scholarly journals Biochar and Zeolite as Alternative Biofilter Media for Denitrification of Aquaculture Effluents

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2703
Author(s):  
Diplina Paul ◽  
Steven G. Hall
Keyword(s):  
Surface Roughness ◽  
Nitrate Removal ◽  
Scale Up ◽  
Arithmetic Mean ◽  
Maximum Height ◽  
Loading Rates ◽  
Aquaculture Effluents ◽  
The Media ◽  
Aquaculture Wastewater ◽  
Better Than

Denitrification processes are crucial in aquaculture as they convert the undesirable nitrate to safer forms of nitrogen. Conventionally, plastic media are used for the biofiltration of wastewater. However, alternative media may be as effective/better than plastic and enhance the sustainability of the system. This study evaluated biochar and zeolite as alternatives for the denitrification of aquaculture effluents. Triplicates of laboratory-scale bioreactors were fabricated to compare the denitrification efficiencies of biochar and zeolite to that of plastic. The bioreactors were fed synthetic aquaculture wastewater having nitrate loading rates of 50, 125, and 150 mg/L. Zeolite exhibited highest values of surface roughness in terms of arithmetic mean height (0.89 µm), maximum height (6.52 µm), and root-mean-square height (1.17 µm), as corroborated by surface profilometry and scanning electron microscopy. The results revealed that under pseudo-steady-state conditions, zeolite displayed the highest nitrate removal efficiency (maximum 95.02 ± 0.01%), which was followed by biochar and plastic (maximum 92.91 ± 0.01% and 92.57 ± 0.02%, respectively) due to its extraordinary surface roughness that provided better adhesion to the bacteria. However, by the end of the study, all the media exhibited comparable rates. Thus, both zeolite and biochar are sustainable alternatives of biomedia for nitrate removal. However, time and labor constraints must be accounted for to scale-up such bioreactors.

PENGEMBANGAN MEDIA BIG BOOK UNTUK MENINGKATKAN HASIL BELAJAR PECAHAN SENILAI SISWA SD

2018 ◽  
Vol 16 (1) ◽  
pp. 67-76
Author(s):  
Disyacitta Neolia Firdana ◽  
Trimurtini Trimurtini
Keyword(s):  
Learning Outcomes ◽  
Large Scale ◽  
Fourth Grade ◽  
Learning Activities ◽  
Equivalent Fractions ◽  
Fourth Grade Students ◽  
Teacher Needs ◽  
The Media ◽  
Test Result ◽  
Better Than

This research aimed to determine the properness and effectiveness of the big book media on learning equivalent fractions of fourth grade students. The method of research is Research and Development  (R&D). This study was conducted in fourth grade of SDN Karanganyar 02 Kota Semarang. Data sources from media validation, material validation, learning outcomes, and teacher and students responses on developed media. Pre-experimental research design with one group pretest-posttest design. Big book developed consist of equivalent fractions material, students learning activities sheets with rectangle and circle shape pictures, and questions about equivalent fractions. Big book was developed based on students and teacher needs. This big book fulfill the media validity of 3,75 with very good criteria and scored 3 by material experts with good criteria. In large-scale trial, the result of students posttest have learning outcomes completness 82,14%. The result of N-gain calculation with result 0,55 indicates the criterion “medium”. The t-test result 9,6320 > 2,0484 which means the average of posttest outcomes is better than the average of pretest outcomes. Based on that data, this study has produced big book media which proper and effective as a media of learning equivalent fractions of fourth grade elementary school.

Abrasive Waterjet Cutting of Aluminum Alloys: Workpiece Surface Roughness

2013 ◽  
Vol 404 ◽  
pp. 3-9 ◽  
Author(s):  
Nihat Tosun ◽  
Ihsan Dagtekin ◽  
Latif Ozler ◽  
Ahmet Deniz
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Aluminum Alloys ◽  
Abrasive Waterjet ◽  
Traditional Methods ◽  
Workpiece Surface ◽  
Abrasive Waterjet Machining ◽  
Waterjet Machining ◽  
Area Of Application ◽  
Better Than

Abrasive waterjet machining is one of the non-traditional methods of the recent years which found itself a wide area of application in the industry for machining of different materials. In this paper, the surface roughness of 6061-T6 and 7075-T6 aluminum alloys are being cut with abrasive waterjet is examined experimentally. The experiments were conducted with different waterjet pressures and traverse speeds. It has been found that the surface roughness obtained by cutting material with high mechanical properties is better than that of obtained by cutting material with inferior mechanical properties.

