<human>: What is the difference between a septic system and a sewage treatment system?
<bot>: The main difference between a septic system and a sewage treatment system is that a septic system uses biological processes to treat waste water, while a sewage treatment system relies on chemical processes. Biological systems are more efficient at removing impurities from wastewater, such as nitrogen compounds, phosphorus, and organic matter. This makes them better suited for small-scale residential applications.