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BIOCONTROL DIAGNOSTICS WORLD PULPPAPER62 INTRODUCTION Papermaking systems utilise several raw materials that introduce microorganisms into the machine system. This includes virgin wood fibre recycled fibre freshwater starch dyes and other chemical additives. Microorganisms proliferate in the warm nutrient-rich environment of the papermaking system and diverse microbial communities result. Inadequate control of microbial growth allows for the formation of surface deposits that slough leading to filter or nozzle plugging and defects e.g. spots or holes or breaks in the sheet. Microorganisms can also proliferate in the felts and machine fabrics negatively impacting water removal and machine or operational efficiency. Traditional key performance indicators including conventional plating techniques and oxidant residuals often indicate adequate dosing and control. However deposition defects and breaks may still be prevalent. There is a need for monitoring tools that provide more accurate information regarding microbial growth and biofilm formation in industrial water systems and allow for more rapid determination of the contribution of microorganisms to sheet defects. The presence of microorganisms in sheet defects and By Liliya Lund Lead Chemist Laura Rice Corporate Scientist Elisa Luth Senior Microbiologist NALCO Water an Ecolab Company Advanced Diagnostic Strategies for Optimal Biocontrol Many traditional monitoring approaches do not provide enough information to respond in a correct or timely manner to an upset situation ability to determine the location of problematic deposits in the process would allow for rapid implementation of the most appropriate microbial control strategy Figure 1. Such information can be acquired through the use of quantitative polymerase chain reaction qPCR techniques. Optimised treatment strategies reduce the volume of treatment chemical required to control problematic deposits. PROBLEMS WITH TRADITIONAL MONITORING TOOLS Many traditional monitoring approaches do not provide enough information for the papermaker to respond in a correct or timely manner to an upset situation. Techniques such as plate counts and adenosine triphophsate ATP measurements fail to represent and discriminate between the different microorganisms present in a sample. Analysis of microbial population using conventional plating techniques is labour intensive time consuming and relies on the ability of an organism to grow on a defined or selective medium. Moreover lengthy incubation periods negate any possibility for pro-active control or preventative measures related to microbial growth in the process. While plating allows for a basic level of identification of organisms it requires that the organism is viable. The need for viable bacteria and lengthy Figure 1. MAP is used to determine the contribution of bacteria to sheet defects and holes and target treatment based on the type and quantity of DNA detected