Historically, pH and acid/alkali reserve were sufficient to assess whether wastes with a pH of >11.5 or <2.5 were Irritant or Corrosive. The methodology for classification now requires wastes to be tested for pH, acid/alkali reserve and in vitro irritancy. This increases testing costs by a magnitude of 20 and the timescale for data reporting by eight weeks, both of which are operationally challenging for clients.
In conjunction with the Environmental Services Association, WRc has undertaken studies to correlate pH and alkali reserve values with the outcome of in vitro irritancy testing. This has provided evidence that the combined pH and acid/alkali reserve methodology for classification is robust within a specific range of values for this specific waste stream. In vitro irritancy testing is now only required when a sample exhibits a combined pH and alkali reserve outside that range.
A similar exercise may need to be undertaken on other process wastes.