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Nitrification

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https://www.readbyqxmd.com/read/27913865/nitrogen-dynamics-in-subtropical-fringe-and-basin-mangrove-forests-inferred-from-stable-isotopes
#1
Carla Roberta Gonçalves Reis, Gabriela Bielefeld Nardoto, André Luis Casarin Rochelle, Simone Aparecida Vieira, Rafael Silva Oliveira
Mangroves exhibit low species richness compared to other tropical forests, but great structural and functional diversity. Aiming to contribute to a better understanding of the functioning of mangrove forests, we investigated nitrogen (N) dynamics in two physiographic types of mangroves (fringe and basin forests) in southeastern Brazil. Because fringe forests are under great influence of tidal flushing we hypothesized that these forests would exhibit higher N cycling rates in sediment and higher N losses to the atmosphere compared to basin forests...
December 2, 2016: Oecologia
https://www.readbyqxmd.com/read/27912011/reduced-snow-cover-alters-root-microbe-interactions-and-decreases-nitrification-rates-in-a-northern-hardwood-forest
#2
Patrick O Sorensen, Pamela H Templer, Lynn Christenson, Jorge Duran, Timothy Fahey, Melany C Fisk, Peter M Groffman, Jennifer L Morse, Adrien C Finzi
Snow cover is projected to decline during the next century in many ecosystems that currently experience a seasonal snowpack. Because snow insulates soils from frigid winter air temperatures, soils are expected to become colder and experience more winter soil freeze-thaw cycles as snow cover continues to decline. Tree roots are adversely affected by snowpack reduction, but whether loss of snow will affect root-microbe interactions remains largely unknown. The objective of this study was to distinguish and attribute direct (e...
December 2016: Ecology
https://www.readbyqxmd.com/read/27912009/resource-stoichiometry-and-the-biogeochemical-consequences-of-nitrogen-deposition-in-a-mixed-deciduous-forest
#3
Meghan G Midgley, Richard P Phillips
Ecosystems often show differential sensitivity to chronic nitrogen (N) deposition; hence, a critical challenge is to improve our understanding of how and why site-specific factors mediate biogeochemical responses to N enrichment. We examined the extent to which N impacts on soil carbon (C) and N dynamics depend on microbial resource stoichiometry. We added N to forest plots dominated by ectomycorrhizal (ECM) trees, which have litter and soil pools rich in organic N and relatively wide C:N ratios, and adjacent forest plots dominated by arbuscular mycorrhizal (AM) trees, which have litter and soil pools rich in inorganic N and relatively narrow C:N ratios...
December 2016: Ecology
https://www.readbyqxmd.com/read/27904989/respirometric-response-and-microbial-succession-of-nitrifying-sludge-to-m-cresol-pulses-in-a-sequencing-batch-reactor
#4
Alberto Ordaz, Mariana Sánchez, Rodrigo Rivera, Rafael Rojas, Alejandro Zepeda
A nitrifying consortium was kinetically, stoichiometrically and molecularly characterized via the in situ pulse respirometric method and pyrosequencing analysis before and after the addition of m-cresol (25 mg C L(-1)) in a sequencing batch reactor (SBR). Five important kinetic and stoichiometric parameters were determined: the maximum oxygen uptake rate, the maximum nitrification rate, the oxidation yield, the biomass growth yield, and the substrate affinity constant. An inhibitory effect was observed in the nitrification process with a recovery of this by up to eight SBR cycles after m-cresol was added to the system...
November 30, 2016: Biodegradation
https://www.readbyqxmd.com/read/27902965/oxygen-transfer-dynamics-and-activated-sludge-floc-structure-under-different-sludge-retention-times-at-low-dissolved-oxygen-concentrations
#5
Haitao Fan, Xiuhong Liu, Hao Wang, Yunping Han, Lu Qi, Hongchen Wang
In activated sludge systems, the aeration process consumes the most energy. The energy cost can be dramatically reduced by decreasing the operating dissolved oxygen (DO) concentration. However, low DO may lead to incomplete nitrification and poor settling performance of activated sludge flocs (ASFs). This study investigates oxygen transfer dynamics and settling performances of activated sludge under different sludge retention times (SRTs) and DO conditions using microelectrodes and microscopic techniques. Our experimental results showed that with longer SRTs, treatment capacity and settling performances of activated sludge improved due to smaller floc size and less extracellular polymeric substances (EPS)...
