scholarly journals PENGOLAHAN LIMBAH CAIR TAHU MENGGUNAKAN BIOREAKTOR ANAEROB SATU TAHAP DAN DUA TAHAP SECARA BATCH

2018 ◽  
Vol 7 (1) ◽  
pp. 34-40
Author(s):  
Florence T.N. Silalahi ◽  
Halimatuddahliana ◽  
Amir Husin
Keyword(s):  
Waste Treatment ◽  
Anaerobic Fermentation ◽  
Liquid Waste ◽  
Cow Dung ◽  
Two Stage ◽  
Biogas Yield ◽  
Second Stage ◽  
One Stage ◽  
Batch Bioreactor ◽  
The One

This research aimed to study the effect of one stage and two stage anaerobic fermentation on the performance of bioreactors in tofu liquid waste treatment. This research started with acclimatization that is adaptation process of microorganism derived from cow dung with tofu liquid waste. Acclimatization is carried out in acid condition (pH 5.5) and in neutral condition (pH 7). This is followed by a batch bioreactor operation for 40 days for one stage anaerobic fermentation (pH 7), while for the first stage of the two stage anaerobic fermentation (pH 5.5) lasted two days and proceeds with the second stage of the two stage anaerobic fermentation (pH 7) lasts 38 days The results obtained were COD removal efficiency of 76.6% for one stage anaerobic and 83.05% for two stage anaerobic. While the VFA concentration in the first stage of the two stage anaerobic increased by 33% of the one-stage anaerobic VFA concentration. One-stage anaerobic biogas yield of 0.24 L/g CODconvertedand 0.27 L/g CODconverted for to two stage anaerobic.

scholarly journals Fermentasi Anaerobik Biogas Dua Tahap Dengan Aklimatisasi dan Pengkondisian pH Fermentasi

2017 ◽  
Vol 1 (1) ◽  
pp. 1 ◽  
Author(s):  
Purwinda Iriani ◽  
Yanti Suprianti ◽  
Fitria Yulistiani
Keyword(s):  
Anaerobic Digestion ◽  
Anaerobic Fermentation ◽  
Biogas Production ◽  
Organic Load ◽  
Cow Dung ◽  
Activation Process ◽  
Two Stage ◽  
One Stage ◽  
Load Rate ◽  
Initial Ph

