Singapore’s National Water Agency, PUB, and the country’s National Environment Agency (NEA) completed a two-year trial started in December 2016 to co-digest food waste and used water sludge for higher energy generation. Water reclamation plants in Singapore currently use waste water sludge to generate biogas, which then provides part of the energy required to power the plant.
The trial project found that the biogas yield from co-digestion of used water sludge and food waste is triple of the biogas generated from the digestion of used water sludge alone. When compared to the separate digestion of used water sludge and food waste, the biogas yield from co-digestion is 40% more.
As part of the trial, up to 40 tons of used water sludge and food waste from 23 premises were treated daily at the facility. The mixture of used water sludge and food waste then undergoes anaerobic digestion, a biological process that breaks down organic materials in the absence of oxygen, to produce biogas for energy generation. The results demonstrate the possibility of making the used water treatment process in water reclamation plants more energy self-sufficient and achieve greater synergy by co-locating the facilities of used water sludge and food waste treatment. This will be implemented at the new Integrated Waste Management Facility (IWMF) and Tuas Water Reclamation Plant (WRP) – collectively known as the Tuas Nexus – which are scheduled to be completed in 2025.
This will also help in dealing with Singapore’s second largest waste stream of food waste, of which only 16% is currently recycled, well below Singapore’s overall recycling rate of about 60%.
(Sources: PUB; Channel NewsAsia)