Single Phase and Two Phase Anaerobic Stabilization in Fluidized Bed Reactors

1983 ◽  
Vol 15 (8-9) ◽  
pp. 333-344 ◽  
Author(s):  
P M Sutton ◽  
A Li
Keyword(s):  
Fluidized Bed ◽  
Process Design ◽  
Pilot Plant ◽  
Single Phase ◽  
Fluidized Bed Reactors ◽  
Phase System ◽  
Two Phase ◽  
Effluent Quality ◽  
Loading Rates ◽  
Scale Design

Pilot plant studies were completed in order to derive information for process design of single and two phase anaerobic fluidized bed systems. A better effluent quality was obtained from the two phase system than from the single phase system at comparable or higher organic loading rates. A full-scale design example is presented to illustrate the implications of the pilot plant results.

Treatment of Oily Cafeteria Wastewater by Single-Phase and Two-Phase Anaerobic Filter

1990 ◽  
Vol 22 (3-4) ◽  
pp. 299-306 ◽  
Author(s):  
Keisuke Hanaki ◽  
Tomonori Matsuo ◽  
Katsuo Kumazaki
Keyword(s):  
Single Phase ◽  
Material Balance ◽  
Phase System ◽  
Two Phase ◽  
Term Operation ◽  
Effluent Quality ◽  
Anaerobic Filter ◽  
Phase Systems ◽  
Better Than

Cafeteria wastewater containing about 30% of lipid on COD basis was treated at 20°C by laboratory-scale anaerobic filter in single-phase system and two-phase systems. Stable COD removal (about 80%) was achieved in spite of large fluctuation in influent COD concentration (normal range of 1,300 - 2,500 mg−l) both in the single-phase system (hydraulic retention time (HRT) longer than 1.3 d) and in the two-phase system (HRT longer than 3.3 d). The single-phase system gave better effluent quality than the two-phase system because the former entrapped suspended solids better than the latter. However, material balance revealed that methane conversion from removed COD was higher in the two-phase system than the single-phase system. The single-phase system perhaps removed lipids by entrapment with filter media without biodegradation, and this might cause clogging problems in long-term operation. The two-phase system is recommended since it degrades lipids better than the single-phase system.

Two-phase anaerobic treatment of cane-molasses alcohol stillage

1997 ◽  
Vol 36 (6-7) ◽  
pp. 441-448 ◽  
Author(s):  
B. G. Yeoh
Keyword(s):  
Single Phase ◽  
Anaerobic Treatment ◽  
Methane Yield ◽  
Phase System ◽  
Treatment Efficiency ◽  
Two Phase ◽  
Kinetic Evaluation ◽  
Cane Molasses ◽  
Loading Rates ◽  
Phase Process

Anaerobic treatment of cane-molasses alcohol stillage was studied in a thermophilic two-phase system comprising two bioreactors for the acidogenic and methanogenic phases respectively in comparison with the single-phase process. The experiments were conducted with HRT ranging from 36.0 to 9.0 days for single-phase and from 32.7 to 5.6 days for two-phase, corresponding to organic loading rates of 3.452 to 14.487 and 4.646 to 20.022 kgCODm−3day−1 respectively. The treatment efficiency was essentially maintained at BOD5 and COD removal of over 85% and 65% respectively in the two-phase process even with higher substrate loading. The acidogenic phase provided satisfactory conversion of initial COD to VFA averaging 15.6% in the degree of acidification. The methanogenic culture pH of both systems was maintained in a range of 7.4 to 7.8 through self regulation. The methane content of the biogas generated from the two-phase process was significantly higher by about 17% than that from the single-phase process, both decreasing with increasing substrate loading and shorter HRT. The mean overall methane yield was found to be 0.168 m3CH4(STP)kg−1 CODadded or 0.292 m3CH4(STP)kg−1 VSadded from two-phase methanogenesis, compared to 0.055 m3CH4(STP)kg−1CODadded or 0.082 m3CH4(STP)kg−1VSadded from single-phase fermentation. However, methane yield in the two-phase process was enhanced only at COD loading rates higher than 2.9 kgm−3day−1 or VS loading rates higher than 1.8 kgm−3day−1. The ultimate methane yield was evaluated graphically to be 0.216 m3CH4(STP)kg−1CODadded, or 0.401 m3CH4(STP)kg−1 VSadded. This indicated a methane yield efficiency of 73-78% for the two-phase anaerobic digestion of cane-molasses alcohol stillage, which was composed of 24.2% and 28.2% of non-biodegradable COD and VS respectively. Kinetic evaluation of the experimental data provided θm (minumum SRT) and K (kinetic constant) values as 6.6 days and 0.166 respectively based on COD, or 7.0 days and 0.160 respectively based on VS. Application of the two-phase anaerobic process on full scale at an industrial treatment plant for alcohol stillage showed mean treatment efficiency in terms of BOD5 and COD reduction of 84.3% and 63.2% respectively at an average loading rate of 5.1 kgCODm−3day−1, which was in good agreement with the bench-scale studies, considering the great variation in the raw wastewater characteristics typical of an industrial operation.

