Green Living: Award-Winning Hong Kong Scientist’s Innovation Turns Sewage Sludge into Energy, Slowing Down the Impact of Climate Change
by Eric Ng (South China Morning Post) Sewage sludge used as feedstock to make methanol cuts down carbon emissions by a quarter compared to coal as the raw material, Polytechnic University professor Ren Jingzheng says; If all 1,200 tonnes of sludge generated in Hong Kong every day is converted to 400 tonnes of methanol, it could cut 120,000 tonnes of carbon dioxide emissions
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Sludge, the mud-like by-product of sewage treatment, can be used as feedstock to make methanol, a motor fuel and industrial chemical, said Hong Kong Polytechnic University’s industrial and systems engineering professor Ren Jingzheng, the recipient of the 2022 Apec Science Prize for Innovation, Research and Education (Aspire).
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However, a US$20 subsidy per tonne of sludge converted will be required for a plant of such scale to be economically viable, they estimated.
Research of the process, published in a paper in January, has attracted interest from the Drainage Services Department, which invited Ren and his team to draft a proposal for potential collaboration to demonstrate the process, he said.
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Ren has secured three grants from the government to conduct research on converting used medical face masks, poultry litter and sewage sludge into energy and valuable products.
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Some waste treatment companies also expressed an interest in financially supporting the work, said Ren, without divulging details.
“In the past, some companies have tried to develop technologies for converting sewage sludge into [useful] products,” he said. “However, they are still not mature. In some cases, their deployment could lead to some new environmental problems such as carbon emission.”
To tackle the problems and lower costs, Ren said his team aims to develop processes that can incorporate multiple feedstocks and produce multiple products, such as using face masks as one of the feedstocks and upgrading the primary product into bio-oil, a clean-burning fuel.
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The Drainage Services Department is experimenting with technology to mix sewage sludge and food waste to generate bio-gas, a renewable fuel, a spokeswoman said. This can also reduce methane emissions at landfills. READ MORE
