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Denitrifying bacteria

Xiangyu Guan, Fei Liu, Jing Wang, Caoxiang Li, Xiaoxuan Zheng
1,4-Dioxane (dioxane), a probable human carcinogen, often exists in industrial wastewater and domestic sewage. In this study, we applied 16S rRNA and metatranscriptomic methods to analyze the dioxane biodegradation mechanism by activated sludge. Tetrahydrofuran (THF) was added as an essential co-metabolite to promote the degradation of dioxane. We found the dioxane removal ratio increased with increasing THF concentrations. When the THF concentration increased from 60.0 to 200.0 mg/L, the dioxane degradation rate was stable...
January 2018: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Zhongshuo Xu, Liyan Song, Xiaohu Dai, Xiaoli Chai
Biodegradable polymer supported denitrification (BPD) system shows good denitrification performance for the wastewater with low nitrate concentrations. In this study, a BPD system using Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) polymer as carbon source was developed to treat the wastewater with high nitrate concentrations. The denitrification performance, utilization ratio of PHBV polymers, and microbial community structure evolution and key denitrifying bacteria were comprehensively studied. Results indicated that an average nitrate removal efficiency of 99% could be achieved with an influent NO3--N concentration of 100 mg L-1 and a hydraulic retention time (HRT) of 7...
January 8, 2018: Chemosphere
Lili Miao, Zhipei Liu
Nitrogen pollution is an increasingly severe worldwide problem because of drainage of nitrogen-containing wastewater and intensive application of nitrogen-containing fertilizers. Denitrification, a key process in nitrogen cycles, is commonly employed for nitrogen removal in engineered wastewater treatment systems. Biological denitrification is performed by denitrifying microbes (bacteria) that use nitrate as terminal electron acceptor. Better understanding the functions of diverse microbial populations in denitrification-based wastewater treatment systems, and the interactions of these populations with operating environments, is essential for improving both treatment performance and system stability...
January 9, 2018: Science China. Life Sciences
Jun Chen, Bingbin Li, Ji Zheng, Jianmeng Chen
Simultaneous removal of SO2 and NO from flue gas can be biologically achieved by the rotating drum biofilter with FeII(EDTA) as a solvent. One issue related with this process is the generation of H2S. To control its generation, the pathways of H2S formation was investigated, and the parametric tests were conducted. The addition of FeII(EDTA) (10 mM) increased the removal efficiency of NO and SO2, while the S2- concentration decreased from 81 mM to 3.5 mM. The parametric tests showed that the high NO concentration favored the SO2 removal and significantly inhibited the H2S generation...
January 10, 2018: Environmental Technology
Xuan Jiang, Diwen Ying, Dian Ye, Runqiu Zhang, Qingbin Guo, Yalin Wang, Jinping Jia
Bioelectrochemical enhanced nitrate removal in wastewater with high total nitrogen and low organic carbon was electrochemically investigated focusing on the relationship between biochemical and electrochemical nitrogen cycles. Under optimized external voltage of -0.6 V, apparent nitrate removal rate of bioelectrochemical denitrification was 76% higher than normal biofilm denitrification. And with the introduction of biofilm on the electrode, new reduction peak of N2O, much larger current density, and 0.4 V positively shift of on-set potential of nitrate reduction reaction were observed, suggesting a synergy of electrochemical reaction and biological reaction through enhanced electrochemical reduction of intermediate products from biological process...
December 26, 2017: Bioresource Technology
Yuting He, Lian Peng, Yumei Hua, Jianwei Zhao, Naidong Xiao
A hybrid constructed wetland (CW) system was operated at pilot scale to evaluate the treatment of domestic wastewater from university dorms in Hubei province, China. The hybrid system consisted of an integrated vertical flow constructed wetland (IVF CW) (a down-flow VF CW and an up-flow VF CW) and a horizontal subsurface flow constructed wetland (HSF CW). The influent for the hybrid CW containing chemical oxygen demand (COD), total phosphorus (TP), total nitrogen (TN), and ammonium nitrogen (NH4+-N) with mean concentrations of 152, 0...
January 8, 2018: Environmental Science and Pollution Research International
Hong Chen, Xuhao Zhao, Yuying Cheng, Mingji Jiang, Xiang Li, Gang Xue
Simultaneous nitrification and denitrification (SND) is a promising single-reactor biological nitrogen-removal method. Activated sludge with and without iron scrap supplementation (Sludge-Fe and Sludge-C, respectively) was acclimated under aerobic condition. The total nitrogen (TN) content of Sludge-Fe substantially decreased from 25.0±1.0 to 11.2±0.4 mg/L, but Sludge-C did not show the TN-removal capacity. Further investigations excluded a chemical reduction of NO3--N by iron and a decrease of NH4+-N by microbial assimilation, and the contribution of SND was verified...
