Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202509035
Aerobic granular sludge (AGS) is an economical and efficient technology, yet its application has been largely confined to sequencing batch reactors (SBRs). This study introduces a novel continuous-flow self-circulating upflow granular sludge bed (Zier) process with separate aeration for treating real domestic wastewater. By regulating operational parameters, the nitrogen removal performance and granular sludge stability were investigated. Under hydraulic retention time of 10 h, self-circulation times of 29–58, and upflow velocity of 11–18 m·h−1, effluent NH4+-N and TN averaged (5±3.4) mg·L−1 and (10±2.8) mg·L−1, respectively, with COD at (30±6.2) mg·L−1. The process maintained sludge stability: mixed liquor suspended solids increased from 5,080 to 6,650 mg·L−1, mean particle size was 209.6 μm, and sludge volume index (SVI) remained at 50–60 mL·g−1. Extracellular polymeric substances (EPS) increased from 26.05 to 68.27 mg·g−1, with proteins (PN) rising from 21.26 to 59.44 mg·g−1 and polysaccharides (PS) from 4.79 to 8.82 mg·g−1, elevating the PN/PS ratio from 4.4 to 6.7. These results confirm that the Zier process preserves granular structure and function in continuous flow. The process demonstrates robust nitrogen removal and offers a novel approach for continuous-flow AGS applications in real wastewater treatment.
Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202509020
The AAOA-MBR (anaerobic-anoxic-oxic-anoxic membrane bioreactor) process is widely used in municipal wastewater treatment, but its multi-stage internal recirculation complicates sludge retention time (SRT) and carbon source distribution. This study systematically regulated three reflux ratios (R1: membrane tank to oxic tank; R2: oxic tank to anoxic I tank; R3: anoxic II tank to anaerobic tank) in a pilot-scale system (0.24 m3·d−1) to reveal their effects on nutrient removal and membrane fouling. When R1:R2:R3 = 300%:200%:100%, effluent COD, TN, TP, and NH3-N met discharge standards. Reducing R1 and R2, thereby decreasing total reflux ratio from R=6 to R=3, shortened SRT, which suppressed nitrifier accumulation and increased effluent COD and TN, but decreased TP. High-throughput sequencing of anoxic I and oxic tanks showed that denitrifying bacteria (Thauera and Ottowia) relative abundances decreased from 0.68% to 0.42% and 0.51% to 0.24%, respectively, while the phosphorus-accumulating organism Candidatus_Accumulibacter increased from 0.78% to 1.12%, enhancing phosphorus removal. Additionally, lowering R1 to 200% caused sludge accumulation in the membrane tank, exacerbating membrane fouling. Thus, internal recirculation ratios must be adjusted based on influent characteristics to balance nutrient removal and membrane performance.
SCIENCE CHINA Materials•2025•DOI: 10.1007/s40843-025-3594-2
The power conversion efficiency (PCE) of organic solar cells (OSCs) has been substantially advanced by optimizing acceptors and cathode interface layers (CILs). Perylene diimide (PDI) has been universally used in acceptors and CILs for OSCs owing to its chemical and photothermal stability, structural tunability, and high electron mobility. Nevertheless, the high planarity of PDI tends to result in excessive aggregation, which suppresses the PCE of the OSCs. Notably, the bay-functionalization strategy of PDI can optimize the light absorption properties, charge transfer (CT), and aggregation behavior, which dramatically boost the PCE of OSCs. Here, a systematic summary of acceptors and CILs based on the bay-substitution of PDI is reviewed. First, the progress history and working principle of OSCs are reviewed, and the mechanisms of the acceptors and CILs, as well as the functional properties of the disparate positions of PDI, are elaborated. Second, the relationship between the performance and structure of the bay-modified PDI acceptors and CILs was discussed in depth. Finally, the conclusions and outlooks of acceptors and CILs for bay-substituted PDI are presented. This review provides valuable insights for optimizing the performance of OSCs by modifying the PDI in bay regions.