A cleaning agent which causes some concern in Europe has been shown to be safe in New Zealand dairy factories because of the way they process their waste water.

The research into the environmental impact of waste water from dairy processing plants is being done by University of Waikato PhD student Zoe Xie.

Ms Xie investigated the common practise in New Zealand dairy factories of using a chemical called EDTA which is added to cleaning agents. It bonds to the likes of calcium and magnesium and is washed away as part of the cleaning in the likes of cheese and milk powder plants.

The European Union has identified EDTA as an environmental concern, saying the amount ending up in waterways there has the potential to kill water-life.

However, Ms Xie said dairy processing plants in New Zealand treated their own wastewater using various processes including aerated sludge. Those processes all but eliminated the amount of the chemical eventually going into the waterways - the tiny amount released was well under the EU’s acceptable levels. "This is a great environmental practice and it's efficient too," Ms Xie said.

She said it was important the New Zealand dairy industry could demonstrate a global commitment to protecting the environment. "About 95 per cent of our dairy products are exported to consumers in more than 140 countries around the world and there's a lot of environmental pressure on the industry. People are looking for items that have been produced in an environmentally sustainable way."

Ms Xie's research topic is particularly relevant for this month's National Agricultural Fieldays, of which the University of Waikato is a strategic partner.