scholarly journals Impact of Dropwise Condensation on the Biomass Production Rate in Covered Raceway Ponds

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 268
Author(s):  
Jack Hoeniges ◽  
Keyong Zhu ◽  
Jeremy Pruvost ◽  
Jack Legrand ◽  
El-khider Si-Ahmed ◽  
...  
Keyword(s):  
Contact Angle ◽  
Los Angeles ◽  
Surface Area ◽  
Optical Thickness ◽  
Biomass Concentration ◽  
Biomass Productivity ◽  
Growth Conditions ◽  
Area Coverage ◽  
Initial Biomass Concentration ◽  
Condensed Water

This study investigates the effect of condensed water droplets on the areal biomass productivity of outdoor culture systems with a free surface, protected by a transparent window or cover to prevent contamination and to control the growth conditions. Under solar radiation, evaporation from the culture causes droplets to condense on the interior surface of the cover. To quantify the effect of droplets on the system’s performance, the bidirectional transmittance of a droplet-covered window was predicted using the Monte Carlo ray-tracing method. It was combined with a growth kinetics model of Chlorella vulgaris to predict the temporal evolution of the biomass concentration on 21 June and 23 September in Los Angeles, CA. A droplet contact angle of 30∘ or 90∘ and a surface area coverage of 50% or 90% were considered. Light scattering by the condensed droplets changed the direction of the incident sunlight while reducing the amount of light reaching the culture by up to 37%. The combined effect decreased the daily areal biomass productivity with increasing droplet contact angle and surface area coverage by as much as 18%. Furthermore, the areal biomass productivity of the system was found to scale with the ratio X0/a of the initial biomass concentration X0 and the specific illuminated area a, as previously established for different photobioreactor geometries, but even in the presence of droplets. Finally, for a given day of the year, the optical thickness of the culture that yielded the maximum productivity was independent of the window condition. Thus, the design and operation of such a system should focus on maintaining a small droplet contact angle and surface area coverage and an optimum optical thickness to maximize productivity.

Determination of the Maintenance Requirements of Activated Sludge

1993 ◽  
Vol 28 (7) ◽  
pp. 139-142 ◽  
Author(s):  
J. Chang ◽  
P. Chudoba ◽  
B. Capdeville
Keyword(s):  
Wastewater Treatment ◽  
Process Development ◽  
Biomass Concentration ◽  
Growth Yield ◽  
Kinetic Studies ◽  
Initial Biomass Concentration ◽  
Aerobic Wastewater Treatment ◽  
Initial Substrate ◽  
Maintenance Requirements ◽  
The Cost

Maintenance energy plays an important role both in basic kinetic studies and in process development. Numerous studies have been devoted to the maintenance concept in various microbial fields but very few in biological wastewater treatment. Using a fermenter coupled to a mass spectrometer, we investigated the influence of the ratio So/Xo (ratio between initial substrate concentration and initial biomass concentration) on the observed sludge growth yield of an oxic-settling anaerobic (OSA) system. By measuring the substrate removed, the oxygen consumed and the carbon dioxide produced, we were able to estimate the substrate fraction used for maintenance purposes. The results indicate that at a high So/Xo ratio, a greater proportion of the substrate is devoted to maintenance thus significantly decreasing the observed growth yield. These findings are of particular importance in view of the cost associated with the disposal of excess sludge in aerobic wastewater treatment processes.

Extracting surface area coverage by superimposing 3D scan data

1999 ◽  
Author(s):  
Peng Li ◽  
Brian D. Corner ◽  
Steven Paquette
Keyword(s):  
Surface Area ◽  
Area Coverage ◽  
3D Scan ◽  
Scan Data

scholarly journals Influence of Light Intensity and Temperature on Cultivation of Microalgae Desmodesmus Communis in Flasks and Laboratory-Scale Stirred Tank Photobioreactor

