(374o) Evaluating Transport Factors to Understand Electrochemical Nutrient Removal and Recovery from Synthetic Animal Wastewater

Concentrated Animal Feeding Operations (CAFOs) are one of the main sources of introducing excessive nutrients, mainly phosphorus and nitrogen, to the environment via manure use as fertilizer. [1] These excessive nutrients are key factors in eutrophication of water bodies, and it is crucial to treat the CAFO effluents before disposal to water bodies, in order to reduce environmental impacts. [2] Furthermore, limited natural resources of phosphorus increases the need for an alternative resource for this nutrient. Simultaneous removal and recovery of phosphorus and nitrogen from wastewaters via an electrochemical approach, as a precipitate called MgNH₄PO₄•6H₂O, i.e., struvite, addresses both excessive amount of nutrients in these effluents and limited resources of natural phosphorus. Struvite also has economic benefit as a slow-release fertilizer. [3] A predictive model of the effects of chemical composition and solution conditions on phosphorus removal from wastewater and recovery as struvite has been introduced in literature. [4] This model requires additional experimental data to validate (or modify) the anticipated effects of temperature and ion concentration on solid phosphorus recovery.

Methodology

In the current study, the effect of ion concentration, temperature, solution agitation, and pH on nutrient removal efficiency and the type of P-containing precipitant recovered will be investigated. This investigation will occur in a bench scale setup with well-defined mass and thermal transport. This study will help with (1) providing a fundamental background knowledge for electrochemical nutrient recovery and removal, (2) enhancing the actual efficiency of electrochemical nutrient recovery by separating the recovery due solely to chemical transport and (3) assisting with validating/modifying the aforementioned literature model.

Results

The initial experiments of this study showed higher phosphorus removal from wastewater in pH of 9 in comparison to pH of 7.6, in agreement with the model prediction. [4] Further investigation of the collected solid phase samples will be used to assess the effect of pH on the type of recovered precipitate. Additional results of solid and liquid phase analyses will be presented at the conference including the effect of other transport factors on the recovered nutrient and the delineation between literature model prediction and experimental results.

References

[1] Z. Belarbi, D. A. Daramola and J. P. Trembly, “Bench-Scale Demonstration and Thermodynamic Simulations of Electrochemical Nutrient Reduction in Wastewater via Recovery as Struvite,” J. Electrochem. Soc., vol. 167, no. 4, Nov. 2020, doi: 10.1149/1945-7111/abc58f.

[2] L. Kekedy-Nagy, et. Al, “Electrochemical Nutrient Removal from Natural Wastewater Sources and its Impact on Water Quality,”

[3] Z. Belarbi and J. P. Trembly, “Electrochemical Processing to Capture Phosphorus from Simulated Concentrated Animal Feeding Operations Waste,” J. Electrochem. Soc., vol. 165, no. 13, pp. E685–E693, Jan. 2018, doi: 10.1149/2.0891813jes.

[4] G. P. Pindine, J. P. Trembly and D. A. Daramola, “Equilibrium-Based Temperature-Dependent Economic Analysis of the Recovery of Phosphorus from Different Wastewater Streams via Chemical Precipitation” ACS EST Water, 2021, 1, 2318–2326.