Complying with stricter non-ionic surfactant limits at an aluminium processor

After consultation with the customer, we were confident that activated carbon would be the right approach, provided that the operating costs were not too high. Initial calculations showed that the annual use of activated carbon could possibly exceed 200 tonnes per year. These calculations were based on the fact that activated carbon is non-selective, adsorbing all organic contaminants.

However, activated carbon also preferentially adsorbs certain substances. The operational cost would be cut considerably if that was the case for these non-ionic surfactants.

To find out, we ran a pilot test. We sent a limited wastewater flow over a small-scale mobile activated carbon filter (capacity 1 m³), so that we could accurately estimate the behaviour of both the adsorption process and the breakthrough curve.

The COD broke through quickly at the outlet of the activated carbon filter, showing that the installation did indeed preferentially adsorb the non-ionic detergents.

This was great news for the company, as it meant that less activated carbon would be required, driving down operating costs. New calculations suggest that just 50 tonnes of activated carbon per year would do the job, cutting consumption costs by 75%. On this basis, the customer promptly gave the green light to a full-scale installation.