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Phosphate Remediation and Recovery from Lake Water using Modified Iron Oxide-based Adsorbents - abstract
Citation:
Nadagouda, M., T. Speth, J. Garland, C. Han, X. Li, J. Lalley, AND D. Dionysiou. Phosphate Remediation and Recovery from Lake Water using Modified Iron Oxide-based Adsorbents - abstract. Presented at AWWA, Logan, UT, September 16 - 18, 2015.
Impact/Purpose:
Nutrient recovery
Description:
As a limiting nutrient in most aquatic ecosystems, increased phosphate (PO43-) concentrations can accelerate eutrophication resulting in the proliferation of potentially toxic harmful algal blooms. In addition to environmental impacts of PO43- pollution, overall reserves of this essential and non-renewable resource are quickly declining while its demand by industries (e.g. for fertilizer production) is increasing. Therefore, new techniques for both remediating and recovering PO43- are an area of emerging concern. One potential technique is PO43- adsorption by iron oxides. Iron oxides, like goethite (α-FeOOH) for example, are readily available and have large surface areas, making them exceptional adsorbents for anions like PO43-. AdEdge Technologies Inc. has taken advantage of the availability and physiochemical properties of goethite in their development of Bayoxide ® E33 Adsorption Media (E33). While originally designed for arsenic remediation, E33 can adsorb a range of anions including PO43-. In this project, the surface of E33 was modified by the addition of silver and manganese nanoparticles to add multi-functionality and enhance PO43- adsorption. After the modification of E33, the samples were characterized to gain insights on their surface area (BET surface area analyzer), point of zero charge (zeta potential analyzer), mineralogy (X-ray diffraction), surface morphology (scanning electron microscopy), and crystal structure (high resolution-transmission electron microscopy). Phosphate adsorption experiments using lake water were conducted to compare the effectiveness of each modified adsorbent. Batch experiments were also conducted to examine adsorption kinetics and equilibrium for PO43- adsorption while column experiments were carried out to explore the effects of continuous-flow adsorption. Results indicate that one of the modified sorbents had an increased capacity for PO43- adsorption in comparison to unmodified E33. In order to evaluate the recovery of PO43- for reuse, desorption experiments were carried out. Desorption using a strongly basic solution (0.10 M NaOH) revealed that that a majority of sorbed PO43- could be desorbed back into solution indicating the possibility of PO43- recovery for reuse using iron oxide-based sorbents. In this presentation, the results on the characterization of the modified E33 and the adsorption of PO43- the real lake water will be reported in detail.
