Principal / Associate Process Engineer

Mott MacDonald; Cambridge; Hybrid; GBP 70,000 - 110,000; Full time

Benefits offered by this job

Private medical insurance

Pension contributions matching

Life assurance

Annual bonus scheme

Holiday entitlement 33–35 days

Job summary

Mott MacDonald is seeking a talented Principal/Associate Process Engineer to join our Water Utilities team supporting Thames Water’s wastewater investment programmes. The role focuses on leading process engineering across feasibility to detailed design, working closely with client teams in Thames Water's Reading offices.

You will review and develop process designs, model systems, and deliver high-quality reports while building strong client relationships and mentoring junior engineers.

Qualifications

• Degree in Chemical Engineering or related engineering discipline.
• Chartered Engineer (CEng) status with a recognised Professional Institution.
• Significant experience in municipal wastewater treatment and/or sludge treatment process design.
• Experience delivering feasibility studies, outline designs and detailed designs for wastewater schemes in the UK.

Responsibilities

• Lead process engineering input across feasibility, concept, outline, and detailed design stages for wastewater and sludge projects.
• Act as a trusted technical advisor to Thames Water and support project development.
• Develop and review process designs, including PFDs, P&IDs, mass balances, hydraulics, and equipment sizing.
• Apply wastewater treatment knowledge including nutrient removal and sludge processing.
• Analyse plant data to identify optimisation opportunities and improve performance.
• Undertake process modelling to support design and investment planning.
• Prepare technical reports, design documents, and client presentations.
• Review and assure engineering deliverables for quality and standards.
• Engage with Thames Water stakeholders and work from Reading offices as required.
• Mentor junior engineers and share best practices.

Skills

Process engineering

Wastewater treatment

Client relationships

Mentoring engineers

Regulatory compliance

Education

Degree in Chemical Engineering

Chartered Engineer (CEng)

Tools

PFDs

P&IDs

Mass balances

Hydraulic calculations

Process modelling software

Job description

Location/s: Cardiff, London, Cambridge, Croydon & Reading; UK

Mott MacDonald is a global engineering, management, and development consultancy with over 20,000 employees across more than 50 countries and 140+ offices.

We work across incredible global industries, delivering exciting work that is defining our future and making an important societal impact in the communities we serve. Our people power our performance - we succeed when they do. With countless opportunities to collaborate, learn, and grow, the possibilities for excellence are as varied as every individual.

Whether you want to grow as a subject matter expert or broaden your experience with roles across our international community, you’re surrounded by global specialists who want to combine their expertise and champion you to be your best. As a proudly employee-owned business, we benefit our clients, our communities, and each other, investing in creating the right space for everyone to feel empowered, included, and valued. Whatever your ambition, Mott MacDonald is where people come to be brilliant.

About the Division

The Water Utilities Division is Mott MacDonald’s centre of excellence for responding to the UK and Ireland's water and wastewater challenges. The work we do is at the forefront of ensuring safe water supplies for future generations, preventing urban flooding, and improving the health of our rivers and coastal environments. Our multi-disciplinary teams provide a variety of services throughout the full project life cycle, from advisory services and feasibility studies to outline and detailed design. Together, we deliver best-in-class solutions to our clients while offering diverse and technically stimulating opportunities to our people.

Overview of the role

We have an exciting opportunity for a talented Principal/Associate Process Engineer to join our team supporting the delivery of Thames Water's wastewater treatment and sludge treatment programmes. The successful candidate will play a key role in developing process solutions across Thames Water's wastewater asset base and will work closely with client teams, building strong relationships through regular engagement within Thames Water's Reading offices.

This role provides an excellent opportunity to influence the planning, design and delivery of major wastewater investment programmes, working collaboratively with Thames Water, contractors and multidisciplinary design teams

Key responsibilities and duties include:

• Lead process engineering input across feasibility, concept, outline, and detailed design stages for wastewater and sludge treatment projects.
• Act as a trusted technical advisor to Thames Water, supporting strategic discussions, project development and investment planning activities.
• Develop and review process designs, including process flow diagrams (PFDs), P&IDs, mass balances, hydraulic calculations, and equipment sizing.
• Apply expertise in wastewater treatment processes, possibly including biological nutrient removal, sludge treatment, digestion, dewatering, and emerging treatment technologies.
• Analyse operational data from wastewater treatment works to identify optimisation opportunities and improve plant performance, resilience, efficiency and compliance.
• Undertake process modelling and simulation to support design development, operational improvement and investment planning.
• Prepare high-quality technical reports, design documentation, business cases, proposals and client presentations.
• Review and approve process engineering deliverables, ensuring technical excellence and compliance with relevant standards and Thames Water requirements.
• Develop and maintain strong working relationships with Thames Water stakeholders through regular engagement, including working from the client's Reading offices as required.
• Mentor and support junior engineers, fostering technical growth and sharing best practice across the business.
• Collaborate with resource coordinators and discipline leads to manage project resources and technical development initiatives.
• Support business development activities, identifying opportunities for growth within the Thames Water framework and contributing to proposals, tenders and client account planning.

