چگونه یک شهر آفریقای جنوبی رودخانه آلوده خود را با استفاده از سنگ، چوب و شن تمیز کرد

How a South African town cleaned up its polluted river using stones, wood and sand

Scientists say system to treat contaminated wastewater offers a model for ensuring food security in a fast-warming climate All it took to turn the murky, heavily polluted waters of South Africa’s Stiebeuel River into a resource clean enough for irrigating a community’s vegetable plots was a collection of stones, heat-treated wood and sand. Without chemicals and using renewable energy, researchers from the University…