Hydrophilic surface to reduce biofouling in new Lanxess RO membranes
Lanxess has expanded its range of reverse osmosis membrane elements for drinking water and wastewater treatment...
COLOGNE, Germany - Specialty chemicals company Lanxess has expanded its range of reverse osmosis (RO) membrane elements for drinking water and wastewater treatment.
Three product grades of the new Lewabrane RO ultra low pressure (ULP) line are now available, which the company said “display higher water permeability than the standard elements”.
The new ULP products are recommended for applications in which a high flow rate, moderate salt rejection and low power consumption are the primary design parameters.
Synthetic organic substances, known as trace elements, can be found in bodies of water in concentrations of a few nanograms to a maximum of a few micrograms per liter. Originating for instance from drugs, household chemicals, industrial chemicals, cosmetic products and crop protection agents, they are introduced into the water system by household and industrial wastewater.
Lanxess said it has designed the ULP membranes to remove such organic compounds “almost entirely even at low operating pressures”.
To reduce the formation of organic deposits – i.e. typical biofouling – in wastewater, the ULP membrane has the most hydrophilic surface of all the Lewabrane product grades.
Due to the hydrophilic behaviour, a thin, protective film of water forms on the membrane surface, which reduces the adsorption of organic substances.
Alexander Scheffler, director membrane business in the LANXESS Liquid Purification Technologies business unit (LPT), said: “Drinking water systems process tremendous volumes of surface water often on a daily basis. Therefore, to minimise investment costs, it is desirable to have a membrane that displays high water permeability and thus a high flow rate, like those in our Lewabrane RO ULP line.”
The alternating strand design (ASD) feed spacers, which are inserted in the membrane elements to create space between their surfaces for flowing water, also reduce fouling, the company said. An alternating strand design, comprising filaments of different thickness, cause uniform overflow and thus counteract biofouling.
The research project on “Modular Treatment and Monitoring in Wastewater Recycling (Multi-ReUse)” was launched in 2016 with funding from the German Federal Ministry of Education and Research (BMBF).
This project aims to develop and improve processes for the economical use of wastewater.
Against this backdrop, the Oldenburgisch-Ostfriesische Wasserverband (OOWV Water Management Association) joined forces with research partners – IWW Zentrum Wasser GmbH and the Biofilm Center at Duisburg-Essen University (UDE) – and equipment companies – inge GmbH, IAB Ionenaustauscher GmbH Bitterfeld (a wholly owned LANXESS subsidiary) and De.EnCon GmbH – to develop flexible processes for producing defined water qualities and volumes.
The results are being implemented at the Nordenham water treatment plant in Lower Saxony in collaboration with the OOWV. This pilot facility is due to go into operation in July 2017. It incorporates membrane elements from LANXESS, including the new ULP products.