Anaerobic digestion of chicken manure as a single substrate by control of ammonia concentration

Anaerobic digestion of high solids chicken manure as a single substrate was conducted at laboratory scale with a reaction volume of 10 l. The organic loading rate was increased gradually from 2.2 to 3.9 gVS l -1 d -1 . To reduce the amount of inhibiting ammonia in the process technical stripping of ammonia was applied, yielding ammonia-phosphate or ammonia-sulfate as valuable side-products. A high specific biogas yield of 623 mlN g -1 VS -1 was produced, despite the high level of free ammonia and of total ammonia nitrogen of up to 1 g/l and above 5 g/l, respectively. The presented results show the technical possibility to use chicken manure as a single substrate for an anaerobic process and demonstrate how to overcome the limitations of the use of substrates with high nitrogen content.