November 27, 2016: Chemosphere
https://www.readbyqxmd.com/read/27900438/start-up-and-bacterial-community-compositions-of-partial-nitrification-in-moving-bed-biofilm-reactor
#6
Tao Liu, Yan-Jun Mao, Yan-Ping Shi, Xie Quan
Partial nitrification (PN) has been considered as one of the promising processes for pretreatment of ammonium-rich wastewater. In this study, a kind of novel carriers with enhanced hydrophilicity and electrophilicity was implemented in a moving bed biofilm reactor (MBBR) to start up PN process. Results indicated that biofilm formation rate was higher on modified carriers. In comparison with the reactor filled with traditional carriers (start-up period of 21 days), it took only 14 days to start up PN successfully with ammonia removal efficiency and nitrite accumulation rate of 90 and 91%, respectively, in the reactor filled with modified carriers...
November 30, 2016: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/27898783/production-of-biomass-crops-using-biowastes-on-low-fertility-soil-2-effect-of-biowastes-on-nitrogen-transformation-processes
#7
J Esperschuetz, S Bulman, C Anderson, O Lense, J Horswell, N Dickinson, B H Robinson
Increasing production of biowastes, particularly biosolids (sewage sludge), requires sustainable management strategies for their disposal. Biosolids can contain high concentrations of nutrients; hence, land application can have positive effects on plant growth and soil fertility, especially when applied to degraded soils. However, high rates of biosolids application may result in excessive nitrogen (N) leaching, which can be mitigated by blending biosolids with other biowastes, such as sawdust. We aimed to determine the effects of biosolids and sawdust on growth and N uptake by sorghum, rapeseed, and ryegrass as well as N losses via leaching...
November 2016: Journal of Environmental Quality
https://www.readbyqxmd.com/read/27896616/seasonal-effects-of-pre-aeration-on-microbial-processes-for-nitrogen-removal-in-constructed-wetlands
#8
Ling Wang, Tian Li
Seasonal effects of pre-aeration on microbial nitrogen performance in constructed wetlands (CWs) involved with anaerobic ammonium oxidation (anammox) process were investigated in this study. Slow natural re-aeration rate was the inhibiting factor for total nitrogen removal in CW without pre-aeration, and partial nitrification was the main way for nitrite generation. Besides partial nitrification, pre-aeration provided nitrite generation in CWs with an alternative way: nitrate reduction. Advantage of pre-aeration of influent was much different under various temperature ranges...
November 29, 2016: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/27883922/technical-and-environmental-evaluation-of-an-integrated-scheme-for-the-co-treatment-of-wastewater-and-domestic-organic-waste-in-small-communities
#9
Lucía Lijó, Simos Malamis, Sara González-García, Francesco Fatone, María Teresa Moreira, Evina Katsou
A technical and environmental evaluation of an innovative scheme for the co-treatment of domestic wastewater and domestic organic waste (DOW) was undertaken by coupling an upflow anaerobic sludge blanket (UASB), a sequencing batch reactor (SBR) and a fermentation reactor. Alternative treatment configurations were evaluated with different waste collection practices as well as various schemes for nitrogen and phosphorus removal. All treatment systems fulfilled the required quality of the treated effluent in terms of chemical oxygen demand (COD) and total suspended solids (TSS) concentrations...
October 24, 2016: Water Research
https://www.readbyqxmd.com/read/27878776/successive-chlorothalonil-applications-inhibit-soil-nitrification-and-discrepantly-affect-abundances-of-functional-genes-in-soil-nitrogen-cycling
#10
Ying Teng, Manyun Zhang, Guangmei Yang, Jun Wang, Peter Christie, Yongming Luo
Broad-spectrum fungicide chlorothalonil (CTN) is successively applied into intensive agriculture soil. However, the impacts of successive CTN applications on soil nitrification and related microorganisms remain poorly understood. A microcosm study was conducted to reveal the effects of successive CTN applications on soil nitrification and functional genes involved in soil nitrogen (N) cycling. The CTN at the dosages of 5 mg kg(-1) dry soil (RD) and 25 mg kg(-1) dry soil (5RD) was successively applied into the test soil at 7-day intervals which resulted in the accumulations of CTN residues...
