Investigation of increasing organic loading rate in the co-digestion of energy crops and cow manure mix

The increase of organic loading rate from 4.45 to 7.78 g-VS/l-d in a one stage, pilot biogas plant was investigated. The experimental was conducted using a co-digestion of cow manure and crop silage mix. The test was dived in three subsequent phases with different feeding ratios. The benefits of optimizing the proportion of crops and loading rate in co-digestion were shown by the fact that during feeding with 79% VS of crop in the feedstock, up to 109% higher specific methane yield was obtained than during the start up phase. It was also found that further increasing the proportion of crop silage up (to 80%) led to a process breakdown with a decrease of methane proportion down to 48%...... The result of this study show, that most agricultural biogas plant have a great potential for a significant capacity increase and technology improvement