NCASI addresses bias in method for determining petroleum hydrocarbons in pulp and paper mill wastewaters and residuals

When the Quebec Ministry of Environment method MA.400 – HYD. 1.1 is applied to samples that contain wood fibre, the wood extractives can cause a large bias in the results, making it appear that there is a large amount of petroleum hydrocarbons present in these samples. The use of an additional silica gel cleanup step, as outlined in NCASI Technical Bulletin No. 910, helps to remove this bias.

Technical Bulletin No. 1055 examines the applicability of method MA.400‐HYD.1.1 for the analysis of untreated wastewaters (influents to wastewater treatment), treated effluents, and wastewater treatment residuals. Samples were collected at five pulp and paper mills located in Quebec, Canada. Researchers found significant levels of wood extractives present in extracts obtained from the application of method MA.400-HYD.1.1. The NCASI cleanup procedure removed a significant portion of polar wood extractives from these extracts. A mass spectrometric screening method is proposed for the analysis of petroleum hydrocarbons present in sample extracts, as an alternative to using the NCASI silica gel column cleanup step.

Results of this study show that the NCASI cleanup procedure and GC/MS data can be used by Member Companies to reduce the bias in determining PHC contamination in pulp and paper mill wastewaters and WWTS residuals using the MA. 400 ‐ HYD.1.1 method.