Model of Biomass Concentration in Membrane Filtration Recycling Systems Subject to Single Substrate-Limited Growth Kinetics

2000 ◽  
Author(s):  
Steven J. Skerlos ◽  
N. Rajagopalan ◽  
Richard E. DeVor ◽  
Shiv G. Kapoor ◽  
Robert A. Sanford
Keyword(s):  
Membrane Filtration ◽  
Microbial Growth ◽  
Nonlinear Differential Equations ◽  
Biomass Concentration ◽  
Metalworking Fluids ◽  
Biomass Growth ◽  
Growth Data ◽  
Monod Equation ◽  
Single Substrate ◽  
Rejection Coefficient

Abstract Membrane filtration has the ability to limit microbiological growth in metalworking fluids (MWFs). To appropriately design and size a membrane filtration system for this application, the rate of microbial removal must be assessed relative to microbial population (biomass) growth. This research utilizes the Monod Equation describing biomass growth limited by a single substrate to evaluate if biomass levels can be maintained below a prescribed level in a perfectly mixed MWF system. The model for predicting biomass in the MWF system is obtained by numerical solution of a system of coupled nonlinear differential equations. The model solution permits membrane filtration design and sizing decisions based on microbial growth data specific to MWF chemistries, microbial species, and manufacturing facilities. It is revealed that the ratio of the filtration rate to the MWF volume must exceed the maximum specific growth rate of microorganisms to control biomass concentrations in the system under arbitrary initial substrate and contamination levels. The control of microbial growth in the system also requires that appropriate cleaning intervals be selected for the membrane filtration process tank. The microbial rejection coefficient, which is characteristic to a given membrane, has a dominant impact on the required cleaning interval.

The effect of the surface-to-volume contact ratio on the biomass production potential of the pipe products in contact with drinking water

2010 ◽  
Vol 10 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Z. G. Tsvetanova ◽  
E. J. Hoekstra
Keyword(s):  
Drinking Water ◽  
Biomass Production ◽  
Microbial Growth ◽  
Biomass Concentration ◽  
Point Of View ◽  
Contact Ratio ◽  
Production Potential ◽  
Static Test ◽  
Growth Promoting ◽  
Construction Product

The biomass production potential (BPP) test is a semi-static test for assessment of microbial growth promoting properties of construction products in contact with drinking water (CPDW). In 2003 the test was selected for incorporation into a scheme for acceptance of CPDW in the framework of implementation of the European Construction Product Directive and Drinking Water Directive. The pass/fail criterion for the BPP test is based on the sum of microbial growth in water and in biofilm caused by substances released from CPDW. The test is performed at a surface-to-volume contact ratio (S/V) of 0.17 cm−1, that is quite different from the practice in buildings and domestic installations, where the usual ratios are 2.1 cm−1 for 3/4 inches pipe, 1.6 cm−1 for 1 inches pipe or 1.0 cm−1 for 1.5 inches pipe. The goal of the study was to evaluate the importance of S/V ratio for performance of the BPP test and for correct assessment of the growth promoting properties of CPDW. The BPP of 10 pipe products were compared under the S/V ratios of 0.17 cm−1 and 1.7 cm−1. The BPP of most polymer products were higher under the S/V ratio of 1.7 cm−1 in individual trials, but the differences were insignificant. However, the planktonic biomass concentrations were 4–14 fold higher at larger S/V ratio and this can be important from hygienic point of view. For acceptance of CPDW, besides a pass/fail criterion for the BPP, the planktonic biomass concentration could be taken as a second criterion for evaluation.

scholarly journals Diseño de un medio para la producción de un co-cultivo de bacterias fosfato solubilizadoras con actividad fosfatasa

2012 ◽  
Vol 17 (1) ◽  
pp. 43 ◽  
Author(s):  
Jimena Paola Angulo-Cortés ◽  
Anamaría García-Díaz ◽  
Aura Marina Pedroza ◽  
María Mercedes Martínez-Salgado ◽  
Viviana Gutiérrez-Romero
Keyword(s):  
Phosphatase Activity ◽  
Microbial Growth ◽  
Culture Media ◽  
Biomass Concentration ◽  
Soil Samples ◽  
Phosphate Solubilizing Bacteria ◽  
Bacterial Strains ◽  
Box Behnken Design ◽  
Phosphate Solubilizing ◽  
Complex Culture

