Case Study

synlait milk pokeno nz

A turnkey solution for dairy factory wastewater systems

Dairy Wastewater
Capacity: 100m³/hr
Location: Waikato, NZ
Tanks: Five
Total storage: 8,160m³

Rendertech has worked with Synlait Milk since 2008, providing Dissolved Air Flotation (DAF) solutions at their two major plants. The first two systems, installed in 2008 and 2014, can each treat 150 m³/hr of wastewater. The third system, installed at their Pokeno milk processing plant in 2019, is designed to process 100 m³/hr of wastewater.

Our solution involved the whole plant: the DAF, wastewater storage tanks, flow metering and discharge to the municipal wastewater system, acid and caustic dosing systems, electrical, automation and control. We also undertook the civil design and obtained building consent. 


The plant needs to meet strict wastewater discharge criteria under its resource consent. The equipment had to be robust and run unattended, allowing the plant to be operated remotely from both on- and off-site. The timeframe for installation was also very tight as the system was required to be in operation for the 2019 dairy season.


This was a fully turnkey project which included design, fabrication, installation and commissioning. With 30 years’ experience with New Zealand dairy companies, we based our design on the large amount of in-house data and best practices built up over that time. As Synlait already operated two Rendertech DAF plants, they could be confident the project would meet all guaranteed parameters.

Particular challenges
Rendertech DAFs are fine tuned to incorporate specific design features for the treatment of dairy factory wastewater. For these applications, pH control is very important and can be difficult to maintain, so the Rendertech DAF includes methods for accurate control.

The DAF provides a large surface area to maximise sludge dryness and bottom scrapers which remove settleable solids. There are no internal plates that require cleaning, minimising downtime.

The completed solution is a robust plant that requires minimum operator and maintenance input, and performs consistently every day.

Storage tanks
As part of the project, Rendertech supplied and installed 5 tanks for both potable and wastewater storage. We specified bolted-steel RTP (rolled, tapered panel) liquid storage tanks from US-based Tank Connection. The potable water tanks have aluminium geodesic domes.

Due to unfavourable ground conditions beneath the potable water tanks, Rendertech undertook detailed geodesic investigation and extensive ground improvements.

Equipment used
DAF plant, RTP storage tanks, Geodesic domes.