A Swedish entrepreneur is trying to market and sell a biodegradable plastic bag that acts as a single-use toilet for urban slums in the developing world.

Once used, the bag can be knotted and buried, and a layer of urea crystals breaks down the waste into fertilizer, killing off disease-producing pathogens found in feces.

The bag, called the Peepoo, is the brainchild of Anders Wilhelmson, an architect and professor in Stockholm.

“Not only is it sanitary,” said Mr. Wilhelmson, who has patented the bag, “they can reuse this to grow crops.”