Formation of landfill leachate:-
Dumped municipal solid waste is composed of many different components. Organic waste, plastic waste, medical waste, unused medicines, sanitary napkins, paints, pesticides and many other chemicals used in households and small establishments.
These wastes may contain some amount of liquid in it, and in addition, the rain which falls over this land fill will seep through all these waste, collecting soluble and suspended particles along with it and collects at the bottom of the landfill. This liquid is called leachate. Leachate is usually hazardous, poisonous and carcinogenic in nature.
Contents of leachate:-
Leachate is poisonous, usually colored liquid which gives a acidic smell.
It usually contains organic compounds like chlorinated hydrocarbons, benzene, toluene, xylene etc...
When leachate seeps into ground water it causes a drop in pH of water and may cause diseases like cholera, typhoid, polio etc..
Why control leachate:-
As said earlier, leachate is extremely dangerous liquid and should be dealt with cautiously.
Leachate will settle at the bottom of the landfill. This leachate will percolate and be absorbed by the soil and the underlying strata. There is also some amount of lateral movement bound to happen.
All these movements is heavily depended on the characteristic of the soil and the clay content present.
Also soil has the capability to absorb chemical and other constituents of leachate. But this also depends on the soil characteristics and the thickness of soil layer.
It is the motive of the engineers to prevent the percolation of leachate into ground water.
How can leachate be controlled:-
Prevention of leachate formation can be a mode, though it is difficult to totally prevent its formation. The quantity of leachate can be reduced if rain water is not allowed to enter into the landfill. This can be done by covering the top layer of soil by non permeable materials or clayey soil.
Most adopted method is lining of the bottom of landfill with synthetic materials. These materials should be non permeable and should not allow the liquid to pass through them into the underlying soil.
Due care must be taken while compaction and filling of waste as to not to damage these layers laid below.
The leachate collected above the layers of non permeable material can be pumped up and treated if necessary. This can be done by laying open joint pipes at the bottom and pumped up to the surface.
This process is costly as huge quantity if synthetic materials are needed for a single landfill.
Comments