LEADING THE WAY: McCain Foods regional environmental manager David Sidebottom on a covered lagoon. Picture: Zhenshi van der Klooster
"IT'S like a giant underground stomach," says David Sidebottom.Before the McCain Foods environment manager is a vast polyethylene sheet covering a lagoon that holds 28 million litres of starchy waste water from the Wendouree potato-processing plant.In the oxygen-deprived lagoon, the waste breaks down anaerobically to produce mostly methane, a potent greenhouse gas.The flammable gas is trapped under the cover then piped away where it is blended with natural gas and used to fire boilers which provide steam for the factory. When the "food" in the waste water is finally broken down by anaerobic bacteria, the water is pumped to the nearby North Ballarat water treatment plant.McCain has two biogas bladders, one has been operating since 1986, which produce about 170,000 megajoules of energy a day.The company was a pioneer in biogas technology and production is now approaching about 10 per cent of the factory's gas energy needs.More than 80 per cent of the biogas is used to produce steam and it is expected that this will improve to about 95 per cent over the next year.Operations director Graham Harvey said more biogas would be created with the conversion of about 30 per cent of the 3000 tonnes of food waste now going directly to landfill.He said engineers were also looking at using some solid potato waste now sold for stock feed to produce biogas.In 1996, McCain invested more than $3 million to build the second covered lagoon.Last year, a further $200,000 was spent on increasing the efficiency of the biogas plant.
