We supported a compact, deployable wastewater treatment line, featuring nano‑bubble aeration, by using CFD and process modelling to understand hydraulics, gas–liquid interaction and residence‑time distribution within the portable unit. The workflow mapped how inlet conditions, internal baffles and aerator placement influence mixing, oxygen transfer potential and short‑circuiting risk under realistic operating envelopes. We built decision metrics around removal efficiency proxies and energy use, allowing trade‑offs between performance and power to be quantified. Parametric variants explored baffle geometry, diffuser layouts and set‑points; verification checks and sensitivities provided assurance that relative performance differences were robust. The results identified configurations that enhance contact and dissolved‑oxygen uniformity while controlling headloss, together with an implementation plan for prototype updates and on‑site testing. The deliverables including concise report, annotated figures and a reproducible model enable Oxfiniti to iterate quickly, communicate clearly with stakeholders and de‑risk scale‑up decisions.