Solar Septic Tank


  • Parnter Name
    Asian Institute of Technology
  • Partner Type
    Technology Partner
  • Contact Info
    Thammarat Koottatep ( Associate Professor
  • Website
  • Descriptive Overview
    Solar Septic Tank is a highly efficient, self-contained, and simple technique. This technology uses free energy from the sun to increase temperature inside the system for the treatment of human feces and urine. Solar septic tank could promote natural bio-augmentation to improve the degradation rates in the system and could effectively inactivate harmful pathogens.
  • Use Case Details
    Field testing has occurred with a communal toilet at 30-40 users per day, and household installations for 3-4 users per day.
  • Dimensions (meters)
    L 1.5m x W 2.7m x H 2m
  • Regularly Scheduled Required Maintenance
    Emptying of solids every 4-5 years
  • Use Cases
    • Single-stall Toilet
    • Multi-stall Toilet
    • Building-level Processing
  • Frontend Description
    Technology serves as a septic system, so it can be used with single- or multi-stall toilets with any user interface of flush configuration. Separation of urine and feces is not necessary; combined solid and liquid waste stream is sent to the reaction tank.
  • Users per Day (Expected)
    Two versions have been field tested: 30-40 users per day and 3-4 users per day.
  • Users per Day (Maximum)
  • Type of Waste Treated
    Combined Stream (solids and liquids)
  • Core Processing Technology
  • Processing Overview
    The reaction tank uses solar energy to power an advanced biochemical process aimed to speed up the metabolic rate of the microbes and promote natural bio-augmentation for removing of organ
  • Processing Capacity
    1,000 L reaction chamber in the current version
  • Processing Parameters
    Application of heat (at sub-lethal temperature about 50-60oC and atmospheric pressure), with the optimal contact time, inactivates pathogens in the liquid. Typical heating time is 6 to 24 hours.
  • Power Systems Overview
    More than 10 kW/d of thermal energy required. Solar collector will produce about 10-15 kWh in a day for raising temperature in a 1000-L solar septic tank.
  • Energy Balance
    Consumes solar thermal energy. No electricity required.
  • Currently in Active Development
  • Commercialization Status
    Seeking Licensees
  • Commercialization Activities
    Seeking commercialization partners to license and bring technology to market. AIT is leading commercialization efforts, including outreach to commercial partners.
  • Intellectual Property Status
    Patent Pending
  • Intellectual Property Details
    Thailand intellectual property and being applied for PCT: 59587 (granted on 22 December 2017). Five patent applications underway in Thailand: 1801003789; 1401003996; 1502004290; 1702000710; 1502004291.
  • Frequency of Emptying Outputs
    Every 4-5 years
  • Solid Emission Characteristics
    Treatment efficiencies of organic/solids removal and E. coli inactivation are found to be 70-90% and 4-5 log reduction, respectively.
  • Liquid Emission Characteristics
    Coupled with novel constructed wetlands, it could achieve effluent COD and TKN concentrations below 50 and 15 mg/L, respectively.
  • Technology Development Milestones
  • Proof of Principle
    TRL: 2 (2014)
    Tested the hypothesis of septic tank operating at high temperatures (laboratory-scale septic tank)
  • First Prototype - Proof of Concept
    TRL: 4 (2015)
    Tested solar energy to increase temperature inside the system. Initial test plans are developed. (first prototype testing)
  • Second Prototype - Verification and Testing
    TRL: 6 (2016)
    Verified performance requirements in the long term under actual conditions and to ensure the technology achieve all of the specified functions. (second prototype testing)
  • Linked Complete Systems
  • None linked