One man's whisky is another man's fish food

Two years ago, Douglas Martin's flat was littered with petri dishes, conical flasks and do-it-yourself incubators. He was experimenting with ways to encourage algae to grow on various types of waste. Progress was slow.

For one, it was harder to get hold of the waste than one might think (very few companies are happy to "pull their shorts down" for their waste to be examined, according to Martin). The set-up was also pretty basic.

Still, he managed to use industrial wastewater to...