Near-infrared spectroscopy-based quantification of substrate and aqueous products in wastewater anaerobic fermentation processes

In this study, a Fourier transform near-infrared (FT-NIR) technique was used for process monitoring of anaerobic fermentation. Orthogonal signal correction (OSC) method was used as NIR spectral preprocessing options. Calibration models were established and the validation of the method was performed with the sucrose, ethanol and volatile fatty acids (VFAs) contents determined by the anthrone and gas chromatography methods, respectively. Spectral range and the number of internal latent variables were optimized for the best correlation coefficient. Test set validation of sucrose resulted in excellent measurement of prediction performance and the correlation coefficient of determination is 0.930. Similar prediction statistics for individual VFA and total VFA contents were obtained. These results proved that the NIR spectroscopy technology is able to quantify the contents of both volatile fatty acids and sucrose in wastewater anaerobic fermentation process.