Search results: Found 14

Listing 1 - 10 of 14 << page
of 2
>>
Sort by
Nitrification in Fixed Bed Reactors Treating Saline Wastewater

Author:
Book Series: Karlsruher Berichte zur Ingenieurbiologie / Institut für Ingenieurbiologie und Biotechnologie des Abwassers, Karlsruher Institut für Technologie ISSN: 01728709 ISBN: 9783866446915 Year: Volume: 47 Pages: XXIV, 173 p. DOI: 10.5445/KSP/1000023321 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: Astronomy (General)
Added to DOAB on : 2019-07-30 20:01:58
License:

Loading...
Export citation

Choose an application

Abstract

Two fixed bed reactors for nitrification with either polyethylene/clay sinter lamellas (FBR A) or porous ceramic rings (FBR B) were continously run for treating synthetic saline wastewater. Seawater from Hafen Büsum was used as an inoculums. The performance of the system was evaluated under different operating conditions. A better overall nitrification without nitrite accumulation was observed in FBR B during continuous incubation. However, in term of ammonia (AOR) and nitrite oxidation rates (NOR) that were determined in batch incubations, FBR A revealed a higher AOR and NOR of 6 and 7 mg N L-1 h-1, compared to the AOR and NOR of 5 and 5.9 mg N L-1 h-1 in FBR B, respectively. For studies of the effect of fluctuating salinity on the nitrification, polyethylene/clay sinter lamellas or porous ceramic rings from FBR A and B, respectively, were used as a source of immobilized nitrifiers. Salt concentrations were decreased from 3.5% to 0.03% via 2, 1 and 0.5% and increased from 3.5% to 5, 7 and 9%. A similar result for AOR and NOR during batch incubation was obtained for both substrata in FBR A and FBR B. The salinity changes influenced more the nitrite oxidizing bacteria (NOB) than the ammonia oxidizing bacteria (AOB). Measurement of oxidation rates during changing conditions show that the NORs were always higher than the AORs in all reactors, especially in initial phase. However, NORs were more sensitive to the salinity fluctuation than AORs, especially at lower salinity. The AORs remained constant for 0.5-3.5% NaCl and dropped to 70% and 68.5% after the salt concentration was brought to 0.034 or 5%, respectively. The NORs decreased significantly to 62% and 87.5% of initial rates after the salt concentration was changed to 2 and 5%, respectively.Non-halotolerant nitrifiers reactors with fresh polyethylene/clay as supporting material were inoculated with water samples taken from a ""Brackwasser""-location at the North Sea and were continuously run. The salt content in medium was 0% at the start and was then increased up to 10.5%. Increases of the salt concentration in a non-salt-adapted FBR suppressed more to NOR than AOR. When salinity was increased from 0.03% to 0.5, 1 and 2%, AORs remained constant. The AORs were approx. 90% of initial rates after the salt concentrations were increased stepwise to 3.5%, whereas the NORs decreased to 85, 52 and 36% of initial rate after salinity was increased to 1, 2 and 3.5%, respectively.

Modellierung der Stoffübertragung beim Niederdruckcarbonitrieren mit Ammoniak und Acetylen

Author:
Book Series: Schriftenreihe des Instituts für Angewandte Materialien, Karlsruher Institut für Technologie ISSN: 21929963 ISBN: 9783731505686 Year: Volume: 63 Pages: XXVIII, 159 p. DOI: 10.5445/KSP/1000057840 Language: GERMAN
Publisher: KIT Scientific Publishing
Subject: Technology (General)
Added to DOAB on : 2019-07-30 20:02:02
License:

Loading...
Export citation

Choose an application

Abstract

A mathematical model has been developed for the description of the transport process for low-pressure carbonitriding with ammonia and acetylene. As an example the case hardening steel 18CrNi8 was used. It can be shown that the concentration profiles of carbon and nitrogen as well as the ammonia exhaust gas concentration are described well. Based on the modelling, first simulation runs could be carried out for further optimization of the heat treatment process.

Astrocytic-neuronal-astrocytic Pathway Selection for Formation and Degradation of Glutamate/GABA

Authors: ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889192434 Year: Pages: 168 DOI: 10.3389/978-2-88919-243-4 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Biology --- Medicine (General) --- Internal medicine
Added to DOAB on : 2015-11-16 15:44:59
License:

Loading...
Export citation

Choose an application

Abstract

Endocrinological research early recognized the importance of intercellular interactions and realized the importance of glutamatergic and GABAergic signaling. In turn this signalling depends on elaborate interactions between astrocytes and neurons, without which neurons would be unable to produce, reuse and metabolize transmitter glutamate and GABA. Details of these subjects are described in this Research Topic by key investigators in this field. It focuses on the intricate and extremely swift pathway producing these amino acid transmitters from glucose in brain but also discusses difficulties in determining expression of some of the necessary genes in astrocytes and related processes in pancreatic islets. However, it does not discuss how closely associated astrocytes and neurons are anatomically, enabling these interactions. This is elegantly shown in this cover image, kindly provided by Professor Andreas Reichenbach (University of Leipzig, Germany).

