A system for reducing total dissolved solids in wastewater can include a vertical reactor that can include a flexible sheet material, where the flexible sheet material can be configured to facilitate the growth and attachment of an algal biofilm. The vertical reactor can include a shaft, where the shaft can be associated with and can support the flexible sheet material, and a drive motor, where the drive motor can be coupled with the shaft such that the flexible sheet material can be selectively actuated. The system can include a fluid reservoir containing a portion of wastewater through which the flexible sheet material is configured to pass as well as a stressor operably configured to stimulate the algae to produce an extracellular polymeric substance. A method of reducing total dissolved solids in wastewater includes moving an algal biofilm through the wastewater and moving the algal biofilm through a gas.