9.5 Potential of an innovative ultrapure water production plant with biological activated carbon filters

Activated carbon (AC) filters are applied in drinking water purification to remove organic pollutants and biofouling precursors. AC particles are microporous and thus have a high capacity to adsorb organic compounds. In biological activated carbon (BAC) filters, micro-organisms form a biofilm on activated carbon granules. These micro-organisms use the organic pollutants and biofouling precursors in the feed water as substrate, counteracting the AC saturation over time. The biofilm may even facilitate desorption and thus AC regeneration.

The Puurwaterfabriek in Emmen (The Netherlands) produces ultrapure water for steam production from municipal wastewater treatment plant effluent. The plant comprises the following sequential processes: ultrafiltration (UF), BAC filters, reverse osmosis (RO) and electro-deionization. The main purpose of the BAC filters is to remove fouling precursors, extending the lifetime of the RO membranes. The BAC filters have also been shown to remove organic micropollutants though.

The BAC filters at the Puurwaterfabriek have been in operation for over 10 years without need for AC replacement. This extreme long AC lifetime is likely related to the UF pre-treatment and the unique design and operation of the BAC filters. However, the exact role of those factors for the overall performance is not completely understood. If these factors are unravelled, the operational costs for the BAC filters and RO units at the Puurwaterfabriek could be reduced. Furthermore, the innovative technology could be extended to other water treatment plants.

Research challenge
To understand how in a treatment plant as the Puurwaterfabriek, UF pre-treatment and BAC filter design and operation allow to minimise BAC filter size and maximise the lifetime of the AC granules and RO membranes. The research will be conducted at both lab and industrial scale.

Specific research challenges will be to:
1. Clarify the influence of oxygen dosing, back washing and volumetric loading rate on the fouling precursor and micropollutant removal in BAC filters.
2. Understand the role of different ultrafiltration approaches in influencing the performances of BAC filters and the reduction of fouling of RO membranes
3. Develop a simple dynamic one-dimensional model to calculate transport, adsorption, desorption and biodegradation of micropollutants and biofouling precursors in BAC particles.

The student will cooperate with another PhD candidate, who will focus on the microbiology of the diverse and metabolic active biofilms growing on the BAC particles.

We are looking for a candidate with an MSc degree in the field of environmental or chemical engineering with additional knowledge on biological water treatment.

We are looking for a candidate with:
· a strong interest in doing scientific research in cooperation with societal stakeholders,
· ample of experience with laboratory work,
· excellent written and oral communication skills,
· an interest to translate the research results into a theoretical model.

The PhD candidate should be willing to work at two different locations: Wetsus and the Puurwaterfabriek in Emmen (The Netherlands).

The research project is part of the Wetsus research theme BIOFILMS.
The following companies are part of the theme:


Promotor: to be defined
Wetsus supervisors: Dr. ir. R.J.W. (Roel) Meulepas, Dr. M.C. (Cristina) Gagliano

For more information contact , (Theme coordinator Biofilms)

Please do NOT send your CV directly to this email address. Only complete applications sent via the website will be evaluated (How to Apply).


Wetsus, Leeuwarden, The Netherlands


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