Falk Harry Michael, Reichling Peter, Andersen Christian, Benz Roland
School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759, Bremen, Germany.
Bioprocess Biosyst Eng. 2015 Feb;38(2):237-49. doi: 10.1007/s00449-014-1263-9. Epub 2014 Aug 21.
An ATR-MIR-FTIR spectrometer was integrated into a laboratory scale anaerobic digestion setup. Automatically, a sludge sample from the digester was transferred to a measurement cell; an IR spectrum was recorded and evaluated by chemometric models to estimate the concentration of the individual volatile fatty acids (VFA). The calibration set included semi-artificial samples spiked with known concentrations of the VFA as well as original samples from a continuous fermentation. High-performance liquid chromatography (HPLC) was used as a reference analysis of the samples. The models were optimized for a low root mean square error of prediction (RMSEP). R(2) for acetic acid, propionic acid, isobutyric acid, butyric acid, valeric acid, and isovaleric acid were 0.94, 0.88, 0.83, 0.75, 0.59, and 0.90, respectively. The accuracy of the models was validated in a second experiment. Considering the complex and heterogeneous sludge composition and the chemical similarity of VFA, absolute concentration and dynamic (increasing and decreasing concentration of VFA) was predicted well for acetic, propionic, isobutyric, and isovaleric acid (in their respective concentration range); Butyric acid could not be detected. The installed setup was able to gather and measure native samples from the digester (every 2 h) automatically over a period of 6 months without problems of clogging or biofouling. The instant and continuous analysis of the concentration of the VFA made it possible to evaluate the current bioprocess status and adjust the organic loading rate accordingly.
一台衰减全反射-中红外傅里叶变换红外光谱仪被集成到实验室规模的厌氧消化装置中。来自消化器的污泥样品会自动转移到测量池中；记录红外光谱并通过化学计量学模型进行评估，以估算各个挥发性脂肪酸（VFA）的浓度。校准集包括添加了已知浓度VFA的半人工样品以及来自连续发酵的原始样品。高效液相色谱法（HPLC）用作样品的参考分析。对模型进行了优化，以实现较低的预测均方根误差（RMSEP）。乙酸、丙酸、异丁酸、丁酸、戊酸和异戊酸的R(2)分别为0.94、0.88、0.83、0.75、0.59和0.90。在第二个实验中对模型的准确性进行了验证。考虑到污泥成分复杂且不均匀以及VFA的化学相似性，对于乙酸、丙酸、异丁酸和异戊酸（在其各自的浓度范围内），绝对浓度和动态变化（VFA浓度的增加和减少）预测良好；未检测到丁酸。所安装的装置能够在6个月的时间内每2小时自动采集和测量来自消化器的天然样品，而不会出现堵塞或生物污染问题。对VFA浓度的即时和连续分析使得评估当前生物过程状态并相应调整有机负荷率成为可能。
