Application of cyclic process for phosphorus and matrix co-enrichment via hydrate technology in various industrial wastewater

Concentrated phosphorus-containing wastewater not only poses environmental risks by causing eutrophication but also represents a notable loss of valuable phosphorus resources that could otherwise be recovered and reused. The cyclopentane hydrate (CPH) formation process offers dual benefits of wastewater treatment and phosphorus enrichment. This study systematically evaluates the co-enrichment effect of a multicycle CPH process using various real wastewater samples containing phosphorus, including livestock and industrial effluents. The dihydrogen phosphate ion was identified as the optimal phosphate species for enrichment within its predominant pH range (2.1–7.2), elucidating the phosphorus enrichment mechanism. The results show that higher initial phosphorus concentrations extend the hydration time required to achieve a conversion exceeding 50 %. Furthermore, analysis of thermodynamic and kinetic behaviors at different concentrations and reaction times revealed that the enrichment factor progressively increased from 1.06 to 1.42. Multicycle enrichment exhibited stable performance, maintaining individual cycle enrichment factors of 1.3–1.4 across various matrices and successfully concentrating phosphorus from 1 % to 3 % over four cycles. Overall, these findings highlight the potential of hydrate-based technology for phosphorus and matrix enrichment from diverse waste streams, thereby promoting resource recycling.