Reinvented Toilet Technology in Development

Nanomembrane Toilet | Cranfield University

Dry Combustion Reinvented Toilet

Image of nanomembrane toilet with seat open and closed

Fully self-contained household toilet system. Frontend resembles a Western-style pedestal toilet with a novel waterless swiping flush mechanism, and all waste processing components are housed within the pedestal. In the backend, solids are extracted by a specifically designed screw, then dried and combusted, while liquids are preheated and purified with a hydrophobic membrane.

Key Features:

  • Single household system: up to 10 users/day
  • System design is completely self-contained, no water or power connections are required
  • Unique waterless flush system minimizes water requirements
  • Heat from the combustion process is used to drive water through the membrane
  • System produces clean water each day for household use
  • Ash requires occasional disposal

Status of Development

Status of development: early prototype
  • Optimized subcomponent performance
  • Frontend and backend component prototypes developed in Cranfield, UK
  • Frontend tested in households in Durban, South Africa. Full system to be tested in 2019
Map with markers in the U.K. and South Africa

Use Cases

  • Household: Designed as a self-contained household unit up to 10 users per day
  • Multi-unit: Core processing technology could be scaled for school, or public/community application

Product is Appropriate For:

Pedestal and wipe application icons
10 TBD 10
Capacity (users/day) Est. Cost ($/user/day) Life Expectancy (Years)

How Does it Work?

1. Frontend

User encounters a pedestal toilet with a unique waterless flush system. A rotating odor barrier and scraper mechanism manages odor and enables dry flushing.

2. Urine/Feces Separation

Solids and liquids are separated by gravity sedimentation. Liquids flow over a weir to liquids processing, while the solids are extracted using a screw.

3. Liquid Processing

A hydrophobic membrane separates clean water from the contaminated urine. The clean water is then sent to a storage tank for later use.

4. Solids Processing

Solids are dried, pelletized and combusted resulting in ash. The combustor being developed is a micro-combustor that can be fed at <1 g/min of dried fecal waste.

An inside view of the nanomembrane toilet

5. Power System

The lifting of the toilet seat powers the bowl. Excess heat from the combustor is used as the driving force for water separation. There are opportunities for electrical energy generation under development from thermal and electrical gradients, to offset residual power requirements.

Inputs


Does the system require an external source of electricity?
No. Energy is generated mechanically and potentially through thermal and electrical gradients.

Does the system require the use of water?
No

Does the system require any other "consumable" inputs?
No

Outputs


How much energy will be recovered?
None. Recovered energy is used in process

How much water will be recovered?
>10 liters/day usable

How much fertilizer or other byproducts will be produced?
10g ash/user/day

Treatment


Solids treatment Combustion

Liquids treatment Membranes

Pathogen treatment success? Confirmed total pathogen removal

Are chemical processes used? No

Are mechanical processes being used? Yes

Are biological processes being used? No

Does the system require any off-site or additional processing? No

Business Considerations


Estimated daily operating cost (not available)

Estimated capex (not available)

Size L 1.25m x W 0.75m x H 1.0m

Maintenance Requirements Water/ash to be emptied daily (by user). Ash to be emptied weekly, and membranes to be cleaned four times a year

Life expectancy 10 years

For more information, please visit: http://www.nanomembranetoilet.org