Wang W. and Y. Wu. | Environmental Science and Pollution Research 26(12):12042-12054

The ability of high-density luffa sponge (HDLS) immobilized microorganisms coupled with permeable reactive barriers (IM Bio-PRBs) were compared to intimate coupling of free microorganisms and permeable reactive barriers (FM Bio-PRBs) to remediate 1,1,1-TCA-contaminated groundwater. IM Bio-PRB performance was superior in removing and preventing the transport of 1,1,1-TCA and inorganic ions (NO₃^-, PO₄^3-, and SO₄^2-) which contributed to faster microorganism growth in the upgradient aquifer. This played a constructive role in reducing the processing load of the following zero-valent iron PRBs and the negative effect of free microorganism cells and inorganic ions on Bio-PRB permeability. In addition, IM Bio-PRBs were more conducive to accelerate the removal of 1,1,1-TCA in long-term remediation and 1,1,1-TCA residual concentration levels lower than the safety standard of 0.2 mg/L. The change of terminal byproducts of contaminated groundwater in Bio-PRBs showed that 1,1,1-TCA could be effectively dechlorinated and mineralized in Bio-PRBs. The reductant H₂S was much more produced and utilized in IM Bio-PRBs. Taken together, sequentially coupled IM Bio-PRBs had a better overall performance, and its service life could be prolonged. It was a different design and idea to update conventional PRB remediation technology and theory.