Effect of different OLR and mixture ratios on biogas production using goat dung and maize silage

Abstract

The aim of this study is to determine the effect of the use of goat excrement, which has not been used much in biogas research, and the use of maize silage on biogas production. The maize silage used does not contain cobs and maize kernels. It was studied under mesophilic conditions in a batch fermentation system with a hydraulic retention time (HRT) of 40 days. In the experiments, anaerobic fermenters with a total volume of 3 L each, with a heating and automatic mixing system were used. The amount of biogas produced was measured using the water displacement principle and the biogas content was measured with a biogas analyzer. Trials were carried out using two different mixing ratios at the same (0.5 grVS/l day) organic loading rate (OLR) and using the same mixing ratio at two different OLR values. The highest biogas production (approximately 40 L) was measured at an OLR value of 0.8 gVS/l d using 65% goat manure and 35% silage in the mixture. Also, the highest methane content was obtained in this application. Although increasing the amount of silage with a constant OLR resulted in a small increase in the biogas generation, the methane content decreased. It was concluded that goat excrement can be used to generate biogas as a substrate.