The Cleantech Open, the world’s largest accelerator of early-stage clean-technology companies, has named Viroment as the winner of the water category. Based in Minneapolis, the company uses technology that processes municipal wastewater sludge and creates two by-products: reusable water and an energy pellet used as a kilo-for-kilo alternative to coal. Viroment’s municipal partner faced a growing challenge of processing the digested waste from its residents, which was traditionally spread on cropland around the local area. Each year, farmers were finding it more and more difficult to accept the sludge, while the processing costs continued to rise. Viroment successfully extracted a clean wastewater by-product from the city’s sludge while producing a cake that could be used as a fertiliser that retains virtually no odour.