January 3, 2018: Environmental Science & Technology
Luong Van Duc, Bongkeun Song, Hiroaki Ito, Takehide Hama, Masashi Otani, Yasunori Kawagoshi
Anaerobic ammonium oxidation (anammox) bacteria were enriched in continuous packed-bed columns with marine sediment. One column (SB-C) was packed with only marine sediment collected from a shrimp-aquaculture pond, and another column (SB-AMX) was inoculated with marine anammox bacteria (MAB) as a control. These columns were continuously fed with natural or artificial seawater including ammonium (NH4+) and nitrite (NO2-). The SB-AMX showed anammox activities from the beginning and continued for over 200 days...
December 28, 2017: Chemosphere
Guo-Jun Xie, Tao Liu, Chen Cai, Shihu Hu, Zhiguo Yuan
To achieve energy neutral wastewater treatment, mainstream anaerobic ammonium oxidation (anammox) has attracted extensive attention in the past decade. However, the relatively high effluent nitrogen concentration (>10 mg N L-1) remains a significant barrier hindering its practical implementation. A novel technology integrating the anammox and denitrifying anaerobic methane oxidation (DAMO) reactions in a membrane biofilm reactor (MBfR) was developed in this study to enhance the mainstream anammox process...
December 20, 2017: Water Research
Sen Qiao, Xin Yin, Jiti Zhou, Li'e Wei, Jiayou Zhong
In this study, an autotrophic denitrification process was successfully coupled with anammox to remove the nitrate by-product via electrochemical technology. When the voltage applied to the combined electrode reactor was 1.5 V, the electrode reaction removed nitrate by using the autotrophic denitrification biomass without affecting the anammox biomass. The nitrogen removal efficiency of the combined electrode reactor reached 99.1% without detectable nitrate at an influent NO2--N/NH4+-N ratio of 1.5. On day 223, using the model calculations based on reaction equations, 19...
December 12, 2017: Chemosphere
Bryce A Figdore, H David Stensel, Mari-Karoliina H Winkler
Three types of nitrifying granules were grown on media simulating anaerobic digestion dewatering reject water and compared for their potential to increase nitrification capacity when added to mainstream flocculent activated sludge treatment. An advantage of nitrification bioaugmentation with sidestream granules instead of flocculent biomass is that the granules can be selectively maintained at longer retention times than flocs and thus provide higher nitrification capacity from bioaugmentation. The three granule types and feeding conditions were: nitrifying granules with aerobic feeding, nitrifying-denitrifying granules with anoxic feeding, and nitrifying-denitrifying/phosphate-accumulating (NDN-PAO) granules with anaerobic feeding...
November 6, 2017: Bioresource Technology
Ruixia Hao, Yanqing Zhou, Jianbing Li, Jianchao Wang
A new process was proposed by integrating a three-dimensional biofilm electrode reactor with sulfur autotrophic denitrification and electrocoagulation within the same reactor. The results indicated that under the wastewater influent condition of NO3--N = 30 mg/L, COD = 45 mg/L, total phosphorus (TP) = 1.5 mg/L, hydraulic retention time (HRT) = 8 h, and I = 400 mA, the NO3--N and TP removal of the proposed process reached 89.8% and 83.0%, respectively. It was observed that the electrocoagulation process improved phosphorus removal, while the simultaneous existence of heterotrophic, hydrogen, sulfur and iron autotrophic denitrifying bacteria led to enhanced and stabilized nitrogen removal...
December 21, 2017: Journal of Environmental Management
M Z Majeed, E Miambi, I Barois, M Bernoux, A Brauman
Tropical rainforest soils harbor a considerable diversity of soil fauna that contributes to emissions of N2O. Despite their ecological dominance, there is limited information available about the contribution of epigeal ant mounds to N2O emissions in these tropical soils. This study aimed to determine whether ant mounds contribute to local soil N emissions in the tropical humid rainforest. N2O emission was determined in vitro from individual live ants, ant-processed mound soils, and surrounding reference soils for two trophically distinct and abundant ant species: the leaf-cutting Atta mexicana and omnivorous Solenopsis geminata...
