Do you know the value of your city’s sewage?

Trucks emptying faecal sludge at Bugolobi Wastewater Treatment Plant in Kampala, Uganda. Photo by Linda Strande.
Trucks emptying faecal sludge at Bugolobi Wastewater Treatment Plant in Kampala, Uganda. Image by Linda Strande.

An introduction to REVAMP – a new tool that estimates and values what reuse products could be made from a city’s wastewater, sewage and organic waste.

As the idea of the circular, resource-efficient economy gains ground, urban planners are increasingly asking not just how much it will cost to clean up “human waste”, but also how much that “waste” might be worth. In SEI’s Initiative on Sustainable Sanitation we’ve been developing a tool that can help city planners understand how they could profit from productive reuse of a wide range of urban organic waste streams.

Every day, an estimated 9.5 million m3 of human excreta and 900 million m3 of municipal wastewater are generated around the world – enough to fill 363,800 Olympic swimming pools. A large share of these goes into lakes, rivers and other waterways with little or no treatment – a major health risk and a relentless pressure on vital ecosystems.

But these waste streams are full of resources that could help meet many of the defining challenges we face: water scarcity, energy access, climate change, the shortfall in food production, while also creating green jobs in the process.

From nice ideas to numbers

Investment in the kind of technologies and services that could make this possible demands some credible numbers. To date, urban planners and managers have lacked tools to estimate the potential for resource recovery at city scale. The few that have been available have focused on a single waste stream or resource reuse option, such as energy generation. Also, they have generally been designed for the large-scale waterborne (sewerage) systems typically found in the Global North; not so useful for the fast-growing cities of the Global South, where on-site sanitation systems (such as pit latrines) are common and likely to remain so.

Our Resource Value Mapping (REVAMP) tool seeks to fill these gaps. The user (probably a city planner, perhaps an entrepreneurial investor, maybe a researcher) only needs to fill in the amounts and characteristics of the different waste streams in the city, and REVAMP will estimate how much energy (biogas or solid fuel), fertilizer and animal protein feed (from insects grown on sludge) can be generated from that waste. It can also give approximate revenues that could be expected from the different reuse options, reflecting local market prices.

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