9.9 Nanofiltration of greywater effluent to remove micropollutants

Despite the considerable improvement in the field of wastewater treatment during the recent decades, discharge of treated wastewater in the environment can still create many problems. Although most wastewater treatments plants can remove efficiently the organic and nutrient content from the wastewater, new threats, the so called emerging compounds (EC), are being addressed now such as micropollutants (MP), antibiotic resistant bacteria and heavy metals. Such compounds can be rather impervious to conventional biological treatment techniques; thus additional treatment steps are needed to remove them. A very effective technique for the removal of EC is hollow fiber nanofiltration (HNF), though there are not enough data available regarding the use of HNF to treat wastewater effluent directly after the secondary settling.

Research challenge
The aim of this study is to assess the fate and removal of micropollutants from greywater using HNF under real conditions from the demo site of Noorderhoek, a decentralized wastewater treatment plant in Sneek. In that plant blackwater combined with kitchen waste are treated anaerobically and the effluent of the digester (after additional removal of N by ANNAMOX and struvite precipitation) is combined with greywater and then treated with activated sludge. The effluent of the activated sludge system will be treated using HNF. Commercially available HNF membrane modules are used, and a relation between, crossflow velocity, recovery and permeate quality will be studied.

Important in this study is the re-use possibility of the HNF permeate, this can be direct, but also after a post-treatment, i.e. by using spiral wound reverse osmosis (SWRO). Here the optimum recovery in combination with HNF is an important aspect in waste-water re-use.
In this study also new insights in treating the membrane concentrate stream need to be developed.

The ideal MSc candidate has solid knowledge and skills in process engineering, environmental technology, (bio)chemical engineering or similar. An interest (or experience) in membrane science and technology is essential. A deep understanding of physical and chemical properties of MPs and membrane materials is a must to understand and manipulate the transport mechanisms by membrane selection, design, and operation. Next to transport of MPs through polymer membranes also a good understanding of (crossflow) membrane processes and biological process is here required.

The research project is part of the Wetsus research theme Advanced Water Treatment. The following companies are part of the theme: Evides, Oasen, Dunea, Vitens, WON, Desah, NXFiltration.

Intended promotors: Prof. H.D.W. Roesink and Prof. dr. ir. W van der Meer
co-promotor: Dr. Ir. J de Grooth
all from the University of Twente.

For more information contact: .

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Wetsus, Leeuwarden, The Netherlands


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