Edwina Beveridge, from Blantyre Farms, says her biogas system paid for itself in two and a half years. Photo: ABC News, Gregory Heap

Sean Murphy writes for ABC News Australia that pig effluent could be used to grow algae or seaweed that is fed back to pigs as part of a closed-loop system for intensive piggeries. Pig manure can also help reduce use of costly fertilizer in the process.

Researchers at Murdoch University’s Algae Research and Development Centre have proven they can grow some aquatic species on untreated pig waste, despite the high concentration of ammonium.

Centre director Dr. Navid Moheimani said algae grew naturally in harsh conditions and was a potentially protein-rich source of food for pigs and other animals. “The algae normally contains one third carbohydrate or sugar, one third protein and one third lipid,” he said. “A lot of algae do not produce a lot of cellulose, which means they are very easily digestible. The other very important thing for us is to find out what sort of other bacteria like pathogens are coming in with the feed and so we’re also testing that.”

Even if the algae were too contaminated to use as a feedstock, Dr. Moheimani said it would greatly increase the production of methane in on-farm biogas systems.

Biogas systems capture methane from manure, turn it into electricity and export it to the national grid. At Blantyre Farms near Young in New South Wales, Australia, they paid $1 million three years ago for such a system. Edwina Beveridge, who runs the 25,000-pig operation, said her investment paid for itself in two and a half years. “It used to cost us about $15,000 a month for electricity and gas and now we get paid about $5,000 a month for selling excess electricity,” she said.

The farm is one of seven piggeries sharing $7 million a year from the Commonwealth’s Emissions Reduction Fund for its greenhouse gas abatement through methane capture. “So not only did the biogas project make good economical sense, it’s good for the environment as well,” she said. “Who would think a pig farmer could also be a renewable energy supplier?”

Despite producing just 0.4 per cent of Australia’s greenhouse gas emissions, the pork industry has been at the forefront of research into carbon abatement and finding other profitable uses for effluent.

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