Trojan Technologies

Week 3 — Where UV Is Installed… and Why Dose Still Matters My colleague Nina Roy hosted her first webinar yesterday, great content and very engaging, and she shared something that stuck with me — the Repetition Rule: research shows people often need to see or hear a message 7 times before it sticks. This is Week 3 of this series and my 9th post on UV… so hopefully it’s starting to land 😊 And yes — it’s Thursday. Last week we discussed how UV destroys ozone at 254 nm. This week, let’s talk about where UV is placed in the system — and why that alone is not enough. 👉 Because placement defines where ozone is removed 👉 But UV dose determines whether it is actually removed In pharmaceutical water systems, UV for ozone destruction is typically installed: • After the storage tank • Before point-of-use • Upstream of sensitive processes The goal is simple: Ensure ozone is fully destroyed before it can impact product or process. 💡 But how much UV dose is actually required? This question isn’t new. Back in 2004, work led by Trojan Technologies research (Dr. Mihaela Stefan) established ozone photolysis kinetics, showing that ozone destruction follows predictable first-order behavior and defining D10 relationships across concentrations. Later, at the 2012 ISPE Annual Meeting, Philip Sumner (Pfizer) presented experimental validation work in high purity/DI water. 💧 The conclusions were interesting: • Historical guidance of ~90 mJ/cm² remains a conservative design basis • For 1 ppm ozone, testing showed only ~70 mJ/cm² was required • For ≤500 ppb ozone, doses requirement is lower than 50 mJ/cm² were sufficient 👉 So if we already understand the dose…why are we still talking about it 10+ years later? Because in real systems: • Ozone concentration is not constant • Flow conditions vary • Test methods have limitations • System design introduces variability 💡And most importantly: We are not designing for “lab conditions” — we are designing for reliable operation. In other words: Dose is not just a number — it is a design decision tied to risk. Next week: 👉 What does “non-detectable ozone” actually mean — and are we designing to the right target? #PharmaWater #UVTechnology #OzoneDestruction #ProcessEngineering #GMP #WaterTreatment #Trojantechnologies #ISPE #Risk #FDA #noaddedsubstances #PW #WFI