<strong>Objective</strong>. To design a complex culture media for the production of biomass and acid phosphatases from phosphate-solubilizing bacteria isolated from soil. <strong>Materials</strong> <strong>and methods</strong>. Phosphate-solubilizing bacteria were isolated from oil palm crop soil samples and selected on SMRS1 agar, which were then assessed with antagonism tests to verify their aptitude to form a co-culture. A Box-Behnken experimental design was applied to<br />evaluate the effect of each one of the culture media components on the production of biomass and phosphatase enzymes at a laboratory scale. Finally, microbial growth and enzyme production curves were carried out in order to determine their production times. <strong>Results</strong>. Five phosphate-solubilizing bacterial strains were isolated and three of them were selected based on their solubilization indices.These Gram negative strains with bacillus morphology were identified as A, B and C; their solubilization indices were 2.03, 2.12, and 2.83, respectively. According to the ANOVA analyses for the Box-Behnken design, the only factor which had a significant effect on the phosphatase activity (p&lt;0.01) was hydrolyzed yeast, and the formulation that generated the highest biomass concentration and phosphatase activity (p&lt;0.01) contained 10, 15 and 2.5 gL-1 of phosphoric rock, sucrose and hydrolyzed yeast, respectively. After 24 hours of incubation at 100 rpm, the highest values of biomass and phosphatase activity were obtained: 11.8 logarithmic units of CFU and 12.9 phosphatase units. <strong>Conclusion</strong>. We determined that the culture media based on phosphoric rock 10 gL-1, hydrolyzed yeast 2.5 gL-1 and commercial sucrose 15 gL-1 was ideal for the production of biomass and phosphatases by the strains evaluated; likewise, we proved that the hydrolyzed yeast was the only factor significantly influential for the production of phosphatases.<br /><br /><strong>Key words</strong>: bio-inoculants, phosphate solubilizing microorganisms, phosphatase activity, Box Behnken design.

scholarly journals A New Rate Law Describing Microbial Respiration

2003 ◽  
Vol 69 (4) ◽  
pp. 2340-2348 ◽  
Author(s):  
Qusheng Jin ◽  
Craig M. Bethke
Keyword(s):  
Respiration Rate ◽  
Microbial Respiration ◽  
Biomass Concentration ◽  
Rate Law ◽  
Monod Equation ◽  
Rate Laws ◽  
General Law ◽  
Threshold Phenomena ◽  
Transport Chain ◽  
Kinetics Of

ABSTRACT The rate of microbial respiration can be described by a rate law that gives the respiration rate as the product of a rate constant, biomass concentration, and three terms: one describing the kinetics of the electron-donating reaction, one for the kinetics of the electron-accepting reaction, and a thermodynamic term accounting for the energy available in the microbe's environment. The rate law, derived on the basis of chemiosmotic theory and nonlinear thermodynamics, is unique in that it accounts for both forward and reverse fluxes through the electron transport chain. Our analysis demonstrates how a microbe's respiration rate depends on the thermodynamic driving force, i.e., the net difference between the energy available from the environment and energy conserved as ATP. The rate laws commonly applied in microbiology, such as the Monod equation, are specific simplifications of the general law presented. The new rate law is significant because it affords the possibility of extrapolating in a rigorous manner from laboratory experiment to a broad range of natural conditions, including microbial growth where only limited energy is available. The rate law also provides a new explanation of threshold phenomena, which may reflect a thermodynamic equilibrium where the energy released by electron transfer balances that conserved by ADP phosphorylation.

More than simply microbial growth curves

2016 ◽  
Vol 1 (2) ◽  
pp. 63 ◽  
Author(s):  
Ji-Dong Gu
Keyword(s):  
Bacterial Growth ◽  
Microbial Growth ◽  
Growth Curves ◽  
Lag Phase ◽  
Growth Data ◽  
Phase Growth ◽  
Simple Task ◽  
Wide Range ◽  
Comparative Results ◽  
Comparative Information

Bacterial growth is a very important piece of information in a wide range of investigation and, in most of the time the data are simply shown directly without any further processing. In a single factor investigation without comparative information to be extracted, this simple approach can be used together with other data to form a comprehensive set of results. When comparison is involved, such direct showing of bacterial growth curves without processing cannot warrant a meaningful comparison thoroughly and further processing of data is necessary. In addition, there is little, if any, quantitative data for the comparison from the display of growth curves and description of a number of curves is not a simple task, especially in a meaningful way for assimilation of the data to readers. With this in mind, I would like to remind of those who plan to show such data as growth curves for their potential publication to carry this further to generate comparative results for a much meaningful interpretation by modeling and calculation from the raw growth data over time of incubation. By calculating with existing equations, the lag phase, growth rate and the biomass can be derived from a series of growth curves for a more effective and meaningful analysis. This approach is not new, but remembrance of such available tool is more important so that research data are shown professionally and also scientifically for meaning presentation and effective assimilation.

