Location: National Soil Erosion ResearchTitle: Development of a regeneration technique for aluminum-rich and iron-rich phosphorus sorption materials
Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2020
Publication Date: 6/23/2020
Citation: Penn, C.J., Scott, I., Huang, C. 2020. Development of a regeneration technique for aluminum-rich and iron-rich phosphorus sorption materials. Water. 12(6):1784. https://doi.org/10.3390/w12061784.
Interpretive Summary: Dissolved phosphorus (P) losses to surface waters are considered the main cause of surface water eutrophication, such as Lake Erie. P removal structures are large landscape-scale filters for treating drainage water before reaching a surface water outlet. These structures utilize filter media that vary in cost, performance, and longevity. Some of the best P filter materials are very expensive, and the ability to regenerate them in a simple and feasible manner would greatly reduce costs by allowing re-use. We tested three different iron (Fe) rich commercial P sorption media: "Alcan", "Phosredeem", and "Biomax" for their ability to be regenerated and reused for filtering P under various conditions. Phosredeem was a poor sorbent compared to the other two materials, and was unable to be regenerated. However, Alcan and Biomax were able to be regenerated twice, allowing for about 80% of previously added P to be recovered. While regeneration with hydroxide solution improved with increased hydroxide concentration, volume, and number of recirculations, acceptable regeneration could be acheived with only five pore volumes and a 1 molar concentration. This will allow for a tremendous cost savings in implementation of such Fe oxide rich media in P removal structures.
Technical Abstract: The reduction of dissolved phosphorus (P) transport to water systems is of critical importance for water quality. Phosphorus sorption materials (PSMs) are media with high affinity for dissolved P, and therefore serve as the core components of P removal structures. These structures can intercept dissolved P in surface and subsurface flows, before discharge into water bodies. While the P removal ability of PSMs has been extensively studied, lesser is known about the capacity to regenerate and recover P from P-saturated PSMs. This article evaluates a methodology to recover the P removal ability of aluminum- and iron-rich P-saturated PSMs. A series of flow-through experiments were conducted, alternating between P sorption (0.5 and 50 mg L''1 P) and desorption with potassium hydroxide (KOH; 5 or 20 pore volumes [PV]), varying residence times (0.5 min and 10 min), and number of recirculations (0, 6 and 24). Across two cycles of sorption-desorption, Alcan, Biomax and PhosRedeem showed an average P recovery of 81%, 79%, and 7%, with standard deviation of 10%, 21% and 6%, respectively. The most effective regeneration treatment was characterized by the largest KOH volume (20 PV) and no recirculation, with up to 100% reported P recovery. Although KOH at 5 PV was less effective, the use of recirculation did increase P recovery. The lifetime of Al/Fe-dominated PSMs in P removal structures can be extended through feasible regeneration techniques demonstrated in this study, for both high and low P concentration scenarios.