Looking to the future in New Zealand wastewater treatment
Auckland, the largest city in New Zealand, had a population of approximately 1.57 million in 2016 – about one-third of New Zealand's total population. As the bustling heart of New Zealand’s economy and culture, Auckland’s rapid growth placed increasing demands on its water supply and wastewater management systems. To meet the these needs, Watercare Service Ltd., New Zealand’s largest water utility and a wholly owned subsidiary of Auckland Council, took on the monumental task of providing sustainable water solutions for the city.
DATE 2025-01-24
In 2018, Watercare supplied around 365 million litres of water to Auckland each day, while simultaneously collecting, treating, and disposing of about 460 million litres of municipal and industrial wastewater. As Auckland’s population grew, the challenges of scaling infrastructure to keep pace with demand because even more pressing.
Infrastructure growth
Auckland’s steady population growth has consistently pushed Watercare to expand and upgrade its facilities. With projections from Statistics New Zealand suggesting that the city’s population could almost double within 25 years, the urgency to modernize infrastructure became clear. In response, Watercare outlined a bold plan to invest NZD 4.9 billion over the next decade in infrastructure projects to provide additional capacity to meet the water and wastewater needs of Auckland’s growing population and industries.
One of the key projects in this long-term strategy was the upgrade of the Mangere Resource Recovery Facility, a critical component of Auckland’s wastewater management system. In 2015, Watercare set out to enhance and expand the plant’s solids stream thickening capacity, focusing on environmental sustainability, safety, and energy efficiency. The goal was to create a reliable, low-maintenance system that could handle future demand while minimizing its environmental footprint – a cornerstone of Watercare’s broader mission.
The project
Alfa Laval Oceania won the competitive tender for the project, tasked with delivering, installatih, and commissioning seven Alfa Laval AS-H 300 Belt Thickener units. These units work by separating liquid from solids through gravity drainage, using a 3-metre-wide porous filter belt. The thickeners were designed to process waste-activated sludge (WAS) and Three-Phase Separator (TPS) sludge, enhancing the facility’s ability to handle growing volumes of wastewater.
The technical design of the Alfa Laval belt thickener units was a key selling point for Watercare. The inclusion of innovative sludge ploughs helped direct sludge into lanes, allowing free water to flow more easily through the areas of the belt not covered by solids. This design improved the efficiency of the thickening process, ensuring that water was separed as quickly and effectively as possible. Additionally, the units were equipped with a ramp feature, allowing operators to adjust the flow of thickened solids in real-time, and a sludge polymer mixing valve that ensured consistent and thorough mixing of polymer intro the sludge for optimal thickening results.
The benefits
The installation of these advanced AL belt thickeners, marking Alfa Laval’s first major order for this belt thickener separation technology in New Zealand, has met and exceeded expectations. According to Paul Doherty, a Watercare Service Project Engineer overseeing the solids steam upgrade at the Mangere WWTP, the equipment has consistently delivered high treatment capacity and reliability levels. The enhanced thickening process improves the facility’s operational efficiency aligns perfectly with Watercare’s broader goals of energy efficiency and sustainability, providing a clear strategic direction for the project.
Bigger picture
While the technical benefits of the Alfa Laval belt thickeners are impressive, they are only part of the larger success story. For Watercare, one of the most significant advantages has been relying on Alfa Laval’s local service network snd expert resources for ongoing support. As Paul Doherty noted, having access to quick and knowledgeable assistance has been invaluable in addressing technical challenges. This partnership between Watercare and Alfa Laval, has proven to be a key factor in ensuring the long-term success of the projects and the continued growth of Auckland’s water infrastructure.
Ultimately, this upgrade is not just about new equipment—it's about future-proofing Auckland's wastewater treatment capabilities while strongly focusing on sustainability, efficiency, and community well-being. The collaboration between Watercare and Alfa Laval highlights how thoughtful planning, cutting-edge technology, and responsive service can come together to meet the complex demands of a rapidly growing city.