Observation in the Surface Roughness of Silicon Wafer during Semi-Fixed Abrasive Machining with Large Grains

2009 ◽  
Vol 69-70 ◽  
pp. 253-257
Author(s):  
Ping Zhao ◽  
Jia Jie Chen ◽  
Fan Yang ◽  
K.F. Tang ◽  
Ju Long Yuan ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Silicon Wafer ◽  
Processing Parameters ◽  
Wafer Surface ◽  
Abrasive Machining ◽  
Fixed Abrasive ◽  
Is Failure ◽  
Better Than

Semi-fixed abrasive is a novel abrasive. It has a ‘trap’ effect on the hard large grains that can prevent defect effectively on the surface of the workpiece which is caused by large grains. In this paper, some relevant experiments towards silicon wafers are carried out under the different processing parameters on the semi-fixed abrasive plates, and 180# SiC is used as large grains. The processed workpieces’ surface roughness Rv are measured. The experimental results show that the surface quality of wafer will be worse because of higher load and faster rotating velocity. And it can make a conclusion that the higher proportion of bond of the plate, the weaker of the ‘trap’ effect it has. Furthermore the wet environment is better than dry for the wafer surface in machining. The practice shows that the ‘trap’ effect is failure when the workpiece is machined by abrasive plate which is 4.5wt% proportion of bond in dry lapping.

Ultra-precision grinding of 4H-SiC wafer by PAV/PF composite sol-gel diamond wheel

2021 ◽  
Vol 13 (9) ◽  
pp. 168781402110449
Author(s):  
Kaiping Feng ◽  
Tianchen Zhao ◽  
Binghai Lyu ◽  
Zhaozhong Zhou
Keyword(s):  
Surface Roughness ◽  
Low Temperature ◽  
Polyvinyl Alcohol ◽  
Feed Rate ◽  
Hot Pressing ◽  
Phenolic Resin ◽  
Sol Gel ◽  
Diamond Wheel ◽  
Sic Wafer ◽  
Better Than

To eliminate the deep scratches on the 4H-SiC wafer surface in the grinding process, a PVA/PF composite sol-gel diamond wheel was proposed. Diamond and fillers are sheared and dispersed in the polyvinyl alcohol-phenolic resin composite sol glue, repeatedly frozen at a low temperature of −20°C to gel, then 180°C sintering to obtain the diamond wheel. Study shows that the molecular chain of polyvinyl alcohol-phenolic resin is physically cross-linked to form gel under low-temperature conditions. Tested by mechanical property testing machines, microhardness tester, and SEM. The results show that micromorphology is more uniform, the strength of the sol-gel diamond wheel is higher, the hardness uniformity is better than that of the hot pressing diamond wheel. Grinding experiments of 4H-SiC wafer were carried out with the prepared sol-gel diamond wheel. The influence of grinding speed, feed rate, and grinding depth on the surface roughness was investigated. The results showed that by using the sol-gel diamond wheel, the surface quality of 4H-SiC wafer with an average surface roughness Ra 6.42 nm was obtained under grinding wheel speed 7000 r/min, grinding feed rate 6 µm/min, and grinding depth 15 µm, the surface quality was better than that of using hot pressing diamond wheel.

Relationships between Textures and Surface Roughness, Frictional Behavior, Erosion and Corrosion Properties of TiN Films

2004 ◽  
Vol 449-452 ◽  
pp. 781-784 ◽  
Author(s):  
Hee Dong Kim ◽  
In Soo Kim ◽  
Dong Young Sung ◽  
Min Gu Lee ◽  
S. Dost ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Corrosion Resistance ◽  
Friction Coefficient ◽  
Physical Vapor Deposition ◽  
Textured Surface ◽  
Corrosion Properties ◽  
Tin Films ◽  
Physical Vapor Deposition Method ◽  
Erosion Corrosion ◽  
Better Than

TiN coated films were prepared by a reactive ion physical vapor deposition method. In this research, we studied the relationships between textures and friction coefficient, erosion-corrosion resistance and corrosion resistance in textured TiN films. The surface roughness of (115) textured TiN films is lower than that of (111) textured TiN films. The friction coefficient of (115) textured surface is similar with that of (111) textured surface of TiN coated films. The erosion-corrosion and corrosion resistance of (115) textured surface is better than that of (111) textured surface of TiN coated films.

