MICROBIOLOGICAL IMPLICATIONS OF USING GRANULAR ACTIVATED CARBON IN
RAPID GRAVITY FILTERS
Report No FR0431
A better understanding will be gained of the microbiological implications of using granular activated carbon as a replacement for sand in rapid gravity filters.
To assess the impact on the microbial quality of water using granular activated carbon as a filtration medium in water treatment.
Granular activated carbon (GAC) is widely used in the treatment of drinking water to remove undesirable tastes and odours and trace organic contaminants. It is also used as part of treatment strategies to minimise the formation of disinfection by-products. Apart from its ability to adsorb a wide range of organic compounds, GAC also encourages the proliferation of micro-organisms. The attached microbial population derive their nutrients from both the soluble fraction in the water and those adsorbed to the carbon particles. Although successful in reducing the organic content of water, the impact of the increased microbial loadings which GAC filtration can create, on the final stage of treatment, is not well understood.
V RESUME OF CONTENTS
This report describes studies conducted as part of the Foundation for Water Research contract "Microbiological Efficiency of Water Treatment" (F-1401) and focuses on the microbiological implications of using granular activated carbon during water treatment. In support of this study, previous work undertaken for the Department of the Environment has been included to provide a complete assessment of GAC in water treatment. During this study, the performance of GAC was evaluated at a full scale treatment works. Investigations were conducted to examine aspects of the operation of the filters and determine their impact on the microbial quality of the effluent water. Consideration was given to an examination of release of GAC particles from the filter bed and their passage into the distribution system.
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