Wastewater treatment system and water storage tanks

Rendertech worked with several partners to supply and install a wastewater treatment system at an infant milk formula plant just south of Auckland. The new, automated operation ensures the factory complies fully with its consented discharge criteria.

THE PROBLEM

The plant at Pokeno represents a $200m investment by Yashili (NZ) Dairy Company, a major producer of infant milk formula for China, which can output over 50,000 tonnes of product annually. Building on a greenfield site, however, Yashili faced tight effluent conditions. So they commissioned Rendertech to provide an onsite wastewater treatment and storage system that would provide treatment before discharging into the municipal sewer.

OUR SOLUTION

Drawing on our extensive experience working with dairy plants, we implemented a low-risk system that we have installed successfully for many such clients around New Zealand. This involves the use of DAF (Dissolved Air Flotation) wastewater treatment plants and RTP (rolled, tapered panel) storage tanks. The DAF system utilises micro-bubbles that are formed when an air-water solution is depressurised to rise impurities to the surface, where they are scraped off and pumped away. Rendertech’s proprietary pH correction system is designed for dairy wastewater. The storage tanks provide a buffer, ensuring an environmentally clean operation.

Collaborative input
We erected three RTP tanks fitted with roofs and mixers for wastewater, and we put up a large (3600m³) tank for potable water, with a separate 400m³ tank for fire water storage. The total supplied tank volume came to 7100m³. We engaged Kawerau Engineering to fabricate the DAF plant, and Hennessy Electrical to do the electrical and automation work, working closely with Babbage Consultants, project managers for Yashili.

Effective odour containment
The DAF plant is housed in a purpose-built structure complete with mechanical ventilation to maintain negative pressure inside, ensuring odours don’t escape. The ventilation air is then deodorised in a Biofilter before discharge to atmosphere.

The full, turnkey system is capable of treating 100m³ of wastewater per hour, resulting in a compliant and safe operation for the high-tech dairy plant.

Equipment used
RTP storage tanks, DAF plants.