Experimental Investigation of Strengthening and Polishing Aeroengine Blades

2011 ◽  
Vol 101-102 ◽  
pp. 909-912
Author(s):  
Guo Ying Zeng ◽  
Deng Feng Zhao
Keyword(s):  
Surface Roughness ◽  
Experimental Investigation ◽  
Fatigue Strength ◽  
Surface Quality ◽  
Three Dimensional ◽  
Experimental Results ◽  
Technological Parameters ◽  
Polishing Process ◽  
Optimum Parameters ◽  
The Media

The three-dimensional vibratory strengthening and polishing technology was used to strengthen and polish aeroengine blades with complicated surfaces. At first, the principle of the strengthening and polishing process was introduced, which combined strengthening process with polishing process. Then, the technological parameters influenced on the surface quality were investigated. The principal variables were the media hardness, the frequency and amplitude of the vibration, and duration of the vibratory strengthening and polishing. The optimum parameters were obtained. Experimental results revealed that, after strengthening and polishing, the surface roughness of aeroengine blades was reduced from Ra0.35-0.5μm to Ra0.1-0.12μm, and fatigue strength was increased by approximately 50%.

Nouvelles (vraies et fausses) de conversions (vraies et fausses) de monarques étrangers, imprimées en France aux XVIe-XVIIe siècles

2021 ◽  
pp. 15-43
Author(s):  
Vincent Masse
Keyword(s):  
17Th Century ◽  
News Report ◽  
News Reporting ◽  
News Reports ◽  
Current Information ◽  
The Media ◽  
False News ◽  
High Level ◽  
Better Than

Printed news reports circulated, in the 16th and 17th century, which revealed the sudden conversion to Christianity – some were real, but several were invented – of powerful monarchs from abroad. How were such announcements written or invented? Different scenarios existed. There was genuine news, to which were added cosmetic and false details, or sometimes overly enthusiastic interpretations. There was false news, although invented, arguably, to simplify the reporting of real upheavals on the scene of world affairs – such as the entrance on the historical stage of the Safavid dynasty, fantasized in the media as the conversion of Ismail I (in 1508) or Abbas I (in 1606). The strange case of La conversion de trois grands rois [The Conversion of Three Great Kings] helps in distinguishing two falsification mechanisms, or in this case two steps: in 1571, it was the fraudulent mixing of excerpts from genuine Jesuit letters; in 1588, 1608 and 1609, the same news report circulated anew, with all of its dates replaced by current ones. Truth and fiction thus intertwined better than they clashed, and paradoxically at the very time when genuine and current information about Persia, India and Indonesia was starting to circulate in Europe. The existence of such chimerical news also indicates that, as the industry of news reporting was developing, the particular desirability of reports on high-level conversions helped them prevail over other news more genuine, yet less appealing.

DEVELOPMENTAL AND PSYCHOLOGICAL TEST SCORES IN CHILDREN OF LOW BIRTH WEIGHT

PEDIATRICS ◽  
1970 ◽  
Vol 45 (1) ◽  
pp. 9-20
Author(s):  
Linda C. Eaves ◽  
J. C. Nuttall ◽  
H. Klonoff ◽  
H. G. Dunn
Keyword(s):  
Birth Weight ◽  
Low Birth Weight ◽  
Test Scores ◽  
Scale Up ◽  
First Year ◽  
Prospective Survey ◽  
Developmental Scale ◽  
And Performance ◽  
Weight Groups ◽  
Better Than

In a prospective survey, 420 out of 502 infants of low birth weight (≶ 2,041 gm, or 4½ lb) and all but one of 207 control children of full birth weight (> 2,500 gm, or 5½ lb) have survived for more than 3 years. One hundred fifty of the low birth weight (LBW) group have passed the age of 6 years. Developmental and psychological tests have given the following results: (1) Control children performed better than LBW infants on the Griffiths Developmental Scale up to the age of 18 months; among the LBW infants mean Griffiths Scores in 250 gm birth weight groups mosty differed significantly in direct relation to the weight. (2) LBW girls scored higher than boys after the first year on the hearing-speech subscale and, to a lesser extent, on the personal-social and performance subscales of the Griffiths test and also on the Stanford-Binet and Graham-Ernhart tests at 4 years of age. (3) Whereas the effect of birth weight on I.Q. became less distinct at 2½ to 4 years, the effect of socioeconomic status only became definite at that age. (4) In general, "small-for-dates" (SFD) children, including those born before term, scored higher than "true prematures" up to the age of 12 months and slightly lower at 2½ to 6½ years, but the differences were only significant in a few weight groups. When the SFD children were subdivided into those born at less than 37 weeks' gestation and those born later, the latter scored significantly better than the former only at 3 and 6 months. (5) Isolated Griffiths infant test scores at 6 months per se have little predictive value for I.Q. scores of children at 4 years of age, even at the extremes of intelligence.