Carbon Capture and Storage

Author:
ISBN: 9783039213993 / 9783039214006 Year: Pages: 178 DOI: 10.3390/books978-3-03921-400-6 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering
Added to DOAB on : 2019-12-09 11:49:15
License:

Loading...
Export citation

Choose an application

Abstract

Climate change is one of the main threats to modern society. This phenomenon is associated with an increase in greenhouse gas (GHGs, mainly carbon dioxide—CO2) emissions due to anthropogenic activities. The main causes are the burning of fossil fuels and land use change (deforestation). Climate change impacts are associated with risks to basic needs (health, food security, and clean water), as well as risks to development (jobs, economic growth, and the cost of living). The processes involving CO2 capture and storage are gaining attention in the scientific community as an alternative for decreasing CO2 emissions, reducing its concentration in ambient air. The carbon capture and storage (CCS) methodologies comprise three steps: CO2 capture, CO2 transportation, and CO2 storage. Despite the high research activity within this topic, several technological, economic, and environmental issues as well as safety problems remain to be solved, such as the following needs: increase of CO2 capture efficiency, reduction of process costs, and verification of the environmental sustainability of CO2 storage.

Selective Catalytic Reduction of NOx

Author:
ISBN: 9783038973645 9783038973652 Year: Pages: 280 DOI: 10.3390/books978-3-03897-365-2 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Chemical Engineering --- Chemistry (General)
Added to DOAB on : 2018-12-14 10:30:46
License:

Loading...
Export citation

Choose an application

Abstract

The most efficient process to reduce NOx emissions from lean exhaust gases, selective catalytic reduction (SCR) with ammonia, has undergone tremendous development over the past decades. Originally only applied in stationary power plants and industrial installations, SCR systems are now installed in millions of mobile diesel engines, ranging from off-road machineries, to heavy-duty and light-duty trucks and passenger cars, to locomotives and ships. All of these applications involve specific challenges due to tighter emission limits, new internal combustion engine technologies, or alternative fuels.Three review articles and 14 research articles in this book describe recent results and research trends of various aspects of the SCR process. Reaction engineering aspects, such as the proper dosage of ammonia or urea, respectively, are as important as further developments of the different SCR catalysts, by deepening the understanding of their functionality or by systematic improvements of their properties, such as low-temperature activity, selectivity, or poisoning-resistance. Another covered aspect is cost reduction through the use of cheaper base materials for the production is active and stable SCR catalysts. Finally, research efforts are reported to develop SCR processes with different reducing agents, which would open doors to new applications in the future. The range of topics addressed in this book will stimulate the reader’s interest as well as provide a valuable source of information for researchers in academia and industry.

Compounds with Polar Metallic Bonding

Author:
ISBN: 9783039210701 / 9783039210718 Year: Pages: 154 DOI: 10.3390/books978-3-03921-071-8 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Chemistry (General) --- Inorganic Chemistry
Added to DOAB on : 2019-08-28 11:21:27
License:

Loading...
Export citation

Choose an application

Abstract

The Special Edition 'Compounds with Polar Metallic Bonding' is a collection of eight original research reports presenting a broad variety of chemical systems, analytical methods, preparative pathways and theoretical descriptions of bonding situations, with the common aim of understanding the complex interplay of conduction electrons in intermetallic compounds that possess different types of dipoles. Coulombic dipoles introduced by electronegativity differences, electric or magnetic dipoles, polarity induced by symmetry reduction—all the possible facets of the term 'polarity'—can be observed in polar intermetallic phases and have their own and, in most cases, unique consequences on the physical and chemical behaviour. Elucidation of the structure–property relationships in compounds with polar metallic bonding is a modern and growing scientific field which combines solid state physics, preparative chemistry, metallurgy, modern analytic methods, crystallography, theoretical calculations of the electronic state and many more disciplines.

