Seven hundred million pigs produce a lot of poo. China's love of pork presents a mountain of a problem for the environment, 1.4 million metric tons (1.5 million tons) of pig poo a year to be precise, but an Australian company believes it has part of the answer.
Why not turn the pig poo into power?
Using a bioreactor called "PooCareTM" and other technology, the pig manure is converted into biofuel for cooking and heating while the residual goes to farmers as nutrient-rich fertilisers.
"The benefits are energy and fuel for farmers as well as preventing further contamination of the environment," said Ravi Naidu, chief scientist at CRC for Contamination Assessment and Remediation of the Environment (CRC Care), a South Australian-based firm involved in drawing up the technology.
"So it's really a green technology from that perspective," Naidu, a University of South Australia professor, said.
The process involves a bioreactor 30m (98 ft) long, 10m (33 ft) high and 4m (13 ft) wide. It is set below ground and waste is fed through it slowly at a pre-determined temperature.
This converts solid waste into a biogas that is then pumped through gas tanks that can be delivered to the local community. The entire process takes about a month, with the first biogenerator already running at a farm in Wuhan, central China.
One in ten pig poos is used as manure
China has an estimated 700 million pigs, producing some two-thirds of the meat consumed there annually, so the scale of the problem can't be underestimated.
Only one tenth of pig waste is used now as manure. It is estimated the nutrients lost in the waste of one pig alone are worth about A$50 ($52) per year. There is a vast disparity in rural and urban incomes with farmers earning around $75 per month.
The potential health hazards are worse.
"Pig waste contains a high level of nitrate, which in liquid form can contaminate ground water and in flake form can contaminate lakes, posing human health risks," Naidu said.
Chinese scientists and Hong Kong-based technology firm HLM Asia Ltd also took part in developing the technology, which costs roughly A$35,000 ($36,400) for one bioreactor. Mass production would bring costs down, Naidu said.
(Reuters Health, Pauline Askin, May 2012)