scholarly journals Properties of the Surface Layer After Trochoidal Milling and Brushing: Experimental Study and Artificial Neural Network Simulation

2019 ◽  
Vol 10 (1) ◽  
pp. 75
Author(s):  
Monika Kulisz ◽  
Ireneusz Zagórski ◽  
Jakub Matuszak ◽  
Mariusz Kłonica
Keyword(s):  
Neural Networks ◽  
Surface Roughness ◽  
Artificial Neural Networks ◽  
Cutting Speed ◽  
Mg Alloy ◽  
Polar Component ◽  
Maximum Height ◽  
Roughness Parameters ◽  
Surface Geometry ◽  
Artificial Neural

The aim of this study was to investigate the effect of milling and brushing cutting data settings on the surface geometry and energy parameters of two Mg alloy substrates: AZ91D and AZ31. In milling, the cutting speed and the trochoidal step were modified (vc = 400–1200 m/min and str = 5–30%) to investigate how they affect selected 2D (Rz, Rku, Rsk, RSm, Ra) and 3D (Sa, Sz, Sku, Ssk) roughness parameters. The brushing treatment was carried out at constant parameters: n = 5000 rev/min, vf = 300 mm/min, ap = 0.5 mm. The surface roughness of specimens was assessed with the Ra, Rz, and RSm parameters. The effects of the two treatments on the workpiece surface were analyzed comparatively. It was found that the roughness properties of the machined surface may be improved by the application of a carbide milling cutter and ceramic brush. The use of different machining data was also shown to impact the surface free energy and its polar component of Mg alloy specimens. Complementary to the results from the experimental part of the study, the investigated machining processes were modelled by means of statistical artificial neural networks (the radial basis function and multi-layered perceptron). The artificial neural networks (ANNs) were shown to perform well as a tool for the prediction of Mg alloy surface roughness parameters and the maximum height of the profile (Rz) after milling and brushing.

Incorporating membrane gas diffusion into a membrane bioreactor for hydrogenotrophic denitrification of groundwater

2005 ◽  
Vol 51 (6-7) ◽  
pp. 357-364 ◽  
Author(s):  
H. Mo ◽  
J.A. Oleszkiewicz ◽  
N. Cicek ◽  
B. Rezania
Keyword(s):  
Hollow Fiber ◽  
Membrane Bioreactor ◽  
Hollow Fiber Membrane ◽  
Nitrate Removal ◽  
Gas Diffusion ◽  
Hydrogen Gas ◽  
Membrane Module ◽  
Permeable Membrane ◽  
Loading Rates ◽  
Doc Concentration

A hydrogenotrophic denitrification system, comprising a suspended growth membrane bioreactor (MBR) with membrane hydrogen gas diffusion, was developed to remove nitrate from groundwater. A hollow fiber gas permeable membrane module was designed for hydrogen delivery and a commercially available hollow fiber membrane module was used for solid/liquid separation. The MBR was operated at an SRT of 20 days and at room temperature. Four nitrate loading rates of 24, 48, 96 and 192 NO3−-N mg l−1 d−1 were applied to the system. As the nitrate loading was raised, pH increased due to increased denitrification and release of OH− ions. The oxidation reduction potential (ORP) remained fairly stable when full denitrification was achieved, but increased when nitrate loading rates reached 192 NO3−-N mg l−1 d−1 and residual nitrate was present in the reactor. Nitrate removal was complete (100%) in the first three nitrate loadings and 72% in the system with 192 NO3−-N mg l−1 d−1. Nitrate utilization rates of 30.6, 23.4, and 37.7 g NO3−-N m−3 d−1 were achieved in the first three loadings. Average effluent dissolved organic carbon (DOC) concentration of approximately 8 mg l−1 was observed in all four nitrate loading regimes, possibly owing to the generation and release of soluble microbial bi-products (SMP).

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