Polylactic Acid (PLA) is a biodegradable, bio-based polymer made from fermented plant sugars. The use of PLA as a feedstock for anaerobic digestion to produce biogas has gained attention as a way to reduce waste and produce renewable energy.

Anaerobic digestion is a biological process that occurs in the absence of oxygen, where microorganisms break down organic matter to produce biogas. The biogas produced through this process consists of methane (CH4) and carbon dioxide (CO2) and can be used as a renewable energy source.

Benefits of using PLA in anaerobic digestion include:

1- Sustainability: PLA is made from renewable resources, and its use in anaerobic digestion helps reduce waste and conserve resources.
2- Reduction of greenhouse gas emissions: Methane produced from anaerobic digestion is a potent greenhouse gas, and the use of PLA helps reduce these emissions by replacing non-renewable energy sources.
3- Energy production: The biogas produced from anaerobic digestion can be used to generate electricity and heat, providing a renewable energy source.
4- Increased yield: The addition of PLA to anaerobic digestion systems can increase the overall yield of biogas, as it is a readily biodegradable material.

However, there are also some negatives associated with the use of PLA in anaerobic digestion:
1- Processing issues: PLA can be difficult to process, as it has a low solubility in water and is resistant to degradation.
2- Cost: The cost of producing PLA can be higher than other feedstocks, and the added processing costs can also make the overall process more expensive.
3- Contamination: The addition of PLA to anaerobic digestion systems can cause contamination if not properly managed, affecting the overall yield and quality of the biogas produced.

The yield of biogas produced per kilogram of PLA can vary based on the type of anaerobic digestion system used, the conditions in the digester, and the quality of the PLA. However, studies have shown that the addition of PLA to anaerobic digestion systems can increase the overall yield of biogas by 10-15%.

When adding PLA to anaerobic digestion systems, it is important to consider the following factors:
– Compatibility: The type of anaerobic digestion system used should be compatible with the characteristics of PLA, such as its low solubility and resistance to degradation.
– Feedstock preparation: The PLA should be properly prepared before being added to the anaerobic digestion system, as contamination can affect the overall yield and quality of the biogas produced.
– Monitoring and control: The conditions in the anaerobic digestion system should be carefully monitored and controlled to ensure that the best conditions are maintained for biogas production.

In conclusion, the use of PLA in anaerobic digestion to produce biogas can provide several benefits, including increased sustainability and reduced greenhouse gas emissions. However, it is important to consider the negatives and properly manage the addition of PLA to ensure the best results. The yield of biogas produced per kilogram of PLA can vary, but the addition of PLA can increase the overall yield of biogas.