In order to improve the removal ability of nitrogen and phosphorus pollutants from sewage with low C/N ratio, this study prepared the glucose polymer-based pyrite tailings with core-shell structure through glucose polymerizing on the surface of pyrite tailings particles and constructed a heterotrophic-sulfur autotrophic mixed-denitrification system. The experimental results show that compared with ordinary pyrite tailings, pyrite tailings modified by glucose polymer can improve the water quality of pH, enhance the ability to remove NO₃⁻ in water, and prolong the ability of mineral to continuously treat sewage, which also has a good removal effect on PO₄³⁻ in water. The results of this study are of great significance to solve the excessive nitrogen and phosphorus in the secondary effluent and alleviate the eutrophication of the natural water.

In this work, a series of clinoptilolite composites decorated with carbon quantum dots (CQDs/clinoptilolite) with hierarchical pore structures was demonstrated that exhibits good photocatalytic performance for the removal of xylene. The technique for the attachment of carbon quantum dots to clinoptilolite was prepared by a hydrothermal method in this study. The structural features were confirmed by SEM, TEM, EDS, XRD, BET, XPS, and solid diffuse reflection measurements, while the degradation mechanism was investigated by adding a trapping agent into the nanocomposites. The introduction of CQDs promoted the separation of photogenerated electrons and holes as well as the generation of reactive radicals, which effectively improved the light utilization and even increased the degradation rate of xylene by 73% at the optimal state. The photocatalytic test was conducted under a different dwell time, catalyst dosage, initial concentration, and illumination intensity. The results showed that the degradation rate of xylene by the CQDs/clinoptilolite catalyst reached 97.4% under the optimal reaction conditions (the catalyst was Catalyst No. 2, the residence time was 90 s, the initial concentration was 2.5 g/m³, the light intensity was three lamps for irradiation, and the catalyst dosage was 0.05 g). In addition, the degradation efficiency of the CQDs/clinoptilolite photocatalyst still reached 78% after eight consecutive catalytic regeneration cycles. This work sheds new light on the degradation of xylene.