Nanofiltration (NF) is a pressure driven membrane process wich operational conditions and treatment performance is between reverse osmosis and utlrafiltration. Unlike ultrafiltration, nanofiltration membranes removes to a high degree dissolved organic matter and present a high rejection of multivalent ions such as calcium, magnesium or sulfate. In comparison to reverse osmosis, nanofiltration presents a moderate removal of monovalent ions (sodium and chloride) but requires lower operative pressure and energy demands. Nanofiltration and reverse osmosis spiral wound membranes, which are commonly employed for drinking water, industrial and reuse applications present several limitations in terms of fouling control:
- The materials employed in NF and RO membranes present low chemical resistance to oxidizing chemicals such as chlorine.
- Flat sheet NF and RO membranes configured in spiral wound modules present low mechanical strength which does not allow applying physically cleanings through backwashes commonly employed in UF and MF membranes.
- Due to the reduced space of the retentate channels of spiral wound configuration, a high effluent quality feedwater and intensive pretreatement is required in order to avoid fouling and clogging of NF and RO membranes.
The aWARE project will evaluate hollow fiber nanofiltration membranes wich present the flexibility and advantages of UF membranes in terms of chemical and physical cleaning fouling control strategies, low pretreatment requirements in comparison to conventional spiral wound RO and NF membranes and a higher rejection of dissolved organic matter including priority and emerging pollutants.
The aWARE project will evaluate the feasibility of using hollow fiber nanofiltration membranes in combination with a biological process in order to separate produced biomass and obtain high quality treated effluent, achieving water treatment and reclamation in a single step.