A new £5 million plant which has the capacity to process a quarter of Scotland's recycled glass has been officially opened.

The "revolutionary" Dryden Aqua plant in Bonnyrigg, Midlothian, uses recycled glass such as old beer and wine bottles to create a filtration system capable of removing parasites and pollutants from water.

The system can be used to filter drinking water, treat industrial waste water or filter the water in swimming pools.

The Scottish Government, which revealed details of the new plant, said it has the potential to generate "significant savings" for the water industry.

Environment Secretary Richard Lochhead, who opened the site, said: "This is a revolutionary system from Dryden Aqua which exemplifies the technological and environmental expertise that Scotland is famous for.

"It is also a major investment in Scotland's green credentials and places us at the forefront of the move towards a zero waste nation.

"This is a great example of upcycling where we create something of higher value than the original substance.

"This technology can be used in developing countries to ensure cleaner, healthier water for all, showcasing the global reach and importance of Scottish innovation, which is a key element of the hydro nation agenda."

The family firm was established in 1980 by Howard Dryden who, along with his sister Marilyn Wakefield, has developed the business into one of the UK's recognised experts in water treatment.

He began working on the concept when he was at university and studying water filtration using sand. The opening of the new plant represents the growth of a business already well established in the UK and Europe.

Chairman Dr Dryden said of the new site: "It's brilliant to have it up and running. It's been 30 years in the coming, so it's just wonderful to be in this position.

"We've been developing this market for at least 15 years now. One of the main markets is the swimming pool industry and we already have over 100,000 swimming pool systems running throughout Europe.

"We'd maxed out the production capacity of our previous plant. That's why we required to build this new plant."

The old glass is processed to become a product known as AFM (active filter media), a type of glass sand which acts as a molecular sieve for the water.

Dr Dryden added: "AFM was designed as a solution for the aquaculture sector, but after over 10 years of R&D (research and development) AFM is now recognised as a high-performing and sustainable replacement for sand in filtration systems, and means that we can help to deliver safe drinking water and clean up waste and process water here in Scotland and across the globe."

Rhona Allison, director of company growth at Scottish Enterprise, said: "Scottish Enterprise has worked closely with Dryden Aqua for a number of years, most recently facilitating the signing of an agreement with Indian firm SVS Aqua to allow the company to deploy its innovative water cleaning technology across remote parts of India.

"By providing an integrated package of support including R&D assistance and export advice, Scottish Enterprise has helped Dryden Aqua realise its ambitious growth plans.

"This new processing plant is another great example of the company's success, ultimately driving home long-term sustainable growth for the Scottish economy."