Systems & Publications¶
QSDsan is built upon the quantitative sustainable design (QSD) methodology, which provides a structured approach to prioritize the research, development, and deployment of early-stage technologies. Leveraging the QSD methodology, QSDsan powers a growing library of systems for wastewater treatment, sanitation, and resource recovery technologies. This page introduces the foundation metholodologies and includes a non-exhaustive list of the published systems with links to their source code in EXPOsan and their publications.
Platform and methodology¶
Research, development, and deployment (RD&D) of innovative technologies are often impeded by the lack of transparent, systematic, and agile approaches to prioritize investment across the expansive landscape of technologies and design/operational decisions. This tutorial review synthesizes research on sustainability analyses to present Quantitative Sustainable Design (QSD) – a structured methodology to expedite the RD&D of water, sanitation, and resource recovery technologies.
Li, Y.; Trimmer, J. T.; Hand, S.; Zhang, X.; Chambers, K. G.; Lohman, H. A. C.; Shi, R.; Byrne, D. M.; Cook, S. M.; Guest, J. S. Quantitative Sustainable Design (QSD): A Methodology for the Prioritization of Research, Development, and Deployment of Technologies. Environ. Sci.: Water Res. Technol. 2022, 8 (11), 2439–2465.
An open-source Python tool that integrates system design, simulation, and sustainability characterization (techno-economic analysis and life cycle assessment) to quickly identify critical barriers, prioritize research opportunities, and navigate multi-dimensional sustainability tradeoffs for technology RD&D.
Li, Y.; Zhang, X.; Morgan, V. L.; Lohman, H. A. C.; Rowles, L. S.; Mittal, S.; Kogler, A.; Cusick, R. D.; Tarpeh, W. A.; Guest, J. S. QSDsan: An Integrated Platform for Quantitative Sustainable Design of Sanitation and Resource Recovery Systems. Environ. Sci.: Water Res. Technol. 2022, 8 (10), 2289–2303.
A multi-criteria decision analysis package that integrates with QSDsan to
compare alternatives across technical, resource-recovery, economic, environmental,
and social criteria.
Lohman, H. A. C.; Morgan, V. L.; Li, Y.; Zhang, X.; Rowles, L. S.; Cook, S. M.; Guest, J. S. DMsan: A Multi-Criteria Decision Analysis Framework and Package to Characterize Contextualized Sustainability of Sanitation and Resource Recovery Technologies. ACS Environ. Au 2023, 3 (3), 179–192.
Water Resource Recovery Facilities¶
Benchmark Simulation Models¶
The Modelling and Integrated Assessment (MIA) Specialist Group of the International Water Association has established benchmark simulation models (BSMs) to provide a consistent environment for wastewater treatment plant (WWTP)/water resource recovery facility (WRRF) evaluation (see BSM webpage and MATLAB implementation and report).
When publishing the paper that introduces QSDsan, we validated the process modeling and dynamic simulation capacities of QSDsan through BSM1. BSM2 is also implemented in EXPOsan.
Validated Python implementation of the BSM1 system by the International Water Association (IWA).
Validated Python implementation of the IWA BSM2 system.
WERF Treatment Trains¶
In Zhang et al., 2026, we developed 18 benchmark combinations of liquid and solid treatment trains, which cover over 70% of the total treatment capacity of publicly owned treatment works (POTWs) in the Contiguous United States. These configurations were based on the Water Environment Research Foundation (WERF, now a part of the Water Research Foundation, WRF), report on net-zero energy solutions for WRRFs.
These simulation models have been implemented in EXPOsan. More details can be found in the interactive page.
Zhang, X.; Rai, S.; Wang, Z.; Li, Y.; Guest, J. S. An Agile Benchmarking Framework for Wastewater Resource Recovery Technologies. npj Clean Water 2025, 9 (1), 4.
Other WRRFs¶
Validated Python implementation of IWA ADM1.
Validated Python implementation of IWA ASM.
Python implementation of the CAS system as described in Shoener et al.
Zhang, X.; Arnold, W. A.; Wright, N.; Novak, P. J.; Guest, J. S. Prioritization of Early-Stage Research and Development of a Hydrogel-Encapsulated Anaerobic Technology for Distributed Treatment of High Strength Organic Wastewater. Environ. Sci. Technol. 2024, 58 (44), 19651–19665.
