Senior Process Mechanical Engineer

Job Description

Job Description

Senior Process Mechanical Engineer – Wastewater Treatment

Location: Fountain Valley, CA (on-site)
Travel: Up to 20–25%

The Senior Process Mechanical Engineer leads process design for wastewater treatment and advanced water reclamation systems from concept through detailed engineering. This role translates process simulations into practical, constructible designs, including hydraulic profiles, process flow diagrams (PFDs), piping and instrumentation diagrams (P&IDs), equipment selection, and facility layouts.

This position requires expertise in biological treatment systems and advanced membrane technologies and plays a key role in delivering high-performance, sustainable water infrastructure solutions.

Process Engineering & Design

• Lead process design from conceptual phase through Issued for Construction (IFC).

• Perform process simulations using tools such as BioWin or equivalent.

• Design biological treatment systems including MBR, MBBR, SBR, IFAS, MLE, Bardenpho, and oxidation ditch processes.

• Develop hydraulic profiles, PFDs, and P&IDs.

• Conduct process calculations, mass balances, and system performance evaluations.

Advanced Treatment Systems

• Design and integrate advanced treatment technologies including MF/UF, NF, RO, and AOP.

• Develop treatment trains for water reuse and advanced reclamation.

• Perform membrane sizing, recovery analysis, and fouling evaluations.

Equipment & Facility Design

• Lead equipment sizing and selection (pumps, blowers, reactors, membrane systems, chemical dosing systems).

• Develop and review plant layouts and general arrangement drawings.

• Ensure efficient process flow, constructability, and maintainability.

Project Delivery

• Manage deliverables through all phases (Conceptual, 30%, 60%, 90%, IFC).

• Ensure designs meet schedule, budget, and quality requirements.

• Lead design reviews and support commissioning and startup activities.

Multidisciplinary Coordination

• Coordinate with mechanical, civil, structural, electrical, instrumentation, and CAD teams.

• Provide input on controls, automation, and system integration.

• Resolve design conflicts and ensure coordinated deliverables.

Technical Leadership

• Mentor junior engineers and review technical work products.

• Contribute to engineering standards and best practices.

• Serve as a subject matter expert in wastewater treatment and water reuse systems.

Business Development Support

• Support technical proposals, design narratives, and preliminary cost inputs.

• Participate in client meetings and technical presentations.

• Assist in evaluating project feasibility and technical risks.

Required Experience

• 10–15 years of experience in wastewater treatment and water reclamation design.

• Experience with process modeling and simulation (BioWin preferred).

• Extensive experience in biological treatment systems (ASP/BNR, MBR, MBBR, SBR, IFAS, MLE, Bardenpho) and advanced treatment technologies (MF/UF, NF, RO, AOP).

• Proven ability to deliver projects from concept through IFC.

• Strong knowledge of applicable standards (AWWA, ASME, ANSI, WEF).

• Experience coordinating multidisciplinary teams.

Education & Certifications

• Bachelor’s degree in Chemical, Environmental, Mechanical, or Civil Engineering (or related field).

• Professional Engineer (PE) license preferred (California strongly preferred).

• Additional training in process modeling software is a plus.

• Combination of office and field work environments.

• Ability to travel up to 20–25% for site visits and client meetings.

• Ability to occasionally lift up to 30 lbs.

• Use of personal protective equipment (PPE) may be required in field environments.