In recent years, Fonterra has expanded a number of their dairy manufacturing sites to increase the overall milk processing capacity of its New Zealand operations. A new dryer was installed at Fonterra’s Pahiatua site in 2015 and a new milk powder dryer is being built at the Co-operative’s Lichfield site. In order to accommodate the increased wastewater flows from the sites, new wastewater treatment plants (WWTPs) were required as part of the overall expansions.
Dairy factory wastewater has a number of characteristics that require careful management, including influent pH swings of 2-13, high fat loads and variable incoming organic and nutrient loads. Variations occur both on a seasonal and daily basis.
A number of innovations and features were incorporated into the Pahiatua and Lichfield treatment plant designs to overcome these challenges including:
Elements of this approach to wastewater treatment in the dairy industry could be adopted in a wider setting. For example in municipal plants treating an industrial wastewater component or municipal oxidation ponds that require upgrading to meet more stringent consent conditions.