Treatment of nitrate-contaminated groundwater using microbially enhanced permeable reactive barrier technology

Abstract

Microbially enhanced permeable reactive barriers (PRBs) are a technology for the remediation of NO₃⁻-N-contaminated groundwater. The removal of NO₃⁻-N from nitrate-contaminated groundwater using a sulfur-based biodenitrification reactor was studied. The average values of the NO₃⁻-N removal efficiency using SSS (sand : cement : S⁰ : scallop shell = 1 : 1 : 1.5 : 2) and SWC (sand : cement : S⁰ : wood chips = 1 : 1 : 1.5 : 0.5) reactors were 97.75% and 90.06%, respectively. In addition, the maximum value of the NO₃⁻-N removal efficiency using the SSS reactor reached 100% with a low NO₂⁻-N accumulation rate, and the scallop shell was essential to stabilize the pH value of the reactor and reduce the production of SO₄²⁻. In the SSS and SWC reactors, Sulfurimonas and Thiobacillus played major roles in the denitrification process, together constituting 72.29% and 84.69%, respectively. With the analysis of organic elements in the composite filler and scanning electron microscopy (SEM), we also found that S⁰ played an important role in the reactor. Therefore, our research could provide some technical insights into the treatment of nitrate-contaminated groundwater.