It is fair to say that Bill Gates knows how to make headlines.

The Microsoft founder was in China yesterday to make a speech on the safe disposal of human waste, and ensured he got maximum exposure by addressing the audience with a jar of human excrement next to him.

The billionaire philanthropist placed the jar on a pedestal next to him to kick off a three-day "Reinvented Toilet" expo in China.

"You might guess what's in this beaker, and you'd be right. Human faeces," Gates said.

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"This small amount of faeces could contain as many as 200 trillion rotavirus cells, 20 billion Shigella bacteria, and 100,000 parasitic worm eggs."I brought it out to draw attention to a serious issue that kills more than 500,000 people every year: poor sanitation."

Mr Gates argued that the global sanitation problem that costs an estimated £170.3bn a year, will "get worse if we don't do something about it"."In places without safe sanitation, there is much more than one [jar's] worth in the environment," he said.

"These and other pathogens cause diseases like diarrhoea, cholera, and typhoid that kill nearly 500,000 children under the age of five every year."

The Bill and Melinda Gates Foundation has invested more than £152 million ($294m) over seven years to create a "pathogen-killing" toilet that can break down human waste and destroy germs.

The new toilets leave behind clean water and solids that can be used as fertiliser, or disposed of safely outdoors without further treatment, Gates claimed.

The toilets operate off grid, without piped-in water, a sewer connection or outside electricity and can work for less than 40 pence per day. Some of the current prototypes are solar powered, or generate their own energy mechanically.

Over 20 companies signed up to the sanitation project, including Clear, Eco-San, SCG Chemicals and Eram Scientific Solutions.

Gates, who tasted water made from faeces and said "he would happily drink it every day", has also invested in a small-scale treatment plant that processes waste from pit latrines, septic tanks and sewers."I watched the piles of faeces go up the conveyer belt and drop into a large bin," Gates described in a blog post.

"They made their way through the machine, getting boiled and treated.

"A few minutes later I took a long taste of the end result: a glass of delicious drinking water."

The plant, called the Omniprocessor, takes in human waste, kills dangerous pathogens, and converts the resulting materials into products with potential commercial value - like clean water, electricity, and fertiliser.

"Population growth, urbanisation, and water scarcity over the next few decades will make it even more difficult for cities in Africa and Asia - cities that are already struggling with inadequate sanitation systems - to break the cycle of disease and poverty associated with unsafe sanitation," Gates said yesterday.

Gates estimated that by 2030, sanitation technology will be a $6 billion (£4.5 billion) a year global business opportunity.

According to figures from the World Health Organisation and Unicef, three in 10 people worldwide, or 2.1 billion, lack access to safe, readily available water at home, and 4.5 billion lack sanitation that is managed safely."We are on the cusp of a sanitation revolution," Gates said. "It's no longer a question of if we can do it. It's a question of how quickly this new category of off-grid solutions will scale. We don't know exactly how long that will take, but we do know it can't happen fast enough."