Chemical oxygen demand (COD) is a critical analytical parameter in the field of waste and wastewater treatment processes, and more specifically in anaerobic digestion processes. However, little is known about the COD measurement quality of anaerobic digestion samples. Taking into account the lack of a general standard method and high quality certified reference materials (CRMs), currently the traceability of the COD determination in such samples is not easy to check. Proficiency testing (PT) is a powerful tool that can be used to test the performance that the participant’s laboratories can achieve. Two PTs related with COD determination have been organised, and the results reported have been compared; showing the importance of continuous participation in proficiency testing (PT) schemes in order to improve the results obtained.
Anaerobic digestion; chemical oxygen demand; proficiency testing; solid samples