Publish Date : 16-Jul-2018
PUB, Singapore's National Water Agency and the National Environment Agency (NEA) will be calling tenders with a total estimated value of more than S$5 billion over the next five years for civil, mechanical and electrical engineering works for the Tuas Nexus.
Tuas Nexus the integration of PUB's Tuas Water Reclamation Plant (Tuas WRP) with NEA's Integrated Waste Management Facility (IWMF) is the first of its kind in the world planned from the ground up. It marks Singapore's first initiative to harness potential synergies of the water-energy-waste nexus by integrating used water and solid waste treatment processes. Construction of the two facilities is expected to commence in 2019 and will be completed in phases from 2023 onwards.
Tuas WRP Features
Tuas WRP is a key component of Singapore's Deep Tunnel Sewerage System (DTSS) Phase 2 and is expected to be ready by 2025. At an initial treatment capacity of 800,000 m3/day, it will be the largest membrane bioreactor (MBR) facility in the world, with an overall 30 per cent more compact footprint compared to conventional plants. A used water superhighway, the DTSS is the backbone of Singapore's used water management system and also ensures long-term water sustainability by contributing to the goal of increasing NEWater supply from 40% to up to 55% of total water demand in the long term.
Unlike conventional WRPs, the Tuas WRP will receive domestic and high-strength industrial used water flows from two separate deep tunnels. It will also feature a unique combination of advanced physical, biological and chemical treatment processes. This includes space-efficient lamella primary sedimentation tanks, two energy-efficient MBR systems to treat the two used water streams separately to higher quality standards for NEWater and Industrial Water production, and a thermal hydrolysis process to increase biogas production and energy recovery, as well as reduce sludge for disposal. The plant will also be equipped with solar panels on its rooftop in the long term, which is expected to generate up to 8MWpeak of additional power.
In another first, PUB will also reclaim high-strength industrial used water to produce Industrial Water at Tuas WRP. Currently, Industrial Water is produced using treated domestic used water at Jurong and Ulu Pandan WRPs. Tuas WRP's MBR system will effectively treat high-strength industrial used water for reuse by industries mainly in Jurong Island and Tuas.
Tenders for Tuas WRP
A total of about 11 construction tender packages is expected to be called over the next five years for Tuas WRP, estimated to be valued at over S$2 billion. The first tender was called in May 2018 for development works at the Tuas WRP site such as support infrastructure, utilities and a near-shore outfall for discharge of excess treated used water into the sea.
The second tender is scheduled to be called by Q4 2018 for the construction of the plant's Influent Pumping Stations. This pumping station will be PUB's deepest pumping station yet, consisting of five deep shafts up to 80 metres (or 30-storeys) underground, which receives used water from the deep tunnels and pumps it up to the treatment modules. PUB plans to call the third tender by early next year for the construction of the Industrial Liquids Module for the treatment of industrial used water to produce Industrial Water. Tenders for eight more contract packages for the construction of other components of Tuas WRP will be called progressively from 2019 onwards.
IWMF Features
The IWMF is an integral part of NEA's long term plan to meet Singapore's solid waste management needs. Unlike a typical Waste-to-Energy plant which treats only incinerable waste, the IWMF will be built with treatment processes for multiple waste streams namely incinerable waste, household recyclables, source-segregated food waste and dewatered sludge from PUB's Tuas WRP. Integrating these processes in one facility will better enable the IWMF to maximise both resource and energy recovery from waste while minimising its environmental footprint.
The IWMF will be built in two phases, with an initial incineration capacity of 2,900 tonnes per day for incinerable waste when the Waste-to-Energy incineration facility is completed in 2023. The remaining facilities in the first phase of the IWMF comprising the Materials Recovery Facility, Food Waste Treatment Facility and Sludge Incineration Facility, will be completed by 2024, which would mark the completion of Phase 1 of the IWMF.
The current plan is to eventually increase the incineration capacity at the IWMF to 5,800 tonnes per day in 2027. The heat from the incineration process will be recovered to generate electricity. Part of the electricity generated will be used to operate the IWMF and Tuas WRP whereas most of the electricity generated will be fed to the grid and will be sufficient to power 300,000 four-room HDB apartments.
Tenders for IWMF
A total of three Engineering, Procurement and Construction (EPC) tender packages and one build tender, estimated to be valued at over S$3 billion will be called over the next five years. The pre-qualification of EPC tenderers will be called in July 2018 to shortlist potential EPC tenderers for the development of key facilities within IWMF Phase 1. The second stage tender for EPC tenders will be called by January 2019. Separately, the build tender for the development of a 230kV Electrical Substation for the Tuas Nexus will be called by December 2018.
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