Biogas potential from damaged bread

Abstract

Latvian bakeries for various reasons result in production of waste and non-standard bread, which cannot be used for food. Damaged bread accumulates and stores mold. The bread utilization is problematic for manufacturers and traders. Environmental solution of this problem can be the usage of damaged bread for biogas production. This article shows the results of investigated biogas potential from five different damaged breads. Sixteen 0.75 liter bioreactors were filled with inoculums or with inoculums mixed together with different bread mass. Anaerobic digestion was provided in a batch mode at temperature 38 °C. The following specific biogas volumes (methane percentage in biogas) were obtained after 30 days anaerobic digestion (AD) process: French bread 0.723 l•-1DOM (50.6 %); Rye flour bread 0.634 l•-1DOM (49.9 %); Wheat flour (coarse) bread 0.731 l•-1DOM (50.9 %); Toaster bread 0.694 l•-1DOM (44.9 %); White bread (with the addition of egg and milk additives) 0.943 l•-1DOM (45.4 %). The results show that damaged bread can be used for biogas production sucessfully.