Author(s): Yale Yah Loo Wong; Fang Yenn Teo
Linked Author(s): Fang Yenn Teo
Keywords: CDS Continuous Deflective Separation Stormwater Treatment Biochar Green Infrastructure Hybrid Systems Artificial Intelligence Sustainable Development
Abstract: Book of Extended Abstracts 41st IAHR World Congress 22-27 June 2025 Singapore HYBRID CDS TECHNOLOGY WITH AI AND GREEN INFRASTRUCTURE FOR SUSTAINABLE URBAN STORMWATER MANAGEMENT Yale Loo Wong1*, Fang Yenn Teo1 1 Faculty of Science and Engineering, University of Nottingham Malaysia email: evxyw17@nottingham. edu. my ABSTRACT For the audiences’ information, Continuous Deflective Separation (CDS) Technology was brought into Malaysia, Singapore, China, and Brunei by a Malaysian/New Zealand JV company in 1999. It was meant to revolutionize Malaysia’s approach to stormwater management. Central to this transformation was adopting CDS technology, a game-changing innovation for removing urban pollutants such as debris, sediments, hydrocarbons, and suspended solids (Jago, 2000). CDS technology exploits particle transport in non-rectilinear flow, enabling the separation of particles by a combined Separation based on size and density separation mechanism with high removal efficiencies (Heist et al., 2004; Jago & Davey, 2002). Compact in design, CDS Stormwater Treatment Devices (STDs or Gross Pollutant Traps (GPTs, as some countries call them) occupy small footprints and prevent clogging with high-flow designs (Shah et al., 2016; Sidek et al., 2016; Zahari et al., 2016). The nozzle-enhanced influent flow is directed at an angle tangential to the 3D perforated stainless steel screen to provide self-cleaning and non-blocking effects. These features align with green infrastructure goals, making CDS a significant advancement in primary and secondary decentralized treatment. The performance of CDS is shown in Table 1. Table 2 summarises the performance substantiation references. Table 1. Performance of CDS Description: CDS Target Capture Gross Pollutants (>5mm) 99% Coarse Sediments (>0.125mm) * 95% Floatable Pollutant 99% Total Solid Suspension (TSS) 85% ** Free oils and grease in spill situation 95% Total Phosphate >20% * By using finer screen, we can achieve more than 0.075mm ** TSS (Particle size is based on 106um PUB SG norm) Table 2. Performance substantiation references NSW EPA Monash University Stormwater Gross Pollutant Treatment Technology Assessment CDS 7 out of top 10 performing devices Urban Stormwater Management Manual Willing and Partners Relative Effectiveness of Gross Pollutants Traps CDS Most effective over the widest range of pollutants Urban Stormwater Best Practice Environmental Management Guidelines EPA, Melbourne Water, Dept of Natural Resources Treatment method vs effectives table Self cleaning circular screens most effective over widest range of pollutants Sediment Capture Table Thiess Environmental Service Particle size capture 100-200 micron up to 79% 200-500 micron up to 99% Brisbane City Council SQID Monitoring Soil Classification of sediment trapped within CDS unit 50% material silt and clay CRCCH Effective Trapping Strategies for Gross Pollutants Summary Table CDS 98% effective for total pollution load UCLA Control Of Oil and Grease in Stormwater Runoff Extract 50-80% of oil and grease attached to sediment CRCCH Removal of Suspended Solids and Associated Pollutants by CDS Conclusion TSS mean efficiency removal 70% TP 30% (due to P being in particulate form) UNSW Stormwater Quality from Road Surfaces CDS Effectiveness 80% of metal contaminants from stormwater through settlement of fine particulates transporting the contaminants PUB Singapore *PUB website Pilot project of CDS P2028 at Pulau Saigon Pumping station drain before Singapore River Removing efficiency of all flotsam, silt and debris control More than 95 % However, its moderate efficiency in removing finer sediment particles necessitates integration with polishing technologies to meet reuse standards (Fig. 1). Fig. 1. CDS flow diagram This study explores the potential of biochar-enhanced filtration as a polishing media to address the limitations of CDS systems. With its high surface area and adsorption capacity, biochar offers a sustainable and cost-effective solution for removing finer particles and emerging pollutants such as microplastics and pharmaceutical residues (Duwiejuah et al., 2020; Castiglioni et al., 2021; Chen et al., 2022; Xiong et al., 2022). A systematic literature review and experimental findings highlight the effectiveness of hybrid CDS systems incorporating biochar and other media, bio-flocculation, and bio-coagulation under varying flow regimes. These hybrid solutions demonstrate improved pollutant removal efficiencies and align with Low-Impact Development (LID) principles and circular economy frameworks (Sage et al., 2015; Liu et al., 2021). The design and construction of a sullage treatment plant at Tiong Nam under the Kuala Lumpur River of Life Phase 2 project demonstrates this approach. This facility successfully treated water quality from Class 4 and 5 to Class 2A, showcasing the effectiveness of hybrid CDS systems in achieving high water quality standards. The treated water, suitable for industrial-grade reuse with minimal additional treatment, highlights the potential of these systems to support sustainable urban water management. This case study was also presented as a poster at the Singapore International Water Week (SIWW) 2024 earlier this year, underscoring the scalability and adaptability of hybrid CDS systems in addressing urban water challenges. Further validation of CDS technology comes from Singapore, where the Public Utilities Board (PUB) conducted extensive studies during its earlier implementation and featured the technology on its official website. The National Parks Board (NParks) of Singapore had approved using CDS technology for their latest Rifle Range Nature Park Development during the Covid-19 locked period. Remote guidance facilitated the design and installation of a CDS unit. The CDS unit is FRP type and was manufactured and fully assembled in Malaysia. This milestone highlights the growing recognition of CDS technology as a sustainable, effective solution with flexible design, installation, and cleanout maintenance choices for urban stormwater management. The author, under the supervision of Professor Fang Yenn Teo, is conducting a scaled-down experiment for the proof of concept. Hopefully, by the time the event is held, this paper will have the results and findings. The findings will emphasize integrating artificial intelligence (AI) into stormwater management using this hybrid AI-assisted CDS system to enhance operational control, enabling real-time adjustments to treat the varying pollutant loads and flow conditions. This innovation supports regulatory compliance and resilience against new classes of pollutants, further advancing the sustainability of urban water management systems. In conclusion, by combining CDS technology with biochar-enhanced filtration, hybrid treatment systems, and AI-driven operational strategies, the stakeholders can continue to address the challenges of urbanization while contributing to the Sustainable Development Goals (SDGs). These innovations, demonstrated through real-world success and recognized by global platforms like SIWW 2024 and Singapore's PUB and NParks, underscore the importance of collaborative efforts in preserving a cleaner planet for future generations. Keywords: CDS, Continuous Deflective Separation, Stormwater Treatment, Biochar, Green Infrastructure, Hybrid Systems, Artificial Intelligence, Sustainable Development. References Castiglioni, M., Rivoira, L., Ingrando, I., Del Bubba, M., & Bruzzoniti, M. C. (2021). 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Year: 2025