Effect of Hydraulic Retention Time on Carbon Sequestration during the Two-Stage Anammox Process

Abstract

In a biological treatment process, hydraulic retention time (HRT) has a certain effect on the operation of the reactor. This study investigated the effect of HRT on carbon sequestration in a two-stage anaerobic ammonium oxidation (anammox) process using a partial nitrification reactor and anammox reactor to determine the optimal carbon sequestration operating conditions. Molecular biotechnology was used to analyze the sludge in the reactor in order to explore the denitrification performance and to determine the carbon sequestration pathway of the microorganisms. The results show that the partial nitrification stage had the highest carbon sequestration rate (0.319 mg/mg·N) when the nitrogen loading rate (NLR) was 0.44 kg·N/m3/d. The NLR of the anammox stage was 0.13 kg·N/m3/d. When the HRT was 33.4 h, the carbon sequestration of the anammox reaction was at its highest, reaching 0.183 mg/mg·N. The results of microbial analysis show that the carbon-fixing gene cbbLR1 was present in the sludge samples during the anammox and partial nitrification stages, and that there was a Calvin cycle carbon sequestration pathway during the growth process. However, the existence of a gene for reducing and immobilizing CO2 by the acetyl-CoA pathway was not detected; further research is thus needed.

Flow rate impact on the performance of immobilized nanoFeCu for sewage treatment and its reusability

“…The performance of immobilized nanoFeCu was better compared to the simultaneous nitrification and denitrification study conducted by Lim et al, [ 44 ] where the ammonia concentration of the effluent was within 20–25 mg/L for a treatment of 8 h; with the influent concentration of 30 to 35 mg/L of ammonia at 0.5 bar. Ma et al [ 45 ] treated the synthetic wastewater with a concentration of ~180 mg/L ammonia via a two‐stage anammox process. A minimum hydraulic retention time (HRT) of 6 h at the partial nitrification stage and 14.5 h at the anammox stage were required to treat the ammonia to <5 mg/L.…”

“…Besides, the secondary sludge formed after the aeration process was harder to treat compared to primary sludge. [ 57 ] Ma et al [ 45 ] removed 180 mg/L ammonia to <5 mg/L via the nitrification and denitrification method, but ~30 mg/L of nitrate was found in the effluent. This could cause blue baby syndrome if no further treatment was adopted to remove nitrate.…”

Nitrogen Contribution Rate of Anammox in Different Systems and Its Relationship with Environmental Factors

“…In natural ecosystems, anammox bacteria are found in oceans [6,7], rivers [8,9], lakes [10,11], estuaries [12], paddy soil [13,14], and natural wetlands [15,16]. In artificial systems, anammox bacteria have been found in bioreactors [17,18] Water 2023, 15, 2101 2 of 17 and artificial wetlands [19,20]. Figure 2 shows the development of the anammox bacteria.…”

Integration of anammox into the MBR process for main stream sewage treatment

“…Anaerobic ammonia oxidation (Anammox) is a new nitrogen removal technology that has attracted increasing attention for treating ammonia-rich wastewater (Park et al 2017;Liu et al 2019;Ma et al 2019a;Wen et al 2020). Under anaerobic conditions, anammox bacteria, as autotrophic microorganisms, can use nitrite as an electron acceptor and ammonia nitrogen as an electron donor and can convert them into N 2 (Mulder et al 1995), which offers the advantages of decreasing operating costs and producing less sludge (Kuenen 2008;Abma et al 2010;Feng et al 2019).…”