In conventional treatment plants, granular media filtration is the most important unit process for maintaining high quality drinking water. Filter condition surveillance is important for tracking the condition of filters. The objectives of this report are to identify, select, evaluate, and provide guidance on condition assessment methods that are less interruptive to normal filter operations than those currently used in the water industry. Methods that are less interruptive can be applied more frequently and require fewer resources. These methods will help utilities to determine the condition of their filters on a more regular basis and assist in achieving optimal filter performance.

The overall objective of this project was to identify, review, and select potential filter evaluation methods that are less interruptive than conventional techniques. These condition assessment methods provide information on the overall process performance of a filter and the condition of the granular media. Three technologies were found to provide meaningful data while reducing the extent of operational interruption during filter evaluations. The conductivity probe and the fiber optic camera were found to be useful for determining the depth of media layers and the degree of intermixing between media types. The fiber optic camera also provided a visual inspection of depth of floc penetration into the bed, presence of coatings on the media, and extent of media fluidization and bed expansion during backwashing. The multi-point head loss probe could be developed as a surrogate for the floc retention profile and for optimizing pre-treatment to achieve greater depth filtration and overall productivity.

Water operators will find a wealth of hands-on information on the operation and maintenance of pretreatment, rapid-rate granular media filtration, slow-sand filtration, and diatomaceous-earth filtration systems in this book. This practical guide provides recommended procedures for operating, monitoring, and maintaining all types of filters used for conventional water treatment. These procedures are tested and time-proven by hundreds of water utilities and filtration experts to provide high filter efficiency, excellent water quality, long filter runs and minimum downtime. The book also gives advice on what not to do-and why-so you can avoid water quality problems, filter damage, and treatment problems in the future.

This manual suggests design operating and performance criteria for specific surface water quality conditions to provide the optimum protection from microbiological contaminants.

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