scholarly journals Initial Energy Content of Cells Improve Efficiency of Activated Sludge Acclimation and Degradation of a Xenobiotic Compound

2016 ◽  
Author(s):  
Nyuk-Min Chong ◽  
Lan Huong Nguyen
Keyword(s):  
Activated Sludge ◽  
Energy Content ◽  
Initial Energy ◽  
Improve Efficiency ◽  
Xenobiotic Compound

scholarly journals Magnetically driven jets and winds from weakly magnetized accretion discs

2019 ◽  
Vol 490 (3) ◽  
pp. 3112-3133 ◽  
Author(s):  
J Jacquemin-Ide ◽  
J Ferreira ◽  
G Lesur
Keyword(s):  
Numerical Simulations ◽  
Energy Content ◽  
Initial Energy ◽  
Accretion Discs ◽  
Analytical Models ◽  
Magnetorotational Instability ◽  
New Class ◽  
Analytical Criterion ◽  
First Time

Abstract Semi-analytical models of disc outflows have successfully described magnetically driven, self-confined super-Alfvénic jets from near-Keplerian accretion discs. These jet-emitting discs (JEDs) are possible for high levels of disc magnetization μ defined as μ = 2/β, where beta is the usual plasma parameter. In near-equipartition JEDs, accretion is supersonic and jets carry away most of the disc angular momentum. However, these solutions prove difficult to compare with cutting-edge numerical simulations, for the reason that numerical simulations show wind-like outflows but in the domain of small magnetization. In this work, we present for the first time self-similar isothermal solutions for accretion–ejection structures at small magnetization levels. We elucidate the role of magnetorotational instability-like (MRI) structures in the acceleration processes that drive this new class of solutions. The disc magnetization μ is the main control parameter: Massive outflows driven by the pressure of the toroidal magnetic field are obtained up to μ ∼ 10−2, while more tenuous centrifugally driven outflows are obtained at larger μ values. The generalized parameter space and the astrophysical consequences are discussed. We believe that these new solutions could be a stepping stone in understanding the way astrophysical discs drive either winds or jets. Defining jets as self-confined outflows and winds as uncollimated outflows, we propose a simple analytical criterion based on the initial energy content of the outflow, to discriminate jets from winds. We show that jet solution is achieved at all magnetization levels, while winds could be obtained only in weakly magnetized discs that feature heating.

The utilization of the dietary energy of pangola and setaria by young growing beef cattle

1982 ◽  
Vol 98 (2) ◽  
pp. 395-404 ◽  
Author(s):  
G. D. Tudor ◽  
D. J. Minson
Keyword(s):  
Protein Content ◽  
Dry Matter ◽  
Production Systems ◽  
Energy Content ◽  
Live Weight ◽  
Initial Energy ◽  
Metabolizable Energy ◽  
Net Energy ◽  
Lower Efficiency ◽  
Tropical Grasses

SUMMARYThe net energy values for growth and fattening of two artificially dried tropical grasses-, pangola (Digitaria decumbens) and setaria (S. sphacelata var. sericea cv. Nandi), of similar estimated metabolizable energy content (8·07 and 7·96 MJ/kg D.M.) were determined with cattle using a slaughter technique. Growing cattle with a mean initial weight of 175 kg were given equal quantities of dry matter of the two grasses at each of three planes of nutrition above maintenance for a period of 152 days.The initial energy, fat and protein content of the total body of the 24 test animals was estimated from regressions relating fasted live weight to theśe components, derived from 12 similar cattle slaughtered at the beginning of the feeding period. The final energy, fat and protein content of the test animals was determined directly by chemical analysis. The metabolizable energy (ME) content of the grasses was estimated from the level of digestible energy (DE) determined with eight cattle, assuming that ME = 0·815 DE.The cattle fed pangola gained more live weight, empty-body weight, fat, protein and energy than animals fed similar quantities of setaria. The net energy value for growth and fattening (NEf) was determined using regressions relating energy retention to the quantity of dry matter eaten. NEf in MJ/kg dry matter was 2·27 for pangola and 1·31 for setaria.Efficiency of utilization of ME for growth and fattening (kf) was.27·7% for pangola and 16·9% for setaria. These values for tropical grasses are lower than any values reported for temperate pasture species. Thus the lower efficiency of utilization of ME may cause the lower production of cattle which graze tropical grasses.It was concluded that as the kf values of different tropical grasses are not constant, kf values should be measured on a wider range of tropical grasses so that this factor can be taken into account when evaluating grasses in animal production systems.

