TY  - JOUR
A1  - Sandmann, Michael
A1  - Münzberg, Marvin
A1  - Bressel, Lena
A1  - Reich, Oliver
A1  - Hass, Roland
T1  - Inline monitoring of high cell density cultivation of Scenedesmus rubescens in a mesh ultra-thin layer photobioreactor by photon density wave spectroscopy
JF  - BMC Research Notes / Biomed Central
N2  - Objective Due to multiple light scattering that occurs inside and between cells, quantitative optical spectroscopy in turbid biological suspensions is still a major challenge. This includes also optical inline determination of biomass in bioprocessing. Photon Density Wave (PDW) spectroscopy, a technique based on multiple light scattering, enables the independent and absolute determination of optical key parameters of concentrated cell suspensions, which allow to determine biomass during cultivation. Results A unique reactor type, called "mesh ultra-thin layer photobioreactor" was used to create a highly concentrated algal suspension. PDW spectroscopy measurements were carried out continuously in the reactor without any need of sampling or sample preparation, over 3 weeks, and with 10-min time resolution. Conventional dry matter content and coulter counter measurements have been employed as established offline reference analysis. The PBR allowed peak cell dry weight (CDW) of 33.4 g L-1. It is shown that the reduced scattering coefficient determined by PDW spectroscopy is strongly correlated with the biomass concentration in suspension and is thus suitable for process understanding. The reactor in combination with the fiber-optical measurement approach will lead to a better process management.
KW  - Photon density wave spectroscopy
KW  - Multiple light scattering
KW  - Process
KW  - analytical technology
KW  - Fiber-optical spectroscopy
KW  - Mesh ultra-thin layer
KW  - photobioreactor
Y1  - 2022
U6  - https://doi.org/10.1186/s13104-022-05943-2
SN  - 1756-0500
VL  - 15
IS  - 1
PB  - Biomed Central (London)
CY  - London
ER  - 
TY  - JOUR
A1  - Hartwig, Anne
A1  - Hass, Roland
T1  - Monitoring lactose crystallization at industrially relevant concentrations by photon density wave spectroscopy
JF  - Chemical engineering & technology
N2  - Lactose is of great industrial importance and its production includes the cooling crystallization from highly concentrated solutions. Monitoring the crystallization process is essential to ensure reproducible product quality. Photon density wave (PDW) spectroscopy enables in-line monitoring of highly concentrated processes in liquid dispersions. It was applied to the determination of the solubility and nucleation points of lactose monohydrate in water, sizing of lactose crystals, and to dissolution as well as crystallization monitoring. Other process analytical technologies (focused-beam reflectance measurement, particle vision and measurement) were used as reference, and the comparison indicates that PDW spectroscopy is very robust against probe fouling and is, thus, a useful tool for monitoring crystallization processes in concentrated suspensions.
KW  - In-line monitoring
KW  - Lactose
KW  - Light scattering
KW  - Photon density wave spectroscopy
KW  - Process analytical technology
Y1  - 2018
U6  - https://doi.org/10.1002/ceat.201700685
SN  - 0930-7516
SN  - 1521-4125
VL  - 41
IS  - 6
SP  - 1139
EP  - 1146
PB  - Wiley-VCH
CY  - Weinheim
ER  -