A specification is only as strong as its sample
Recovered fuels are heterogeneous. Input materials, moisture, processing settings and storage conditions can change within a day or across a production campaign. A single convenient grab sample may describe that handful accurately while saying little about the lot delivered to the buyer.
Quality assurance begins by defining the lot and a sampling plan before results are known. The European Investment Bank’s summary of EN ISO 21640 describes class compliance using samples across a defined lot of up to 1,500 tonnes, sampled according to ISO 21645 and assessed statistically. Commercial contracts may choose smaller lots or more frequent testing where variability or plant sensitivity requires it.
Keep the evidence chain intact
The plan should state where increments are taken, how many are combined, how the sample is reduced and prepared, and which laboratory method is used. ISO publishes companion methods for SRF sampling, calorific value, ash and moisture. Consistent methods allow results from production and receipt to be compared on the same basis.
Trace-element results also need context. Detection limits and measurement uncertainty matter near a rejection boundary. The contract should say whether compliance uses a mean, median, percentile or maximum and how uncertainty is treated rather than leaving that decision until a disputed load arrives.
What the certificate of analysis should show
A buyer should be able to connect every reported result to the material it represents. At minimum, the certificate should identify the producer, material and lot; sampling date and method; laboratory and test method; result, unit and basis; applicable statistical measure; detection limit or uncertainty where relevant; and the agreed target and rejection limit.
For an EN ISO class, the certificate should report NCV, chlorine and both required mercury statistics in the correct units and bases. The wider commercial schedule then records moisture, ash, particle size, physical form and the chemical parameters selected for the destination plant.
| Record | What it should establish |
|---|---|
| Lot identity | Origin, production period, quantity and delivery reference |
| Sampling | Date, location, increments, method and responsible party |
| Laboratory result | Value, unit, as-received or dry basis, and test method |
| Statistics | Mean, median, 80th percentile or maximum where applicable |
| Decision rule | Target, rejection limit, uncertainty treatment and approval status |
| Retention | Sealed dispute sample, custody record and retention period |
Agree the remedy before an off-spec lot
A complete quality schedule sets test frequency, independent-check rights and what happens when production or receiving results differ. Options can include a price adjustment, controlled blending or reprocessing, rejection, return freight and escalation to a retained sample at an agreed independent laboratory.
The contract should also distinguish routine targets from absolute rejection limits. That protects both parties: normal variation can be managed without disguising a result that the receiving plant cannot legally or safely accept.
Quality and shipment legality are separate checks
A load can meet its NCV, chlorine, mercury and physical specification yet still be unable to move because its waste classification, notification, consent, destination operation or receiving permit is not in order. Conversely, shipment consent does not guarantee that the load meets the buyer’s technical requirements.
Regulation (EU) 2024/1157 governs waste shipments, with most provisions applying from 21 May 2026. The procedure depends on the material, route, destination and intended treatment. Those legal checks should run alongside quality assurance, with consistent material descriptions across the contract, laboratory records and shipment documents.