WASTEWATER
Alternative COD monitoring tool helps pulp and paper operations By Stephanie Horner, Maggie Grierson and Robert Menegotto
Recalcitrant COD is composed of organics that do not readily oxidize under biological conditions and are problematic in pulp and paper effluents. © Igor Groshev – stock.adobe.com
T
he EUREKA Cluster for Water provides transnational collaboration for innovative projects in water and environment. “Novel Concepts for the Reduction of Recalcitrant COD in Water Intensive Industries” is a recent project that focuses on the pulp and paper industry. (www.acqueau.eu) Recalcitrant COD can also be referred to as hard COD in some industries. It is composed of organics that do not readily oxidize under biological conditions and are problematic in pulp and paper effluents. MANTECH’s photoelectrochemical Chemical Oxygen Demand (peCOD) method was used to evaluate COD reduction by new technologies used at various stages of the pulp and paper wastewater treatment process. The peCOD method eliminates the use of mercury, dichromate and concentrated acid, and generates COD results in 15 minutes. The core of the peCOD
42 | February 2017
technology utilizes the high oxidation potential of UV irradiated TiO2 nano-particulates to fully oxidize all present species. The testing range is 0.7 mg/L-15,000 mg/L of COD. Incorporating dilution can extend this range. The peCOD method is approved by the Ontario Ministry of the Environment and Climate Change (MOECC Method E3515). It is also an approved ASTM International method for drinking water treatment plants (raw and treated water). Through the pulp and paper project, MANTECH is working with a variety of international research partners to evaluate and verify the correlation of peCOD to conventional dichromate COD. FPInnovations, located in PointeClaire, Quebec, is one of the Canadian research partners working with MANTECH. FPInnovations compared MANTECH’s
automated L100 and online P100 peCOD analyzers to the conventional dichromate testing method. A variety of samples from both kraft and mechanical pulp mills across Canada were collected and sent to their lab for analysis. Both filtered and unfiltered samples were run in triplicate for COD, on each of the peCOD models, and using the dichromate method. The automated L100 peCOD is a benchtop model for analyzing multiple grab samples. Sample preparation, such as filtering, is completed by the operator, with the remainder of the peCOD analysis running unattended. The online P100 peCOD is fully automated to analyze one sample stream at a time. It can filter, and connect directly to Supervisory Control and Data Acquisition (SCADA) system. Both systems were operated at FPInnovations to verify their variability and robustness, using an abrasive sample matrix.
Environmental Science & Engineering Magazine