As Chinese cities have grown rapidly over the past decades, untreated sludge—the toxic by-product of the municipal sewage treatment process has quietly contaminated China’s soil, groundwater, and croplands.
China’s wastewater plants produce more than 40 million tonnes of sludge annually—enough to fill five great pyramids of Giza—but less than 20 per cent is treated. Chinese cities have largely relied on exporting sludge to landfills and incinerators or illegally dumping untreated sludge into waterways or onto farmland.
The success of China’s waste-to-energy transition will hinge on whether the country can implement the right mix of policy directives, market incentives, partnerships, and successful operating models for methane capture.
Encouragingly, China’s 2015 Water Pollution Action Plan tackles the country’s long-overlooked wastewater/sludge problem by setting ambitious targets to improve its underdeveloped sludge treatment capacity. The plan mandates that most prefecture-level cities must achieve 90 per cent toxic-free sludge treatment by 2020.
However, immense infrastructural changes certainly do not happen overnight. For Chinese cities in particular, a number of key challenges and requirements loom large. China’s 13th Five-Year Plan highlights a huge financing deficit—31.6 billion yuan (US$4.6 billion)—for advanced sludge treatment and disposal facilities.
Moreover for China’s massive sludge mountains, the solution is more complicated than simply employing anaerobic digestion technology. The quality and amount of sludge and potential markets for methane, as well as other products, varies in each city. Many Chinese cities realise there is no “one-size-fits-all” technology to address the varying municipal and industrial sludge challenges.
But as the Chinese government pushes for ambitious water targets and low-carbon development goals, and as global expertise grows, the opportunities for advancing sludge treatment and mitigating methane emissions have never been riper.
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