November 23, 2016: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/27878774/a-model-for-determination-of-operational-conditions-for-successful-shortcut-nitrification
#11
Xiaoguang Liu, Mingu Kim, George Nakhla
Accumulation of nitrite in shortcut nitrification is influenced by several factors including dissolved oxygen concentration (DO), pH, temperature, free ammonia (FA), and free nitrous acid (FNA). In this study, a model based on minimum dissolved oxygen concentration (DOmin), minimum/maximum substrate concentration (Smin and Smax), was developed. The model evaluated the influence of pH (7-9), temperature (10-35 °C), and solids retention time (SRT) (5 days-infinity) on MSC values. The evaluation was conducted either by controlling total ammonium nitrogen (TAN) or total nitrite nitrogen (TNN), concentration at 50 mg N/L while allowing the other to vary from 0 to 1000 mg N/L...
November 23, 2016: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/27878347/detection-and-diversity-of-the-nitrite-oxidoreductase-alpha-subunit-nxra-gene-of-nitrospina-in-marine-sediments
#12
Sundas Rani, Hyeon-Woo Koh, Sung-Keun Rhee, Hirotsugu Fujitani, Soo-Je Park
Nitrite-oxidizing bacteria (NOB) are chemolithoautotrophs that catalyze the oxidation of nitrite to nitrate, which is the second step of aerobic nitrification. In marine ecosystems, Nitrospina is assumed to be a major contributor to nitrification. To date, two strains of Nitrospina have been isolated from marine environments. Despite their ecological relevance, their ecophysiology and environmental distribution are understudied owing to fastidious cultivation techniques and the lack of a sufficient functional gene marker...
November 22, 2016: Microbial Ecology
https://www.readbyqxmd.com/read/27875770/evaluation-of-permeable-pavement-responses-to-urban-surface-runoff
#13
Meysam Kamali, Madjid Delkash, Massoud Tajrishy
The construction of permeable pavement (PP) in sidewalks of urban areas is an alternative low impact development (LID) to control stormwater runoff volume and consequently decrease the discharge of pollutants in receiving water bodies. In this paper, some laboratory experiments were performed to evaluate the efficiency of a PP subjected to sediment loadings during its life span. Simple infiltration models were validated by the laboratory experiments to evaluate the trend and extend of PP infiltration capacity throughout the life of the pavement operation...
November 19, 2016: Journal of Environmental Management
https://www.readbyqxmd.com/read/27873113/low-c-n-ratio-raw-textile-wastewater-reduced-labile-c-and-enhanced-organic-inorganic-n-and-enzymatic-activities-in-a-semiarid-alkaline-soil
#14
Mahnaz Roohi, Muhammad Riaz, Muhammad Saleem Arif, Sher Muhammad Shahzad, Tahira Yasmeen, Muhammad Arslan Ashraf, Muhammad Atif Riaz, Ishaq A Mian
Application of raw and treated wastewater for irrigation is an extensive practice for agricultural production in arid and semiarid regions. Raw textile wastewater has been used for cultivation in urban and peri-urban areas in Pakistan without any systematic consideration to soil quality. We conducted a laboratory incubation study to investigate the effects of low C/N ratio raw textile wastewater on soil nitrogen (N) contents, labile carbon (C) as water-soluble C (WSC) contents, and activities of urease and dehydrogenase enzymes...
November 21, 2016: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/27873111/bioaugmentation-of-a-continuous-flow-self-forming-dynamic-membrane-bioreactor-for-the-treatment-of-wastewater-containing-high-strength-pyridine
#15
Cheng Hou, Jinyou Shen, Dejin Zhang, Yi Han, Dehua Ma, Xiuyun Sun, Jiansheng Li, Weiqing Han, Lianjun Wang, Xiaodong Liu
For the treatment of high-strength pyridine containing wastewater, a bioaugmented continuous-flow self-forming dynamic membrane bioreactor (CSFDMBR), which was consisted of a continuous flow airlift reactor (CFAR) and a dynamic membrane bioreactor (DMBR), was developed in this study. The results indicated that through the bioaugmentation by Rhizobium sp. NJUST18, CSFDMBR could be successfully started, which was confirmed by complete removal of pyridine, efficient nitrification, and significant increase of biomass...
