Centralised sewerage systems concentrate human excreted nutrients, mix them with clean water and then dump them into larger bodies of water.
This standardised systems incredible mismanagement of resources requires a massive subsidy from fossil fuels. It removes our valuable outputs from the source (where they are best managed) at great cost.
Separation and Composting can return the nutrients back to the fields where the food was grown. When done right it is healthy, happy and in harmony. Goals for our world.