Check the comparison
Are inlet and outlet samples comparable in timing, flow and operating conditions? Changes in dilution, sampling location or feed composition can affect the apparent reduction. Keep concentration and mass-loading questions separate when quantities change.
Follow the contaminant across phases
Contaminants may move into solids, a separated oil phase or a gas stream. That transfer may be an intended treatment step, but its value depends on how the resulting stream is managed. A removal claim should state the system boundary and account for relevant residuals.
Ask what supports a degradation claim
Where biodegradation is the proposed mechanism, consider transformation products, biological and geochemical indicators, and an appropriate mass balance. Isotope or other pathway-specific evidence may add value in suitable cases. The evidence package should match the contaminant, process and consequence of a wrong conclusion.
Connect the claim to the decision
A screening result, a pilot observation and a performance guarantee answer different questions. Identify which conclusion is justified now and what must still be demonstrated. Avoid using evidence from a different waste chemistry or operating range as if it directly validates this project.
Concentration alone cannot distinguish degradation from dilution or transfer. Mass balance, transformation products and mechanism-specific evidence help resolve the cause.
- Water outlet
- Recovered phase
- Residuals / gas
A lower water concentration may mean transfer, transformation or both. Follow the mass across the system.
Sources & context
Background reading checked 9 October 2026. The review questions and structures above are BGF editorial guidance; the references are not BGF project evidence or endorsements. Apply them to the relevant site, data and agreed scope.