Residents of California's Arcata City flush their toilets with pride. That is because their wastewater is purified by a pioneering system of marshes in a wildlife sanctuary, where plants and animals feed on the nutrients.

The innovative system was dreamt up by officials, professors and activists who wanted to build a low-cost sustainable sewage system for Arcata's population. After initial treatment in a sewage plant where the sludge is separated off, the city's wastewater travels through a network of oxidation ponds and marshes, before being let out into the nearby Humboldt Bay.

The sanctuary has transformed the city's coastline, which was previously home to a landfill site and defunct industrial areas. Wildlife abounds and the water discharged into the bay is pure enough to drink.

Source: Al Jazeera