SUEZ, Engineering and Construction, Innovation and Technical Direction, 16 place de l'Iris, 92040 La Défense, France.
SUEZ, Innovation Differentiation Unit, CIRSEE, 38 rue du président Wilson, 78230 Le Pecq, France.
Sci Total Environ. 2024 Nov 20;952:175918. doi: 10.1016/j.scitotenv.2024.175918. Epub 2024 Aug 30.
GAC filtration of municipal wastewater was optimized and intensified, making its implementation and operation directly after secondary clarification possible and relevant. GAC was first selected based on laboratory tests. Performances on organic micropollutants were linked to the repartition of BET surface between micropores and meso/macropores. At pilot scale, in order to limit the impact of head loss, downflow declogging sequences (DCS) were implemented and upflow filtration tested. 6 to 12 DCS per day led to a 4.7-5.5-fold increase of particles retention capacity between backwashes (cycle duration of 20-120 h), and upflow operations improved head loss evolution profile with only a slight GAC (<15 %) expansion. DCS allows backwash frequency reduction, enabling significant water savings. Both adaptations maintained high organic micropollutants removals compared to a review of 16 GAC studies at pilot or full-scale, results being in the upper range. A specific dose of 2.0-2.5 g GAC/gC was necessary to obtain an average removal of pharmaceuticals and benzotriazole of 80 % at 20 min contact time, which is comparable to PAC and low granulometry GAC. Higher doses are needed for PFAS but >80 % removals are achievable. Particles, TKN, particulate phosphorus and organic matter are well removed by GAC filtration in both configurations. Biological activity is observed through nitrogen transformation in the GAC bed. Heavy metals are greatly removed in GAC filtration, in particular Cd, Cu, Ni and Pb, probably through biosorption onto the biofilm, developed within the GAC bed. For wastewater reuse applications, GAC filtration has an added value through physicochemical quality improvement and fecal contamination indicators removal of 1 log, facilitating the implementation and optimizing the design of a post-disinfection. Antibiotic resistant bacteria and antibiotic resistance genes are also partially retained in GAC filtration. Finally, biological wastewater treatments combined to GAC filtration is a good solution to effectively treat organic micropollutants together with heavy metals and preparing post-disinfection for reuse.
优化和强化城市污水的 GAC 过滤，使其能够在二级澄清后直接进行实施和运行，并具有实际意义。首先根据实验室测试选择 GAC。有机微污染物的性能与 BET 表面在微孔和中/大孔之间的分配有关。在中试规模下，为了限制水头损失的影响，采用了下行反冲洗顺序（DCS）并测试了上流过滤。每天进行 6 至 12 次 DCS 可使反冲洗之间的颗粒截留能力提高 4.7-5.5 倍（循环持续时间为 20-120 小时），而上流操作可改善水头损失的演变情况，仅使 GAC 略有膨胀（<15%）。DCS 可减少反冲洗频率，从而显著节省用水。这两种方法均保持了较高的有机微污染物去除率，与 16 项在中试或全规模下的 GAC 研究相比，结果处于较高水平。在 20 分钟接触时间下，为了实现 80%的药物和苯并三唑的平均去除率，需要 2.0-2.5 g GAC/gC 的特定剂量，这与 PAC 和小粒径 GAC 的去除率相当。对于 PFAS，则需要更高的剂量，但可实现>80%的去除率。在这两种配置中，颗粒、TKN、颗粒磷和有机物都可以通过 GAC 过滤很好地去除。通过 GAC 床中的氮转化可以观察到生物活性。重金属在 GAC 过滤中被大量去除，特别是 Cd、Cu、Ni 和 Pb，这可能是通过生物膜在 GAC 床内的生物吸附实现的。对于废水再利用应用，GAC 过滤通过改善物理化学质量和去除 1 个对数的粪便污染指标具有附加价值，这有助于实施和优化后消毒的设计。抗生素抗性细菌和抗生素抗性基因也部分保留在 GAC 过滤中。最后，将生物废水处理与 GAC 过滤相结合是一种有效的方法，可以同时处理有机微污染物和重金属，并为再利用做好后消毒的准备。
