Ammonia-oxidizing activity of different ammonia-oxidizing microorganisms (AOMs), such as ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), and complete ammonia oxidizers (comammoxs), were investigated by adding the inhibitors such as 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide, octyne, and KCLO in biofilm systems with different salinities. It was found that the ammonia-oxidizing activity of all AOMs gradually decreased with increasing salinity. The ammonia-oxidizing activity of AOB was consistently higher than those of AOA and comammox at different salinities. Moreover, nitrite-oxidizing bacteria (NOB) were more sensitive to changes in salinity than AOMs. Metagenomic analysis revealed that nitrifiers were detected at high level, with the AOB Nitrosomonas sp. comprising 24.9 % and the NOB Nitrospira sp. comprising 47.2 % of all nitrifiers. The main functional genes involved in the nitrification reaction were amoABC, hao, and nxrAB. This study demonstrates that higher abundance of functional microorganisms and genes is related to the ammonia-oxidizing activity and ammonia removal contribution rate.
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http://dx.doi.org/10.1016/j.biortech.2025.132248 | DOI Listing |
Chemosphere
March 2025
Environmental Microbiology Group, Institute of Water Research, University of Granada, Granada, 18003, Spain; Department of Microbiology, University of Granada, Granada, 18071, Spain.
There is increasing awareness of the presence of anticancer drugs (ACDs) in wastewater. Nonetheless, how ACDs affect the performance of wastewater treatment systems and their microbial populations remains largely unclear. This study investigated the effects of three common ACDs (cyclophosphamide, tamoxifen, and methotrexate) at varying concentrations on physicochemical parameters and drug removal efficiency in an aerobic granular sludge (AGS) system operated in a continuous-flow reactor.
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February 2025
Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada; School of Civil & Environmental Engineering, Queensland University of Technology, Brisbane, Queensland, Australia. Electronic address:
Aerobic granular sludge (AGS) reactors are promising for treating high ammonia wastewaters, yet the roles of granules and flocs in nitrogen removal under varying carbon to nitrogen (COD/N) ratios remain unclear. This study investigated microbial communities and their contributions to N removal as the COD/N ratio shifted from 6 to 4, and to 2. Results showed granules contributed 53-64 % nitrification capacity at higher COD/N ratios (6 and 4), but flocs contributed more (50-63 %) at a ratio of 2.
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February 2025
Environment Research Institute, Shandong University, Qingdao, Shandong, China.
The oxidation of ammonia to nitrite, which constitutes the initial and rate-limiting step in the nitrification process, plays a pivotal role in the transformation of ammonia within soil ecosystems. Due to its susceptibility to a range of pollutants, such as heavy metals, pesticides, and pharmaceuticals, nitrification serves as a valuable indicator in the risk assessment of chemical contaminants in soil environments. Here, we analyzed the effects of cadmium (Cd) treatment on soil potential nitrification rate (PNR), and the abundance of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) communities.
View Article and Find Full Text PDFBioresour Technol
May 2025
School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao 266525, PR China.
Ammonia-oxidizing activity of different ammonia-oxidizing microorganisms (AOMs), such as ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), and complete ammonia oxidizers (comammoxs), were investigated by adding the inhibitors such as 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide, octyne, and KCLO in biofilm systems with different salinities. It was found that the ammonia-oxidizing activity of all AOMs gradually decreased with increasing salinity. The ammonia-oxidizing activity of AOB was consistently higher than those of AOA and comammox at different salinities.
View Article and Find Full Text PDFBioresour Technol
April 2025
Department of Civil and Environmental Engineering, Graduate School of Engineering, Tohoku University, 6-6-06 Aza, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579, Japan; Graduate School of Environmental Studies, Tohoku University, 6-6-06 Aramaki Aza Aoba, Aoba-ku, Sendai, Miyagi 980-8579, Japan.
As technoscience advances, widespread use of nanoparticles (NPs) has resulted in environmental risks. This study focuses on the potential stress of 0-200 mg/L yttrium oxide (YO) NPs on the activated sludge stability. YO NPs progressively suppressed nitrification, caused significant NO accumulation (200 mg/L) and diminished activities of key functional enzymes.
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