Produksi biogas pada skala rumah tangga umumnya menggunakan teknologi fermentasi anaerobik di dalam satu biodigester (satu tahap), yang mengakomodasi dua tahap utama prinsip pembentukan biogas, yakni tahap asetogenesis dan tahap metanogenesis. Permasalahan yang muncul dari penggunaan digester biogas satu tahap adalah ketidakseimbangan proses fermentasi (peningkatan laju beban organik, waktu retensi senyawa organik yang lebih cepat, dan produktivitas biogas yang menjadi tidak maksimal). Untuk mengatasi hal tersebut, dilakukan penelitian yang bertujuan melakukan produksi biogas melalui sistem fermentasi anaerobik dua-tahap (two-stage anaerobic digestion), yang didukung dengan pengaturan pH pada proses metanogenik. Pada penelitian ini telah dilakukan proses aklimatisasi (aktivasi) bakteri yang menunjang proses asetogenik dan metanogenik pada skala laboratorium (19 L), dan selanjutnya menjadi inokulum untuk proses fermentasi skala pilot dengan kapasitas biodigester asetogenik 125 L dan metanogenik 500 L. Hasil proses aklimatisasi bakteri asetogenik pada media kotoran sapi menunjukkan adanya kestabilan pH yang dibutuhkan untuk reaksi asetogenik, yaitu pada kisaran pH 5-6, sedangkan kontrol menunjukkan perubahan pH yang masih ada di rentang pH netral yaitu 6-7. Kotoran sapi yang telah melalui proses asetogenik selama 2 minggu (pH awal 5,5), menjadi bahan baku pembuatan biogas pada digester metanogenik. Hasil dari proses metanogenik menunjukkan terjadinya peningkatan volume biogas dan komposisi gas metana (CH4) di dalam biogas. Komposisi CH4 tertinggi diperoleh pada hari ke-20 yakni 74,82% dengan volume produksi biogas tertinggi ada pada hari ke-22, dengan laju 8,87 L/hari. Potensi energi tertinggi yang diperoleh mencapai 217,66 kJ/hari.Generally, biogas production on the household scale is using one-stage anaerobic fermentation technology, which accommodates two main processes of biogas production, namely acetogenesis and methanogenesis. An obstacle of using one-stage biogas digester is the imbalance of the fermentation process that indicated by the increase of organic load rate and shorter retention time that lead to un-optimal biogas productivity. This research undertook the application of two-stage anaerobic digestion, supported by adjusting the initial pH for both acetogenic and methanogenic processes. Firstly, the research initiated by acclimatization (activation) process of acetogenic and methanogenic bacteria via fermentation in laboratory scale (19 L) digesters, separately. The results of acetogenic bacteria acclimatization process on cow dung media showed the pH stability needed for the reaction acetogenic, in the range of 5-6, while the control showed the pH changes still in the neutral pH range (6-7). The substrate from lab-scale acetogenic and methanogenic digester, then used as a starter for pilot-scale digester (125 L and 500 L, respectively). The mixture of water and cow dung were adjusted at initial pH 5.5 on acetogenic digester for 2 weeks. Those material were used for biogas production in the methanogenic digester. The result of the methanogenic process showed an increasing volume of biogas and the composition of methane (CH4) in the biogas. The highest CH4 composition was obtained on the 20th day, which reached 74.82%, and the highest volume of biogas production was at day 22, with the rate of 8.87 L/day. The highest energy potential obtained was 217.66 kJ/day.

scholarly journals STUDY ON CO-FERMENTATION OF COW DUNG AND GIANT DIRT IN SEMI-CONTINUOUS ANAEROBIC DIGESTER

2018 ◽  
Vol 54 (2A) ◽  
pp. 287
Author(s):  
Nguyen Le Phuong
Keyword(s):  
Anaerobic Digester ◽  
Pistia Stratiotes ◽  
Cow Dung ◽  
Two Stage ◽  
One Stage ◽  
Input Material ◽  
Mixing Rates ◽  
Set Up ◽  
The One ◽  
Two Stages

Study on co-fermentation of cow dung (CD) and giant dirt (GD - Pistia stratiotes L.) in semi-continuous anaerobic digester aims to test biogas quantity and quality by time. Three mixing rates counted based on ODM of each material were chosen: 100 %CD, 50 %CD + 50 %GD, and 100 %GD. The experiments were set up in laboratory conditions with two types of digesters: one-stage digesters and two-stage digesters (triplicate for each treatment). After 80 days, the biogas produced from the one-stage digesters was not significantly different to the two-stage digesters with similar input material. The highest production of biogas came from digesters of 100 %GD - 235.8 L for the one-stage and 240.3 L for the two-stages. The medium production came from digesters of 50 %CD + 50 %GD - 127.8 L for the one-stage and 118.4 L for the two-stages. After one month, the percentage of CH4 was high enough for burning and almost giant dirt was digested that limited of a blockage inside the digesters. The results showed that co-fermentation of GD and CD is an alternative for livestock raising households to produce biogas for energy purpose.

scholarly journals Robust Optimization of Airplane Passenger Seating Assignments

Aerospace ◽  
2018 ◽  
Vol 5 (3) ◽  
pp. 80 ◽  
Author(s):  
R. Milne ◽  
Mostafa Salari ◽  
Lina Kattan
Keyword(s):  
Integer Programming ◽  
Robust Optimization ◽  
Mixed Integer Programming ◽  
Numerical Results ◽  
Mixed Integer ◽  
Two Stage ◽  
Second Stage ◽  
One Stage ◽  
Slack Time ◽  
The One

