The four modes of disposal of wastes are:-
1.Landfill-The waste substance or material is dumped under the ground.
2.Sewage treatment-treating the waste material and then dicarding it into the river for irrigation purpose.
3.Preparation of compost-biodegradable wastes get converted or mixed with compost which is can be used as manure.
4.Incarnation -burning of wastes.
Hope this helps u..................^_^