It can turn sewage into potable water that's currently used for irrigation and groundwater recharge.
Unfortunately the sludge is too contaminated with industrial waste, pharmaceuticals, etc., to use directly as fertilizer. Alas, the sludge is dried and used as landfill cover so the nutrients it contains are wasted.
In Mexico City these contaminants in treated sewage are generally ignored and the water and sludge are used for agriculture. These contaminants end up in the soil, ditch water, and to a lesser extent agricultural produce.
Science and engineering could solve these problems. All it takes is a commitment to protect our environment and recycle our waste.
Every human deserves toilets that don't spread disease, don't pollute the environment, are not difficult to maintain, and recycle water and nutrients.
My parents and my wife's parents live in rural areas and their toilets are connected to septic systems. They drink surface water, rain or snow melt, and their wastewater goes into the ground. Most of this lower quality water is pumped up for agricultural uses, but a certain amount of it ends up in domestic water supplies and surface water, some of it in the domestic water of people who are not as well off as they are.
This is a recognized problem where my wife's parents live and new conventional septic tank installations have been prohibited. Expensive micro sewage treatment plants are required instead. These are powered by electricity and produce consumable waste (filters, etc...) that end up in landfills. If they are not maintained they are no better than septic tanks.
Composting toilets are frequently mentioned as an alternative to septic systems but these are not flush-and-forget and require a certain commitment to safety and maintenance. Affluent people who enjoy flush-and-forget toilets themselves really shouldn't be promoting alternative sanitation systems to those not as fortunate as themselves.
Human communities need sophisticated sewage treatment systems. That's just the way it is. My great grandma lived with an outhouse on the family ranch, but that's not a safe sanitary system when there are near eight billion humans mostly living in cities, suburbs, and villages.
= new reply since forum marked as read