December 19, 2017: Folia Microbiologica
Yinqi Tang, Meng Li, Danning Xu, Jianjun Huang, Jingmei Sun
Aerobic denitrifiers coupled with a denitrification agent were applied in the sediment of an urban river for the bioremediation of nitrogen pollution. The results revealed that 14.7% of the total nitrogen in the sediment was removed after 115 days of treatment and the nitrate nitrogen concentration removal rate was enhanced in the overlying water. Compared with the control, the total transferable nitrogen in the sediment increased from 0.097 to 0.166 mg/g, indicating that more nitrogen is likely to be involved in the biogeochemical cycling of nitrogen...
December 13, 2017: Environmental Science and Pollution Research International
V F Velho, B S Magnus, G C Daudt, J A Xavier, L B Guimarães, R H R Costa
N2O-production was investigated during nitrogen removal using aerobic granular sludge (AGS) technology. A pilot sequencing batch reactor (SBR) with AGS achieved an effluent in accordance with national discharge limits, although presented a nitrite accumulation rate of 95.79% with no simultaneous nitrification-denitrification. N2O production was 2.06 mg L-1 during the anoxic phase, with N2O emission during air pulses and the aeration phase of 1.6% of the nitrogen loading rate. Batch tests with AGS from the pilot reactor verified that at the greatest COD/N ratio (1...
December 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Jinlan Xu, Haiyang Zhang, Rong Zhao, Fanxing Kong
The main objective of this study was to investigate how signal molecules enhance bacterial quorum aggregation on a zeolite capping layer for sustainable inhibition of ammonium release from contaminated sediment. Sediment remediation experiments were carried out by using nitrifying bacteria (WGX10, WGX18), denitrifying bacteria (HF3, HF7) and two kinds of signal molecules (OHHL, C8-HSL). The results showed that nitrifying bacteria and denitrifying bacteria could significantly aggregate on zeolite after adding 1...
December 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
L Pelaz, A Gómez, G Garralón, A Letona, M Fdz-Polanco
A denitrifying pilot plant was designed, constructed and operated for more than five months. The plant treated domestic wastewater with high ammonium nitrogen concentration, which had previously undergone an anaerobic process at 18 °C. The process consisted of one biofilter with 2 h of hydraulic retention time for denitritation. Different synthetic nitrite concentrations were supplied to the anoxic reactor to simulate the effluent of a nitritation process. This work investigates the advanced denitritation of wastewater using the organic matter and other alternative electron donors present in an anaerobic treatment process effluent: methane and sulfide...
December 7, 2017: Bioresource Technology
K Ghyselbrecht, A Monballiu, M H Somers, I Sigurnjak, E Meers, L Appels, B Meesschaert
Anaerobic digestion is widely used to produce renewable energy. However, the main drawback is the limited conversion efficiency of organic matter. Applying an advanced oxidation process (AOP) as a digestate post-treatment is able to increase this conversion efficiency but will also lead to the oxidation of ammonium to nitrite or nitrate. In this lab scale study, the fate of the latter in the digester was investigated. Nitrite and nitrate were therefore added in concentrations that could arise from rate limiting ammonium concentrations (1...
December 8, 2017: Environmental Technology
Peter M H Kroneck
The enzymes nitrous oxide reductase (N2OR) and cytochrome c oxidase (COX) are constituents of important biological processes. N2OR is the terminal reductase in a respiratory chain converting N2O to N2 in denitrifying bacteria; COX is the terminal oxidase of the aerobic respiratory chain of certain bacteria and eukaryotic organisms transforming O2 to H2O accompanied by proton pumping. Different spectroscopies including magnetic resonance techniques, were applied to show that N2OR has a mixed-valent Cys-bridged [Cu1...
December 7, 2017: Journal of Biological Inorganic Chemistry: JBIC
Chunjing Liu, Jianzhi Xie, Manli Song, Zhiling Gao, Dongxing Zheng, Xia Liu, Guohui Ning, Xu Cheng, Harry Bruning
Poor nitrogen removal efficiency (mainly nitrate, NO3--N) at low temperatures strongly limits application of subsurface wastewater infiltration systems (SWISs). Seven psychrophilic strains (heterotrophic nitrifying bacteria and aerobic denitrifying bacteria) were isolated and added to SWISs to investigate the effect of embedding and direct-dosing bioaugmentation strategies on sewage treatment performance at low temperature. Both bioaugmentation strategies improved ammonium (NH4+-N) removal efficiencies, and the embedding strategy also exhibited satisfactory NO3--N and total nitrogen (TN) removal efficiencies...
December 2, 2017: Bioresource Technology
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