Senior Python Engineer

Senior Python Engineer - Digital Twin & Mechanistic Modelling Contract: 6 Months Location: Midlands (Hybrid, 3 days per week onsite) Start Date: ASAP Rate: £500 per day (Inside IR35) We're looking for a Senior Python Engineer with expertise in mechanistic modelling, first-principles simulation, and digital twin development to support the creation of advanced digital twin capabilities for wastewater treatment sites. This role offers the opportunity to work at the intersection of engineering, data science, and software development, building high-fidelity models that enable process optimisation, forecasting, and operational decision-making across sewage treatment operations. The Role You will design and develop physics and chemistry-based models of wastewater treatment processes, translating engineering principles into scalable, production-ready Python solutions. Key responsibilities include: • Developing first-principles models for wastewater treatment processes, including activated sludge systems, sedimentation, hydraulics, biological reactions, and process control systems. • Translating mass balances, reaction kinetics, and process design equations into robust computational models. • Building clean, modular, and well-tested Python applications for simulation and optimisation. • Integrating mechanistic models into real-time digital twin environments. • Combining sensor and operational data, including flow rates, dissolved oxygen, and ammonia measurements, with simulation models. • Delivering capabilities such as predictive forecasting, scenario analysis, and process optimisation. • Calibrating and validating models using operational data, including parameter estimation and uncertainty analysis. • Working with SCADA systems, historians, and data pipelines to support model integration. • Collaborating closely with process engineers, data scientists, and operational stakeholders to deliver practical, business-focused solutions. • Explaining complex modelling outcomes to both technical and non-technical audiences. Required Experience • Strong Python engineering experience, 5+ years. • Proven expertise in mechanistic, physics-based, or first-principles modelling. • Strong understanding of differential equations and numerical methods; mass and energy balances; reaction kinetics. • Experience within at least one of the following: wastewater or sewage treatment; environmental engineering; chemical or bioprocess engineering; process systems engineering. • Experience with scientific computing tools such as NumPy, SciPy, and pandas. • Hands-on use of optimisation and modelling libraries including Pyomo, CasADi, or similar. • Experience with Git and software engineering best practices, including testing and documentation. Desirable Experience • 10+ years' experience in Python engineering, mechanistic modelling, or digital twin development. • Experience developing reusable Python modules and libraries. • Background in utilities, water, energy, manufacturing, or infrastructure sectors. • Experience delivering digital twin, asset intelligence, smart operations, IoT, or industrial transformation projects. • Knowledge of wastewater modelling frameworks such as ASM models or STOAT. • Experience with digital twin architectures and hybrid modelling approaches that combine machine learning with mechanistic models. • Exposure to cloud platforms such as Azure or AWS. • Experience working with industrial IoT or real-time systems. • Familiarity with visualisation tools including Matplotlib and Plotly. About You You are a strong problem-solver who can translate complex real-world processes into mathematical and computational models. Comfortable working across engineering, software, and data disciplines, you take pride in developing accurate, reliable solutions that deliver measurable operational value. If you're interested in applying advanced Python engineering and modelling expertise to real-world infrastructure challenges, we'd love to hear from you. Please apply promptly to be considered.