The examination of poultry feather digestility for biogas production

Abstract

To determine the optimal ratio of feather to water, the properties affecting mixing and the digestibility of feather were considered. All treatments with 1:1 feather: water ratio were unsuitable for mechanical mixing, although treatments with 1:2 and 1:3 feather: water ratio proved satisfactory regarding agitation. Large-scale applicability of treatments was decided upon the extent of digestion based on the measured extinction values. The determination of optimal bacillus: feather ratio aimed at defining the minimal amount of inoculating bacterium which allows effective digestion of keratin and cost-effectiveness. It could be stated that the proliferation of the bacteria results in the decrease of pH. The most significant pH decrease was observed at 5% bacillus: feather ratio. The amount of necessary phosphate-buffer also increased, which is an unfavorable change concerning cost-effectiveness. The degree of feather digestion showed no significant differences in the treatments of 1 and 3% bacillus: feather ratio, so we recommend the application of 1% bacillus: feather ratio under industrial-scale circumstances with respect to materialand cost-saving concerns. Based on the experimental results it can be concluded that the treatment of 1% bacillus: feather ratio and 1:3 feather: water ratio is optimal for industrial-scale application with regard to material- and cost-saving, as well as biodegradability concerns.