Forward osmosis with an algal draw solution to concentrate municipal wastewater and recover resources

Abstract

This study aimed to concentrate and recover resources from municipal wastewater with a novel forward osmosis (FO) system. The FO system used synthetic seawater as the draw solution (DS) to extract water from the feed solution (FS) (synthetic raw municipal wastewater). Because ammonium passed through the FO membrane from the FS to the DS, we cultivated an algal strain (Chlorella vulgaris) in the DS to remove and recover ammonium. For three consecutive FO cycles, the algal FO system removed 35.4% of the ammonium from the DS, increased the concentrations of COD and PO 3− 4 − P in the FS by 43.0%, and achieved a water flux of 11.59 ± 0.49 L m −2 hr −1 . Throughout the FO cycles, the algal biomass concentration of the DS stayed at 606 ± 29 mg COD/L due to simultaneous algal growth and DS dilution. This FO process may be feasible to implement for full-scale applications to concentrate wastewater and recover resources. © 2019 Water Environment Federation • Practitioner points• A novel forward osmosis (FO) system with an algal draw solution (DS) concentrated municipal wastewater and recovered resources (ammonium). • Ammonium but not organic matter or phosphate diffused across the FO membrane from the feed solution (FS) to the DS. • The algal FO system increased COD/phosphate concentration in the FS by 43.0% and removed 35.4% of ammonium from the DS. • The water fluxes in the algal FO system and the control were 11.59 and 12.02 L m −2 hr −1 , respectively. • The novel algal FO process has the potential to improve full-scale efficiency by concentrating municipal wastewater and recovering nutrients.

Effects of temperature, pH, feed, and fertilizer draw solution concentrations on the performance of forward osmosis process for textile wastewater treatment

“…Unlike other membrane processes, which remove water from a salt solution using a semipermeable layer at extremely high pressure, FO isolates salts from water sources by simply utilizing an osmotic concentration slope (Karunakaran, Chaturvedi, et al, 2021;Phuntsho et al, 2016;Raval & Koradiya, 2016;. A concentrated draw solution (DS) that has a high osmotic gradient is used to draw water from saline water (Hawari et al, 2016;Karunakaran, Mungray, et al, 2021;Rood et al, 2020). Fertilizer drawn FO (FDFO) has added interest as the dilute fertilizer DS could be used for agricultural activities such as fertigation (Chang et al, 2020;K et al, 2021;Phuntsho et al, 2011).…”

Engineered osmosis – sustainable technology for water recovery, product concentration and energy generation

“…The advantage of this approach was that the algae could capture and utilize the ammonium that diffused to the DS. 78 2.4 Application of FO in the pharmaceutical industry 2.4.1 Concentration and recovery of active pharmaceutical ingredients. The pharmaceutical industry utilizes significant quantities of solvent for various upstream/downstream processes, and thus the concentration of active pharmaceutical ingredients (APIs) is crucial to meet the standards of sustainable processing.…”

“…The advantage of this approach was that the algae could capture and utilize the ammonium that diffused to the DS. 78…”

Enhancing ammonium rejection in forward osmosis for wastewater treatment by minimizing cation exchange

“…In addition, the permeated and accumulated ammonium in DS could further escape into the water when water recovery from DS is conducted [8,13]. Thirdly, the escape of ammonium from FS also results in less recovery efficiency when nutrient recovery from wastewater is targeted.…”