The Biochemistry of Enhanced Phosphorus Removal by Activated Sludge

1985 ◽  
Vol 17 (11-12) ◽  
pp. 303-304 ◽  
Author(s):  
J. B. Heymann
Keyword(s):  
Activated Sludge ◽  
Membrane Transport ◽  
Phosphorus Removal ◽  
Energy Content ◽  
High Energy ◽  
High Rate ◽  
Terminal Electron Acceptor ◽  
Structural Cell ◽  
Cell Material ◽  
Active Membrane

The design and operation of an activated sludge plant which aims to achieve maximum phosphorus removal should be based on sound biochemical principles. This poster presents the biochemical reactions believed to be responsible for observed variations in the concentration of different phosphorus species in such plants. Excess phosphorus removed in the aerated stage of plant configurations such as the Phoredox process (i.e. more than is necessary for sludge metabolism) is accumulated in the sludge in the form of polyphosphate. The most likely major function of this compound is to supply energy for active membrane transport of specific carbon sources into the cells in the anaerobic stage, acetate being one such compound. The energy for this process is derived from the hydrolysis of polyphosphate to orthophosphate which is then released into the medium around the cells. Five possible mechanisms are proposed to describe this process. From the microbial viewpoint the main advantage of active membrane transport is the high rate at which compounds transported becomes available inside the cell. In the absence of a terminal electron acceptor such as oxygen or nitrate, carbon compounds absorbed cannot be oxidized. Accumulation as such would inhibit further absorption and may lead to disturbance of intracellular conditions. Absorbed material is therefore converted to a reserve to be stored for later use. Indications are that sewage feed composition favours the formation of one reserve compound: poly-β-hydroxybutyrate (PHB). In the presence of oxygen, the cell is able to oxidise PHB at a high rate relative to other reserves such as glycogen and triglycerides. The energy produced in this way is far in excess of what the cell needs for normal metabolism and results in an ‘over-production' of adenosine triphosphate (ATP) far in excess of that needed for biosynthesis. In its role as energy carrier, ATP formed due to the oxidation of PHB cannot be accumulated. Instead, to control the ATP:ADP ratio (ADP = adenosine diphosphate) in the cell, the energy is transferred from ATP to polyphosphate by polyphosphate kinase. When the sludge is recirculated to the anaerobic stage, some of this polyphosphate is used for active membrane transport. The success of excess phosphorus removal by activated sludge revolves firstly around the degree of PHB formation in the anaerobic stage. Any chemical or physical agent inhibiting this process would reduce the extent of phosphorus removal. The second important factor is the extent of ATP ‘over-production' which is mainly determined by biosynthetic activities. An increase in biosynthesis of structural cell components would lead to a higher rate of ATP utilization for energy and thus decrease polyphosphate formation. These are the central concepts on which enhanced phosphorus removal in activated sludge plants should be based. It seems that phosphorus removal in the Phoredox process represents an interplay between structural cell biosynthesis and reserve material synthesis. The organic compounds in the sewage feed play a decisive role in determining the set of processes which is going to occur. It is hypothesized that compounds needed in the biosynthesis of cell material would result in the so-called ‘normal' phosphorus removal, while substances with high energy content and lower biosynthetic value would favour ‘excess' phosphorus removal. The building blocks of cell material usually contain high amounts of nitrogen (such as proteins and nucleic acids) while the compounds usually associated with high energy content contain very little nitrogen (such as carbohydrates and lipids). This concept is reflected in the importance and value attached to the COD:TKN ratio, which roughly approximates the ratio of non-nitrogen containing compounds to nitrogen-rich compounds. In view of the above-mentioned ideas, this parameter can be refined to the following proposed ratio: In the formulation of these concepts, conventional biochemical principles were applied to old and new observations in a relatively new field. However, very little quantitative information regarding the validity of these hypotheses are available and care should be taken not to see these as the final answer.

scholarly journals Bowen–York model solution redux

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Emel Altas ◽  
Bayram Tekin
Keyword(s):  
Energy Content ◽  
Analytical Form ◽  
Initial Energy ◽  
Model Solution ◽  
Linear Momentum ◽  
Hamiltonian Constraint ◽  
Initial Value ◽  
Relativistic Case ◽  
Stationary Part ◽  
Dynamical Time

AbstractInitial value problem in general relativity is often solved numerically; with only a few exceptions one of which is the “model” solution of Bowen and York where an analytical form of the solution is available. The solution describes a dynamical, time-asymmetric, gravitating system with mass and linear momentum. Here we revisit this solution and correct an error which turns out to be important for identifying the energy-content of the solution. Depending on the linear momentum, the ratio of the non-stationary part of the initial energy to the total ADM energy takes values between [0, 0.592). This non-stationary part is expected to be turned into gravitational waves during the evolution of the system to possibly settle down to a black hole with mass and linear momentum. In the ultra-relativistic case (the high momentum limit), the maximum amount of gravitational wave energy is 59.2% of the total ADM energy. We also give a detailed account of the general solution of the Hamiltonian constraint.

