Best available technique for treating incinerator ash washing water

Het wassen van bodemas is een noodzakelijke stap in het verouderingsproces om bodemassen vrij toepasbaar te maken in de bouw (meer informatie in het nieuwbericht)The resulting wastewater needs to be treated before it can be discharged. The wastewater has a number of challenging characteristics (salt, high pH, heavy metals, high COD) whereby it was not immediately clear whether standard techniques would be suitable.

In our laboratory we began with simple tests to check whether the wastewater was toxic to the treatment biomass. This proved not to be the case. Then we set up a pilot test to optimise the treatment result. The water was first treated physically and chemically to remove as much of the dissolved metals as possible, and then biologically in a SBR (sequential batch rector) to further remove metals and COD.

As discharge regulations for this type of wastewater still need to be determined, Rijkswaterstaat (RWS – Directorate General for Public Works and Water Management) kept careful oversight. We therefore conducted extra analyses and contra analyses through RWS on the effluent from the pilot test. The feasibility test showed that:

Far reaching removal of metals is possible through a combination of precipitation and biological treatment.

The biomass in the SBR works well under the extreme conditions of the waste water.

This best available technique can be used for the treatment of incinerator ash wastewater.
RWS has still to determine discharge regulations, after which it will become clear what the best treatment route is and whether further optimisation is necessary.

For more information contact Thommy Verschuuren.

Thommy Verschuuren works at Orvion looking from innovative and often unexpected angles at the challenges that face customers. He likes to show that cost savings and sustainable development can go hand in hand. “Often the green solution is also the economically advantageous solution, but it just does not occur to you”.

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