Immobilized algae‐based treatment of herbicide‐ contaminated groundwater

Scenedesmus species, immobilized on alginate gel was found effective in removing nitrate, atrazine, magnesium, phosphorus, zinc, oxadiazon, and triallate from groundwater in a continuous flow reactor. The lab- scale experiments with synthetic groundwater, made of 8.8 mg/L NO3 -N and 90 µg/L atrazine were performed at a hydraulic retention time of seven days and the temperatures of 20 and 35 °C. The highest uptake of nitrate and atrazine was observed at 20 °C (97% and 70%, respectively). When tested in actual groundwater, 92% of nitrate, 100% of magnesium, 99.9% of phosphorus, and 92% of zinc were successfully removed at the end of 29 days treatment operations. The algal beads removed 100% of oxadiazon and triallate in the first 10 days, but some of the herbicides diffused back into the solution toward the end of the treatment process.