COMPARATIVES STUDY ON THE EFFECT OF WET AND DRY SUBSTRATES ON BIOGAS YIELD

Abstract

The objective of this study is to compare the use ofwetanddry wastes as substrates for anaerobic digestion and its effect on biogas yield.Different quantities of substrates and co-substrates (wet and dried) were weighed and mixed vigorously with corresponding quantity of distilled water to form the fermentation slurry in the digesters; the digesters were operated at 45°C in batch anaerobic digesters for 25 days. The results showed that the average volume of biogas obtained from the dried animal wastes co-digested with dried fruit wastes and wet animal wastes co-digested with wet fruit wastes was found to be 0.2928 kg and 0.0972 kg per day respectively. When the fermentation process was performed with dried animal wastes only and wet animal wastes only the value of the average volume of biogas obtained were calculated to be 0.1508 and 0.0892 kg per day respectively. Thus biogas yield using dried substrates comparatively gave a better biogas yield than wet substrates. In conclusion, the use of dried wastes for biogas production suggests superior energy recovery, saving resources and engineering investment as compared to the use of wet wastes as substrates.