We present a method that reduces the time it takes to complete the passenger boarding of an airplane. In particular, we describe a two-stage mixed integer programming (MIP) approach, which assigns passengers to seats on an airplane based on the number of bags they carry aboard the plane. The first stage is an MIP that assigns passengers to seats to minimize the time to complete the boarding of the plane. The second-stage MIP also determines seating assignments, while constraining the total boarding time to that determined by the stage-one MIP and maximizing weighted slack times to provide a more robust assignment. Numerical results show that this two-stage approach results in lower average boarding times than the one-stage approach, when the time it takes passengers to walk and sit in their seats is random. Experiments indicate that the magnitude of the improvement is not very sensitive to variations in the slack time weights.

Two-Stage Procedure for the Quantitative Determination of Autoprothrombin III Concentration and Some Applications

1967 ◽  
Vol 18 (01/02) ◽  
pp. 198-210 ◽  
Author(s):  
Ronald S Reno ◽  
Walter H Seegers
Keyword(s):  
Prothrombin Time ◽  
Factor Vii ◽  
Two Stage ◽  
Pronounced Increase ◽  
One Stage ◽  
Assay Procedure ◽  
Bovine Plasma ◽  
The One ◽  
Autoprothrombin C

SummaryA two-stage assay procedure was developed for the determination of the autoprothrombin C titre which can be developed from prothrombin or autoprothrombin III containing solutions. The proenzyme is activated by Russell’s viper venom and the autoprothrombin C activity that appears is measured by its ability to shorten the partial thromboplastin time of bovine plasma.Using the assay, the autoprothrombin C titre was determined in the plasma of several species, as well as the percentage of it remaining in the serum from blood clotted in glass test tubes. Much autoprothrombin III remains in human serum. With sufficient thromboplastin it was completely utilized. Plasma from selected patients with coagulation disorders was assayed and only Stuart plasma was abnormal. In so-called factor VII, IX, and P.T.A. deficiency the autoprothrombin C titre and thrombin titre that could be developed was normal. In one case (prethrombin irregularity) practically no thrombin titre developed but the amount of autoprothrombin C which generated was in the normal range.Dogs were treated with Dicumarol and the autoprothrombin C titre that could be developed from their plasmas decreased until only traces could be detected. This coincided with a lowering of the thrombin titre that could be developed and a prolongation of the one-stage prothrombin time. While the Dicumarol was acting, the dogs were given an infusion of purified bovine prothrombin and the levels of autoprothrombin C, thrombin and one-stage prothrombin time were followed for several hours. The tests became normal immediately after the infusion and then went back to preinfusion levels over a period of 24 hrs.In other dogs the effect of Dicumarol was reversed by giving vitamin K1 intravenously. The effect of the vitamin was noticed as early as 20 min after administration.In response to vitamin K the most pronounced increase was with that portion of the prothrombin molecule which yields thrombin. The proportion of that protein with respect to the precursor of autoprothrombin C increased during the first hour and then started to go down and after 3 hrs was equal to the proportion normally found in plasma.

Standardization of Factor VIII – IV. Establishment of the 3rd International Standard for Factor VIII: C Concentrate

1983 ◽  
Vol 50 (03) ◽  
pp. 697-702 ◽  
Author(s):  
T W Barrowcliffe ◽  
A D Curtis ◽  
D P Thomas
Keyword(s):  
Factor Viii ◽  
High Purity ◽  
Collaborative Study ◽  
World Health ◽  
Current Standard ◽  
Two Stage ◽  
International Standard ◽  
One Stage ◽  
The One ◽  
Health Organization

