“The smell alone when you cross the bridge tells you something’s wrong,” says Renison Ruwa, deputy director of the Kenya Marine and Fisheries Research Institute.

The bridge in question is Mtwapa bridge, which straddles Mtwapa Creek in Mombasa, Kenya. And the smell to which Ruwa is referring stems from this very creek, into which waste from the nearby Shimo la Tewa prison—and indeed many other places—is directly dumped.

The prison’s growing population has long overwhelmed the capacity of its septic system, causing excess raw sewage to be discharged into the creek for many years—dumping which can have grave long-term effects on the area.

The beautiful coral reefs of the nearby Mombasa Marine Park are very vulnerable to such pollution, as are local fish and crabs. Wastewater pollution not only has the potential of disrupting local ecosystems and biodiversity, but also potentially tourism revenue. 

Prison management officer Kenrodgers Kyalo Mutemi and Sarah den Hering of GreenWater on the path connecting the prison to the constructed wetland area. Photo by UNEP/Nairobi Convention

The prison has not been spared from the changes in Mtwapa Creek. “We’ve had to move prison officials out of some buildings,” acknowledges Kenrodgers Kyalo Mutemi, an officer at Shimo La Tewa—the structures were condemned as inhabitable because of the stench.

A low-cost and long-term solution to manage the prison’s wastewater in a sustainable, environmentally friendly way is sorely needed to safeguard the social, environmental, and economic benefits provided by the creek.

A new project involving the Kenya Marine and Fisheries Research Institute, Shimo la Tewa prison, the National Environment Management Authority and GreenWater aims to address this problem using constructed wetland technology to manage wastewater at the prison.

Prison management officer Kenrodgers Kyalo Mutemi and Sarah den Hering of GreenWater on the path connecting the prison to the constructed wetland area. Photo by UNEP/Nairobi Convention

Constructed wetlands

Constructed wetlands, known as “green infrastructure”, mimic the functions of natural wetlands, namely water filtration. In other words, the prison’s wastewater will be directed towards a constructed wetland, which will have a plant, gravel or sand filter that mimics nature’s processes and removes harmful pollutants from the water.

“Once certified as suitable, the project will then redirect the treated water to grow food crops at the prison farm to improve food security and nutrition at the prison,” says United Nations Environment Programme’s (UNEP) Regional Seas project manager Jared Bosire. “The water will also be used for aquaculture by constructing, stocking and managing a fish pond at the prison,” he adds.

SOURCE UN ENVIRONMENT PROGRAM

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Taxonomy

• Wetlands
• Constructed Wetlands
• Wetlands