Open AccessNear‐infrared spectroscopic online monitoring of process stability in biogas plants
Author(s) -
Stockl Andrea,
Oechsner Hans
Publication year - 2012
Publication title -
engineering in life sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.547
H-Index - 57
eISSN - 1618-2863
pISSN - 1618-0240
DOI - 10.1002/elsc.201100065
Subject(s) - mesophile , biogas , anaerobic digestion , pulp and paper industry , calibration , acetic acid , bioenergy , environmental science , methane , biogas production , renewable energy , thermophile , biofuel , chemistry , waste management , mathematics , engineering , biology , biochemistry , organic chemistry , genetics , statistics , electrical engineering , bacteria , enzyme
The conditions laid down in the Renewable Energy Source Act for production of electricity from biogas have led to an enormous expansion of new biogas plants in the recent years in Germany. Through near‐infrared reflection spectroscopy ( NIRS ) process stability of a biogas digester can be monitored online. This study presents the development of NIRS calibrations on acetic acid equivalents, acetic acid, and propionic acid concentrations in the digester substrate. Thereby, differences between thermophilic and mesophilic operations were measured and presented for the first time. Good calibration models were achieved by artificially increasing concentrations of the above‐mentioned acids in two 400 L experimental biogas digesters with mesophilic and thermophilic operation and applying support vector regression. The presented values demonstrate that calibration with NIRS is possible. In the thermophilic digester, a calibration model with a ratio of standard deviation and standard error of prediction ( RPD ) value of 3.21 was achieved for the parameter acetic acid and in the mesophilic digester a RPD of 4.91 for the same acid. For the parameter propionic acid, calibration models with RPD values of 4.23 and 4.78 were achieved for the thermophilic‐ and mesophilic‐operated digesters, respectively. The presented NIRS calibration can be used to develop an early warning system for process stability, which can be used for reliable optimization of biogas production to increase the methane yield.