SummaryAn international collaborative study was carried out to establish a replacement for the current (2nd) international standard for Factor VIII: C, concentrate. Twenty-six laboratories took part, of which 17 performed one-stage assays, three performed two-stage assays and six used both methods. The proposed new standard, an intermediate purity concentrate, was assayed against the current standard, against a high-purity concentrate and against an International Reference Plasma, coded 80/511, previously calibrated against fresh normal plasma.Assays of the proposed new standard against the current standard gave a mean potency of 3.89 iu/ampoule, with good agreement between laboratories and between one-stage and two- stage assays. There was also no difference between assay methods in the comparison of high-purity and intermediate purity concentrates. In the comparison of the proposed standard with the plasma reference preparation, the overall mean potency was 4.03 iu/ampoule, but there were substantial differences between laboratories, and the two-stage method gave significantly higher results than the one stage method. Of the technical variables in the one-stage method, only the activation time with one reagent appeared to have any influence on the results of this comparison of concentrate against plasma.Accelerated degradation studies showed that the proposed standard is very stable. With the agreement of the participants, the material, in ampoules coded 80/556, has been established by the World Health Organization as the 3rd International Standard for Factor VIII :C, Concentrate, with an assigned potency of 3.9 iu/ampoule.

scholarly journals Study on the Leakage and Inter-Stage Pressure Drop Characteristics of Two-Stage Finger Seal

2021 ◽  
Vol 11 (5) ◽  
pp. 2239
Author(s):  
Hailin Zhao ◽  
Hua Su ◽  
Guoding Chen ◽  
Yanchao Zhang
Keyword(s):  
Pressure Drop ◽  
Pressure Difference ◽  
Radial Displacement ◽  
Mean Square ◽  
The Finite Element Method ◽  
Axial Pressure ◽  
Two Stage ◽  
One Stage ◽  
The One ◽  
Lower Contact

To solve the high leakage and high wear problems faced by sealing devices in aeroengines under the condition of high axial pressure difference, the two-stage finger seal is proposed in this paper. The finite element method and computational fluid dynamics (FEM/CFD) coupling iterative algorithm of the two-stage finger seal is developed and validated. Then the performance advantages of two-stage finger seal compared to the one-stage finger seal are studied, as well as the leakage and the inter-stage pressure drop characteristics of two-stage finger seal are investigated. Finally, the measure to improve the inter-stage imbalance of pressure drop of two-stage finger seal is proposed. The results show that the two-stage finger seal has lower leakage and lower contact pressure than the one-stage finger seal at high axial pressure difference, but there exists an inter-stage imbalance of pressure drop. Increasing the axial pressure difference and the root mean square (RMS) roughness of finger element can aggravate the imbalance of pressure drop, while the radial displacement excitation of rotor has little influence on it. The results also indicate that the inter-stage imbalance of pressure drop of the two-stage finger seal can be improved by increasing the number of finger elements of the 1st finger seal and decreasing the number of finger elements of the 2nd finger seal.

scholarly journals Two-stage alkaline and acid pretreatment applied to sugarcane bagasse to enrich the cellulosic fraction and improve enzymatic digestibility

Detritus ◽  
2020 ◽  
pp. 106-113
Author(s):  
Longinus Ifeanyi Igbojionu ◽  
Cecilia Laluce ◽  
Edison Pecoraro
Keyword(s):  
Sugarcane Bagasse ◽  
Maleic Acid ◽  
Ethanol Yield ◽  
High Yield ◽  
Enzymatic Digestibility ◽  
Acid Pretreatment ◽  
Two Stage ◽  
Second Stage ◽  
One Stage ◽  
Naoh Pretreatment

