Measurement Of Biomass Concentration Research Articles

Effect of Zeolite NaY and Ca-Montmorillonite on Ethanol Production Using Synthetic Molasses

The influence of Ca-Montmorillonite (Ca-MNT) and zeolite NaY addition on ethanol production from synthetic molasses by S. cerevisiae 251 TP(3-2) was studied by the measurement of biomass concentrations and metal ion concentration with respect to fermentation time. Addition of 5 g/L Ca-MNT and 10 g/L zeolite NaY resulted in an increase in both ethanol concentration and ethanol production rate. This increase was 24 and 40% for ethanol concentration and 65 and 87% for production rate, respectively. From the ion analyses, it was observed that the NaY added to the medium decreased the toxic concentration of zinc, manganese, and iron cations and acted also as a pH regulator. Ca-MNT added to the medium decreased the concentration of Na+ ions, which is known to have a toxic effect on glycolysis and cell concentration. These effects caused improvement in the ethanol production rate.

On-line control of light intensity in a microalgal bioreactor using a novel automatic system

The influence of light intensity upon biomass and fatty acid productivity by the microalga Pavlova lutheri was experimentally studied using a novel device. This device was designed to automatically adjust light intensity in a photobioreactor: it takes on-line measurements of biomass concentration, and was successfully tested to implement a feedback control of light based on the growth rate variation. Using said device, batch and semicontinuous cultures of P. lutheri were maintained at maximum growth rates and biomass productivities – hence avoiding photoinhibition, and consequent waste of radiant energy. Several cultures were run with said device, and their performances were compared with those of control cultures submitted to constant light intensity; the biomass levels attained, as well as the yields of eicosapentaenoic and docosahexaenoic acids were calculated – and were consistently higher than those of their uncontrolled counterpart.

A cost–benefit analysis of methods for the determination of biomass concentration in wastewater treatment

The measurement of biomass concentration is important in biological wastewater treatment. This paper compares the accuracy and costs of the traditional volatile suspended solids (VSS) and the proposed suspended organic carbon (SOC) methods. VSS and SOC values of a dilution system were very well correlated ( R 2 = 0.9995 ). VSS and SOC of 16 samples were determined, the mean SOC/VSS ratio (0.52, n = 16 , σ = 0.01 ) was close to the theoretical value (0.53). For costing analysis, two hypothetical cases were analysed. In case A, it is assumed that 108 samples are analysed annually from two continuous reactors. Case B represents a batch experiment to be carried out in 24 incubated serum bottles. The savings, when using the SOC method, were £11 987 for case A and £90 for case B. This study suggests the use of SOC method as a time saving and lower cost biomass concentration measurement.

Estimation of multiple biomass growth rates and biomass concentration in a class of bioprocesses.

In this paper, an approach to the estimation of multiple biomass growth rates and biomass concentration is proposed for a class of aerobic bioprocesses characterized by on-line measurements of dissolved oxygen and carbon dioxide concentrations, as well as off-line measurements of biomass concentration. The approach is based on adaptive observer theory and includes two steps. In the first step, an adaptive estimator of two out of three biomass growth rates is designed. In the second step, the third biomass growth rate and the biomass concentration are estimated, using two different adaptive estimators. One of them is based on on-line measurements of dissolved oxygen concentration and off-line measurement of biomass concentrations, while the other needs only on-line measurements of the carbon dioxide concentration. Simulations demonstrated good performance of the proposed estimators under continuous and batch-fed conditions.

Estimation of kinetic rates in batch Thiobacillus ferrooxidans cultures

In this work, the key problem of estimation in bioprocesses when no structural model is available is dealt with. A nonlinear observer-based algorithm is developed in order to estimate kinetic rates in batch bioreactors. The algorithm uses the measurements of biomass concentration and either substrate concentration or redox potential to perform the estimation of the respective specific kinetic rates. For this purpose, a general mathematical model description of the process is provided. The estimation algorithm design is based on a nonlinear reduced-order observer. The observer performance is validated with experimental results on a Thiobacillus ferrooxidans batch culture.

A novel fiber optic probe for on-line monitoring of biomass concentrations

A fiber optic biomass probe for on-line measurement of biomass concentration was designed. Results of biomass concentration monitoring experiments with suspended cells of baker's yeast as well as an experimental cultivation of S. cerevisiae are presented. The device was able to observe biomass concentrations of 14 g l−1S. cerevisiae. By means of correlations the capability of estimating the biomass concentration from the probe signal is demonstrated.

Developmental studies of an adaptive on‐line softsensor for biological wastewater treatments

AbstractEfficient monitoring and automatic control systems for biological wastewater treatment processes, especially those dealing with bioinhibitory pollutants, such as phenol, are urgently required in order to meet increasingly stringent environmental regulations. Practical on‐line sensors of variables that describe water quality, such as BOD or individual toxic pollutants such as phenol, are not commercially available; e.g. phenol is generally monitored off‐line by spectrofluorometry. Inference software sensors could be an attractive alternative for on‐line monitoring of these variables. As a first step towards the development of inferential sensors for biological wastewater treatment processes, we consider in this study, a simplistic version of such a process which consists of a continuous culture of Pseudomonas putida Q5 degrading phenol. In this work, we propose a neural network based inferential sensor for phenol monitoring using on‐line biomass concentration measurements by spectrophotometry. The network was built with wavelets as the basis functions and the adaptive algorithm for the weights was based on a Lyapunov stability analysis. Predicted phenol output of the network showed good agreement with experimental data, over fairly broad ranges of inlet phenol concentration and dilution rate step changes. Simulations were conducted to find convergence conditions and to investigate possible sources for errors in phenol estimates.