Replacement of the Final Settling Basin by a Fluidized Pellet Bed Separator to Improve Efficiency of Activated Sludge System

1993 ◽  
Vol 27 (11) ◽  
pp. 253-256 ◽  
Author(s):  
Norihito Tambo ◽  
Genzou Ozawa ◽  
Yasuhiko Kihara ◽  
Akira Ohba
Keyword(s):  
Activated Sludge ◽  
Treatment System ◽  
High Rate ◽  
Sludge Treatment ◽  
Settling Basin ◽  
Separation Technology ◽  
Improve Efficiency ◽  
Conventional Activated Sludge ◽  
Activated Sludge System ◽  
Bed Separation

A new high rate separation technology, i.e. a fluidized pellet bed separation of activated sludge, is proposed to improve conventional activated sludge treatment system and the related dewatering process.

Pharmaceuticals and health care products in wastewater effluents: the example of carbamazepine

2003 ◽  
Vol 3 (4) ◽  
pp. 131-137 ◽  
Author(s):  
K. Stamatelatou ◽  
C. Frouda ◽  
M.S. Fountoulakis ◽  
P. Drillia ◽  
M. Kornaros ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Consumption Rate ◽  
Solid Phase ◽  
Organic Content ◽  
Operating Conditions ◽  
Anaerobic Sludge ◽  
Aquatic Environments ◽  
Short Term ◽  
Xenobiotic Compound

Persistence and impact of pharmaceutics in the environment are discussed. The case of carbamazepine (CBZ), a widely used antiepileptic drug detected in rivers, lakes, sludges and even in ground water is examined. CBZ fate was investigated in all possible routes that may follow after it has been discharged to the sewage system: activated sludge, anaerobic digestion sludge, seawater, fresh water and soil. Carbamazepine slowed down, i.e. caused a decrease in the COD consumption rate in the activated sludge process, especially after longer term exposure, while the anaerobic sludge process was unaffected in the operating conditions that were applied. The compound was not degraded under either short term or long term exposure to either aerobic or anaerobic degradation processes. Carbamazepine seemed to biosorb to solid phases (soil, sludge) and this strength of sorption was related to the organic content of the solid phase. These results explain why CBZ is a very persistent xenobiotic compound, as is apparent from its detection in appreciable amounts in various aquatic environments.

scholarly journals Energy and protein nutrition of early-weaned pigs. 1. effect of energy intake and energy: protein on growth, efficiency and nitrogen utilization of pigs between 8–32 d

1980 ◽  
Vol 43 (2) ◽  
pp. 289-304 ◽  
Author(s):  
K. J. McCracken ◽  
S. M. Eddie ◽  
W. G. Stevenson
Keyword(s):  
Least Squares Method ◽  
Energy Content ◽  
Skim Milk ◽  
Nitrogen Retention ◽  
Growth Efficiency ◽  
Initial Energy ◽  
Feed Conversion ◽  
Response Curves ◽  
Protein Levels ◽  
Rate Of Increase

1. The effect of energy and protein intake on the growth, food efficiency and nitrogen retention of artificially-reared pigs was studied over three 8 d periods between 8–32 d of age in an experiment employing a 5×3×2 factorial design. The factors were initial energy: N value (I; 250, 355, 460, 565 or 670 kJ/g N), rate of increase of 1 at 8 d intervals (0, 12.5 or 25%) and plane of nutrition (three times daily to appetite or 75% of this intake).2. The range of energy: N values was obtained by formulating five diets based on dried skim milk, lactose and casein and feeding appropriate combinations of two diets. The diets, which were pelleted, contained 100 g maize oil/kg and the gross energy content was approximately 20 MJ/kg.3. N digestibility was high at all three age intervals, reaching 0.99 on the diet containing the highest dietary crude protein (N × 6.25) level. Metabolic faecal N excretion was found to be 1.1 g/kg dry matter (DM) intake.4. Growth rate, feed conversion ratio (kg food intake/kg wt gain; FCR), N retention (NR) and the proportion of digested N retained (NR:apparent digested N (ADN)) were significantly (P < 0.001) affected by I values at all age intervals and the responses were quadratic. Response curves were calculated by the least squares method and optimum values of I determined for each of the criteria.A constant energy:N value of approximately 400 kJ/g N was indicated by growth, FCR and NR optima but the NR:ADN value fell from 0.77 for the 8–16 d period to 0.60 for the 24–32 d period at this I value. It is concluded that a suitable compromise would be an I value of 470 kJ/g N increasing by 10%/week.5. There was a significant interaction between plane of nutrition and I values on FCR between 16–24 d (P < 0.001) and 8–32 d (P < 0.01) indicating that FCR was better at high protein levels and worse at low protein levels when the diets were fed on the lower plane of nutrition.