November 21, 2016: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/27871745/the-effect-of-dissolved-oxygen-concentration-do-on-oxygen-diffusion-and-bacterial-community-structure-in-moving-bed-sequencing-batch-reactor-mbsbr
#16
Yongfeng Cao, Chaosheng Zhang, Hongwei Rong, Guilin Zheng, Limin Zhao
The effect of dissolved oxygen concentration (DO) on simultaneous nitrification and denitrification was studied in a moving bed sequencing batch reactor (MBSBR) by microelectrode measurements and by real-time PCR. In this system, the biofilm grew on polyurethane foam carriers used to treat municipal sewage at five DO concentrations (1.5, 2.5, 3.5, 4.5 and 5.5 mg/L). The results indicated that the MBSBR exhibited good removal of chemical oxygen demand (92.43%) and nitrogen (83.73%) when DO concentration was 2...
October 24, 2016: Water Research
https://www.readbyqxmd.com/read/27866737/enhanced-nitrogen-loss-from-rivers-through-coupled-nitrification-denitrification-caused-by-suspended-sediment
#17
Xinghui Xia, Ting Liu, Zhifeng Yang, Greg Michalski, Shaoda Liu, Zhimei Jia, Sibo Zhang
Present-day estimations of global nitrogen loss (N-loss) are underestimated. Commonly, N-loss from rivers is thought to be caused by denitrification only in bed-sediments. However, coupled nitrification-denitrification occurring in overlying water with suspended sediments (SPS) where oxic and anoxic/low oxygen zones may coexist is ignored for N-loss in rivers. Here the Yellow and Yangtze Rivers were taken as examples to investigate the effect of SPS, which exists in many rivers of the world, on N loss through coupled nitrification-denitrification with nitrogen stable ((15)N) isotopic tracer simulation experiments and in-situ investigation...
November 17, 2016: Science of the Total Environment
https://www.readbyqxmd.com/read/27864130/role-of-macrophyte-and-effect-of-supplementary-aeration-in-up-flow-constructed-wetland-microbial-fuel-cell-for-simultaneous-wastewater-treatment-and-energy-recovery
#18
Yoong-Ling Oon, Soon-An Ong, Li-Ngee Ho, Yee-Shian Wong, Farrah Aini Dahalan, Yoong-Sin Oon, Harvinder Kaur Lehl, Wei-Eng Thung, Noradiba Nordin
This study investigates the role of plant (Elodea nuttallii) and effect of supplementary aeration on wastewater treatment and bioelectricity generation in an up-flow constructed wetland-microbial fuel cell (UFCW-MFC). Aeration rates were varied from 1900 to 0mL/min and a control reactor was operated without supplementary aeration. 600mL/min was the optimum aeration flow rate to achieve highest energy recovery as the oxygen was sufficient to use as terminal electron acceptor for electrical current generation...
November 3, 2016: Bioresource Technology
https://www.readbyqxmd.com/read/27860363/web-alert-microbial-nitrification
#19
Lawrence P Wackett
No abstract text is available yet for this article.
November 14, 2016: Environmental Microbiology Reports
https://www.readbyqxmd.com/read/27859034/ecological-functions-provided-by-dung-beetles-are-interlinked-across-space-and-time-evidence-from-15-n-isotope-tracing
#20
Beatrice Nervo, Enrico Caprio, Luisella Celi, Michele Lonati, Giampiero Lombardi, Gloria Falsone, Gabriele Iussig, Claudia Palestrini, Daniel Said-Pullicino, Antonio Rolando
Maintaining multiple ecological functions ('multifunctionality') is crucial to sustain viable ecosystems. To date most studies on biodiversity-ecosystem functioning (BEF) have focused on single or few ecological functions and services. However, there is a critical need to evaluate how species and species assemblages affect multiple processes at the same time, and how these functions are interconnected. Dung beetles represent excellent model organisms because they are key contributors to several ecosystem functions...
November 14, 2016: Ecology
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