“They call me ‘Mama Poo,” Anne told me matter-of-factly as we strolled through a dusty pathway in Silanga, a small neighborhood in the expansive Kibera slums of Nairobi, Kenya. “And I like that,” she added. Anne Nudge is a sales representative for Peepoople AB, a Swedish social enterprise that, last October, launched a pilot project in Silanga marketing and selling “The Peepoo" – a single-use, personal toilet that sanitizes human waste quickly, preventing it from contaminating the surrounding environment. After just a few weeks, the bag transforms the waste into a nutrient-rich fertilizer. The Peepoo bags, which sell at a...