2015 ◽  
Vol 52 (2) ◽  
pp. 59-70 ◽  
Author(s):  
J. Vanags ◽  
L. Kunga ◽  
K. Dubencovs ◽  
V. Galvanauskas ◽  
O. Grīgs
Keyword(s):  
Light Intensity ◽  
Shake Flask ◽  
Scale Up ◽  
Biomass Concentration ◽  
Biomass Productivity ◽  
Pilot Scale ◽  
Laboratory Scale ◽  
Stirred Tank ◽  
Light Limitation ◽  
Maximum Biomass

Abstract Optimization of the microalgae cultivation process and of the bioprocess in general traditionally starts with cultivation experiments in flasks. Then the scale-up follows, when the process from flasks is transferred into a laboratory-scale bioreactor, in which further experiments are performed before developing the process in a pilot-scale reactor. This research was done in order to scale-up the process from a 0.4 1 shake flask to a 4.0 1 laboratory-scale stirred-tank photobioreactor for the cultivation of Desmodesmus (D.) communis microalgae. First, the effect of variation in temperature (21-29 ºC) and in light intensity (200-600 μmol m-2s-1) was studied in the shake-flask experiments. It was shown that the best results (the maximum biomass concentration of 2.72 g 1-1 with a specific growth rate of 0.65 g g-1d-1) can be achieved at the cultivation temperature and light intensity being 25 °C and 300 μmol m2s-1, respectively. At the same time, D. communis cultivation under the same conditions in stirred-tank photobioreactor resulted in average volumetric productivities of biomass due to the light limitation even when the light intensity was increased during the experiment (the maximum biomass productivity 0.25 g 1-1d-1; the maximum biomass concentration 1.78 g 1-1).

scholarly journals Optimization of heterotrophic cultivation of Chlorella sp. HS2 using screening, statistical assessment, and validation

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hee Su Kim ◽  
Won-Kun Park ◽  
Bongsoo Lee ◽  
Gyeongho Seon ◽  
William I. Suh ◽  
...  
Keyword(s):  
Biomass Concentration ◽  
Biomass Productivity ◽  
Nitrogen Sources ◽  
Full Potential ◽  
Chlorella Sp ◽  
Bg11 Medium ◽  
Heterotrophic Cultivation ◽  
Dipotassium Phosphate ◽  
Burman Design ◽  
Major Nutrients

AbstractThe heterotrophic cultivation of microalgae has a number of notable advantages, which include allowing high culture density levels as well as enabling the production of biomass in consistent and predictable quantities. In this study, the full potential of Chlorella sp. HS2 is explored through optimization of the parameters for its heterotrophic cultivation. First, carbon and nitrogen sources were screened in PhotobioBox. Initial screening using the Plackett-Burman design (PBD) was then adopted and the concentrations of the major nutrients (glucose, sodium nitrate, and dipotassium phosphate) were optimized via response surface methodology (RSM) with a central composite design (CCD). Upon validation of the model via flask-scale cultivation, the optimized BG11 medium was found to result in a three-fold improvement in biomass amounts, from 5.85 to 18.13 g/L, in comparison to a non-optimized BG11 medium containing 72 g/L glucose. Scaling up the cultivation to a 5-L fermenter resulted in a greatly improved biomass concentration of 35.3 g/L owing to more efficient oxygenation of the culture. In addition, phosphorus feeding fermentation was employed in an effort to address early depletion of phosphate, and a maximum biomass concentration of 42.95 g/L was achieved, with biomass productivity of 5.37 g/L/D.

scholarly journals Enhanced Hydrophilic and Electrophilic Properties of Polyvinyl Chloride (PVC) Biofilm Carrier

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1240
Author(s):  
Haifeng Cai ◽  
Yang Wang ◽  
Kai Wu ◽  
Weihong Guo
Keyword(s):  
Contact Angle ◽  
Zinc Oxide ◽  
Surface Area ◽  
Polyvinyl Chloride ◽  
Positive Charge ◽  
Sem Images ◽  
Biofilm Carrier ◽  
Surface Contact Angle ◽  
Bacterial Adsorption ◽  
Scanning Electron

