Science Behind the
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visit to a portable toilet, or ‘portaloo’, is an unpleasant experience for any festival-goer, but unavoidable when nature calls. Judging by the distinctive TARDIS-like look of the blue plastic box overflowing with acrid chemicals, you’d be forgiven for thinking the portable toilet is a modern invention.
While the idea of a self-contained, transportable toilet was born in the 1940s for shipyard workers, we have actually been using chemical toilets for hundreds of years. Old-fashioned outhouses are one of our oldest examples, and consisted of a simple wooden box over a hole in the ground. Users would pour lye or lime down the hole after finishing their ‘business’ to help purge the smell. Lye (otherwise known as sodium hydroxide) and lime (or calcium oxide) are both strong alkalis that react with urea – the main chemical in urine – to produce ammonia through a process known as alkaline hydrolysis. Ammonia not only has a very strong smell which overpowers the odour of human waste, it also kills bacteria and is hence commonly found in household cleaning products. A word of caution though: lye and lime mix very well with water to form basic, corrosive solutions, that are damaging to the skin. For the wellbeing of the next visitor, users had to be careful not to spill any on the seat! Speaking of cleaning products, it is also important not to clean wooden outhouses with bleach. One of the ingredients in bleach is sodium hypochlorite, which reacts with ammonia to produce a cocktail of hydrogen chloride, chlorine gas, and the toxic chemical chloramine. If ammonia is present in a higher concentration than bleach, there is a chance that liquid hydrazine may be formed – this is used in rocket fuel and, as you can probably imagine, would bring new meaning to the phrase ‘explosive diarrhea’!
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