The use of mobile covering systems in order to absorb the smells is a very interesting solution for the problem of the daily covering even during a short period of time when the organic material is still put on the landfill.

At the moment the most used method applied to the urban litters landfills consists in covering periodically (even every day) the deposited waste materials with a layer of earth and/or with an inert material.
In this way the landfills are made with alternate layer of garbage (thickness varying from 0,5 to 2 metres each) and inert material (thickness from 0,1 to 0,3 metres each). When the volume of the whole heap has reached the authorised capacity everything is covered by a layer of material suitable to be used as road and / or as a yard.

The systems used to make the daily covering must be carried out as follows:
- The environmental condition hasn't to be ruined
- The problem of pollutant spread by wind must be eliminated
- The emission of smell must be reduced
- The entry of insects and animals inside the landfills must be restricted.

Actually the daily deposit of inert material or earth sometimes even very argillaceous, on the waste materials involves many disadvantages such as:
- The non exploitation of one side of the landfill occupied by the inert material
or earth.
- Difficult retrieval of earth or inert material in some places where there are landfills
- Expensive shipping and labour
- The huge work doesn't meet a satisfying result of the means of work during the rainy period. In this period the covering of the garbage is really difficult because the earth is completely imbued with water. As a consequence the strength of the workers doesn't obtain a good result even using different kinds of means.
- Dangerous bags of bio-gas can develop between the layers.

A second method used consists in covering the garbage with simple plastic tarpaulin, above all as protection from the atmospheric precipitation in order to avoid the increasing of leachate.

A third method consists in spraying the surface of garbage with particular kind of enzymes. They are very useful to capture and metabolise the exhalations.
In spite of these devices the exhalations are able to reach the atmosphere. The volume will depend from the atmospheric conditions, owing to the scarcely filtrating efficacy of the earth or of the inert material overlapped (in the first case), the effect of the only covering (in the second case), the enzymatic effect limited to just the superficial layer (in the third case).

Inside the treatment installation and in the plants involved with the accumulation of discarded organic fluid substances the only way used just now consists in putting under the soil the containers of fluid materials or making them mechanically tight. The results are economically heavy and very often inadequate.