Modelling is the beating heart of modern wastewater treatment, but until now, it’s been locked behind programming skills and costly software. That’s changing with SIMPO, an online platform that lets anyone build, test, and share advanced wastewater treatment models without writing a single line of code.
Developed by researchers at Sun Yat-sen University and published in Water & Ecology, SIMPO (Simplified Intelligent Modelling Platform Online) is a cloud-native, open-source environment designed to make activated sludge and nutrient-removal models accessible for real-world operators and researchers alike.
The platform uses a graphical, drag-and-drop interface to let users visually design complex processes. It’s validated against AQUASIM, the long-standing industry benchmark, achieving nearly identical accuracy with a weighted Nash Sutcliffe efficiency above 0.999.
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How SIMPO lowers barriers for modellers and utilities
Traditional wastewater treatment modelling tools require advanced programming or expensive licences, making them inaccessible to many utilities and students. SIMPO’s goal is to eliminate that threshold.
Users can connect process modules, add tanks or reactors, and run real-time simulations directly in their browser. The software automatically checks for stoichiometric balance errors, visualises outputs and evaluates performance.
Co-lead author Dr Feng Jiang said SIMPO was designed to make professional-grade models available to everyone. “By democratising access to advanced modelling tools, SIMPO empowers a broader community to innovate in wastewater treatment,” he explained in the study.
Beyond accessibility, SIMPO introduces built-in algorithms for sensitivity analysis, uncertainty assessment, and parameter estimation, analytical steps that traditionally require custom scripts or months of manual calibration.
Why this matters for real-world wastewater operations
For engineers, SIMPO provides an opportunity to optimise plant processes without needing bespoke code. Case studies included in the paper show the platform detecting and fixing subtle mathematical errors in published activated-sludge models, such as unbalanced stoichiometric matrices and missing reaction kinetics.
This capability could have major implications for Australian utilities seeking to enhance treatment efficiency or evaluate greenhouse gas emissions from biological processes. The researchers argue that shared, error-checked digital models can help bridge the gap between academic research and plant-level design.
Students also benefit. SIMPO’s pre-loaded library includes classic Activated Sludge Model (ASM) frameworks (ASM1-ASM3) and process configurations such as A2O, AO, and UCT. This allows learners to visualise biological nutrient removal without being overwhelmed by code.
What sets SIMPO apart from other modelling platforms
While commercial software such as BioWin, GPS-X and SUMO dominate professional practice, they often restrict users to fixed model templates. In contrast, SIMPO allows complete transparency and modification through an open ASM-style matrix editor.
The tool’s cloud-collaboration features also mark a shift toward open science. Researchers can publish models privately during peer review, then make them public for replication once their paper is accepted. Each shared model and dataset is version-controlled, ensuring traceability and credit for contributors.
This approach directly addresses long-standing reproducibility issues in environmental engineering, where complex models are often shared only as equations in PDFs rather than as executable code.
The next step: linking modelling and artificial intelligence
The research team envisions SIMPO as a bridge between mechanistic and AI-assisted modelling. Current integrations include the KIMI language model, which helps users summarise and interpret modelling papers. Future updates will add APIs for AI systems such as DeepSeek, enabling hybrid workflows that combine traditional process models with data-driven algorithms.
In effect, SIMPO could become the foundation for intelligent, self-improving wastewater systems, where model calibration and optimisation evolve continuously as new operational data arrive.
Towards a more open modelling culture
As the water sector moves toward digital twins and smart infrastructure, open, accessible tools like SIMPO could democratise innovation. For smaller councils and utilities, simulating biological and chemical processes without proprietary software could accelerate upgrades and improve environmental compliance.
In the words of the authors, SIMPO represents “an efficient, reliable and open solution for wastewater treatment modelling.” Its free-to-use design and collaborative ethos signal a future where modelling knowledge becomes a shared utility rather than a specialist privilege.
Explore the platform at www.simpowater.org.