse. Refuse is burnt Suited in crowded cities where sites for land filling are not available High construction and operation costs Sometimes used to reduce the volume of solid wastes for land filling

Composting

Similar to sanitary land filling and yields a stable end product good soil conditioner and may

be used as a base for fertilizers.

Methods for compositing:

1. Open window composting:

Refuse is placed in piles, Heat buildup in the refuse piles due to biological activity, Pile is turned

up for cooling and aeration to avoid anaerobic conditions, Moisture content is adjusted to

about 60%, Piled again and process is repeated.

2. Mechanical composting:

Process of stabilization is expedited by mechanical devices of turning the compost, Compost is

stabilized in about 1 to 2 weeks, To enrich compost night soil, cow dung etc are added to the

refuse, Usually done in compost pits. Arrangements for draining of excess moisture are

provided at the base of the pit. The pit is filled by alternate layers of refuse (laid in layers of

depth 30 40 cm) and night soil or cow dung. Material is turned every 5 days or so and after

about 30 days it is ready for use.

Disposal by hog feeding

Refuse is ground well in grinders and then fed into sewers

Disposal of garbage into sewers BOD and TSS increases by 20-30%

Fermentation or Biological Digestion

Biodegradable Waste convert to compost

Recycle whatever is possible

Hazardous wastes dispose it by suitable methods

Landfill or incinerate the rest

environmental engineeringzxzbx z,n zjhcgjzhgkj sgsdjhf ksfhjs kjsgfsjhgfkj s

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