Fluoride Action Network

Potable-quality water recovery from primary effluent through a coupled algal-osmosis membrane system.

Source: Chemosphere Feb;240:124883. Epub 2019 Sep 16. | September 16th, 2019 | Authors: Jiang W, Lin L, Gedara SMH, Schaub TM, Jarvis JM, Wang X, Xu X, Nirmalakhandan N, Xu P.
Industry type: Water Treatment


  • Demonstrated algal-membrane system for potable water recovery from wastewater.
  • The product water met USEPA primary and secondary drinking water standards.
  • Chemical cleaning using NaOH was effective to restore FO membrane performance.
  • FO was effective to prevent RO membrane fouling during wastewater treatment.


A coupled algal-osmosis membrane treatment system was studied for recovering potable-quality water from municipal primary effluent. The core components of the system included a mixotrophic algal process for removal of biochemical oxygen demand (BOD) and nutrients, followed by a hybrid forward osmosis (FO)-reverse osmosis (RO) system for separation of biomass from the algal effluent and production of potable-quality water. Field experiments demonstrated consistent performance of the algal system to meet surface discharge standards for BOD and nutrients within a fed-batch processing time of 2-3 days. The hybrid FO-RO system reached water productivity of 1.57 L/m2-h in FO using seawater as draw solution; and permeate flux of 3.50 L/m2-h in brackish water RO (BWRO) and 2.07 L/m2-h in seawater RO (SWRO) at 2068 KPa. The coupled algal-membrane system achieved complete removal of ammonia, fluoride, and phosphate; over 90% removal of calcium, sulfate, and organic carbon; and 86-89% removal of potassium and magnesium. Broadband characterization using high resolution mass spectrometry revealed extensive removal of organic compounds, particularly wastewater surfactants upon algal treatment. This study demonstrated long-term performance of the FO system at water recovery of 90% and with membrane cleaning by NaOH solution.

*Abstract online at https://www.sciencedirect.com/science/article/pii/S0045653519321228