Final answer:
Sewage systems are found in urban areas with centralized sewage treatment plants managing high volumes of wastewater, while septic tanks are individual systems used in rural areas for sewage treatment with anaerobic decomposition and drain field filtration.
Step-by-step explanation:
Sewage systems are used in urban areas and septic tanks are used in rural areas. A sewage system typically refers to a large-scale infrastructure where sewage from residential and industrial establishments is treated at a sewage treatment plant. These plants are capable of handling the high volume of wastewater generated in densely populated cities through a combination of primary, secondary, and tertiary treatments. The primary treatment involves solid removal, secondary treatment consists of bacterial decomposition, and tertiary treatment offers extra filtration of the wastewater before it can be safely released into the environment or reused.
On the other hand, a septic tank system is an individual sewage treatment system designed for homes in rural settings where a centralized sewage treatment plant is not feasible. It includes a septic tank, where sludge settles and microorganisms decompose the organic solids anaerobically, and a drain field that filters the remaining liquid. Water pollution can become an issue if the septic tank is improperly maintained or installed in unsuitable soil types.