Hydrolysis rate constants at 10-25 degrees C can be more than doubled by a short anaerobic pre-hydrolysis at 35 degrees C

摘要

Hydrolysis is the first step of the anaerobic digestion of complex wastewater and considered as the rate limiting step especially at low temperature. Low temperature (10-25 degrees C) hydrolysis was investigated with and without application of a short pre-hydrolysis at 35 degrees C. Batch experiments were executed using cellulose and tributyrin as model substrates for carbohydrates and lipids. The results showed that the low temperature anaerobic hydrolysis rate constants increased by a factor of 1.5-10, when the short anaerobic pre-hydrolysis at 35 degrees C was applied. After the pre-hydrolysis phase at 35 degrees C and decreasing the temperature, no lag phase was observed in any case. Without the pre-hydrolysis, the lag phase for cellulose hydrolysis at 35-10 degrees C was 4-30 days. Tributyrin hydrolysis showed no lag phase at any temperature. The hydrolysis efficiency of cellulose increased from 40 to 62%, and from 9.6 to 40% after 9.1 days at 15 and 10 degrees C, respectively, when the pre-hydrolysis at 35 degrees C was applied. The hydrolysis efficiency of tributyrin at low temperatures with the pre-hydrolysis at 35 degrees C was similar to those without the pre-hydrolysis. The hydrolytic activity of the supernatant collected from the digestate after batch digestion of cellulose and tributyrin at 35 degrees C was higher than that of the supernatants collected from the low temperature (<= 25 degrees C) digestates. (C) 2016 Elsevier Ltd. All rights reserved.