Ferrihydrite-impregnated granular activated carbon (FH@GAC) for efficient phosphorus removal from wastewater secondary effluent

Mahardika, Dedy,Park, Hak-Soon,Choo, Kwang-Ho Elsevier 2018 CHEMOSPHERE - Vol.207 No.-

<P><B>Abstract</B></P> <P>Adsorptive removal of phosphorus from wastewater effluents has attracted attention because of its reduced sludge production and potential P recovery. In this study, we investigated granular activated carbons (GACs) impregnated with amorphous ferrihydrite (FH@GAC) for the sorption of phosphorus from aqueous solutions. Preoxidation of intact GAC surfaces using an oxidant (e.g., hypochlorite) and strong acids (e.g., HNO<SUB>3</SUB>/H<SUB>2</SUB>SO<SUB>4</SUB>) was performed to create active functional groups (e.g., carboxyl or phenolic) for enhanced iron binding, leading to greater phosphorus uptake. Both the rate and the capacity of phosphorus sorption onto FH@GAC had significant, positive relationships (Pearson correlation coefficient r > 0.9) with the product of surface area and Fe content. The pseudo-second-order reaction kinetics explained the P sorption rate better than the pseudo-first-order reaction kinetics, whereas the Langmuir model fit the P sorption isotherm better than the Freundlich model. The iron content in the FH@GAC increased significantly (>10 mg/g) when GAC (e.g., BMC1050) was preoxidized by a 1:1 (w/w) concentrated HNO<SUB>3</SUB>/H<SUB>2</SUB>SO<SUB>4</SUB> mixture. The Langmuir maximum P sorption capacity of a functionalized FH@BMC1050 adsorbent prepared with acid pretreatment was estimated to be substantial (5.73 mg P/g GAC corresponding to 526 mg P/g Fe). This sorption capacity was superior to that of a FH slurry, possibly because the nano-sized FH formed inside the GAC pores (<2.5 nm) can bind phosphate ions more effectively than FH aggregates. Fixed-bed column reactor operation with bicarbonate regeneration showed potential for efficient, continuous phosphorus removal by FH@GAC media.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Granular activated carbons impregnated with ferrihydrite (FH@GAC) were synthesized. </LI> <LI> Phosphorus sorption rate and capacity by FH@GAC relied on surface area and Fe content. </LI> <LI> More FH was attached to oxidized GAC surfaces leading to enhanced P sorption. </LI> <LI> FH@GAC media in a column reactor were demonstrated alongside HCO<SUB>3</SUB> <SUP>−</SUP> regeneration. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Nutrient Requirements of Exercising Swamp Buffalo, Bubalus bubalis, from Materials Balance and In Vivo Body Composition by the Body Density Method. I. Aspects of Energy and Protein Metabolism in Working Cows

Mahardika, IG.,Sastradipradja, D.,Sutardi, T.,Sumadi, IK. Asian Australasian Association of Animal Productio 2000 Animal Bioscience Vol.13 No.5

Four young swamp buffalo cows of similar age ranging in weight between 280 to 380 kg and trained to do physical work were used in a study to determine energy and protein requirements for draught using a $4{\times}4$ Latin square designed experiment. The experiment consisted of field trials employing 4 levels of work load, e.g. no work as control, and loads amounting 450 to 500 Newton (N) pulled continuously for 1, 2 and 3 h daily for 14 consecutive days. Cows were fed king grass (Penisetum purpuroides) ad libitum and were subjected to materials balance trials. Body composition was estimated in vivo by the body density method and daily energy expenditure (EE) was calculated from ME minus retained energy (RE). The results show that EE while not working ($EE_{resting}$) was $0.42kgW^{0.75}MJ/d$ and maintenance ME ($ME_m$) was $0.37kgW^{0.75}MJ/d$. ME requirement increased to 1.65 times maintenance for the work of 3 hours. The energy expended for doing exercise ($E_{exercise}$) was 9.56, 20.0 and 25.86 MJ/cow for treatments 1, 2 and 3 II, respectively. Fat retention was absent in all groups of working cows, but protein retention was only negative for cows undertaking 3 h work. The relationship between $E_{exercise}$ (MJ), work load (F, kN), work duration (t, h) and body mass (W, kg) was found to be: $E_{exercise}=(0.003F^{1.43}t^{0.93})/W^{0.09}MJ$. The maintenance requirement for digestible protein was $2.51kgW^{0.75}g/d$, whereas digestible protein for growth ($DP_{growth}$) and for work ($DP_{work}$) followed the equations: $DP_{growth}=[(258+1.25W^{0.75}){\Delta}Wkg/d]g$ and $DP_{work}=[12.59e^{0.95t}]g$, respectively The coefficients a, b and c for the calculation of $E_{exercise}$ components according to the Lawrence equation were found to be 2.56 J/kgW.m, 5.2 J/kg load carried.m and 0.29, respectively, thus efficiencies to convert ME into work were 0, 16.09, 27.3 and 32.44% for control, 1, 2 and 3 h/d work, respectively. ME and DP requirements for a 250 to 400 kg working buffalo cow allowing to growth up to 0.5 kg/d are presented.

