Department of Chemical Engineering, School of Engineering, University of Santiago de Compostela, Campus Vida, E-15782, Santiago de Compostela, Spain.
J Environ Manage. 2020 Jun 1;263:110395. doi: 10.1016/j.jenvman.2020.110395. Epub 2020 Mar 19.
One of the main drawbacks of upflow anaerobic sludge blanket (UASB) reactors that treat low-strength sewage at room temperature is related to the low quality of their effluents in terms of dissolved methane, organic matter, and nitrogen content. The present study aims to evaluate the feasibility of using an integrated fixed-film activated sludge (IFAS) system as an alternative post-treatment technology to mitigate the environmental impact of such effluents. For this purpose, a pilot plant composed of a UASB (120 L) followed by an IFAS (66 L) system was operated for 407 days. Special attention was paid to the suspended biomass retention capacity and the dissolved methane and nitrogen removal potential of the IFAS post-treatment system. Furthermore, the role of carriers on denitrification and nitrification processes and the microbial communities present in the biofilm were also analyzed. Average total chemical oxygen demand (CODT) and ammonium removal efficiencies of 92 ± 3% and around 57 ± 16% were attained throughout the entire operation, respectively. During a first period in which biomass was maintained in both biofilms and suspension, and nitrite was the main electron acceptor, maximum nitrogen removal and methane removal efficiencies of 32.5 mg TN L-1 and 93% were observed in the IFAS system, respectively. However, throughout the second period, in which suspended biomass was completely washed out from the IFAS system, and nitrate became the main electron acceptor, these values decreased to 18 ± 4 mg TN Lfeed-1 and 77 ± 12%, respectively. Surprisingly, throughout the entire operation, it was observed that around 50 and 41% of the total nitrogen and methane removals observed in the IFAS system, respectively, were carried out in the aerobic compartment. Aerobic methane oxidizers and anammox were detected with significant relative abundances in the biofilm carriers used in the anoxic and aerobic compartments using 16S rRNA gene amplicon sequencing analysis. Therefore, the use of an IFAS system could be suited to diminish greenhouse gas emissions and nutrients concentration for those sewage treatment plants that used UASB systems, especially in countries with temperate and warm climates.
上流式厌氧污泥床（UASB）反应器在处理室温下低浓度污水时存在一个主要缺点，即其出水在溶解甲烷、有机物和氮含量方面的水质较差。本研究旨在评估采用一体化固定膜活性污泥（IFAS）系统作为替代后处理技术来减轻此类废水环境影响的可行性。为此，采用由 UASB（120L）和 IFAS（66L）系统组成的中试装置进行了 407 天的运行。特别关注 IFAS 后处理系统的悬浮生物量保留能力以及溶解甲烷和氮的去除潜力。此外，还分析了载体在反硝化和硝化过程中的作用以及生物膜中存在的微生物群落。整个运行过程中，总化学需氧量（CODT）和氨氮的平均去除效率分别达到 92%±3%和 57%±16%左右。在第一个阶段，生物量同时存在于生物膜和悬浮液中，亚硝酸盐是主要的电子受体，IFAS 系统中最大的氮去除和甲烷去除效率分别为 32.5mgTN L-1和 93%。然而，在第二个阶段，悬浮生物量完全从 IFAS 系统中被冲洗掉，硝酸盐成为主要的电子受体，这些值分别下降到 18±4mgTN Lfeed-1和 77%±12%。令人惊讶的是，在整个运行过程中，观察到 IFAS 系统中分别约有 50%和 41%的总氮和甲烷去除是在好氧区进行的。使用 16S rRNA 基因扩增子测序分析，在缺氧和好氧区使用的生物膜载体中检测到了好氧甲烷氧化菌和厌氧氨氧化菌，它们具有显著的相对丰度。因此，对于那些使用 UASB 系统的污水处理厂，特别是在温带和温暖气候的国家，使用 IFAS 系统可以减少温室气体排放和营养物浓度。
