Flushing With No Water
By Derek Lam 14 June, 2017
2.4bn people lack clean sanitation but flushing toilets may not be the answer; Derek Lam expands on an alternative
Clean water and sanitation is a human right. When people, in particular children, have access to clean water, sanitation and hygiene, they lead healthier and more successful lives. Water, sanitation and hygiene are interdependent and these three core issues are grouped together to represent a growing sector.
However, according to UNICEF, there are about 2.4 billion people worldwide without access to proper sanitation and about 946 million people who have to resort to open defecation. Ending open defecation is of utmost importance as contact with human waste can cause diseases such as cholera, typhoid, hepatitis and diarrhoea. Providing clean and safe toilets and changing the behaviour of entire communities towards sanitation are therefore key.
Flushing & dry toilet systems
When we talk about providing toilet facilities, the first thing that often comes to mind is flushing toilets. Common in cities and communities with sewage systems and water treatment plants, flushing toilets consume 1.5 to 2 litres of water per use and are not without its flaws.
A flushing toilet consumes 1.5 to 2 litres of water per use…
For example, during the SARS incident in 2003 in Hong Kong, a malfunction and blockage of the drainage system in Amoy Garden caused such poor ventilation that the aerosol disease back-flowed to the flushing toilets in the building. Therefore, flushing toilets are not necessarily safe if not taken care of properly.
…in countries where water supply is scarce, dry sanitation is an alternative
In countries where water supply is scarce, dry sanitation which can treat human waste without the use of water is an alternative to flushing toilets. There are many traditional dry sanitation facilities such as composting toilets, biological toilets and chemical toilets being used worldwide. However, most of these toilets use anaerobic digestive systems where human waste is kept and stored in an enclosed container for a period before disposal. The risk of flammable and explosive gas emissions and bad smells are the biggest challenges for such dry sanitation techniques.
DEHTLET (Dehydration Toilet): a waterless, chemical-free system
So how can dry sanitation be improved? After the SARS incident, we started to investigate an alternative to current dry sanitation methods and to develop a simple new way to treat human waste safely and without smell.
DEHTLET (Dehydration Toilet) is an aerobic, non-pipe & non-mechanical human waste digestive system that does not use water or chemicals
After several years of research and development, the DEHTLET system was created and was granted a patent in the UK in May 2009. DEHTLET is short for ‘Dehydration Toilet’ and it is an aerobic, non-pipe and non-mechanical human waste digestive system that does not make use of water and chemicals. The system makes use of gravity to filter solid waste from urine. Ventilation also dehydrates the solid waste and oxidizes the urine and most importantly drives odour away. The highlight of the whole system is a wavy separation board, which speeds up the dehydration process by natural wind.
Without any flammable and explosive gas emissions from aerobic digestion, the system is therefore safe and free of smells unlike current models. Eventually, dry organic matters may be collected for agricultural use or disposal if necessary; while urine may be collected as an energy source to produce electricity. Moreover, DEHTLET also has a significantly low carbon footprint as it minimises the unavoidable transportation needed in traditional flushing toilets for service and maintenance.
|Advantages of DEHTLET
Wide range of application locations
The DEHTLET system can typically be used for seasonal homes and remote areas where flush toilets are inconvenient or unavailable. Moreover, it can be useful in drought-prone areas, conservation areas and areas with high water tables.
The pilot installation of the DEHTLET toilet system was launched in Sutton Community Farm in the UK in 2010. This installation complied with local authority requirements as no sewage was generated. In addition, as the UK is a windy country, the installed unit does not use electricity and the system is still in perfect conditions 7 years on.
The pilot installation of the DEHTLET toilet system was launched in Sutton Community Farm in the UK in 2010…
…the installed unit is still in perfect conditions 7 years on
DEHTLET was also involved in the post-disaster reconstruction of Pengzhou City after the Sichuan Earthquake in 2011. Two portable units were installed to allow easy access to sanitation facilities in more rural areas and a permanent unit was built to serve the village after the disaster.
DEHTLET was also involved in the post-disaster reconstruction of Pengzhou City after the Sichuan Earthquake in 2011
Later, DEHTLET was put to use in Hong Kong. The first 2 units were installed at the TungWah Group of Hospitals Ma Tso Lung Composite in 2013 and in November 2014, 4 more units were set up. A DEHTLET unit was also installed as part of a community project led by the University Of Hong Kong in 2015 in Kam Tin.
DEHTLET provides a safe, affordable & hygienic method to treat human waste without polluting the environment
In sum, by making use of natural means, DEHTLET provides a safe, affordable and hygienic method to treat human waste in any location without polluting the environment. With the DEHTLET patent now covering 29 countries (including 19 African countries), this invention can help alleviate sanitation and water pollution challenges around the world.
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