On the Problem of “Two-Phase” Activated Sludge

1991 ◽  
Vol 24 (7) ◽  
pp. 59-64 ◽  
Author(s):  
R. W. Szetela
Keyword(s):  
Activated Sludge ◽  
Single Phase ◽  
Phase System ◽  
Two Phase ◽  
Wastewater Treatment Process ◽  
Sludge Stabilization ◽  
Technological Advantage ◽  
In Series ◽  
State Models ◽  
Activated Sludge Systems

Steady-state models are presented to describe the wastewater treatment process in two activated sludge systems. One of these makes use of a single complete-mix reactor; the other one involves two complete-mix reactors arranged in series. The in-series system is equivalent to what is known as the “two-phase” activated sludge, a concept which is now being launched throughout Poland in conjunction with the PROMLECZ technology under implementation. Analysis of the mathematical models has revealed the following: (1) treatment efficiency, excess sludge production, energy consumption, and the degree of sludge stabilization are identical in the two systems; (2) there exists a technological equivalence of “two-phase” sludge with “single-phase” sludge; (3) the “two-phase” system has no technological advantage over the “single-phase” system.

Prediction of Two-Phase Pressure Drop and Density Distribution From Mixing Length Theory

1963 ◽  
Vol 85 (2) ◽  
pp. 137-150 ◽  
Author(s):  
S. Levy
Keyword(s):  
Single Phase ◽  
Continuous Medium ◽  
Phase System ◽  
Mixing Length ◽  
Test Results ◽  
Two Phase ◽  
Pressure Drops ◽  
Mixing Length Theory ◽  
Phase Pressure ◽  
Good Agreement

Single-phase turbulent mixing length methods are used to predict two-phase flow. Two-phase density and velocity distributions and two-phase pressure drops are derived by treating the two-phase system as a continuous medium where the turbulent exchanges of momentum and density are equal. Good agreement is obtained between test results and analytical predictions.

Experimental Investigation of Evacuated Tube Solar Collector with Annular Heat Exchanger

2014 ◽  
Vol 592-594 ◽  
pp. 2355-2359
Author(s):  
Narasimhe Gowda ◽  
B. Putta Bore Gowda ◽  
R. Chandrashekar ◽  
G. Ugrasen ◽  
R. Keshavamurthy
Keyword(s):  
Closed System ◽  
Single Phase ◽  
Working Fluid ◽  
Maintenance Cost ◽  
Phase System ◽  
Two Phase ◽  
Solar Water ◽  
Water Heaters ◽  
Solar Water Heaters ◽  
Evacuated Tube