Polyvinyl chloride (PVC) biofilm carrier is used as a carrier for bacterial adsorption in wastewater treatment. The hydrophilicity and electrophilicity of its surface play an important role in the adsorption of bacteria. The PVC biofilm carrier was prepared by extruder, and its surface properties were investigated. In order to improve the hydrophilicity and electrophilic properties of the PVC biofilm carrier, polyvinyl alcohol (PVA) and cationic polyacrylamide (cPAM) were incorporated into polyvinyl chloride (PVC) by blending. Besides, the surface area of the PVC biofilm carrier was increased by azodicarbonamide modified with 10% by weight of zinc oxide (mAC). The surface contact angle of PVC applied by PVA and cPAM at 5 wt %, 15 wt % was 81.6°, which was 18.0% lower than pure PVC. It shows the significant improvement of the hydrophilicity of PVC. The zeta potential of pure PVC was −9.59 mV, while the modified PVC was 14.6 mV, which proves that the surface charge of PVC changed from negative to positive. Positive charge is more conducive to the adsorption of bacteria. It is obvious from the scanning electron microscope (SEM) images that holes appeared on the surface of the PVC biofilm carrier after adding mAC, which indicates the increase of PVC surface area.

Influence of the initial substrate to microorganisms concentration ratio on the methanogenic inhibition test

2003 ◽  
Vol 48 (6) ◽  
pp. 17-22 ◽  
Author(s):  
I. Moreno-Andrade ◽  
G. Buitrón
Keyword(s):  
Methane Production ◽  
Concentration Ratio ◽  
Suspended Solids ◽  
Great Influence ◽  
Biomass Concentration ◽  
Inhibition Test ◽  
Initial Concentration ◽  
Initial Biomass Concentration ◽  
Initial Substrate

The influence of the initial substrate to microorganisms ratio (So/Xo) on the inhibition of the methane production caused by 4-chlorophenol, 4CP, was studied. The effect of the 4CP on glucose degradation was evaluated measuring the quantity of methane produced during the test. One part of the inoculum was used as it came from its origin and another was fed with ethanol in order to maintain its activity. The inhibition tests were carried out using the same initial concentration of glucose, three initial suspended solids concentrations and eight initial concentrations of 4CP. The use of ethanol-acclimatized sludge presented a great influence on the inhibition results, since the inhibition was greater in the raw sludge than the acclimated one. Significant differences in the inhibition tests were found depending on the initial So/Xo ratio with respect to the glucose as substrate. It was observed that the inhibition decreases as the So/Xo decreases, in other words as the initial biomass concentration increases. When the results were analyzed in respect to the 4CP it was observed that the inhibition increases as the So/Xo increases. Also, it was observed that for the same value of So/Xo there is an increase of the inhibition when the quantity of Xo decreases.

Explanation of Biological Meaning of the So/Xo Ratio in Batch Cultivation

1992 ◽  
Vol 26 (3-4) ◽  
pp. 743-751 ◽  
Author(s):  
P. Chudoba ◽  
B. Capdeville ◽  
J. Chudoba
Keyword(s):  
Mixed Culture ◽  
Biomass Concentration ◽  
Batch Cultivation ◽  
Kinetic Constants ◽  
Cell Multiplication ◽  
Waste Products ◽  
Substrate Removal ◽  
Initial Biomass Concentration ◽  
Initial Substrate ◽  
Exogenous Substrate

It is shown that the most important parameter in batch cultivation of mixed cultures is the ratio of the initial substrate concentration to the initial biomass concentration (So/Xo as COD/biomass). When the ratio is sufficiently low (below 2-4 depending on the mixed culture history) no cell multiplication takes place during the exogenous substrate removal. Under these conditions, a biomass increase is mostly due to the synthesis of storage polymers. It is also shown that the observed yield, Yobs, decreases with increasing So/Xo ratio. Under the high So/Xo conditions, more energy is spent for cell multiplication, which results in greater part of substrate being oxidized. Batch cultivation at high So/Xo ratios results also in higher concentrations of microbial polymers produced as waste products of mixed culture microorganisms. It is concluded that for the biodegradation studies with the aim to obtain kinetic constants it is necessary to work at low So/Xo ratios to prevent mixed culture microorganisms from substantial multiplication. This is necessary because cell multiplication during batch cultivation of mixed culture changes the proportion among slow-growers and fast-growers. This is the only way to obtain the kinetic constants which are representative of the original mixed culture.

