Geopolymer-based composite filtration materials for deep purification of wastewater: Efficient nitrogen removal and...

Geopolymer-based composite filtration materials were synthesized for the first time using activated carbon (AC) to enhance wastewater purification. Under oligotrophic conditions, the AC-GP filter reduces the concentrations of total nitrogen (TN) and total organic carbon (TOC) in the effluent to 6.5 mg/L and 6 mg/L, respectively. This is achieved through carbon released from hydroxyethyl cellulose (HEC), which promotes microbial community development, thereby enabling the simultaneous removal of nitrogen and carbon. Also, it exhibited strong adaptability and high efficiency in eliminating emerging contaminants (ECs), achieving removal rates exceeding 90% for erythromycin (ERY) and 50% for sulfamethoxazole (SMX). Microbial analysis revealed that AC-GP promoted biodiversity and zoned iterative removal of conventional pollutants and ECs. Compared with traditional ceramsite or quartz-based filters, the proposed system demonstrated superior removal efficiency, operational simplicity, and cost-effectiveness. This work provides an important reference for the construction of geopolymer-based composite materials, which is conducive to the efficient purification of carbon, nitrogen and ECs under oligotrophic conditions, and ensures water quality safety and sustainability.