The effects of aeration and agitation on the measurement of yeast biomass using a laser turbidity probe

The paper reports the measurement of biomass concentration using a laser turbidity probe. A suspension of Bakers’ yeast (0.5−50 gl-1) was subjected to various conditions of agitation and aeration in a stirred tank reactor and the turbidity measured using the probe. Both agitation and aeration were found to influence the turbidity. At any constant biomass concentration, the effect on the turbidity measurement of changing agitation or aeration rate independently was linear, while at any constant conditions of agitation and aeration rate, the relationship between turbidity and biomass concentration was non-linear. The results indicate that, in a bioprocess with non-particulate medium, it is possible to correct for the effects of aeration and agitation on turbidity measurement using a multivariate calibration model. A procedure for calibration and correction of measurements for the effects of agitation and aeration is presented and is verified using experimental data. This procedure may be generalised for other applications.

On‐line estimation of biological variables during pH controlled lactic acid fermentations

Indirect measurement of lactose, galactose, lactic acid, and biomass concentration from on-line sodium hydroxide weight measurements have been obtained for pure and mixed batch cultures of Streptococcus salivarius ssp. thermophilus 404 and Lactobacillus delbrueckii subsp. bulgaricus 398 conducted at controlled pH and temperature. Linear correlations were established between the equivalent sodium hydroxide concentration and the lactose (substrate), galactose and lactic acid (products) concentrations while nonlinear relationships were developed between biomass and lactic acid concentrations. These nonlinear relationships took into account the inhibitory effect of lactic acid on growth and acidification. The indirect measurements of biomass concentration were introduced into a nonlinear estimator of the state variables and of the specific growth and lactic acid production rates. Good agreement was found between estimated and measured biomass concentrations (error index ranging from 10.8% to 12.6%). The results showed the feasibility of on-line estimation of biomass concentration and of the specific kinetics from NaOH addition weight measurements and its applicability for monitoring lactic acid fermentations. Using off-line measurements of L(+) and D(-) lactic acid concentrations, the evolution of the concentration of each strain in mixed cultures was obtained from the relationships proposed for the mixed cultures. (c) 1994 John Wiley & Sons, Inc.

Spectrophotometric determination of mycelial biomass

The optical density (450 nm) of samples of homogenized fungal biomass correlated linearly with the dry weight of the biomass in the samples. As shown for broths of the filamentous microfungus Neurospora sitophila, the sensitivity of the technique depended on the extent of fragmentation of fungal hyphae during homogenization: increased fragmentation increased sensitivity. The method applied during all phases of growth, was as accurate as the conventional dry weight technique and permitted rapid and simple measurement of biomass concentration.

A Method of using off-line Measurements in an On-line Estimator of Biomass Concentration for a Penicillin Fermentation, and its Effects on the Quality of the Estimates

A method of improving on-line estimation of the biomass concentration for a fed-batch penicillin fermentation, by using the information available in off-line measurements of biomass concentration, is presented. The on-line estimator was based on a well known, two parameter model that relates respiratory activity, in the form of carbon dioxide evolution rate measurements, to growth and non growth associated culture activities. The off-line measurements were used to identify one of the model parameters. In an illustrative example, estimation is shown to be improved using off-line measurements that are delayed by up to 24.5 hours. The quality of the estimation was found to decrease with increasing analysis delay.

Spectrophotometric method for high biomass concentration measurements

Continuous monitoring of concentration is important in the optimal control of bioreactors. Spectrophotometry provides a simple, accurate, and rapid way for measuring cell concentration of unicellular microorganisms, based on either Beer's law or calibration curves prepared using standard solutions. However, this method is limited to a low range of microbial concentrations, because Beer's law deviates significantly at high concentrations. In the present investigation, based on experimental work, a new technique is posed to monitor the concentration of microbial cells as high as 100 g DW/L. this is achieved by using a mixture of known concentration as reference, rather than the "ideal blank" with zero concentration of analyte. As a result, a new equation is developed that, although applied here only to microbial concentration, in principle can be used for monitoring the concentration of any optically sensitive material.

Continuous measurement of biomass concentration in laboratory-scale fermenters using a led ? electrode system

An LED (Light Emitting Diode) - electrode system for on-line measurement of biomass in small scale laboratory fermenters has been developed. The system comprises a high intensity light emitting diode (LED) of 500 mcd luminosity coupled with a photodiode detector. Detector output is amplified and fed to a microprocessor control and logging system. Satisfactory operation has been achieved over 12 months intensive use.