Candidate specification

We are looking for an individual who is passionate about improving wastewater infrastructure, building long-term client relationships and delivering innovative solutions for one of the UK's largest water utilities.

Essential

• Degree in Chemical Engineering or a related engineering discipline.Chartered Engineer (CEng) status with a recognised Professional Institution.
• Significant experience in municipal wastewater treatment and/or sludge treatment process design.
• Strong understanding of wastewater treatment technologies, including activated sludge processes, nutrient removal, tertiary treatment and sludge processing.
• Experience delivering feasibility studies, outline designs and detailed designs for wastewater treatment schemes within the UK water sector.
• Ability to build and maintain strong client relationships and operate effectively within client organisations.Experience working within collaborative delivery models, frameworks or long‑term water industry programmes.
• Strong understanding of wastewater treatment operational challenges and opportunities for process optimisation.Excellent technical report writing and communication skills.
• Proven ability to review and assure technical calculations, reports and engineering deliverables.Ability to mentor and develop engineers and contribute positively to team growth.
• Willingness to travel regularly and work from Thames Water's Reading offices to support client engagement and programme delivery.

Desirable

• Experience working on AMP programmes and wastewater capital delivery frameworks.
• Demonstrable experience of working collaboratively with UK water utility clients, preferably Thames Water.
• Familiarity with Thames Water standards, design procedures and governance processes.
• Experience supporting business development, account management and strategic client engagement activities.
• Knowledge of digital delivery tools, process modelling software and data‑driven performance optimisation techniques.Commitment to continuous professional development and application of industry best practice.

UK Immigration

Mott MacDonald Ltd. are not currently offering sponsorship to candidates under the Skilled Worker visa route in the UK. This decision is as a consequence of the changes made to the Skilled Worker route by the UK Government in April 2024. We continue to welcome applications from candidates who are eligible for alternative immigration routes in the UK, that do not require sponsorship as a Skilled Worker now or in future.

Agile working

At Mott MacDonald, we believe it makes business sense for you and your manager to choose how you can work most effectively to meet your client, team, and personal commitments. We offer a hybrid working policy that embraces your well‑being, flexibility, and trust.

Equality, diversity, and inclusion

We put equality, diversity, and inclusion at the heart of our business, seeking to promote fair employment procedures and practices to ensure equal opportunities for all. We encourage individual expression in our workplace and are committed to creating an inclusive environment where everyone feels they can contribute.

Accessibility

We want you to perform your best at every stage in the recruitment process. If you are disabled or need any support to enable you to apply or attend an interview, please contact us at [e-mail] and we will talk to you about how we can support you.

We offer some fantastic benefits including:

Health and wellbeing

• Private medical insurance for all UK colleagues.
• Health cash plan to support you with every day health costs and treatments.
• Access to Peppy, providing free support from menopause experts for all UK colleagues.
• A variety of wellbeing support is available through our comprehensive wellbeing program, including access for you and your family.
• Ability to flex your salary to opt into a wide range of health benefits, many of which can be extended to your family too.

Financial wellbeing

• We match employee pension contributions between 4.5% and 7%.
• Life assurance equal up to 4 x your basic salary, with an option to increase the level of cover to 6 x your salary.
• Our income protection scheme provides a financial benefit, as well as absence and return to work support due to long‑term illness or injury.
• Flexible benefits, including increased life assurance cover, critical illness insurance, payroll saving and will writing.
• As an independently owned business we share the financial success of the business with all our colleagues in various ways including annual bonus schemes.

Lifestyle

• A minimum of 33-35 days holiday each year, inclusive of public holidays and dependent on level, with the ability to buy or sell leave through our flexible benefits programme.
• Holiday entitlement increased to a minimum of 35 days after 5 years’ service.
• Variety of employee saving schemes and discounts from high‑street retailers.

Enhanced family and carers leave

• Enhanced family leave policies, including 26 weeks paid maternity and adoption leave, and two weeks paid paternity/partner leave.
• Our shared parental leave matches maternity leave meaning we pay up to 24 weeks at full pay.
• Up to five additional days leave are provided for those with significant caring responsibilities, two of which are paid.

Learning and development

• Primary annual professional institution subscription.
• A broad range of opportunities to enhance both technical and soft skills through mentoring, formal training, and self‑development options.

Networks, communities, and social outcomes

• Join a wide range of groups including our Advanced Employee Networks which support our LGBTQ+, gender, race and ethnicity, disability, and parents/carers communities.
• Make a difference within our communities through our social outcomes.