Using water more economically: research on Biological Activated Carbon Filtration for decentralised wastewater treatment plants

Calls to use water more sustainably and climate resiliently are increasing worldwide. Increasing demand and dehydration in certain regions have increased the pressure on extracting drinking water. One solution to this problem is the decentralised treatment of wastewater from residential areas, where (ideally grey and black) wastewater is treated locally so that the water can be reused, for example for irrigation of a city's green spaces.

'To the BAK' project
The decentralised treatment systems used so far unfortunately do not yet remove micro-pollutants, such as pharmaceuticals. As a result, temporary underground storage or discharge into surface water will not be allowed in the future. Within the Project on the BAK, Desah and Bioclear earth are investigating whether we can develop an addition to existing technology that does remove these contaminants, so that the reuse of water at district level becomes possible and meets all legal requirements, including those of the future.
BAK stands for Biologically Active Carbon. Activated carbon has been used for decades. Its action is that toxic compounds adhere to the large internal surface of activated carbon, which consists of a fine microstructure with very many small pores. Over time, saturation of the activated carbon occurs and it has to be replaced. The idea of a BAK is that by inoculation with specially selected bacteria, the unwanted compounds are broken down and the activated carbon filter is regenerated.

What makes the Biological Activated Carbon Filter (BAK) unique?
The uniqueness of our approach is to enable the controllability of microbiological processes in activated carbon filters. We believe this can be done by applying an appropriate pre-treatment technique. To do so, we want to compare different pre-treatment methods to select the most efficient one. The idea is that after a pre-treatment step, we can better regulate the processes in a BAK, for example by reducing the supply of bacteria from the wastewater or by adding specific micropollutant-degrading bacteria at the right place in the system. The end goal is to create a well-manageable, controllable and low-maintenance filtration system that is applicable in decentralised wastewater treatment plants at district level.

Would you like to know more about the BAK project? If so, contact Sybrand Metz of Desah.

This research is partly made possible by Samenwerkingsverband Noord Nederland, European Fund for Regional Development, Province of Groningen, Province of Fryslân and the Municipality of Groningen.
Project number OPSNN0399