Development of Sustainable Technology for Effective Reject Water Treatment

Aleksandra Szaja (), Maria Sawicka and Rafał Smagała
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Aleksandra Szaja: Faculty of Environmental Engineering and Energy, Lublin University of Technology, Nadbystrzycka 40B, 20-618 Lublin, Poland
Maria Sawicka: Faculty of Environmental Engineering and Energy, Lublin University of Technology, Nadbystrzycka 40B, 20-618 Lublin, Poland
Rafał Smagała: Faculty of Environmental Engineering and Energy, Lublin University of Technology, Nadbystrzycka 40B, 20-618 Lublin, Poland

Sustainability, 2025, vol. 17, issue 14, 1-22

Abstract: This study examined a strategy for effective reject water treatment involving hydrodynamic cavitation (HC) combined with subsequent adsorption using natural zeolites. Two experiments were conducted: The first involved the selection of optimal pre-treatment conditions of HC for biodegradability and to reduce the ammonium nitrogen and phosphate content. Three inlet pressures of 3, 5, and 7 bar and two types of cavitation inducers, i.e., multiple- and single-hole orifice plates, were evaluated. Adsorption experiments were conducted in batch mode using natural zeolite, and three doses of zeolite (50, 100, and 200 g/L) and six contact times (4–24 h) were examined. In the HC experiments, the application of 3 bar pressure, a single-hole cavitation inducer, and a cavitation time of 30 min resulted in the removal of ammonia nitrogen and phosphates amounting to 26.5 and 23%, respectively. In this case, 3.6-fold enhancement in the biodegradability index was also found. In the second experiment, the use of zeolite led to a decrease in the remaining content of both ammonia nitrogen and phosphates, improving the chemical oxygen demand-to-total nitrogen ratio. The highest removal efficacy was found for the highest zeolite dose of 200 g/L and the longest cavitation time of 24 h. Under these conditions, the ammonia nitrogen and phosphate removal rates were 70 and 94%, respectively.

Keywords: reject water; hydrodynamic cavitation; adsorption; zeolite; ammonia nitrogen; phosphates; energy aspects; sustainable technology development (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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