Why Sample Preparation Matters for RDF Quality

While laboratory testing is critical in assessing RDF quality, representative sampling and sample preparation are what make analysis meaningful.

RDF is highly heterogeneous. A representative 100kg sample may contain plastics, paper, wood, textiles, and inert materials, each with its own particle size, density, and chemical characteristics such as moisture, ash or chlorine content.

Effective sample preparation transforms this varied material into a small, homogeneous sub-sample. When a sub-sample properly reflects the wider batch, laboratories can produce reliable and repeatable RDF analysis results by following UKAS-accredited methods based on the current industry standards (ISO/CEN).

Behind the Scenes: Sample Preparation at Alfred H Knight

Earlier this year, our clients, Powerday, visited our state-of-the-art sample preparation facility in Dundonald, Scotland. During the visit, our experts demonstrated each stage of the sample preparation process and how our quality-driven approach supports reliable waste analysis for their MRF operations.

Receiving and Logging
Every sample begins its journey in our secure reception area. Here, we log, label, and assign unique ID numbers to the clients’ materials. This maintains full traceability.

Initial Particle Size Reduction and Physical Tests
The received sample containers are emptied onto a clean floor and thoroughly mixed. Before particle size reduction, the sample may undergo a physical test, such as Bulk Density, to record its original properties.

Once complete, the material is recombined and mixed again. Non-grindable items, which could damage the shredder, are visually identified, removed, and recorded as removed ash contributors (RAC). The remaining material is shredded to reduce particle size, then thoroughly mixed and subdivided. This careful preparation ensures consistent RDF quality and reliable RDF analysis results.

Drying and Further Particle Size Reduction
Samples are dried to record the moisture content of the sample and remove excess moisture before being milled or cut to the appropriate particle size for laboratory analysis. Consistent sizing helps reduce variability within the sample.

Homogenisation and Sub-Sampling
Once prepared, our technicians homogenise the material to create an even distribution of all components. Precise sub-samples are then extracted using calibrated equipment, providing material that accurately reflects the original waste stream.

Documentation and Quality Assurance
Each preparation stage is documented and verified by our quality team, providing complete transparency from receipt to dispatch.

How Representative Sampling Could Support Your RDF Quality

Through representative sampling, correct sample preparation and controlled laboratory workflows, Alfred H Knight helps waste operators build reliable analytical datasets for their recovered materials.

During our documented visit, Powerday saw how robust preparation translates into trustworthy results, with tailored sampling plans, consistent handling and distribution, and clear laboratory processes providing a strong foundation for accurate RDF analysis and improved operational insight across their MRF.

This approach delivers wider benefits across the sector, helping operators achieve:

• Confidence in RDF quality backed by representative data
• Stronger evidence for customers and regulators
• A clearer understanding of process performance and material flows
• Customer assurance supported by transparent, verifiable results
• Compliance aligned with current ISO/CEN standards

If you’re looking for expert support for your waste, recycling, or MRF operations, get in touch via our contact page to see how our team can support your operations.

Powerday’s Commitment to Reliable RDF Quality

As a family-owned waste management company, Powerday is committed to reducing the UK’s environmental impact through sustainable waste solutions. Processing thousands of tonnes of material every week across their Material Recovery Facilities (MRFs), they work with diverse and rapidly changing waste streams.

To maintain reliable RDF quality, Powerday requires samples that accurately represent its material flows. This supports confident decision-making, helps validate composition data, and assists in demonstrating compliance with regulatory standards.

Alfred H Knight supports Powerday with this through specialist sample preparation services.

Look Out for Part Two of Our Powerday Spotlight

In Part Two, we’ll explore how Alfred H Knight helps Powerday build swift and accurate profiles of their RDF through expert analysis. Look out for this in the coming weeks.