Green Toilet: Turning Toilet waste into Clean Power

An inexpensive and easy to maintain “green toilet” is set to be trialled in Ghana this year 2016. This remarkable toilet uses no water but can convert human waste into ​cheap ​electricity and ​clean water.​ ​Spurred on by ​the Gates ​Foundation’​s Reinvent ​the Toilet ​challenge, ​a team of ​engineers and ​designers from ​Cranfield ​University in ​the UK created ​what has been ​dubbed the “​Nano Membrane ​Toilet.” ​

The ​university’​s green toilet ​was the winner ​of the award ​for ​Excellence in ​the Field of ​Environmental ​Technology ​Research, by a ​panel chaired ​by HSH Prince ​Albert II of ​Monaco in March ​2015. ​

The toilet is ​for single-​household use, ​and can easily ​accommodate 10 ​family members, ​accepting a ​mixture of ​faeces and urine.​

Remember ​the Archimedes ​screw? Well, ​that concept is ​utilised in the ​”flushing” of ​the toilet as ​the unique ​mechanism moves ​waste into the ​toilet without ​the need for ​water. ​

At least ​40 percent of ​the world’s ​population, 2.5 ​billion people, ​practice open ​defecation or ​lack sanitation ​facilities. ​This is not ​only devastating ​to human health ​but to the ​environment. ​Added to this ​is the over 2.0 ​billion people ​living in urban ​areas of the ​world, many ​using toilets ​connected to ​septic tanks ​that are often ​not safely ​emptied, or ​using other ​systems that ​empty raw ​sewage into the ​environment. ​


How the nano-​membrane green toilet ​works

green toiletAs the ​designers say, ​the magic ​begins when the ​lid is closed.​ Gizmodo ​describes the ​process, ​explaining that ​at the bottom ​of the toilet, ​the rotating ​mechanism ​sweeps waste ​into a ​sedimentation ​chamber. This ​also blocks the ​escape of odours.​

The waste is ​then filtered ​through a ​nanotech ​membrane that ​separates water ​vapour from the ​rest of the ​waste. This ​action prevents ​pathogens and ​pieces of solid ​waste from ​being carried ​further by the ​water. The ​water travels ​through a ​chamber filled ​with “nano-​coated ​hydrophilic ​beads.” The ​beads help the ​water vapour to ​condense, where ​it falls into a ​collection ​chamber as ​clean water. ​

Here is where ​the Archimedes ​screw comes ​into play. The ​screw drives ​the residual ​solid waste and ​pathogens into ​a second ​chamber where ​it is ​incinerated and ​is converted ​into ash and ​energy. The ash ​is clean and ​pathogen-free ​and can be used ​as fertiliser. ​Enough energy ​is produced to ​charge cell ​phones or other ​small ​electrical ​devices. ​

Sociological issues are also addressed

Besides the over two billion people without toilets in the world, there are at least 650 million people without access to clean drinking water. That number could easily grow much higher as water becomes scarce in many regions of the planet. Couple lack of water with the lack of toilets and the health and sanitation issues are magnified.

Solar panels for electricity are actually too expensive when we look at the economic boundaries in many regions today, so something cheap, easy to use and simple to maintain is the answer. Building toilets and the sewage systems needed to take care of waste when there is no water is also not feasible.

It will be interesting to follow the trial run of the Cranston nano-membrane toilet this year. The plan is to rent the toilets through a local organisation, helping to spread the costs in keeping within the Gates Foundation’s challenge of the toilets costing less than five cents per person per day. If things go well, the number of applications for the toilet’s use are endless, such as the military, construction industry, and outdoor events.

Source: Digital Journal


  1. Very interesting. I am very excited with the Technology and I am waiting with curiosities the results of trial. It the trial goes well, the worldwide upscaling can resolve the increase issue of WASH

    1. True Dismas,

      Making this work will help solve a lot of WASH problems.

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