Cold-Region Water Resource Recovery Laboratory, Environmental Systems Engineering, Faculty of Engineering and Applied Science, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada.
Cold-Region Water Resource Recovery Laboratory, Environmental Systems Engineering, Faculty of Engineering and Applied Science, University of Regina, 3737 Wascana Parkway, Regina, SK S4S 0A2, Canada.
Sci Total Environ. 2023 Jun 1;875:162633. doi: 10.1016/j.scitotenv.2023.162633. Epub 2023 Mar 6.
Aerobic granular sludge (AGS) is promising for water resource recovery. Despite the mature granulation strategies in sequencing batch reactor (SBR), the application of AGS-SBR in wastewater treatment is usually costly as it requires extensive infrastructure conversion (e.g., from continuous-flow reactor to SBR). In contrast, continuous-flow AGS (CAGS) that does not require such infrastructure conversion is a more cost-effective strategy to retrofit existing wastewater treatment plants (WWTPs). Formation of aerobic granules in both batch and continuous-flow mode depends on many factors, including selection pressure, feast/famine conditions, extracellular polymeric substances (EPS), and environmental conditions. Compared with AGS in SBR, creating proper conditions to facilitate granulation in continuous-flow mode is challenging. Researchers have been seeking to tackle this bottleneck by studying the impacts of selection pressure, feast/famine conditions, and operating parameters on granulation and granule stability in CAGS. This review paper summarizes the state-of-the-art knowledge regarding CAGS for wastewater treatment. Firstly, we discuss the CAGS granulation process and effective parameters (i.e., selection pressure, feast/famine conditions, hydrodynamic shear force, reactor configuration, the role of EPS, and other operating factors). Then, we evaluate CAGS performance in removing COD, nitrogen, phosphorus, emerging pollutants, and heavy metals from wastewater. Finally, the applicability of the hybrid CAGS systems is presented. At last, we suggest that integrating CAGS with other treatment methods such as membrane bioreactor (MBR) or advanced oxidation processes (AOP) can benefit the performance and stability of granules. However, future research should address unknowns including the relationship between feast/famine ratio and stability of the granules, the effectiveness of applying particle size-based selection pressure, and the CAGS performance at low temperatures.
好氧颗粒污泥（AGS）在水资源回收方面具有广阔的应用前景。尽管序批式反应器（SBR）中已有成熟的颗粒化策略，但AGS-SBR 在废水处理中的应用通常成本较高，因为它需要广泛的基础设施改造（例如，从连续流反应器改为 SBR）。相比之下，不需要进行这种基础设施改造的连续流AGS（CAGS）是对现有废水处理厂（WWTP）进行改造的更具成本效益的策略。在批式和连续流模式下形成好氧颗粒取决于许多因素，包括选择压力、饥饿/饱食条件、胞外聚合物（EPS）和环境条件。与 SBR 中的 AGS 相比，在连续流模式下创造适当的条件来促进颗粒化具有挑战性。研究人员一直在寻求通过研究选择压力、饥饿/饱食条件和操作参数对 CAGS 中颗粒化和颗粒稳定性的影响来解决这一瓶颈问题。本文综述了用于废水处理的 CAGS 的最新研究进展。首先，我们讨论了 CAGS 的颗粒化过程和有效参数（即选择压力、饥饿/饱食条件、水动力剪切力、反应器构型、EPS 的作用和其他操作因素）。然后，我们评估了 CAGS 从废水中去除 COD、氮、磷、新兴污染物和重金属的性能。最后，提出了混合 CAGS 系统的适用性。最后，我们建议将 CAGS 与膜生物反应器（MBR）或高级氧化工艺（AOP）等其他处理方法相结合，可以提高颗粒的性能和稳定性。然而，未来的研究应解决未知问题，包括饥饿/饱食比与颗粒稳定性之间的关系、基于粒径的选择压力的有效性以及 CAGS 在低温下的性能。