Effect of initial biomass concentration on the growth of immobilized Nitrosomonas europaea

1994 ◽  
Vol 42 (1) ◽  
pp. 153-157 ◽  
Author(s):  
R. H. Wijffels ◽  
A. W. Schepers ◽  
M. Smit ◽  
C. D. de Gooijer ◽  
J. Tramper
Keyword(s):  
Biomass Concentration ◽  
Nitrosomonas Europaea ◽  
Initial Biomass Concentration

A Mathematical Model of Volatile Fatty Acids (VFA) Production in a Plug-Flow Reactor Treating the Organic Fraction of Municipal Solid Waste (MSW)

1993 ◽  
Vol 27 (2) ◽  
pp. 201-208 ◽  
Author(s):  
E. D. Negri ◽  
J. Mata-Alvarez ◽  
C. Sans ◽  
F. Cecchi
Keyword(s):  
Mathematical Model ◽  
Fatty Acids ◽  
Municipal Solid Waste ◽  
Volatile Fatty Acids ◽  
Flow Reactor ◽  
Plug Flow ◽  
Biomass Concentration ◽  
Organic Fraction ◽  
Initial Biomass Concentration ◽  
Suspended Biomass

A mathematical model of a plug-flow reactor with a fluid recycle has been elaborated to simulate the VFA production process treating the organic fraction of the municipal solid waste. An alternative hydrolytic reaction model (homogeneous - heterogeneous) is proposed. The effect of a possible methanization step is also considered. The effect of process parameters (solid retention time (SRT), pH, recycle ratio) on the reactor performance is analyzed for parameters based on fruit and vegetable waste. The sensitivity of the model to proposed parameters (suspended biomass and initial biomass concentration) is also evaluated. It is found that the reactor production is very sensitive to the system pH. At low SRT, the production of volatile fatty acids (VFA) is proportional to this parameter. As the SRT increases methanization can reduce the VFA production. The effect of the recycle is negligible for the system and operating conditions studied. The effect of suspended biomass and initial biomass concentration was found to be also negligible. For the system analyzed, the pH is a critical parameter and a plug-flow arrangement (without recycle) seems to be the more reasonable election.

scholarly journals RETRACTED ARTICLE: Increased biomass productivity in green algae by tuning non-photochemical quenching

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Silvia Berteotti ◽  
Matteo Ballottari ◽  
Roberto Bassi
Keyword(s):  
Heat Dissipation ◽  
Biomass Productivity ◽  
Growth Conditions ◽  
Complex Stress ◽  
Biofuel Production ◽  
Photochemical Quenching ◽  
Protein Accumulation ◽  
Potential Productivity ◽  
Wide Range ◽  
Non Photochemical Quenching

Abstract Photosynthetic microalgae have a high potential for the production of biofuels and highly valued metabolites. However, their current industrial exploitation is limited by a productivity in photobioreactors that is low compared to potential productivity. The high cell density and pigment content of the surface layers of photosynthetic microalgae result in absorption of excess photons and energy dissipation through non-photochemical quenching (NPQ). NPQ prevents photoinhibition, but its activation reduces the efficiency of photosynthetic energy conversion. In Chlamydomonas reinhardtii, NPQ is catalyzed by protein subunits encoded by three lhcsr (light harvesting complex stress related) genes. Here, we show that heat dissipation and biomass productivity depends on LHCSR protein accumulation. Indeed, algal strains lacking two lhcsr genes can grow in a wide range of light growth conditions without suffering from photoinhibition and are more productive than wild-type. Thus, the down-regulation of NPQ appears to be a suitable strategy for improving light use efficiency for biomass and biofuel production in microalgae.

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