Wastewater Story — Science STD 7 — Question

Septic tanks are suitable for places such as hospitals, isolated buildings and clusters of houses where there is no sewage. Local governments or private corporations usually provide septic tanks in areas that have no direct connection to main sewage pipes. The septic tank system consists of a small sewage treatment system. Aeroplanes and trains usually have chemical toilets. A chemical toilet uses chemicals to disinfect human waste and remove its bad odour. That is why trains and aeroplanes do not have elaborate plumbs and sewage.