Environmental Engineering Reference
In-Depth Information
bioreactor systems and, further on, to the post-treatment fermentation
steps. On-line PAT measurements in pipeline systems at fermentation plants
have huge importance and potential. This is especially important for
heterogeneous slurries with a tendency to segregate. For bioslurries with a
significant total solid content, this could easily lead to measurements with
highly excessive sampling errors, if measured at-line in a static manner. A
very important factor regarding the accuracy of measurement concerns the
optimal analytical sample volume.
10.3.7 Multivariate data analysis: chemometrics as the final
tool for PAT
Multivariate data analysis is the important third stage of the PAT triangle.
Chemometric data analysis is explorative data analysis or, as described by
the International Chemometric Society (ICS, 2006), 'Chemometrics is the
science of relating measurements made on a chemical system or process to
the state of system via application of appropriate mathematical or statistical
methods'.
Various methods of multivariate data analysis exist in chemometrics.
These can be divided into three main types: (a) data description; (b)
discrimination and classification; (c) regression and prediction (Esbensen,
2001). The main focus of biogas PAT studies is on multivariate regression
and prediction of process parameters by processing near-infrared (NIR)
spectra and other multivariate data from image analysis, electronic tongue
or acoustic data sets of the heterogeneous bioslurry.
Chemometric data analysis gives an overview of the state of the chemical
and/or biological processes based on analytical measurements. The idea of
chemometrics is to let the process or the data structures unfold their
relations themselves. From chemometric data analysis it is possible to
decrease the required number of parameters (components) in order to
describe the investigated phenomena, even though multivariate data analysis
often starts with a much higher number of variables (Esbensen, 2001).
￿ ￿ ￿ ￿ ￿ ￿
10.3.8 On-line AD monitoring possibilities
To summarise, process analytical technologies - including NIR, other light
sources and acoustic (noise) sensor technology as PAT tools for on-line AD
monitoring and process control - have produced better and better results in
the past decade. Practical and commercial implementations are rapidly
developing and on-line monitoring tools are receiving more and more
attention from biogas plant operators (Holm-Nielsen, 2008; Jacobi et al.,
2011; Madsen et al., 2011).
Search WWH ::




Custom Search