Principal Process Engineer - Water & Wastewater Treatment

Principal Process Engineer - Water & Wastewater Treatment

Join to apply for the Principal Process Engineer - Water & Wastewater Treatment role at Mott MacDonald.

At Mott MacDonald, we’re passionate about creating infrastructure that improves lives and strengthens communities. Our New Zealand team has delivered some of the country’s most impactful projects—from Te Kaha Stadium in Christchurch to the Snells Beach Wastewater Treatment Plant. We’re now looking for a Principal Process Engineer to join our Auckland office and help us deliver technically challenging and meaningful water and wastewater treatment solutions.

The Opportunity

As a Principal Process Engineer, you’ll play a key role in shaping our water and wastewater treatment projects across Aotearoa. You’ll lead and mentor junior engineers, guide multidisciplinary teams, and apply your technical expertise to deliver innovative, sustainable solutions.

This is a fantastic opportunity for someone with a strong background in chemical or process engineering who is passionate about design excellence, collaboration, and community impact.

What You Will Do

• Lead the technical design and delivery of complex water and wastewater treatment projects, including mass balances, process flow diagrams, aeration and nutrient removal calculations, chemical dosing requirements, sludge production rates, and more.
• Work on new wastewater treatment plants, MBR designs, plant upgrades, biological nutrient removal, biosolids processing and digestion, long-term strategy and feasibility studies for water, wastewater and biosolids treatment.
• Maintain currency with the latest technologies by liaising with suppliers and our global team of treatment experts.
• Mentor and support junior engineers, fostering a culture of growth and collaboration.
• Coordinate multidisciplinary project teams, ensuring high-quality outcomes.
• Engage with clients, contractors and stakeholders throughout the project lifecycle.
• Contribute to project planning, technical reviews and quality assurance.
• Promote innovation, sustainability and continuous improvement in design.

About You

Why Mott MacDonald?

Apply Now

If this role resonates with you—even if you don’t meet every requirement—we encourage you to apply. We’re committed to building a diverse team and welcome people who share our values of inclusion, collaboration, adaptability, and integrity.

Join us and help shape the communities of tomorrow.

Employee Ownership

Our employee ownership model means no external investors, just us, creating a culture of shared success. Our employees have a stake and a voice in our business, giving them a direct connection to our success through performance bonuses.

As your career grows, so does your stake, recognising your long-term impact and contribution. Your voice matters, with the opportunity to connect directly with senior leadership through formal channels to help shape our future.

Our Benefits Package

You've Got This!

We endorse a diverse and inclusive workplace and aim to provide suitable opportunities for employees including part-time and job-share roles where possible. If you are interested in this role and looking for a part-time permanent opportunity, please apply.

Details

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