Anaerobic slurry co-digestion of poultry manure and straw: effect of organic loading and temperature

• Published in: Journal of environmental health science and engineering 2013-07, Vol.11 (1), p.15-15, Article 15
• Main Authors: Babaee, Azadeh, Shayegan, Jalal, Roshani, Anis
• Format: Article
• Language: English
• Subjects: Biodegradation; Biogas; Composting; Earth and Environmental Science; Environment; Environmental Economics; Environmental Engineering/Biotechnology; Environmental Health; Environmental Law/Policy/Ecojustice; Fatty acids; Manures; Methane; Methods; Nitrogen; Quality of Life Research; Research Article; Temperature; Waste management; Waste Management/Waste Technology
• ISSN: 2052-336X; 2052-336X
• DOI: 10.1186/2052-336X-11-15

In order to obtain basic design criteria for anaerobic digestion of a mixture of poultry manure and wheat straw, the effects of different temperatures and organic loading rates on the biogas yield and methane contents were evaluated. Since poultry manure is a poor substrate, in term of the availability of the nutrients, external supplementation of carbon has to be regularly performed, in order to achieve a stable and efficient process. The complete-mix, pilot-scale digester with working volume of 70 L was used. The digestion operated at 25°C, 30°C and 35°C with organic loading rates of 1.0, 2.0, 2.5, 3.0, 3.5 and 4.0 kg Volatile solid/m 3 d and a HRT of 15 days. At a temperature of 35°C, the methane yield was increased by 43% compared to 25°C. Anaerobic co-digestion appeared feasible with a loading rate of 3.0 kg VS/m 3 d at 35°C. At this state, the specific methane yield was calculated about 0.12 m 3 /kg VS with a methane content of 53–70.2% in the biogas. The volatile solid (VS) removal was 72%. As a result of volatile fatty acid accumulation and decrease in pH, when the loading rate was less than 1 or greater than 4 kg VS/m 3 d, the process was inhibited or overloaded, respectively. Both the lower and higher loading rates resulted in a decline in the methane yield.