Microbiological characterisation of white pigment slurries : a strategy for bacteria management
The microbiological characterisation as well as the application of microbiocides for the storage and protection of mineral dispersions is of ever-increasing interest for scientists and industrialists and includes many challenges for the mineral slurry producer and user. Increasing conversion from dry pigment handling to water-based dispersions is taking place over a wide range of production applications, for example, papermaking filler products and coating formulations in both the paper and paint industries. The requirements for the delivery of preserved slurried products begins from the moment the mineral is extracted or synthetically produced. The process conditions are as important regarding bacterial colonisation and control as the delivery and storage strategy of the end-product itself. This thesis attempts to give a detailed insight into the background issues and procedures needed to provide an environment of "good housekeeping", essential in optimising the microbiological control needed for preservation and acceptable application of the pigment in its end-use. On this base, the latest research on the bacterial strains, their identification, measurement and growth dynamics in real-time are presented, and new biocide strategies, applicability and constraints are discussed. Illustrations are given throughout of the sources of microbiological contamination likely to occur during production, storage and transportation. Based on the current knowledge being gained from combining active Research and Development and on the ground applications expertise, new possibilities for optimising microbiological quality control are described.