scholarly journals Explaining the low luminosity of Uranus: a self-consistent thermal and structural evolution

2020 ◽  
Vol 633 ◽  
pp. A50 ◽  
Author(s):  
Allona Vazan ◽  
Ravit Helled
Keyword(s):  
Energy Content ◽  
Structural Evolution ◽  
Initial Energy ◽  
Planetary Science ◽  
Composition Gradient ◽  
Internal Cooling ◽  
Composition Distribution ◽  
Convective Mixing ◽  
Deep Interior ◽  
Composition Gradients

The low luminosity of Uranus is a long-standing challenge in planetary science. Simple adiabatic models are inconsistent with the measured luminosity, which indicates that Uranus is non-adiabatic because it has thermal boundary layers and/or conductive regions. A gradual composition distribution acts as a thermal boundary to suppress convection and slow down the internal cooling. Here we investigate whether composition gradients in the deep interior of Uranus can explain its low luminosity, the required composition gradient, and whether it is stable for convective mixing on a timescale of some billion years. We varied the primordial composition distribution and the initial energy budget of the planet, and chose the models that fit the currently measured properties (radius, luminosity, and moment of inertia) of Uranus. We present several alternative non-adiabatic internal structures that fit the Uranus measurements. We found that convective mixing is limited to the interior of Uranus, and a composition gradient is stable and sufficient to explain its current luminosity. As a result, the interior of Uranus might still be very hot, in spite of its low luminosity. The stable composition gradient also indicates that the current internal structure of Uranus is similar to its primordial structure. Moreover, we suggest that the initial energy content of Uranus cannot be greater than 20% of its formation (accretion) energy. We also find that an interior with a mixture of ice and rock, rather than separated ice and rock shells, is consistent with measurements, suggesting that Uranus might not be “differentiated”. Our models can explain the luminosity of Uranus, and they are also consistent with its metal-rich atmosphere and with the predictions for the location where its magnetic field is generated.

Demonstrating Nutrient Cost Gradients: A Brooklyn Case Study

2014 ◽  
Vol 84 (5-6) ◽  
pp. 244-251 ◽  
Author(s):  
Robert J. Karp ◽  
Gary Wong ◽  
Marguerite Orsi
Keyword(s):  
Low Income ◽  
Energy Content ◽  
Food Selection ◽  
The United States ◽  
United States Department ◽  
Micronutrient Deficiencies ◽  
Caloric Density ◽  
Low Income Families ◽  
The Cost ◽  
The Impact

Abstract. Introduction: Foods dense in micronutrients are generally more expensive than those with higher energy content. These cost-differentials may put low-income families at risk of diminished micronutrient intake. Objectives: We sought to determine differences in the cost for iron, folate, and choline in foods available for purchase in a low-income community when assessed for energy content and serving size. Methods: Sixty-nine foods listed in the menu plans provided by the United States Department of Agriculture (USDA) for low-income families were considered, in 10 domains. The cost and micronutrient content for-energy and per-serving of these foods were determined for the three micronutrients. Exact Kruskal-Wallis tests were used for comparisons of energy costs; Spearman rho tests for comparisons of micronutrient content. Ninety families were interviewed in a pediatric clinic to assess the impact of food cost on food selection. Results: Significant differences between domains were shown for energy density with both cost-for-energy (p < 0.001) and cost-per-serving (p < 0.05) comparisons. All three micronutrient contents were significantly correlated with cost-for-energy (p < 0.01). Both iron and choline contents were significantly correlated with cost-per-serving (p < 0.05). Of the 90 families, 38 (42 %) worried about food costs; 40 (44 %) had chosen foods of high caloric density in response to that fear, and 29 of 40 families experiencing both worry and making such food selection. Conclusion: Adjustments to USDA meal plans using cost-for-energy analysis showed differentials for both energy and micronutrients. These differentials were reduced using cost-per-serving analysis, but were not eliminated. A substantial proportion of low-income families are vulnerable to micronutrient deficiencies.

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