Nutrient Requirements of Exercising Swamp Buffalo, Bubalus bubalis. II. Details of Work Energy of Cows and Its Relation to Heart Rate

Mahardika, I.G.,Sastradipradja, D.,Sutardi, T.,Sumadi, I.K. Asian Australasian Association of Animal Productio 2000 Animal Bioscience Vol.13 No.7

Four young swamp buffalo cows of similar age ranging in body weight (W) between 280 to 380 kg and trained for doing physical exercise were used in two consecutive experiments, each using a latin square design, to determine energy expenditure for draught. The experiments consisted of field trials using 4 levels of work load, i.e. no work as control and loads amounting 450 to 500 Newton (N) continuous traction for respectively 1, 2 and 3 h daily for 14 consecutive days for experiment 1, and no work, traction loads equaling 5, 10 and 15% of W for 3 h daily for 14 days for experiment 2. Heart rate during rest and exercise was monitored using PE-3000 HR monitor. Cows were fed only king grass (Penisetum purpuroides) ad libitum and were subjected to balance trials. Body composition was estimated in vivo by the body density method and daily energy expenditure (EE) was calculated from ME minus RE. RE was calculated from the changes in body-protein and -fat measured before and immediately after the 14 d experimental period assuming an energy equivalent of 39.32 MJ/kg fat and 20.07 MJ/kg protein. $E_{exercise}$ ($EE_{work}\;-\;EE_{resting}$), which was the energy spent for doing the traction during 1, 2 and 3 h was 7.13, 15.45 and 19.90 MJ, respectively. $EE_{work}$ for the 1 h treatment group was 39.75 MJ/d equivalent to 1.30 times $EE_{resting}$. The values for the 2 and 3 h treatment groups were 1.75 and 1.86 times resting energy requirement, respectively. Absolute efficiency of work in all exercise trials of experiment 2 was around 27.28%. The increases of daily $E_{exercise}$ values were correlated to elevation of heart rate (HR) according to the equation $E_{exercise}=(0.270HR^{0.363}\;-\;1)$ MJ, while draught force related to heart rate according to the equation DF (N)=6.66 HR - 361.62. Blood glucose and triglyceride levels were gradually elevated with time during the course of exercise. Mean values of blood glucose were 91.7, 115.0 and 116.2 mg/dl for cows after 1, 2 and 3 h pulling loads at 15% W respectively as compared to 88.2 mg/dl prior to work. In the same order and treatment, mean blood triglyceride concentrations were 13.5, 13.3 and 14.8 mg/dl, and 11.5 mg/dl for control. For blood lactate, the values were 1.68, 1.63 and 1.66 mM, and 0.80 mM for control. Glucose was used as the major source of energy during the initial phase of exercise, but for prolonged work, fat will replace carbohydrate as the main substrate. Accumulation of lactate persisted for some time at the end of the exercise trials.

Design and experimental evaluation of a bird-mimicking flapping-wing system

Nanang Mahardika,Quoc Viet Nguyen,HoonCheol Park 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.4

Precision machining by discharge pulse counting methods in micro EDM processes

Muslim Mahardika,Gunawan Setia Prihandana,Kimiyuki Mitsui 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.11

Due to the occurrences of debris, the ability of micro-EDM to produce precise dimension is degraded, hence positioning display indicator of micro-EDM machine is not accurately measure the real dimension. Therefore, imprecise workpiece dimension is happen. In order to overcome this problem, in this paper, the use of discharge pulse counting methods to correct this error is introduced. The dimension error from micro-EDM processes by using discharge pulse counting method is much smaller than when using the positioning display indicator of micro-EDM machine. Hence, by using discharge pulse counting method, high precision machining can be achieved.

