Estimation of Chlamydomonas reinhardtii biomass concentration from chord length distribution data

Online monitoring lignocellulosic particles by focus beam reflectance measurement for efficient bioprocessing

Lignocellulose presents a promising alternative to fossil fuels. Monitoring the mass and size changes of lignocellulosic particles without disrupting the process can assist in adjusting pretreatment and enzymatic hydrolysis, where conventional sieving methods fall short. A method utilizing focused beam reflectance measurement (FBRM) was developed to establish mathematical correlations between FBRM chord information (chord length and count) and particle characteristics (weight and size) quantified through sieving. Results indicate particle size exhibits a linear correlation with the square weighted median chord length (Lsqr) with R2 at 0.93. Further, real-time bulk particle mass can be predicted using Lsqr and chord count (R2 0.98). These correlations are applicable in range 53 μm to 358.5 μm. Real-time monitoring of enzymatic hydrolysis of corn stalks has demonstrated the practical applicability of FBRM. This study introduces a novel approach for online characterization of lignocellulosic particles, thereby enhancing lignocellulosic biorefineries.

Chitosan flakes-mediated diatom harvesting from natural water sources

Diatom is a unicellular photosynthetic microalga that is found in diverse environments. These are decorated with siliceous cell walls called frustules. Diatoms have long been favoured by grazers such as microscopic protozoa and dinoflagellates. However, grazers typically remain intact in laboratory culturing and feed on diatom in culturing vessels and reducing biomass yield. The isolation and cultivation of diatoms in laboratories hamper diatoms' diversity and vast industrial potential. Chitosan, a biopolymer, has been widely used with other polyelectrolytes to flocculate various organic and inorganic colloids at acidic pH. Dissolved chitosan (acidic pH) has been used in various natural water samples and wastewater system for dewatering. However, untreated chitosan flakes have never been evaluated in a heterogeneous natural water environment. Since diatoms have silica surfaces, we tested chitosan for diatom separation and optimized chitosan concentration and other parameters to obtain grazer-free diatom starter culture from raw water. We also elucidated the mechanism for chitosan flakes-mediated diatom flocculation through adsorption kinetics and molecular dynamic simulation analysis. The results of this study are statistically optimized and validated, with a significant R² value of 0.99 for the proposed model.

On-Line Monitoring of Biological Parameters in Microalgal Bioprocesses Using Optical Methods

Microalgae are promising sources of fuels and other chemicals. To operate microalgal cultivations efficiently, process control based on monitoring of process variables is needed. On-line sensing has important advantages over off-line and other analytical and sensing methods in minimizing the measurement delay. Consequently, on-line, in-situ sensors are preferred. In this respect, optical sensors occupy a central position since they are versatile and readily implemented in an on-line format. In biotechnological processes, measurements are performed in three phases (gaseous, liquid and solid (biomass)), and monitored process variables can be classified as physical, chemical and biological. On-line sensing technologies that rely on standard industrial sensors employed in chemical processes are already well-established for monitoring the physical and chemical environment of an algal cultivation. In contrast, on-line sensors for the process variables of the biological phase, whether biomass, intracellular or extracellular products, or the physiological state of living cells, are at an earlier developmental stage and are the focus of this review. On-line monitoring of biological process variables is much more difficult and sometimes impossible and must rely on indirect measurement and extensive data processing. In contrast to other recent reviews, this review concentrates on current methods and technologies for monitoring of biological parameters in microalgal cultivations that are suitable for the on-line and in-situ implementation. These parameters include cell concentration, chlorophyll content, irradiance, and lipid and pigment concentration and are measured using NMR, IR spectrophotometry, dielectric scattering, and multispectral methods. An important part of the review is the computer-aided monitoring of microalgal cultivations in the form of software sensors, the use of multi-parameter measurements in mathematical process models, fuzzy logic and artificial neural networks. In the future, software sensors will play an increasing role in the real-time estimation of biological variables because of their flexibility and extendibility.