Self-sustaining Smoldering Solids Treatment


  • Parnter Name
    University of Toronto
  • Partner Type
    Technology Partner
  • Contact Info
    University of Toronto Centre for Global Engineering Dr. Yu-Ling Cheng (
  • Descriptive Overview
    Dewatered fecal material (fuel) is transferred via piston and peristaltic pump onto the top of a column of granular particles in a reactor. The heat from the reaction zone lower down in the column dries the fuel as is moved down the column to the combustion zone by removal of not material from the base of the column. Reaching the combustion zone fuel is smoldered (low oxygen combustion).
  • Use Case Details
    SURT – household and community 1. Initially household toilet design: 10 users per day. 2. Could be scaled-up for family application at 15-20 users per day, with potential for community(multi-stall) application with one system per stall.
  • Use Cases
    • Single-stall Toilet
    • Multi-stall Toilet
  • Frontend Description
    Multiple gravity-based solid/liquid separation designs have been evaluated and field tested. Effective solid/liquid separation is achieved without modifying user behavior.
  • Users per Day (Expected)
    Currently designed for 5 to 20 users, accommodates variable input rates.
  • Users per Day (Maximum)
  • Type of Waste Treated
    Solids Processing
  • Core Processing Technology
    Dry Combustion
  • Processing Overview
    Solid fecal material (fuel) is transferred via a pump to a column and mixed with granular beads which are still hot from the preceding smoldering cycle. Once the mixing/drying process concludes, air is introduced and smoldering beings.
  • Processing Capacity
    Ranges from 0.6 to 3kg/day
  • Processing Parameters
    Unique peristaltic pump is used to transfer solids through the system. Processing takes 6-8 hours at approximately 600oC and 1 bar.
  • Gas Processing
    Post smoldering gases undergo catalytic conversion for emissions reduction and additional heat generation.
  • Power Systems Overview
    External power source is required.
  • Energy Balance
    Solar panels or other off-grid energy sources may be used to supply the <200 watts per day required. The aspirational goal that projections show is possible is to achieve a power requirement low enough to fit within the capacity of solar or other off-grid home systems that are common in many regions.
  • Currently in Active Development
  • Commercialization Status
    Seeking Licensees
  • Commercialization Activities
    System integration work has led to iterative development of functional prototypes for laboratory testing in Toronto, and multiple field tests in Coimbatore, India with local workers user group. Commercialization partners to license technology for further product development, manufacturing, and launch. Also seeking partners to integrate liquid treatment and develop products.
  • Intellectual Property Status
    Patent Pending
  • Intellectual Property Details
    PCT patent filed.
  • Frequency of Emptying Outputs
    Solids (ash) to be emptied monthly by user
  • Solid Emission Characteristics
    Estimated 10 g ash per person per day generated.
  • Technology Development Milestones
  • Proof of Concept
    TRL: 3 (2015)
    A TRL 3 smoldering process was discussed by the team in the publication Fuel in 2015.
  • Lab Prototype
    TRL: 5 (2016)
    Functional lab prototype was reached in 2016
  • Field Tests
    TRL: 6 (2017)
    Field tests in Coimbatore, India with local workers user group began in 2017 and is on-going, with technology iterations underway.
Patent Number Description Link
WO2018010033 Treatment of fecal matter by smoldering and catalysis Link