Pick up the correct arrangement among the given sets below and pick up the correct arrangement which can be used for sewage disposal.
Set 3
The correct sequence is given as follows:
Composting pits: It is used for making compost which is a very good fertiliser for plants and is better than chemical fertilisers.
Septic tanks: Untreated wastewater from a property flows into the septic tank, where the solids separate from the liquids. Some solids, such as soap scum or fat, will float to the top of the tank to form a scum layer. Heavier solids, such as human and kitchen wastes, settle to the bottom of the tank as sludge. Self-forming bacteria in the tank help the system "digest" these solids or sludge. The remaining liquids flow out of the tank to a land drainage system or drain field.
Chemical toilets: A chemical toilet is a toilet which uses chemicals to deodorise the waste instead of storing it in a hole or piping it away to a sewage treatment plant.