Hybrid NF-MBR & RO System for High Water Recovery

Technology Overview

Reclaimed water is a critical source of water in Singapore and globally. Common practical limit of existing technology based on microfiltration/ultrafiltration-membrane bioreactor (MF/UF-MBR) + reverse osmosis (RO) for water reclamation is 75-85% recovery due to RO membrane fouling.

A hybrid system consists of a high retention nanofiltration-membrane bioreactor (NF-MBR) + RO is developed to achieve more than 90% of water recovery at 10 L/m2.h flux rate. NF-MBR produces superior quality effluent because NF membrane can retain low molecular weight organics and scale forming divalent ions. Thus, membrane fouling in downstream RO process can be alleviated significantly, which allows higher recovery. In addition, the inherent advantages of lower fouling potential of RO feed water include: (i) reduced chemical usage and energy consumption associated with RO membrane fouling, (ii) extend the RO membrane lifespan, and (iii) reduced water production cost.

The technology owner is interested in seeking technology licensing collaborator or manufacturing partner. 

Technology Features & Specifications

The NF-MBR+RO system for water reclamation consists of a biological process with side-stream NF membrane unit (NF-MBR) for wastewater processing to produce superior quality effluent as feed water for downstream RO unit to produce clean water. The key features of NF-MBR unit are the novel low pressure NF membrane and customized biological process. Conventional NF membranes are not suitable for direct wastewater processing due to high operating pressure requirement and severe membrane fouling potential. However, the novel hollow fiber NF membrane only requires operating pressure <2 bar, possesses a positively charged selective layer, molecular weight cut off (MWCO) of <500 Da, rejection of Mg2+ and Ca2+ ~90%. It has very low rejection of Na+ ions (<15%) while maintaining high rejection of the divalent ions, is the key to achieve such a low operating pressure condition. In addition, the bioprocess is customized for elevated salt environment in the bioreactor. When coupled with the optimized biological process, the NF-MBR offers several advantages over conventional MF/UF-MBR include a superior quality of effluent water and less sludge production. 

Potential Applications

This technology could be applied in the following areas:

  • Wastewater reclamation
  • Industrial water recycling

Customer Benefits

  • High recovery water reclamation
  • Lower chemical use, less energy consumption associated with RO membrane fouling
  • Longer RO membrane lifespan
  • Less sludge production
  • Reduced water production cost

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