Optimising GAC Regeneration Frequency

Regeneration of granular activated carbon (GAC) is a significant operating cost at many water treatment works. Identification of new problem organic micropollutants (e.g. pesticides, pharmaceuticals) is creating additional costs and operating problems for GAC. Usually, regeneration frequency is established with a high degree of security to minimise risk of breakthrough of contaminants. Depending on the quality of the feed water and the design of the system, bed life and typical regeneration frequency can range from 1-2 years to up to several years. For a large water treatment works of say 100 Ml/d, increasing the bed life from 2 to 2.5 years can reduce operating costs by over £100,000 per annum.

WRc has started a Portfolio project (CP393) to develop a software tool for predicting GAC bed life with greater confidence to allow regeneration frequency and operating cost to be reduced. The tool will be pre-calibrated with existing data, but will be capable of being readily updated with operational data for specific works.  This will reduce operating costs whilst maintaining security of treatment through better prediction of breakthrough profiles. By providing better evaluation of the performance of GAC, it will also provide a risk assessment tool for Drinking Water Safety Plan development and implementation.

Four UK water companies are supporting the Portfolio project which is part of WRc’s £1.5 million collaborative research programme.