As I understand it, chlorine and heat treatment are how pathogens are killed in waste-water treatment plants. E.g., https://bio.libretexts.org/Bookshelves/Micro

As I understand it, chlorine and heat treatment are how pathogens are killed in waste-water treatment plants. E.g., https://bio.libretexts.org/Bookshelves/Microbiology/Book%3A_Microbiology_(Boundless)/17%3A_Industrial_Microbiology/17.3%3A_Wastewater_Treatment_and_Water_Purification/17.3B%3A_Wastewater_and_Sewage_Treatment https://bio.libretexts.org/Bookshelves/Microbiology/Book%3A_... If you're ever in Boston, the Deer Island Treatment Plant offers tours and they're fascinating. (The odour is only challenging for a brief part of the tour)