A research team at the Hong Kong University of Science and Technology (HKUST) has developed an urban food waste management framework to identify appropriate waste management solutions for cities based on the moisture of their waste.
Chen Guaghao, HKUST Chair Professor of the Department of Civil and Environmental Engineering, led a study into the food waste composition, wastewater generation, energy consumption and treatment of 29 large cities around the world.
The study found the key factor affecting food waste treatment efficiency was its moisture load, and that higher moisture loads were linked to increased treatment costs and emissions.
The HKUST team, in collaboration with researchers from Huazhong University of Science and Technology, then developed the Urban Biowaste Flux (UBF) framework, which identified which cities had conditions to adopt an integrated waste management system – diverting food waste into the sewage network and combining it with landfill or incineration.
The study found that cities such as Hong Kong, where fresh ingredients and soup-based diets are common, were more likely to generate wetter food waste streams.
The HKUST researchers learnt that using food waste grinders to divert waste into the city’s sewage system could improve overall waste treatment efficiency.
“Using Hong Kong as an example, our analysis of food waste and wastewater samples shows that food waste accounts for 57.78 per cent of the total chemical oxygen demand entering the biowaste treatment system,” said HKUST PhD Student Dr Zou Xu.
“This demonstrates why we must rethink how food waste is managed.”
By applying an integrated waste management system to Hong Kong as dictated by the UBF framework, the researchers found that landfill expenditure could decrease by about $105,724,836, resulting in an 11 per cent reduction in Hong Kong’s total waste-management costs.
Researchers also found that the integrated treatment could reduce Hong Kong’s direct and indirect greenhouse gas emissions by a combined 46.61 per cent.
“Our study shows that among 29 cities worldwide, 27 would reduce per capita annual energy consumption by about 20.60 per cent, and 26 would reduce per capita greenhouse gas emissions by about 22.60 per cent if integrated treatment were adopted,” said Guangaho.
“Of course, cities differ, and not all will be suited to the same model, but for those with high food waste moisture load and high solid-waste processing costs, integrated treatment is a practical path forward.
“We hope this research provides a scientific foundation for cities to formulate more appropriate strategies for food waste management.”
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