Survey on nitrogen removal and membrane filtration characteristics of Chlorella vulgaris Beij. on treating domestic type wastewaters

2013 ◽  
Vol 68 (3) ◽  
pp. 695-704 ◽  
Author(s):  
Yu-Hsuan Wang ◽  
Chuen-Mei Wu ◽  
Wan-Lin Wu ◽  
Ching-Ping Chu ◽  
Yu-Jen Chung ◽  
...  
Keyword(s):  
Nitrogen Source ◽  
Chlorella Vulgaris ◽  
Membrane Filtration ◽  
Domestic Wastewater ◽  
Nitrifying Bacteria ◽  
Biomass Growth ◽  
Filtration Cycle ◽  
The Mean ◽  
Cell Residence Time ◽  
Uf Membranes

The main objective of this study is to evaluate the nitrogen assimilation and filtration characteristics of Chlorella vulgaris Beij. when treating domestic wastewaters. Chlorella could assimilate organic nitrogen, ammonia and nitrate in wastewater, and the mean cell residence time (MCRT) to achieve the maximum biomass content in a bioreactor was different for each individual nitrogen source used. The experimental results showed that using nitrate as the only nitrogen source was the most favorable for biomass growth. With ammonia and nitrate coexisting in the aquatic phase, Chlorella possibly utilized ammonia first, and this was unfavorable to subsequent biomass growth. Nitrifying bacteria in wastewaters significantly affected Chlorella growth as they possibly competed with Chlorella in assimilating ammonia and nitrate in domestic wastewater. In a submerged ultrafiltration (UF) membrane module, with an initial concentration of 850 mg/L of Chlorella, the optimized flux was 0.02 m3/(m2·h), and the filtration cycle was 30 min. A ‘dual membrane bioreactor (MBR)’ configuration using UF membranes for Chlorella incubation was proposed. MBR1 provides an environment with long MCRT for efficient nitrification. The converted nitrate is assimilated by Chlorella in MBR2 to sustain its growth. UF permeate from MBR1 is bacteria-free and does not affect the growth of Chlorella in MBR2. MCRT of Chlorella growth is controlled by the UF membrane of MBR2, providing the flexibility to adjust variations of nitrogen composition in the wastewater.

Kinetics of Microbial Ferrous-Iron Oxidation by Leptospirillum Ferriphilum: Effect of Ferric-Iron on Biomass Growth

2009 ◽  
Vol 71-73 ◽  
pp. 259-262 ◽  
Author(s):  
Tunde Victor Ojumu ◽  
Jochen Petersen
Keyword(s):  
Ferrous Iron ◽  
Microbial Growth ◽  
Ferric Iron ◽  
Iron Oxidation ◽  
Iron Concentration ◽  
Biomass Concentration ◽  
Reaction Conditions ◽  
Leptospirillum Ferriphilum ◽  
Ferrous Iron Oxidation ◽  
Kinetics Of

The kinetics of microbial ferrous-iron oxidation have been well studied as it is a critical sub-process in bioleaching of sulphide minerals. Exhaustive studies in continuous culture have been carried out recently, investigating the effects of conditions relevant to heap bioleaching on the microbial ferrous-iron oxidation by Leptospirillum ferriphilum [1-3]. It was postulated that ferric-iron, which is known to be inhibitory, also acts as a stress stimulus, promoting microbial growth at higher total iron concentration. This paper investigates this phenomenon further, by comparing tests run with pure ferrous-iron feeds against those where the feed is partially oxidised to ferric at comparable concentrations. The findings clearly suggest that, contrary to reactor theory, it is indeed ferrous iron concentration in the reactor feed that determines biomass concentration and that ferric iron concentration has little effect on microbial growth. Further mathematical analysis shows that the phenomenon can be explained on the basis of the Pirt equation and the particular reaction conditions employed in the test work.

scholarly journals A simplified model for A. Niger FS3 growth during phytase formation in solid State fermentation

2009 ◽  
Vol 52 (spe) ◽  
pp. 151-158 ◽  
Author(s):  
Michele Rigon Spier ◽  
Luiz Alberto Junior Letti ◽  
Adenise Lorenci Woiciechowski ◽  
Carlos Ricardo Soccol
Keyword(s):  
Growth Models ◽  
Biomass Concentration ◽  
Fungal Growth ◽  
Simplified Model ◽  
Biomass Growth ◽  
Enzyme Formation ◽  
Biomass Determination ◽  
Fermentation Parameters ◽  
First Time ◽  
Good Agreement

A simplified model to describe fungal growth during citric pulp fermentation for phytase production was described for the first time. Experimental data for biomass growth were adjusted to classical mathematical growth models (Monod and Logistic). The Monod model predictions showed good agreement with the experimental results for biomass concentration during 96 hours of fermentation. Parameters such as yield of biomass from oxygen (Y X/O), maintenance coefficient (m) and specific growth rate (µ) were compared showing a good correlation between the data and the model. An alternative method for biomass determination in this process was developed since a great correlation was found between biomass growth and enzyme formation.

Sign in / Sign up

Export Citation Format

Share Document