Recycled eggshells break into profits

Researchers from Glasgow Uni-versity and Queen's University, Belfast, claim to have found a way of extracting a profit from chicken eggshell waste.

The United Kingdom produces 10,500 tonnes of the waste and it costs some firms more than Pounds 1,000 a week to dispose of it. Under pending legislation, that cost is set to quadruple because the shells will have to be dried before disposal in landfill sites.

Instead of spending Pounds 110,000 a year on burial, the egg industry could soon be re-cycling it for the valuable collagen it contains, according to Michael Healy, of the department of chemical engineering at Queen's.

The final product has a number of applications in commerce and medicine. Various types of collagen are used in operations for the replacement of the oesophagus and in anti-ageing creams in cosmetics. The collagen produced by this process is mainly Type-X; Dr Healy speculates that it could be used for coating catheters.

The Ministry of Agriculture, Fisheries and Food is considering a request for a grant to develop these ideas. In a paper presented to this month's Institution of Chemical Engineers research conference, Dr Healy and colleagues stress the necessity from both an environmental and commercial point of view of exploiting the "vast waste source of biomaterial from the food industry". They see it as a wasted resource rather than a problem to be got rid of. However, he said the prospect of eggshell banks appearing on the high street alongside paper and bottle banks was "a long way off".

Dr Healy is also working on extracting high-quality chitin from prawn shell waste. In the past, prawn shells were boiled with sodium hydroxide, creating more chemical waste. He plans to use microbes for removing the minerals from the shell rather than hydrochloric acid. Enzymes will then be used to release the collagen and micro-organisms will be used for the chitin. Chitin is used as a joint replacement material.