Nitrate Removal from Groundwater Using Immobilized Heterotrophic Algae

• Published in: Water, air, and soil pollution Vol. 231; no. 1
• Main Authors: Mollamohammada, Sara, Aly Hassan, Ashraf, Dahab, Mohamed
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 2020; Springer; Springer Nature B.V
• Subjects: Algae; Alginic acid; Atmospheric Protection/Air Quality Control/Air Pollution; Batch reactors; Beads; Carbon sources; Cells; Chlorella sorokiniana; Climate Change/Climate Change Impacts; Earth and Environmental Science; Environment; Environmental monitoring; Groundwater; Groundwater treatment; Hydrogeology; Nitrate removal; Nitrates; Nitrogen removal; Nutrient removal; Reactors; Removal; Seaweed meal; Sequencing; Sodium; Sodium alginate; Soil Science & Conservation; Uptake; Water pollution treatment; Water Quality/Water Pollution; Water, Underground; Biological nitrate treatment; Nitrate removal, nitrogen, heterotrophic growth
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/s11270-019-4334-3

The treatment efficiency of Chlorella sorokiniana and Scenedesmus species , immobilized in sodium alginate, was evaluated for removing nitrate from groundwater. The experiments were performed initially in batch mode and the best-performing conditions were replicated in sequencing batch reactor mode. S. sp. showed a higher nitrate uptake in short term than C. sorokiniana . Immobilized S. sp. and C. sorokiniana cells showed 90% nitrate removal in 9 and 12 days, respectively. The optimal ratio of algal beads/water was found to be 12.5% (v:v). Comparatively, suspended S. sp. cells were able to remove only up to 35% of nitrate in 8 days. Alginate immobilized S. sp. beads were capable of uptaking nitrate for 100 consecutive days in sequencing batch reactor mode. When tested in actual groundwater, 90% of nitrate was eliminated in 2 days without need for any additional carbon source. Immobilized algal beads can be a low-cost alternative technique to remove nitrate from groundwater as they are water-insoluble, non-toxic, easy to harvest, and offer high removal efficiency.