Why is wet waste difficult to burn?
Wet waste is difficult to burn, or combust, for two reasons: steam and cooling.
When water boils, it creates steam. The steam displaces the oxygen around the flame. With less oxygen available for burning, the flame will slowly suffocate.
Cooling relates to the temperature in the burning pile and the ignition temperatures of the materials being burned. Ignition temperature is the temperature at which the material starts burning.
Water has an ignition temperature of 100˚ Celsius. That is when it boils. Most solid materials have ignition temperatures that are much higher and they will not burn at 100˚ Celcius.
Because water has the lowest ignition temperature out of all the materials in the pile (100˚ Celcius), the temperature in the waste pile will not get above 100˚ Celcius until all the water has vapourized. This is the principle of cooling.
However, 100˚ Celcius is way too low for any other material to burn. So, the other material will not burn properly until all the water is gone and the temperature in the pile rises.
If more wet waste is continuously thrown on top of the pile at the incineration facility, the combustion process will never be fully utilized.
Some governments prohibit wet, moist and undrained waste in incineration facilities.
By draining your waste, you reduce the amount of water it contains and help the waste burn better at the incineration facility.