Search results for "denitrification"
showing 10 items of 132 documents
Nitrogen removal from on-site treated anaerobic effluents using intermittently aerated moving bed biofilm reactors at low temperatures
2005
Abstract On-site post-treatment of anaerobically pre-treated dairy parlour wastewater (DPWW e ; 10 °C) and mixture of kitchen waste and black water (BWKW e ; 20 °C) was studied in moving bed biofilm reactors (MBBR). The focus was on removal of nitrogen and of residual chemical oxygen demand (COD). Moreover, the effect of intermittent aeration and continuous vs. sequencing batch operation was studied. All MBBRs removed 50–60% of nitrogen and 40–70% of total COD (COD t ). Complete nitrification was achieved, but denitrification was restricted by lack of carbon. Nitrogen removal was achieved in a single reactor by applying intermittent aeration. Continuous and sequencing batch operation provid…
Seasonal cycle of benthic denitrification and DNRA in the aphotic coastal zone, northern Baltic Sea
2020
Current knowledge on the seasonality of benthic nitrate reduction pathways in the aphotic, density stratified coastal zone of the Baltic Sea is largely based on data from muddy sediments, neglecting the potential contribution of sandy sediments. To gain a more comprehensive understanding of seasonality in this part of the Baltic Sea coast, we measured rates of benthic denitrification, anammox and dissimilatory nitrate reduction to ammonium (DNRA) monthly in the ice-free period of 2016 in both sandy and muddy aphotic sediments, northwestern Gulf of Finland. No anammox was observed. The seasonal cycle of denitrification in both sediment types was related to the hydrography-driven development …
Achievement of partial nitrification under different carbon-to-nitrogen ratio and ammonia loading rate for the co-treatment of landfill leachate with…
2019
Abstract Partial nitrification (PN) is a technically and economically effective solution for the treatment of wastewater featuring low C/N ratio, allowing to achieve approximately 25% energy saving and 40% carbon source for denitrification. This study investigated the effect of different carbon to nitrogen ratio (C/N) and ammonia loading rate (ALR) on PN performances in a sequencing batch reactor (SBR) treating landfill leachate with municipal wastewater. The aim was to find an optimum range for C/N and ALR to maximize PN performances. Results demonstrated that a proper balancing between ALR and C/N is crucial to achieve high PN efficiency. The results highlighted the existence of an optimu…
Agro-ecological benefits of faba bean for rainfed Mediterranean cropping systems
2017
This paper reviews the main results from a set of experiments carried out in a semiarid Mediterranean environment during the past 25 years on faba bean (<em>Vicia faba</em> L.), a crop traditionally grown in southern Italy and Sicily under rainfed conditions. These experiments focused on the residual effects of faba bean on subsequent crop(s) and assessment of the nitrogen (N) balance during the crop cycle, paying attention to both the environmental release of N (losses via volatilisation and denitrification) and estimates of N2 fixation as influenced by tillage system, intercropping, and presence/absence of mycorrhizal inoculum. Faba bean relied on N2 fixation more than other g…
Plant species identities and fertilization influence on arbuscular mycorrhizal fungal colonisation and soil bacterial activities
2016
International audience; Plant species influence soil microbial communities, mainly through their functional traits. However, mechanisms underlying these effects are not well understood, and in particular how plant/ microorganism interactions are affected by plant identities and/or environmental conditions. Here, we performed a greenhouse experiment to assess the effects of three plant species on arbuscular mycorrhizal fungal (AMF) colonization, bacterial potential nitrification (PNA) and denitrification activities (PDA) through their functional traits related to nitrogen acquisition and turnover. Three species with contrasting functional traits and strategies (from exploitative to conservat…
A comprehensive comparison between halophilic granular and flocculent sludge in withstanding short and long-term salinity fluctuations
2018
The effects of salinity fluctuations on the activity of autochthonous halophilic bacteria in aerobic granular sludge (AGS) and flocculent activated sludge (FAS) reactors were investigated. The response of nitrifiers and denitrifiers activity to drastic and moderate salinity shocks in the short-term (ST) and long-term (LT) was examined. The BOD5removal efficiency decreased only in the reactors subjected to the drastic LT salinity increase. Nevertheless, stable performances were achieved 18 days after the shock in the AGS-R1 (90%), whereas after 27 days in the FAS-R1 (82%). The loss in nitritation efficiency was higher in the FAS reactors and was proportional to the shock intensity. Nitritati…
Efficient recycling of nutrients in modern and past hypersaline environments
2019
The biogeochemistry of hypersaline environments is strongly influenced by changes in biological processes and physicochemical parameters. Although massive evaporation events have occurred repeatedly throughout Earth history, their biogeochemical cycles and global impact remain poorly understood. Here, we provide the first nitrogen isotopic data for nutrients and chloropigments from modern shallow hypersaline environments (solar salterns, Trapani, Italy) and apply the obtained insights to ¿ 15 N signatures of the Messinian salinity crisis (MSC) in the late Miocene. Concentrations and ¿ 15 N of chlorophyll a, bacteriochlorophyll a, nitrate, and ammonium in benthic microbial mats indicate that…
Changes in soil mineral N content and abundances of bacterial communities involved in N reactions under laboratory conditions as predictors of soil N…
2016
Proper management of soil fertility requires specific tools for predicting N availability for crops as a consequence of different fertilization strategies. More information is required, especially for organic fertilizers, depending on their mineralization rate, composition, and processing (i.e., fresh or composted manure), as well as their effects on soil properties. Laboratory soil incubations were used as a proxy for understanding plant–soil N dynamics under field conditions. Chemical and microbiological measurements as contents of mineral N, potentially mineralizable N and the abundance of key genes regulating the overall N cycle were used as predictors of mineral N availability to maize…
Bacterial community structure and removal performances in IFAS-MBRs: A pilot plant case study
2017
Abstract The paper reports the results of an experimental campaign carried out on a University of Cape Town (UCT) integrated fixed-film activated sludge (IFAS) membrane bioreactor (MBR) pilot plant. The pilot plant was analysed in terms of chemical oxygen demand (COD) and nutrients removal, kinetic/stoichiometric parameters, membrane fouling and sludge dewaterability. Moreover, the cultivable bacterial community structure was also analysed. The pilot plant showed excellent COD removal efficiency throughout experiments, with average value higher than 98%, despite the slight variations of the influent wastewater. The achieved nitrification efficiency was close to 98% for most of the experimen…
Nitrogen Loss from Pristine Carbonate-Rock Aquifers of the Hainich Critical Zone Exploratory (Germany) Is Primarily Driven by Chemolithoautotrophic A…
2017
Despite the high relevance of anaerobic ammonium oxidation (anammox) for nitrogen loss from marine systems, its relative importance compared to denitrification has less been studied in freshwater ecosystems, and our knowledge is especially scarce for groundwater. Surprisingly, phospholipid fatty acids (PLFA)-based studies identified zones with potentially active anammox bacteria within two superimposed pristine limestone aquifer assemblages of the Hainich Critical Zone Exploratory (CZE; Germany). We found anammox to contribute an estimated 83% to total nitrogen loss in suboxic groundwaters of these aquifer assemblages at rates of 3.5-4.7 nmol L -1 d -1, presumably favored over denitrificati…