Plasma Catalysis

Author:
ISBN: 9783038977506 Year: Pages: 246 DOI: 10.3390/books978-3-03897-751-3 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Chemical Engineering --- Technology (General)
Added to DOAB on : 2019-04-05 10:34:31
License:

Loading...
Export citation

Choose an application

Abstract

Plasma catalysis is gaining increasing interest for various gas conversion applications, such as CO2 conversion into value-added chemicals and fuels, N2 fixation for the synthesis of NH3 or NOx, methane conversion into higher hydrocarbons or oxygenates. It is also widely used for air pollution control (e.g., VOC

Carbonates

Author:
ISBN: 9783038977223 Year: Pages: 146 DOI: 10.3390/books978-3-03897-723-0 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Physics (General) --- Science (General)
Added to DOAB on : 2019-04-05 10:34:31
License:

Loading...
Export citation

Choose an application

Abstract

This Special Issue is aimed at presenting the state of the art of the multidisciplinary science concerning all aspects of volcanic plumes, of relevance to the volcanology, climatology, atmospheric science, and remote sensing communities.

Multiscale and Innovative Kinetic Approaches in Heterogeneous Catalysis

Authors: ---
ISBN: 9783039211791 / 9783039211807 Year: Pages: 214 DOI: 10.3390/books978-3-03921-180-7 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering
Added to DOAB on : 2019-08-28 11:21:27
License:

Loading...
Export citation

Choose an application

Abstract

Kinetics and reactor modeling for heterogeneous catalytic reactions are prominent tools for investigating and understanding catalyst functionalities at nanoscale and the related rates of complex reaction networks. This book illustrates some examples related to the transformation of simple to more complex feedstocks, including different types of reactor designs, i.e., steady-state, transient plug flow reactors, and TAP reactors for which there is sometimes a strong gap in the operating conditions from ultra-high-vacuum to high-pressure conditions. In conjunction, new methodologies have emerged, giving rise to more robust microkinetics models. As exemplified, they include the kinetics and the dynamics of the reactors and span a large range of length and time scales. The objective of this Special Issue is to provide contributions that can illustrate recent advances and novel methodologies for elucidating the kinetics of heterogeneous reactions and the necessary multiscale approach for optimizing the reactor design. This book is dedicated to postgraduate and scientific researchers, and experts in heterogeneous catalysis. It may also serve as a source of original information for the elaboration of lessons on catalysis for Master students.

Carbon, Nitrogen and Phosphorus Cycling in Forest Soils

Author:
ISBN: 9783038976820 / 9783038976837 Year: Pages: 238 DOI: 10.3390/books978-3-03897-683-7 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Biology --- Forestry
Added to DOAB on : 2019-06-26 08:44:06
License:

Loading...
Export citation

Choose an application

Abstract

The majority of carbon stored in the soils of the world is stored in forests. The refractory nature of some portions of forest soil organic matter also provides the slow, gradual release of organic nitrogen and phosphorus to sustain long term forest productivity. Contemporary and future disturbances, such as climatic warming, deforestation, short rotation sylviculture, the invasion of exotic species, and fire, all place strains on the integrity of this homeostatic system of C, N, and P cycling. On the other hand, the CO2 fertilization effect may partially offset losses of soil organic matter, but many have questioned the ability of N and P stocks to sustain the CO2 fertilization effect.

Keywords

carbon distribution index --- moisture gradient --- soil organic matter fraction --- soil degradation --- soil available nitrogen --- soil available phosphorus --- temperature --- stand density --- charcoal --- forest soil --- carbon mineralization --- microbial activity --- nitrification --- polyphenols --- temperature --- soil microbial communities --- PLFA --- seasons --- nitrogen dynamics --- gross nitrogen transformations --- Daxing’an Mountains --- climatic factors --- soil nutrients --- forest types --- principal component analyses --- soil structure --- soil pH --- Oxisol --- variable-charge soils --- aluminum accumulator --- seasonal trends --- beech forests --- soil enzymes --- organic matter --- multilevel models --- near natural forest management --- Pinus massoniana plantation --- Cunninghamia lanceolata plantation --- soil greenhouse gas flux --- biolability --- tree-DOM --- dissolved organic matter (DOM) --- carbon --- dissolved organic carbon (DOC) --- stemflow --- throughfall --- alpine forest --- ammonia-oxidizing bacteria --- ammonia-oxidizing archaea --- ammonium --- nitrate --- revegetation --- microbial biomass --- chloroform fumigation extraction --- enzyme activities --- stoichiometric homeostasis --- the Three Gorges Reservoir --- Eucalyptus sp. --- wood volume --- second production cycle --- annual increment average --- soil fertility --- nutrient cycling --- Chamaecyparis forest --- humic substances --- 31P nuclear magnetic resonance spectroscopy (31P NMR) --- P species --- topography --- net primary productivity --- climate zone --- climate --- soil N --- litter N --- climate change --- manuring --- manure pelleting --- northern temperate --- pyrolysis --- information review --- leaf N:P ratio --- P resorption efficiency --- soil P fractions --- P stock --- stand age

Listing 1 - 10 of 14 << page
of 2
>>
Sort by
Narrow your search