what is vermin cake?

 Low cost and on-site sewage disposal systems such as septic tanks, chemical toilets, composition pitetc. are very suitable for isolated buildings or a small cluster of houses. The excreta collected in these toilets can be used for generating biogas. Vermin processing toilet is a type of toilet in which human excreta is treated through earthworms. Earthworms convert human excreta intovermin cake that is a good variety of natural manure.