Kim, G.-Y.; Molitor, H. R.; Zhang, X.; Li, Y.; Shoener, B. D.; Schramm, S. M.; Morgenroth, E.; Snowling, S. D.; Hartnett, E.; Bradley, I. M.; Pinto, A. J.; Guest, J. S. Development of an Open-Source Process Simulator for Microalgae-Based Tertiary Phosphorus Recovery. npj Clean Water 2025, 9 (1), 13.
Non-sewered sanitation systems (NSSSs)¶
Lohman, H. A. C.; Li, Y.; Zhang, X.; Morgan, V. L.; Watabe, S.; Rowles, L. S.; Cusick, R. D.; Guest, J. S. Defining Economic and Environmental Typologies across 77 Countries to Prioritize Opportunities for Nonsewered Sanitation. Environ. Sci. Technol. 2025, 59 (29), 15101–15114.
Rowles, L. S.; Morgan, V. L.; Li, Y.; Zhang, X.; Watabe, S.; Stephen, T.; Lohman, H. A. C.; DeSouza, D.; Hallowell, J.; Cusick, R. D.; Guest, J. S. Financial Viability and Environmental Sustainability of Fecal Sludge Treatment with Pyrolysis Omni Processors. ACS Environ. Au 2022, 2 (5), 455–466.
Trimmer, J. T.; Lohman, H. A. C.; Byrne, D. M.; Houser, S. A.; Jjuuko, F.; Katende, D.; Banadda, N.; Zerai, A.; Miller, D. C.; Guest, J. S. Navigating Multidimensional Social–Ecological System Trade-Offs across Sanitation Alternatives in an Urban Informal Settlement. Environ. Sci. Technol. 2020, 54 (19), 12641–12653.
Based on the Eco-San system developed by Yixing Eco-sanitary Manufacture Co., Ltd.
Watabe, S.; Lohman, H. A. C.; Li, Y.; Morgan, V. L.; Rowles, L. S.; Stephen, T.; Shyu, H.-Y.; Bair, R. A.; Castro, C. J.; Cusick, R. D.; Yeh, D. H.; Guest, J. S. Advancing the Economic and Environmental Sustainability of the NEWgenerator Nonsewered Sanitation System. ACS Environ. Au 2023, 3 (4), 209–222.
Note: the NEWgenerator system is under non-disclosure agreement (NDA), thus unit design is not publicly available, but the system design is implemented in EXPOsan.
Wang, Z.; Feng, J.; Shi, B.; Mendoza, J. A.; Zhang, X.; Trousdale, N.; Cusick, R. D.; Yee, S.; Guest, J. S. The Potential of Thermomechanical and Thermochemical Processes to Enable Sustainable Household Sanitation. Environ. Sci. Technol. 2026, 60 (8), 6227–6238.
Based on the work described in Trotochaud et al. for the Reclaimer 2.0 system designed by researchers at Duke University.
Other Systems¶
Ahmad, A.; Kawale, H. D.; Summers, S.; Bogarin Cantero, B. C.; Allen, C. M.; Hajj, R. M.; Davidson, P. C.; Zhang, Y.; Li, Y. Financial Viability and Carbon Intensity of Hydrothermal Waste Valorization Systems for Bio-Based Asphalt Binder. Chemical Engineering Journal 2026, 528, 172283.
Müller, I. E.; Lin, A. Y. W.; Otani, Y.; Zhang, X.; Wu, Z.-Y.; Kisailus, D.; Mouncey, N. J.; Guest, J. S.; Rad, B.; Ercius, P.; Yoshikuni, Y. Cost-Effective Urine Recycling Enabled by a Synthetic Osteoyeast Platform for Production of Hydroxyapatite. Nat Commun 2025, 16 (1), 4216.
Feng, J.; Strathmann, T. J.; Guest, J. S. Hydrothermal-Based Wastewater Solids Management for Targeted Resource Recovery and Decarbonization in the Contiguous U.S. Environ. Sci. Technol. 2025.
Elijah, B. C.; Ahmad, A.; Li, Y.; Plazas-Tuttle, J.; Rowles, L. S. Assessing the Relative Sustainability of Point-of-Use Water Disinfection Technologies for Off-Grid Communities. ACS Environ. Au 2024, 4 (5), 248–259.
Si, B.; Wang, Z.; Watson, J.; Summers, S.; Li, Y.; Yu, S.; Yang, H.; Yang, Z.; Heyne, J. S.; Jiang, J.; Ren, Z. J.; Ma, H.; Wang, C.; Wang, P.; Zhang, Y. A Circular Hydrothermal Refinery for Sustainable Aviation Fuel from Food Waste. Nat Sustain 2026, 1–11.
Additional Publications¶
Papers published by external users.