10 Advancements in Environmental Engineering

Ecosan Systems
Use of a composting toilet is demonstrated at a yoga retreat in Goa, India in February 2012. Pots with material to cover waste and aid in decomposition are kept next to the latrine. © EyesWideOpen/Getty Images

Ecosan (ecological sanitation) systems include various designs of environmentally friendly toilets or latrines that generally require little or no water, while isolating waste in a way that prevents odor and disease. In many cases, the resulting waste can even be composted and used as fertilizer or fuel. Some designs immediately separate the urine and feces (urine diversion systems). Some require covering the waste with sawdust, lye, sand or other material to eliminate odor, remove moisture and assist with decomposition for disposal or composting. Such systems are ideal for places where water is scarce, since they usually require no connection to a plumbing or sewer system.

One brand -- EcoSan -- was introduced in 2000. It's a stand-alone toilet; lifting the lid causes waste to make its way through a coiled conveyor over 25 or so days, all the while evaporating and venting the liquid waste and breaking down the solid waste using biological processes. Dry, odorless matter only 5 to 10 percent of its original mass is eventually deposited into a receptacle for removal and repurposing.

An ecosan toilet described by Unicef India is similar to a large outhouse with a concrete bunker underneath each toilet. The floor-level toilets have separate holes for liquids (which are diverted to pots outside) and solids, plus a cleansing water basin and a hole for users to drop a handful of lime, sawdust, ash or something similar after depositing solid waste to help with decomposition, moisture reduction and odor control.

There are other ecosan toilet construction methods and products that vary in price, functionality and complexity.

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