Liu Jun, Yin Shunchang, Xu Dong, Piché-Choquette Sarah, Ji Bin, Zhou Xin, Li Jun
School of Modern Agriculture, Jiaxing Vocational & Technical College, Jiaxing 314036, China.
Department of Civil Engineering, Tongji Zhejiang College, Jiaxing 314051, China.
Polymers (Basel). 2022 Sep 5;14(17):3688. doi: 10.3390/polym14173688.
The separation of light and heavy sludge, as well as the aggregation rate of floccular sludge, are two critical aspects of the rapid granulation process in sequencing batch reactors (SBRs) in the early stages. In this study, we investigated the impact of a method to improve both sludge separation and granulation by coupling effluent sludge external conditioning with FeCl addition and then reintroducing it into the SBR. By supplementation with 0.1 g Fe (g dried sludge (DS)), the concentration of extracellular polymeric substances (EPS) and sludge retention efficiency greatly increased, whereas the moisture content and specific oxygen uptake rate (SOUR) sharply decreased within 24 h external conditioning. Aggregates (1.75 ± 0.05 g·L) were reintroduced into the bioreactor once daily from day 13 to day 15. Afterwards, on day 17, aerobic granules with a concentration of mixed liquor suspended solids (MLSS) of 5.636 g/L, a sludge volume index (SVI) of 45.5 mL/g and an average size of 2.5 mm in diameter were obtained. These results suggest that the external conditioning step with both air-drying and the addition of Fe enhanced the production of EPS in the effluent sludge and improved rapid aggregation and high sludge retention efficiency. Consequently, the reintroduced aggregates with good traits shortened the time required to obtain mature aerobic granular sludge (AGS) and properly separate light and heavy sludge. Indeed, this method jump-started the aggregation, and rapid granulation processes were successful in this work. Additionally, while the removal efficiency of chemical oxygen demand (COD) and nitrogen from ammonium (NH-N) decreased when reintroducing the treated sludge into the SBR, such properties increased again as the AGS matured in the SBR, up to removal efficiencies of 96% and 95%, respectively.
轻质污泥与重质污泥的分离以及絮状污泥的聚集速率，是序批式反应器（SBR）早期快速颗粒化过程的两个关键方面。在本研究中，我们探究了一种通过将出水污泥外部调节与添加氯化铁相结合，然后再将其重新引入SBR来改善污泥分离和颗粒化的方法的影响。通过添加0.1 g铁（每克干污泥（DS）），细胞外聚合物（EPS）的浓度和污泥保留效率大幅提高，而在24小时的外部调节内，含水量和比氧摄取率（SOUR）急剧下降。从第13天到第15天，每天将聚集体（1.75±0.05 g·L）重新引入生物反应器。之后，在第17天，获得了混合液悬浮固体（MLSS）浓度为5.636 g/L、污泥体积指数（SVI）为45.5 mL/g且平均直径为2.5 mm的好氧颗粒。这些结果表明，空气干燥和添加铁的外部调节步骤增强了出水污泥中EPS的产生，并改善了快速聚集和高污泥保留效率。因此，重新引入的具有良好特性的聚集体缩短了获得成熟好氧颗粒污泥（AGS）以及正确分离轻质和重质污泥所需的时间。事实上，这种方法启动了聚集过程，并且在本研究中快速颗粒化过程取得了成功。此外，当将处理后的污泥重新引入SBR时，化学需氧量（COD）和铵态氮（NH-N）的去除效率下降，但随着AGS在SBR中成熟，这些性能再次提高，分别达到96%和95%的去除效率。
