Real Stories of Pollution Cleanup Using Bioremediation.

Together with #ALL4BIOREM, we’re excited to launch our Success Story Series! In the coming weeks, we’ll be showcasing real-life case studies that demonstrate how nature-based solutions - like #bioremediation - can transform contaminated environments into cleaner, healthier ecosystems.

Success Story:

Integration of Bioelectrochemical systems & Phytoremediation for decontamination of Metal(liod)s polluted groundwater.

Short Description:

Contaminated groundwater puts enormous strain on already stressed water. If the metal(liod)s associated contamination is deliberately introduced or present in deep soil strata, these pollutants can weaken the aquifer's ability to self-purify and sustain healthy groundwater. Bioelectrochemical system (BES) and phytoremediation technologies (one of a type of bioremediation) can sequentially not only remove the metal, but also reduce the toxicity of treated water. The higher levels of metal(liod)s and extreme physical parameters (such as pH and salinity) of water can limit the choice of potential plants for phytoremediation. However, a coupled BES with phytoremediation can remove this issue. In this way, the BES can operate in multistage configuration, and the effluents generated (i.e. exhausted anolyte and treated catholyte) can be fed to subsurface vertical flow constructed wetland systems.

Methods:

Selection of tolerant macrophytes for the phytoremediation of metal(liod)s polluted groundwater.
Definition of a cathodic approach aiming to remove wide range of metals & metalliods from polluted groundwater through direct reduction & coprecipitation in BES reactors.
Identification of sustainable applied voltages in BES reactors to enable metal removal from polluted groundwater, thus preventing electroactivity decay due to high anodic potential.
Preliminary and lower TRL integration of BESPhytoremediation and subsequent characterization of toxicity reduction.
Upscaling of BES reactors and use of sequential BES reactors for sequential metals removal.
Integration of Upscaled-BES and coupling with phytoremediation for continuous batch remediation.

Outcomes:

Overall, by using the combined BES-phytoremediation application, the contaminated groundwater was treated efficiently. By using BES, up to 90% of the metal(liod)s content from the polluted groundwater was removed. However, as anticipated, the treated water was still having acidic pH (~4) and a high level of dissolved solids, as well as the remaining 10% of metals. This was also accompanied with the exhausted anolyte that was used as carbon source for the electrogenic biofilm on anode, and the spent buffer (i.e. containing electrolytes recovered in the concentration chamber) of the up-scaled BES reactor. The treated groundwater along with the other effluents was combined and fed to constructed wetlands for phytoremediation. This combined process reduces nutrient levels, adjusts pH and salinity, and completely eliminates the ecotoxicity of the final treated water.