Combined antibiotic and heavy metal pollution has generated considerable concern. Constructed wetlands (CWs) have been shown to efficiently remove pollutants; however, the microbial community responses to combined pollutants remain enigmatic. In this study, seven microcosm CWs were planted with Myriophyllum aquaticum, spiked with tetracyclines (TCs) (300-30,000 μg/L), alone or with Cu(II), to investigate the response of plant-associated microbial communities. TCs and the Cu/TC ratio greatly affected the performance of CWs. Tetracyclines led to higher microbial diversity, evenness and richness, while UniFrac distances and principal coordinate (PC_O) and redundancy analyses revealed that the co-presence of TCs and Cu(II) led to variations in bacterial communities. Proteobacteria, Cyanobacteria and Bacteroidetes were the dominant microbial phyla and Cloacibacterium, Hydrogenophaga, Rheinheimera and Denitratisoma accounted for 6.2-21.0% of all genera. Therefore, the co-occurrence of heavy metals should be considered when judging the removal potential of TCs in phytoremediation.

Coagulation can effectively recover substances from wastewater; however, there is a lack of efficient coagulants for simultaneous recovery of organic matter, nitrogen, and phosphorus. We prepared a composite polysilicate metal (CSM) flocculant by combining Fe³⁺ and Mg²⁺ ions in polysilicic acid (PSiA). According to the results of scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR), the CSM exhibited a larger amorphous phase along with new compounds, including Mg₃Fe₂(SiO₄)₃ and hydroxyl metals. The CSM demonstrated a higher coagulation efficiency than PSiA and polymeric ferric sulfate, particularly for PO₄³⁻-P and NH₄⁺-N removal. The metal/silicate molar ratio substantially influenced the structure and composition of the CSM, along with the coagulation efficiency, with an optimal ratio of 3:1. Additionally, we proposed a novel preparation strategy to achieve an optimum CSM basicity (B*) for coagulation by adjusting the initial pH of PSiA (pH_Initial) without adding an alkali agent. The results demonstrated that the optimum B* can be obtained by adjusting pH_Initial to 0.5 or 1. The overall optimum coagulation performance for the simultaneous removal of organic matter, PO₄³⁻P, and NH₄⁺-N from wastewater was 68.5%, 99%, and 17.5%, respectively. This study provides a feasible approach for synchronous pollutant recovery from wastewater.

Livestock and poultry farming effluents (LPFE) have become a significant source of pollution in the agricultural water environment, with nitrogen (N) and phosphorus (P) being the major pollutants. The use of inexpensive Mg2⁺ -modified materials as crystallization carriers can enhance the struvite crystallization and precipitation reaction, enabling efficient recovery of N and P nutrients from LPFE. In this study, Mg2⁺ -modified corncob biochar (CCBC-Mg) and Mg2⁺ -modified natural zeolite (NZ-Mg) were assessed for their simultaneous recovery of N and P from LPFE. BET, SEM-EDS, FTIR, XRD and adsorption isotherm and adsorption kinetics modelling were used to study the N and P adsorption properties and mechanisms. The results showed that Mg2⁺ modification significantly enhanced the simultaneous ammonia nitrogen (AN) and total phosphorus (TP) recovery of the two materials. After modification, corncob biochar (CCBC-Mg) showed the best P recovery performance, while natural zeolite (NZ-Mg) showed the best AN recovery, with adsorption quantities reaching 116.99 mg/g and 47.50 mg/g, respectively. The findings demonstrated that the adsorption processes for both AN and phosphate across all materials adhered to the pseudo-second-order kinetic model and Langmuir isotherm, collectively indicating that monolayer adsorption governed by chemical interactions was the predominant mechanism. CCBC and NZ mainly adsorbed AN and TP by electrostatic attraction and ion exchange, whereas CCBC-Mg and NZ-Mg, mainly relied on struvite precipitation on the material surface. The Mg2⁺ - modification increased the solution pH and formed Mg-P precipitates on the material surface, providing a favourable alkaline environment and nucleation conditions for the struvite reaction, thereby promoting the simultaneous recovery of AN and TP by the materials. This study could provide a theoretical basis for the design of struvite carrier for the simultaneous recovery of AN and TP from LPFE by the struvite precipitation method, and promote the application of this process in livestock and poultry farming effluent treatments.