Now-a-days evacuated tubes solar water heaters are increasingly use in South India because of good thermal efficiency and high water temperature could be achievable as compared to flat plate solar collectors. Low manufacturing and maintenance cost also attract people to go for evacuated tube solar water heaters. This paper reports experimental results of two types of evacuated tube solar water heaters. To evaluate the performance of evacuated tube solar water heater, single-phase forced system and two-phase closed forced systems were considered. In two-phase closed system sunflower oil was used as working fluid to heat water. Throughout the study two-phase closed system shows better performance compared to single-phase open collector system and their efficiency almost 10 to 12% higher. But, because of high initial cost of two-phase system, the pay back periods of both collector systems is almost same. In two phased closed system higher temperature of water could be achieved, which is very useful to operate advanced system.

scholarly journals Production strategy influence on the economic viability of a family fish farm in Pará state, Amazon, Brazil

2021 ◽  
Vol 9 (1) ◽  
pp. 540-549
Author(s):  
Marcos Ferreira Brabo ◽  
Gerfeson Almeida da Silva ◽  
Daniel Abreu Vasconcelos Campelo ◽  
Galileu Crovatto Veras ◽  
Andréia Santana Bezerra ◽  
...  
Keyword(s):  
Single Phase ◽  
Net Present Value ◽  
Cost Benefit ◽  
Phase System ◽  
Operational Cost ◽  
Internal Rate Of Return ◽  
Two Phase ◽  
Cost Benefit Ratio ◽  
The Cost ◽  
Capital Return

The objective of this study was to analyze the influence of the adoption of single-phase and two-phase system on the economic feasibility of tambaqui (Colossoma macropomum) family production in the Tracuateua municipality, Pará state. The operational cost methodology and economic efficiency indicators were adopted to compare these rearing systems. The annual production was 4,200 kg and 5,826 kg. The operational costs were R$ 26,169.00 and R$ 34,365.00, the total operational cost was R$ 27,505 and R$ 35,701.00, and the total operational cost per kg was R$ 6.55 and R$ 6.13 for single-phase and two-phase systems, respectively. Regarding the indicators, the net present value was R$ 24,180.70, the internal rate of return was 24%, the cost-benefit ratio was 1.19, and the capital return period was four years in the single-phase system. In the two-phase period, the net present value was R$ 48,582.06, the internal rate of return was 29%, the cost-benefit ratio was 1.25, and the capital return period was 3.6 years. Despite the demand for greater investment, the two-phase system proved to be more profitable than the single-phase system, promoting even a reduction in unit production cost.

scholarly journals Comparative simulation study of gas-phase propylene polymerization in fluidized bed reactors using aspen polymers and two phase models

2013 ◽  
Vol 19 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Ahmad Shamiria ◽  
M.A. Hussaina ◽  
Farouq Mjallic ◽  
Navid Mostoufid
Keyword(s):  
Molecular Weight ◽  
Gas Phase ◽  
Production Rate ◽  
Fluidized Bed ◽  
Average Molecular Weight ◽  
Phase Model ◽  
Propylene Polymerization ◽  
Flow Index ◽  
Fluidized Bed Reactors ◽  
Two Phase

A comparative study describing gas-phase propylene polymerization in fluidized-bed reactors using Ziegler-Natta catalyst is presented. The reactor behavior was explained using a two-phase model (which is based on principles of fluidization) as well as simulation using the Aspen Polymers process simulator. The two-phase reactor model accounts for the emulsion and bubble phases which contain different portions of catalysts with the polymerization occurring in both phases. Both models predict production rate, molecular weight, polydispersity index (PDI) and melt flow index (MFI) of the polymer. We used both models to investigate the effect of important polymerization parameters, namely catalyst feed rate and hydrogen concentration, on the product polypropylene properties, such as production rate, molecular weight, PDI and MFI. Both the two-phase model and Aspen Polymers simulator showed good agreement in terms of production rate. However, the models differed in their predictions for weight-average molecular weight, PDI and MFI. Based on these results, we propose incorporating the missing hydrodynamic effects into Aspen Polymers to provide a more realistic understanding of the phenomena encountered in fluidized bed reactors for polyolefin production.

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