Chemical Regeneration of Activated Carbon: Preliminary Studies

This report was produced for the Urban Water Research Association of Australia, a now discontinued research program.

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Report No UWRAA 20

December 1990

SYNOPSIS

This investigation was funded by the Urban Water Research Association of Australia. The aim of the study was to investigate possible chemical regenerants for granular activated carbon used in drinking water treatment.

The eighteen month study was divided into three sections. The areas covered and the key findings are summarised below:

1. Bench Scale Adsorption/Regeneration Experiments

Batch and column experiments were used to study adsorption of organics onto activated carbon and the removal of adsorbed material by the regeneration process.

It was found that treatment with alkali then acid removed significant amounts of adsorbed organic material and produced regeneration efficiencies of up to 90%.

2. Regeneration Studies on Carbon from the North Richmond Water Treatment Works

Regeneration procedures were tested on activated carbons that had been used for taste and odour removal at the North Richmond Water Treatment Works over a two year period. Substantial amounts of adsorbed organic material were removed from the surface by the regeneration procedure. Adsorption experiments showed the capacity of the regenerated carbon approached that of virgin carbon.

3. Complementary Investigations and Optimisation Experiments

These studies were conducted to determine optimum conditions for adsorbed organics removal in terms of desorption time, concentration of alkali and temperature.

The results indicated that the optimum conditions were:

i) two hours desorption time

ii) 1.0M sodium hydroxide concentration

iii) temperature of 50°C

Preliminary work on the characterisation of the carbon surface and the desorbing organics was undertaken with the aim of understanding the processes taking place at the solid/liquid interface during adsorption and during the alkali and acid stepsof the regeneration.

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