EFFECT OF SLEEP ANGLE ON THE AERODYNAMIC FORCE GENERATION OF A NOVEL SLEEP TWIST ROUND (STR) VERTICAL BLADE FOR WIND TUEBINE

( Nanang Mahardika ),( Ja Choon Jung ),( Mi Hye Jang ) 조선대학교 공학기술연구원 2013 공학기술논문지 Vol.6 No.4

In this paper, the effect of blade``s sleep (swept) angle towards the normal force coefficient (Cn) and tangential force coefficient (Ct) is investigated by using Blade Element-Momentum Theory (BEMT)-based multiple stream tube model for rotating condition. For three different tip speed ratio (TSR), multiple stream tube model suggests that the variation in terms of standard deviation of Cn and Ct are up to 3.3 times less for the model with higher swept angle (β). For startup condition, Computational Fluid Dynamic (CFD) analysis by using commercial software is conducted to calculate the torque variation at twelve different blade positions relative to the wind direction for seven different models. Unlike the Gorlov mathematical model for helical turbine, CFD analysis predicted that the average torque is increasing as the swept angle increases. Meanwhile, the variation of torque is up to 10 times less for the models with higher swept angle. These results suggest that the implementation of swept angle can increase the fatigue life and the startup performance of the blades.

Assessment of Drug-Induced Cardiac Arrhythmicity using Deep Learning Approach

Nurul Qashri Mahardika T,Yedam Yoo(유예담),Aroli Marcelinus,Ki Moo Lim(임기무) 한국통신학회 2022 한국통신학회 학술대회논문집 Vol.2022 No.2

One of the considering things about drug development is some drugs can cause Torsade de Pointes (TdP) which is harmful to society. Thus, the Comprehensive in vitro proarrhythmia assay (CiPA) project was successful in classifying to assess drug-induced arrhythmias through a logistic regression model using qNet as a TdP risk assessment biomarker. However, obtaining that result through in silico simulation is inefficient. We propose using the CNN model to classify three levels of proarrhythmic risk: high, intermediate, and low. To obtain net charges and calcium transients, we use the ToRd myocyte cell model. Drug effects were implemented using IC50 and Hill coefficient. There are 12 drugs as CNN model training data and 16 drugs as test data. qNet variability, qInward variability, CaD90 variability, CaD50 variability, and Ca resting variability are used as input in the CNN model independently. As the result, qInward variability showed better performance for the three classifications, 83% high-risk drug, 80% intermediate, and 80% low-risk drug.

Indonesian EFL Teachers’ Practice of Online Informal Learning of English: Perceived Understandings and Benefits to Language Skills

I Gusti Ngurah Agung Wijaya Mahardika,Utami Widiati,Yazid Basthomi,Nunung Suryati,Tengku Intan Suzila Tengku Sharif 아시아테플 2023 The Journal of Asia TEFL Vol.20 No.3

Despite the abundance of studies on EFL students’ online informal learning of English (OILE), EFL teachers’ OILE practice has been left largely unexplored. Considering that EFL teachers are instrumental in providing support and guidance for students’ OILE, the present study attempted to provide holistic and updated empirical evidence of EFL teachers’ OILE, addressing these research questions: (1) What OILE activities do EFL teachers know and practice? and (2) How do EFL teachers perceive OILE benefits to their language skills? The study was conducted based on explanatory sequential mixed method design involving 219 EFL teachers teaching at junior and senior high schools. The data were collected using an online questionnaire and semi-structured in-depth interviews with 15 selected teachers and analyzed using descriptive statistics and thematic analysis. The study revealed that despite their unfamiliarity with the OILE concept, EFL teachers practiced OILE and perceived OILE positively and considered OILE to be beneficial in maintaining and improving their English. However, most of the EFL teachers have practiced OILE in low frequency. They reported that their low OILE practice level was attributed to lack of time, struggle for English, unfamiliarity with OILE activities, fear of making mistakes, and fear of judgment.

NONLINEAR OSCILLATION MODEL FOR EXPLAINING THE DISTRIBUTION OF POSITION DEVIATION IN SELF-ORGANIZED NANOPARTICLES

MASTURI,MAHARDIKA PRASETYA AJI,HASNIAH ALIAH,EUIS SUSTINI,KHAIRURRIJAL,MIKRAJUDDIN ABDULLAH 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.1

A model for explaining deviations of positions in self-organized nanoparticles on a substrate from their corresponding positions in perfect organization is proposed. The model predictions were compared with SEM/TEM images and reported by some authors. We found a consistence between the model predictions with the data of Ag, Fe3O4 and SiO2 nanoparticles organization on various substrates.

Effect of low-frequency vibration on workpiece in EDM processes

Gunawan Setia Prihandana,Muslim Mahardika,M. Hamdi,Kimiyuki Mitsui 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.5

High-frequency vibration aided EDM has become one of the ways to increase material removal rate in EDM process, due to the flushing effect caused by vibration. However, utilizing high-frequency vibration, especially in ultrasonic range consumes a lot of setup cost. This work presents an attempt to use a low-frequency vibration on workpiece of stainless steel (SS 304) during EDM process. The workpiece was vibrated with variations of low-frequency and low-amplitude. The results show that the application of low-frequency vibration in EDM process can be used to increase the material removal rate, and decrease the surface roughness and tool wear rate.