A Laboratory-Scale Study on the Production of High-Value Products from Broiler Litter Involving Solid-State Anaerobic Digestion and Mushroom Cultivation

Abstract

There is a need to investigate alternate uses and treatments of broiler litter that lessen environmental impacts and decrease costs associated with its disposal. Anaerobic digestion is a biological process in which organic material is converted to a renewable fuel source. However, the substrate for anaerobic digestion often requires some form or pretreatment. Certain types of fungus have been investigated as a pretreatment for anaerobic digestion, one of which is Pleurotis ostreatus or the oyster mushroom, which also produces an edible fruiting body. Thus, this study was performed to investigate the use of broiler litter for oyster mushroom cultivation and anaerobic digestion in terms of effects their effects on broiler litter characteristics, effects of mushroom cultivation on anaerobic digestion, and the yields associated with the two treatments. It was found that the addition of 75% wheat straw was required to culture edible oyster mushrooms using broiler litter and that mushroom yields were larger than those for 100% wheat straw. Mushroom cultivation had either negative to no impacts on subsequent methane yields from anaerobic digestion. However, it was also found that lignin and soluble phosphorus contents could be reduced by mushroom cultivation while soluble nitrogen and extractives contents were increased. It was also found that nitrate concentrations were increased by mushroom cultivation, which could explain the decrease in yields from subsequent anaerobic digestion. Although methane yields were not increased by fungal pretreatment, it was concluded that the cultivation of oyster mushrooms on broiler litter could have significant impacts by adding more value to the waste material through the production of edible mushrooms and the improvement of fertilizer value. It was also concluded that there is a need for further research to explain the decrease in methane production following the fungal pretreatment, and to possibly find an additional pretreatment to account for this. Several questions were answered as to the general concept of utilizing broiler litter for both oyster mushroom cultivation and anaerobic digestion, but many other question must be answered before the findings discussed can be used to make recommendations to those involved in the poultry and mushroom industries