Sugarcane bagasse (SB) is made up of cellulose (32-43%), hemicellulose (19-34%) and lignin (14-30%). Due to high recalcitrant nature of SB, pretreatment is required to deconstruct its structure and enrich the cellulosic fraction. A two-stage NaOH and maleic acid pretreatment was applied to SB to enrich its cellulosic fraction. SB used in the present study is composed of cellulose (40.4 wt%), hemicellulose (20.9 wt%), lignin (22.5 wt%) and ash (4.0 wt%). After one-stage NaOH pretreatment, its cellulosic fraction increased to 61.8 wt% and later increased to 80.1 wt% after the second-stage acid pretreatment. Lignin fraction decreased to 3.0 wt% after one-stage NaOH pretreatment and remained unaffected after the acid pretreatment step. Hemicellulose fraction decreased substantially after the second-stage pretreatment with maleic acid. Pretreated SB displayed high crystallinity index and improved enzymatic digestibility. Hydrolysates of pretreated SB contained very low amount of xylose and subsequent fermentation by Saccharomyces cerevisiae -IQAr/45-1 resulted to ethanol level of 8.94 g/L. Maximal ethanol yield of 0.49 g/g (95.8% of theoretical yield) and productivity of 0.28 g/L/h was attained. At the same time, biomass yield and productivity of 0.47 g/g and 0.27 g/L/h respectively were obtained. Two-stage NaOH and maleic acid pretreatment led to ~ two-fold increase in cellulosic fraction and enhanced the enzymatic digestibility of SB up to 70.4%. The resulted enzymatic hydrolysate was efficiently utilized by S. cerevisiae -IQAr/45-1 to produce high yield of ethanol. Thus, optimization of enzymatic hydrolysis at low enzyme loading is expected to further improve the process and reduce cost.

scholarly journals Identification of Sources of Inter-Laboratory Variation in Factor VIII Assay

1977 ◽  
Author(s):  
T.B.L. Kirkwood ◽  
C.R. Rizza ◽  
T.J. Snape ◽  
I. Rhymes ◽  
D.E.G. Austen
Keyword(s):  
Factor Viii ◽  
Systematic Difference ◽  
Normal System ◽  
Two Stage ◽  
Initial Dilution ◽  
One Stage ◽  
Collaborative Studies ◽  
Freeze Dried ◽  
Sources Of Variation ◽  
The One

A repeated finding of national and international collaborative studies of standard Factor VIII preparations has been that systematic differences exist between laboratories in their measurement of the relative activities of the same pairs of Factor VIII preparations.A workshop meeting was held at the Oxford Haemophilia Centre (England) during 23rd-26th November 1976 to investigate which of the possible sources of variation between laboratories were responsible. Participants from 16 British laboratories (9 one-stage, 7 two-stage) performed a total of 273 assays using three freeze-dried preparations of differing purity (a plasma, an intermediate and a high purity concentrate). The results of assays with each participant using their normal system established that, if the participants were a representative cross-section, approximately one-third of one-stage laboratories would show a systematic difference from the overall mean of at least 16%, with a similar figure for the two-stage laboratories of 9%. Various features of the assay systems were then modified in a controlled series of experiments. The results showed conclusively that i) differences between reagents accounted for most of the variation between laboratories and, ii) the two-stage assays were, on average, detecting relatively more activity in the more purified preparations than the one-stage assays. The results also suggested that the use of buffer as opposed to haemophilic plasma for the initial dilution of concentrates did not affect the assay results.

The Relation between Staphylocoagulase Reacting Factor and Proteins Induced by Vitamin K Absence

1975 ◽  
Author(s):  
B. M. Bas ◽  
A. D. Muller ◽  
H. G. Hemker
Keyword(s):  
Vitamin K ◽  
Vitamin K Antagonists ◽  
The Other ◽  
Two Stage ◽  
One Stage ◽  
Echis Carinatus ◽  
The Difference ◽  
The One ◽  
Factor Assay

Five different ways of estimating prothrombin are applied to the plasma of persons receiving vitamin K antagonists, to know: the one-stage assay, the two-stage assay, the Echis Carinatus Venom assay, the coagulase-reacting factor assay and the immunological assay. The Protein Induced by Vitamin K Absence analogous to prothrombin (PIVKA-II) can be shown to be co-estimated in all but the one-stage assay. There are minor differences, however, between the other four tests. The most practical way to assess both prothrombin and PIVKA-II seems to be the coagulase-reacting factor assay. The difference between the one-stage assay and the others can be explained on basis of the new data on the role of vitamin K in prothrombin biosynthesis. The differences between the other tests are smaller and remain to be explained.

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