Solid waste can be mainly divided into 3 categories:-

1. Municipal solid waste – this is also known as household solid waste. It mainly consists of construction and demolition debris, sanitation residue and waste from streets. This type of waste is generated mainly from commercial and residential complexes.
2. Hazardous waste – industrial and hospital waste is considered hazardous because it may contain toxic substances. Direct exposure to chemicals like mercury and cyanide in hazardous waste can be fatal.
3. Hospital waste – this type of waste consists of anatomical waste, blood cultures, discarded medicines etc. These wastes are in the form of swabs, body fluids, syringes, bandages etc.

Disposal of solid waste is done mostly through a sanitary landfill. A sanitary landfill is a depression in a impermeable soil layer that is lined with an impermeable membrane. The three main characteristics which distinguishes a sanitary landfill from an open dumping ground are :-

• The landfill needs to be carefully selected and is prescribed for a particular type of waste only.
• The waste material is spread out and compacted with a heavy machinery.
• The waste is covered each day with a layer of compacted soil.

The following steps should be taken before assigning a dumping a ground as a sanitary landfill:-

• Pollutants (leachates) seep from the bottom of a sanitary landfill and percolate to the ground water aquifer. Hence to prevent this, it is necessary to install leachate collection systems and monitoring systems to detect the groundwater pollution.

• The organic material present in the solid waste decomposes due to the action of microorganisms. The anaerobes produce methane which is poisonous and highly explosive when mixed with air. Hence to prevent this, impermeable barriers must be provided in the landfill. Also, a venting system should be installed. This venting system collects the blocked gas and vents it to the surface where it can be diluted and dispersed in to the atmosphere.