Study on Interaction of Influencing Factors on Propionic Acid Content in the Process of Anaerobic Hydrolysis and Acidogenesis

High-concentration anaerobic fermentation of cow manure was investigated using anaerobic batch reactors under laboratory conditions at 20 °C. The quadratic orthogonal rotational combination design was employed. The influencing law of the temperature, the liquid concentration and retention time on prop ionic acid content was explored. The ranges of temperature, liquid concentration and retention time were 25 °C to 35°C, 6% to 10% and 2 to 12 days respectively. The influencing law of interactive effect on prop ionic acid content was analyzed with two-parameter method. The experimental results showed that prop ionic acid content was greatly influenced by temperature, retention time was second to it, and liquid concentration was the least. There was a big interactive effect between liquid concentration and temperature, between liquid concentration and retention time respectively. However, there was a little interactive effect between temperature and retention time.