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SINGAPORE: PUB, Singapore’s national water agency, has been able to deliver for Singapore a robust, clean and sustainable water supply over the decades because of its strong commitment to research, technology and innovation. With a belief in nurturing continuous innovation for the long run, the agency aims to further harness R&D to meet tomorrow’s water demand at today’s energy and sludge footprint.

It has set long-term targets to drive the next phase of innovation, namely to reduce energy used in desalination by more than two-thirds, increase NEWater recovery to 90 percent at low energy levels, and make used water treatment fully energy self-sufficient while halving sludge generation. It has also identified several promising technologies which will contribute towards reaching each of these targets.

Today’s Challenges

R&D has been key to Singapore achieving a robust and sustainable water supply today. Our island-nation’s unique environment – which combines limited natural water resources and land to collect rain with the vagaries of dry weather – requires innovative solutions. NEWater and desalinated water were made possible by technological breakthroughs following decades of R&D effort to short-circuit the natural water cycle so as to make water supply more weather-resilient. Together, they meet up to 70 percent of today’s water demand and up to 85 percent in 2060.

The challenges faced in producing potable water varies with the type of source water used. While seawater and used water streams offer a potentially inexhaustible supply of water, the current desalination energy requirement and NEWater recovery rate pose the greatest barriers to their sustainable use. These unconventional sources require between five and 17 times more energy to produce as compared to the conventional treatment of rainwater. In addition, producing treated used water – before it is channelled to NEWater production – generates sludge which is costly to dispose.

Meeting future water demand with today’s technologies will see PUB’s energy footprint quadruple from the current 1,000GWh/year to 4,000GWh/year, and the amount of sludge generated double from the current 300,000 tonnes/year to over 600,000 tonnes/year by 2060. This is unsustainable and can only be overcome by leveraging technological innovations.

Innovating For Tomorrow

To stay ahead of the curve, PUB spearheads national water R&D initiatives and invests in the development of new, innovative technologies across the water loop to sustainably increase future water resources and improve the efficiency of water treatment processes and operations.

Since 2002, PUB together with research partners and the National Research Foundation have invested S$453 million in over 600 water R&D projects in collaboration with partners from 27 countries. These projects span across the technology readiness spectrum – from basic research to lab-scale prototypes, pilot studies and demonstration plants before full-scale deployment and commercialisation.

“R&D is the process of looking for solutions today to solve problems of the future. As we become increasingly reliant on desalination and water reuse, the challenge is to ensure that technological advancements continue to keep up with increasing water demand so that these sources remain sustainable,” said Harry Seah, PUB’s Assistant Chief Executive (Future Systems and Technology).

“PUB is pushing the frontier of water technology to tackle the pressing challenges in energy and sludge management efficiency and is on track to meet its long-term targets. The key to this is collaboration with the local and global research community to develop real, applicable solutions to keep water supply secure and affordable,” he added.

R&D Targets And Key Projects

For almost two decades, PUB has been working with water industry partners and institutes of higher learning to accelerate the development of new technologies to be tested and implemented in its facilities. It is focusing its R&D efforts on increasing water resources while reducing energy usage and sludge generation.

In line with this, PUB has set long-term targets to drive the next phase of innovation:

a) Low Energy Desalination

Desalinated water is Singapore’s fourth national tap and is its most energy-intensive source. It currently meets up to 30 percent of water demand and will meet 30 percent of future demand in 2060. PUB’s target is to reduce the energy consumption of the desalination process by more than half from the current 3.5kWh/m3 to 1.5kWh/cubic m in the short term, and eventually to 1kWh/cubic m, as a system, in the long-term.

Seawater Reverse Osmosis, the current desalination method, pushes seawater through membranes which filter out salts and impurities. PUB is demonstrating Electro-deionisation technology at its R&D Facility in Tuas and testing Biomimetic Membranes, which are new and more efficient methods inspired by science and nature, to desalinate water at low energy levels.

b) Increasing NEWater Recovery at Low Energy

Singapore produces high-grade reclaimed water on a scale unprecedented anywhere in the world. NEWater currently makes up to 40 percent of water demand and will meet up to 55 percent of future demand in 2060. NEWater is produced from treated used water which is put through an efficient 3-stage process of microfiltration, reverse osmosis (RO) and ultraviolet disinfection.

PUB’s short-term target is to increase the NEWater recovery rate from the current 75 percent to 90 percent at the same energy consumption of 0.4kWh/cubic m for its energy-intensive RO treatment stage. The long-term target is a 90 percent NEWater recovery at less than half the energy consumption rate for RO treatment.

The Flow Reversal Technology demonstrated at the Kranji NEWater Factory and the Electrodialysis reversal-reverse osmosis (EDR-RO) system piloted at the Ulu Pandan Water Reclamation Plant have the potential to reach PUB’s long term target sustainably.

c) Energy Self-Sufficiency and Sludge Reduction in Used Water Treatment

Used water treatment is a critical part of protecting public health and the environment, as well as the backbone of NEWater production. PUB is actively testing technologies which have the potential to make the used water treatment process energy self-sufficient, producing as much energy as it uses. PUB has set the target for its water reclamation plants to move from the current 25 percent energy self-sufficiency to 75 percent in the short-term, and ultimately to 100 percent energy self-sufficiency in the long term.

Energy self-sufficiency and sludge management are inextricably linked. Thus, PUB also aims to reduce the amount of sludge generated by the used water treatment process by more than 50 percent in the long term, through harnessing the biogas generation potential of sludge. This will allow double the amount of used water to be treated in the long-term at today’s sludge footprint.

A novel combination of energy-efficient technologies for used water treatment is being validated at the Ulu Pandan Wastewater Treatment Demonstration Plant. Sludge reduction and enhanced biogas production also is being demonstration by a Thermal Hydrolysis Process (THP) at the Jurong Water Reclamation Plant. These technologies will be deployed at the future at Tuas Water Reclamation Plant, a highlight of the Deep Tunnel Sewerage System Phase 2.

Singapore International Water Week

These technologies will be showcased at the TechXchange and Water Innovation Pavilion at the Singapore International Water Week 2018, held from 8 – 12 July 2018.

TechXchange and the Water Innovation Pavilion will feature local and international companies with game-changing innovative technologies. The Innovation Pavilion features how these technologies work and highlights how some of these technologies were adopted by PUB.

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