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PUB, NEA test-project that uses food waste to generate electricity to be expanded

SINGAPORE — National water agency PUB and the National Environment Agency (NEA) plan to scale up their two-year pilot to eventually use food waste to generate electricity once Tuas Nexus opens in 2025.

PUB, NEA test-project that uses food waste to generate electricity to be expanded

There are 23 premises such as schools, army camps and hawker centres contributing their food waste to the co-digestion plant at Ulu Pandan.

SINGAPORE — National water agency PUB and the National Environment Agency (NEA) plan to scale up their two-year pilot to eventually use food waste to generate electricity once Tuas Nexus opens in 2025.

Tuas Nexus comprises the Tuas Water Reclamation Plant and Integrated Waste Management Facility, which are located at the western tip of Singapore. They are expected to be able to process up to 400 tonnes of used water sludge and food waste — 10 times more than what is processed at the Ulu Pandan Water Reclamation Plant now.

This process creates biogas, which is rich in methane and can be converted to electricity.

In December 2016, the PUB set up a co-digestion facility at the Ulu Pandan plant where used water sludge, which is waste water from residences and commercial facilities, is combined with disposed food products to produce biogas.

Solid food waste separated from the liquid waste, seen at Singapore’s first co-digestion demonstration plant PUB at the Ulu Pandan Water Reclamation Plant. Photo: Najeer Yusof/TODAY

The facility does not produce enough biogas for now to facilitate the conversion into electricity, but the PUB has found that it can successfully produce three times the yield of biogas than if it were to treat used water sludge separately.

Dr Kelvin Koh, 41, general manager of the Ulu Pandan Water Reclamation Plant, said that the generation of more biogas would allow Singapore to reduce its net energy consumption and achieve energy self-sufficiency for used water treatment.

By constructing the Integrated Waste Management Facility and Tuas Water Reclamation Plant in the same area, the PUB would also be able to reduce the energy it uses.

“In the future, we will want to achieve energy self-sufficiency for used water treatment, and by generating more biogas, it will help to reduce our net energy consumption.

“Since there is synergy between the co-location of these two facilities, including reduction in some of these processes, we can streamline many of these processes, helping us to achieve energy net reduction.”

There are 23 premises such as schools, army camps and hawker centres contributing their food waste to the co-digestion plant at Ulu Pandan.

Every day, food waste trucks from the NEA go to the participating contributors to collect up to 14 tonnes of such waste, which consists of vegetable trimmings and inedible fruit, for example.

These are put through an organic extrusion press to separate the fibrous portions from parts of the waste.

The extracted food waste is then combined with water sludge from the water reclamation plant at Ulu Pandan.

The mixture then undergoes anaerobic digestion — which is a biological process that breaks down organic materials in the absence of oxygen — to produce biogas for energy generation, including electricity.

Up to 40 tonnes of used water sludge and food waste are treated at the facility daily.

For food distributor Tian Sheng Fresh Produce, contributing its food waste to the project has allowed it to save up to S$10,000 a year.

Previously, the company would either distribute food that failed its quality-control checks to charities or sell such food items to food-and-beverage companies at a lower cost.

Remaining food that could not be eaten, such as those with mould, would be sent for incineration. However, this incurred costs such as transporting the food to NEA’s incinerators and paying for the NEA certification for disposal by incineration.

Ms Genevieve Tan, 40, chief operating officer of Tian Sheng Fresh Produce, said: “With this project, we are able to contribute the food waste to other sources of energy or other purposes.

“I think that’s more beneficial to the environment as well. We have embarked on this for about a year and the cost savings can be quite significant, at about almost S$10,000 over a year. We are very happy to be part of this project and hopefully, we can expand the scale.”

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