Insights into Poultry Waste Biogas Plant

Anaerobic digestion of poultry litter is a sustainable way to manage poultry industry waste. Poultry litter is one of the best raw materials for the production of biogas. Infact, the biogas potential of poultry manure is better than that of cow manure and sewage sludge. Let us have a deeper understanding of the generation of biogas from poultry waste:

Working of a Poultry Waste Biogas Plant

Poultry waste has high biogas potential but it can be challenging to digest it alone due to high nitrogen content resulting in ammonia inhibition. Co-digestion of poultry litter with carbon-rich substrates can optimize the carbon-to-nitrogen (C/N) ratio, improve microbial activity, and increase biogas yield. The popular feedstock for co-digestion of poultry litter include crop residues, food wastes, energy crops and sewage sludge.

Fresh poultry waste and co-digestion substrate are weighed and stored in a collection tank before its passage to the homogenization tank where the waste stream is diluted with fresh/recycled water and mechanically mixed to obtain a uniformly mixed waste stream. The slurry is passed through a macerator to obtain uniform particle size of 5-10 mm and pumped into the primary anaerobic digester where stabilization of the waste takes place. The effluent from the primary digester is fed to the secondary anaerobic digester so as to ensure complete degradation of the waste stream.

Biogas from both the digesters are collected and sent to the biogas purification unit. Apart from water vapours, biogas contain significant amount of hydrogen sulfide (H₂S) gas which needs to be removed due to its highly corrosive nature. The removal of H₂S takes place in a desulphurization unit.

Gas is dried and vented into a CHP unit to produce electricity and heat. The size and nature of the CHP system depends on the amount of biogas produced daily. The digested substrate is passed through screw press for dewatering and then subjected to solar drying and conditioning to give high-quality organic fertilizer.

The press water is treated in an effluent treatment plant based on activated sludge process which consists of an aeration tank and a secondary clarifier. The treated wastewater is recycled to meet in-house plant requirements.

A chemical laboratory is necessary to continuously monitor important environmental parameters such as BOD, COD, VFA, pH, ammonia, C:N ratio at different locations for efficient and proper functioning of the process.

The continuous monitoring of the poultry waste biogas plant is achieved by using a remote monitoring system, such as Supervisory Control and Data Acquisition (SCADA) system. This remote system facilitates immediate feedback and real-time adjustment, which can result in energy savings.

Conclusion

Anaerobic digestion of poultry waste requires optimum C/N balance, ammonia control, and system optimization. Co-digestion of poultry waste, with carbon-rich substrates such as food waste and sewage sludge, improves efficiency, making it viable for slaughterhouses and poultry farms.

Also Read: Biogas Digester – Working Principle and Benefits