There has been a rising momentum on the recycling and reuse of wastewater for potable and non-potable uses in Southeast Asian countries. This has led to the construction of vital water infrastructure leveraging research, innovation and advanced technologies to strengthen water security in the region. One major development in this direction is the construction of the Tuas Water Reclamation Plant (TWRP) in Singapore that aims to reclaim, treat and reuse domestic and industrial wastewater. The TWRP will be capable of converting approximately 85 per cent of the domestic wastewater into NEWater – high-grade tertiary treated wastewater. It will make use of advanced processes and technologies like membrane bioreactor (MBR), reverse osmosis (RO), supervisory control and data acquisition (SCADA)-based automation, digital information management systems like ProjectWise, radio frequency identification (RFID), etc. It also integrates various waste-to-energy (WtE) initiatives to strategically benefit from the TWRP’s co-location with the National Environment Agency’s (NEA) Integrated Waste Management Facility (IWMF).

Significance and progress of TWRP

The under-construction TWRP, being implemented by Singapore’s National Water Agency, PUB, is expected to be one of the largest and groundbreaking resource recovery facilities in the world. It is being constructed under the second phase of the Deep Tunnel Sewerage System, which, in addition to the construction of the TWRP for treating wastewater, includes the construction of deep tunnels and link sewers to collect and transport wastewater at an estimated cost of around SGD 6.5 billion. A joint venture between Black and Veatch and AECOM is engaged as the lead consultant for the project while CH2M Hill Singapore is the detailed design consultant.

In terms of its treatment capacity, the WRP is expected to treat 650 million litres per day (mld) of domestic sewage water and 150 mld of industrial water, taking the total capacity of the plant to 800 mld. It will also have a NEWater treatment capacity of 114 mld. The plant was 33 per cent completed as of November 2024, and is targeted to be operational by 2027. The TWRP will be co-located with NEA’s IWMF, together forming the Tuas Nexus. The combination will aid in integrating wastewater and solid waste treatment processes in Singapore, maximising energy efficiency and resource recovery in the form of NEWater.

Advanced technologies and digital leaps

The TWRP has been planned to receive wastewater from the western part of Singapore through two separate deep tunnels, one to carry domestic wastewater and the other to convey industrial wastewater. The treatment process will have several steps to maximise the efficiency of the procedure. The first step of treatment involving the coarse screen shaft will help remove large debris from the domestic and industrial wastewater streams. In the second step, the domestic water streams will undergo biologically enhanced primary treatment through the processes of biosorption and lamella sedimentation tanks. This will help maximise the capturing rate of biosolids, assuring higher energy recovery and a reduced carbon footprint. Following this, a step feed bioreactor will ensure optimal conditions for microorganisms to decompose soluble substances. Eventually, the treated effluent will be fed into the RO membrane in a three-stage process followed by ultraviolet disinfection.

The TWRP is likely to leverage several state-of-the-art technologies to boost water self-sufficiency in Singapore. It is expected to use MBR technology to treat the separate streams of industrial and domestic wastewater. In line with this, MemPulse MBR technology will be deployed by DuPont, a multinational chemical company, at the plant. The project will be the largest MBR-based water reclamation plant in the world once completed. It will also deploy the RO process with the use of DuPont’s FilmTech RO elements to further purify the water treated by the MBR process.

Furthermore, several digital leaps will be incorporated in the TWRP to enable efficient and sustainable operations. For instance, the plant will deploy piezometers, a tube-shaped instrument to measure water pressure and groundwater levels. Additionally, strain gauges are expected to be used to monitor the plant’s performance and ensure its structural integrity. For this, 200 piezometers and 50 arc weldable strain gauges have been provided by Encardio Rite to ensure the safety, efficiency and effective monitoring of the water reclamation processes at the TWRP.

In addition, the ABB Ability 800xA control platform and SCADA by ABB Industrial Automation have also been deployed to ensure effective real-time monitoring of the facility and quick resolution of issues. The overall system will integrate over 100,000 input and output signals from assets including pumping stations, a wet weather facility, biosolids, into one consolidated control platform. This will provide complete supervision of operations across the network of the TWRP. Information management systems such as ProjectWise, cloud services and others will also be used to enhance operational productivity while RFID will be adopted for data collection relating to manpower.

Initiatives related to WtE conversion and energy optimisation

The IWMF is Singapore’s first integrated facility to treat incinerable waste, source-segregated food waste and dewatered sludge. It will employ various WtE initiatives, ensuring effective use of treated wastewater for producing energy. The co-location of the TWRP with the IWMF is expected to achieve synergies in material handling, energy production, water and other aspects. The food waste will be carried from the IWMF to the TWRP for co-digestion with wastewater sludge, while the dewatered sludge from the WRP will be transported to the IWMF for treatment and electricity production. In terms of energy supply, power generated from the WtE process at the IWMF will be supplied to the TWRP and biogas and steam will be conveyed from the TWRP to the IWMF to enhance the plant’s thermal efficiency. Besides, water and foul exhaust air will be carried from the TWRP to IWMF for usage and combustion, while wastewater will be conveyed from the IWMF to the TWRP for treatment.

To optimise energy consumption, the plant has been strategically constructed to leverage natural lighting and ventilation. This will help save energy. To efficiently use the solar power, the roof space area in the facility has been planned and maximised. The facility has also been designed in a systematic manner to lower manpower requirement to operate and maintain of the plant.

In sum

The TWRP is poised to be a long-term solution to close the demand-supply gap in Singapore. It will facilitate better and wider utilisation of NEWater and reuse of industrial water. Currently, the use of reclaimed water meets around 40 per cent of Singapore’s water demand. Going forward, the TWRP through its advanced processes and efficient operations is likely to meet the growing water needs of the industrial and domestic sectors in Singapore. Besides, there is scope to expand the TWRP’s domestic treatment capacity to 1,550 mld and industrial treatment capacity to 350 mld in the future as per Singapore’s wastewater treatment requirements to help augment the country’s water supply system in a more effective manner.