SOLID WASTE MANAGEMENT

 

Problems posed by Solid Waste Disposal:

 

      It is expensive. For example, the US currently spends over $300 million a year just to landfill disposable diapers. In many cities, waste disposal is the second largest expenditure after education.

 

      Solid waste disposal often takes up valuable and costly land.

 

      Landfills pollute groundwater while incinerators cause air pollution

 

      Garbage disposal and incineration represent a waste of valuable resources. Aluminum cans and other metals when recycled could be a valuable resource. Throwing away these resources thus cause the exploitation of more resources

 

Sustainable management of Solid Wastes:

 

Three approaches can be adopted to attain a sustainable management of Solid Wastes. These include:

a)              Reduction Approach - which calls for lower levels of material consumption in society.

b)             Reuse and

c)              Recycling Approach - which attempts to maximize the life span of a material in the production-consumption cycle.

 

Reduction Approach:

 

This approach calls for reduction in the per capita consumption of natural resources through one or more of the following approaches.

      Purchase more durable items

      Buy more efficient products - automobiles, houses and appliances.

      Cut consumption by reducing luxury items.

      Manufacturers can reduce the sizes of their products so to cut down on material used per unit

 

Reuse and Recycle Approach

 

      Advocates of the Reuse approach calls for a continuous use of materials in an attempt to cut down on the consumption of new resources. For example, boxes, clothes, appliances that may be trash-bound could be donated to others for reuse.

 

      Recycling is another form of Reuse but usually involves some form of conversion from one state of the material to another. For example, in recycling, a glass will have to be crushed and melted before it will be used to make a new glass.

 

      Japan, Mexico, North Korea and Netherlands are leaders in Paper Recycling.

 

Composting: a form of recycling that occurs when organic matter such as kitchen wastes, yard waste (leaves and branches) and even paper and cardboard are allowed to decompose.

 

EVOLUTION IN METHODS OF URBAN WASTE DISPOSAL

 

1) Open Waste Dumps

Dumps are open sites where trash are deposited and occasionally burned to reduce the volume of the accumulating garbage. Earliest form of waste disposal currently abandoned in economically advanced countries but common in poor developing countries.

 

Problems:

1.  Attracts rats and flies

 

2.  Wind shifts brings an odorous smell to offend residents living close

to the dump

 

3.  Burning the garbage causes black smoke, filled with toxic

byproducts from burning rubber, plastic etc to fill the air.

 

4.  Rain and snow melt trickle through the garbage and carry

materials into surface and groundwater supplies

 

2) Sanitary Landfills

A sanitary landfill is an excavation, or a hollow in the ground in which garbage is dumped, compacted and covered daily with a fresh layer of dirt.

 

Advantages:

      It reduces odors caused by the rotten garbage and prevents air pollution caused by periodic burning of waste in an open dump.

 

      Because a soil layer is placed over the trash, compacted, and then generally sloped to reduce water percolation into the garbage, groundwater contamination can be greatly reduced.

 

      The protective layer of soil also reduces insects and other pests that could carry disease.

 

      The garbage can also be reclaimed - returned to some previous use. For example, a stadium or a shopping mall can be built on the site. In Denver - Colorado, a shopping mall, stadium and a park have been constructed on former landfills.

 

Disadvantages:

 

      If the soil or rock is permeable, there could be a considerable seepage that would lead to groundwater pollution.

 

      Rotten debris produces methane, which is a potentially explosive gas.

 

      Requires large tracts of expensive land

 

3) Incineration

 

It is a system in which unseperated trash - containing plastics, metals, paper, yard waste and glass - is burned and the heat produced during combustion is often used to generate steam for industrial processes, home heating or electrical power generation.

 

Advantages:

 

      It captures energy that would otherwise be lost.

 

      It requires less land than landfills and Dumps.

 

Disadvantages:

 

Incinerators that burn plastics and other materials containing chlorine emit a dangerous class of compounds called Dioxins that have been linked to cancer and weakens the immune system.