NAVENE ELANGOVAN Today Online 29 Jan 19;
SINGAPORE — National water agency PUB plans to scale up its two-year pilot plan with the aim 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, are 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 and food waste 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.
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, 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 National Environment Agency (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.”
PUB, NEA trial method of using waste water sludge and food waste to generate more energy
Gwyneth Teo Channel NewsAsia 29 Jan 19;
SINGAPORE: A new method of using both waste water sludge and food waste to generate biogas will be implemented at Tuas Nexus plant when it opens in 2025.
This follows a two-year trial of the method which has yielded successful results, said PUB and the National Environment Agency (NEA) on Tuesday (Jan 29).
Currently, all water reclamation plants in Singapore use waste water sludge - solids from household waste water – to generate biogas, which is then used as part of the electricity mix to power the plant.
By adding food waste to the treatment process, it can triple the biogas yield, said PUB and NEA in a joint media release.
As part of the trial, which was done at Ulu Pandan Water Reclamation Plant, up to 40 tonnes of used water sludge and food waste from 23 premises were treated daily at the facility.
The trial generally found that mixing sludge and food waste increased the efficiency of biogas production by 200 per cent compared to processing sludge alone, and by 40 per cent compared to processing both sources separately.
At the Ulu Pandan facility, biogas from sludge currently supplies 25 per cent of the plant's electricity needs. Mixing food waste and sludge can increase this to 40 per cent, after taking into consideration efficiency losses from converting biogas to electricity.
This technology will lead to operational efficiencies at Tuas Nexus, said the agencies.
"We can streamline a lot of processes, including reduction of some of these processes, helping us achieve net energy reduction," said Dr Kelvin Koh, general manager of Ulu Pandan Water Reclamation.
The food waste used in the trial was collected daily from 23 premises, including army camps, schools, markets and hawker centres, as well as F&B outlets.
Participating organisations were required to segregate food waste from other types of general waste on-site, and place it into dedicated food waste bins.
Source: CNA/aa(gs)
PUB, NEA find a way to convert sludge and food waste into energy
Cheryl Teh Straits Times 29 Jan 19;
SINGAPORE - What gets flushed down your toilet every day might just not be wasted. After a two-year trial, Singapore's national water agency PUB and the National Environment Agency (NEA) have found a way to make sure of this.
Mix what is flushed down the loo (water sludge) with table scraps, and this stomach-churning mixture becomes a potent recipe for energy. If scaled up, the biogas produced in the process can actually power a large portion of Singapore's water treatment plants.
This is a prime example of how Singapore is turning trash to treasure, particularly in view of 2019 being designated as Singapore's Year of Zero Waste.
The trial, which started in December 2016, involved 40 tonnes of used water sludge (from toilets) and food waste.
Two truckloads arrive every day at the PUB's treatment facility in Old Toh Tuck Road from 23 locations from around Singapore, including Maju Camp, the University Town at the National University of Singapore, and food distributor Tian Sheng Fresh Produce, among others.
The sludge and food waste were then combined, and went through "anaerobic digestion" - a biological process that breaks down organic materials - to produce biogas, the natural fuel produced when organic matter reacts with bacteria.
The sludge and food waste were previously "digested" separately to produce biogas. But when they were combined, the PUB and NEA found that the biogas yield tripled.
The agencies are aiming for this co-digestion process to provide the large amounts of energy required to treat used water in Singapore in the future. This, they hope, will maximise the recovery of resources from food waste, while allowing the Republic to take a step towards energy self-sufficiency in the used water treatment process.
Senior Minister of State for the Environment and Water Resources Amy Khor said that the funds are for projects specifically targeting zero waste, particularly in the areas of packaging waste, food waste, and electrical and electronic waste.
However, only 16 per cent of food waste (a major waste stream in Singapore) was recycled, said Mr Tan Meng Dui, CEO of NEA. He added that this rate was low, in comparison to Singapore's overall recycling rate of about 60 per cent.
"As the second-largest waste stream disposed of, there is great potential to not only reduce food wastage at the point of consumption, but also to recycle better by developing technologies to turn food waste into higher-value products, such as biogas, for energy recovery," Mr Tan said.
"We look forward to the continued support of the community and industry to co-create zero-waste solutions in this Year Towards Zero Waste," Mr Tan added.
"Positive results from the trial show that it is possible to make the used water treatment process in water reclamation plants more energy self-sufficient," said Mr Harry Seah, PUB assistant chief executive, future systems and technology.
Mr Seah added that as a result of the latest success, the process was likely to be scaled up, in the form of co-locating the facilities of used water sludge and food waste treatment at the new Tuas Nexus.
"This is in line with our continued efforts to innovate and leverage technologies that will allow us to meet future water demand at today's energy footprint," Mr Seah said.
The Tuas Nexus, which consists of the Integrated Waste Management Facility and Tuas Water Reclamation Plant, is scheduled to be completed in 2025.
