Model‐based investigation of the chemical phosphorus removal potential of the peroxide regenerated iron‐sulfide control technology

Abstract

In this study, the potential of using peroxide regenerated iron‐sulfide control (PRI‐SC®) for chemical phosphorus removal utilizing the existing iron sulfide found in wastewaters was investigated in batch tests and compared in full‐scale facility‐wide simulations to using iron salts. PRI‐SC is a combination treatment that utilizes iron salts and hydrogen peroxide in a synergetic fashion, where hydrogen peroxide is used in regenerating the spent iron salt in situ in the form of iron sulfide, yielding ferric iron and colloidal sulfur. A simplified kinetic model was developed, calibrated, and integrated into a facility‐wide model to simulate the process at the full‐scale. Experimental results showed that dosing hydrogen peroxide, even at doses lower than the stoichiometrically required to oxidize iron sulfide, freed, and oxidized sulfide bound ferrous iron to ferric iron, which was consequently hydrolyzed and affected phosphorus removal. Higher dosing of hydrogen peroxide did not affect change in the speciation of sulfur remaining predominantly as elemental sulfur. Simulations showed that the application of PRI‐SC with supplemental ferric iron dosing was able to cut the costs of chemicals addition up to 53% while maintaining a steady‐state effluent phosphate concentration below 0.01 mg/L. Practitioner points The kinetic model was used to optimize ferric iron and hydrogen peroxide dosing. The developed model can be integrated in existing wastewater process simulators. Dosing hydrogen peroxide effectively oxidized ferrous iron to ferric iron. The combination of hydrogen peroxide and iron salts can reduce the chemical addition cost by 53%.

Effect of Fe3+ on the nutrient removal performance and microbial community in a biofilm system

“…Fe 3+ is one of the metal ions used in chemical P removal ( Ping et al, 2023 ). The presence of Fe 3+ can promote a range of polymerization reactions leading to the formation of multinuclear hydroxyl complexes characterized by long linear structures, which can be removed via neutralization, adsorption bridging, and flocculation sweeping, followed by P removal via precipitation and separation ( Ismail et al, 2022 ). In addition, as an indispensable constituent of numerous functional proteins (such as cytochromes and iron-sulfur and iron-nickel proteins), Fe is an essential element for microbial growth ( Saoudi et al, 2022 ), and is active in cellular metabolic reactions ( Wang et al, 2021 ).…”