How are anaerobic digesters typically fed?

Anaerobic digesters are typically fed based on the mass of volatile solids. This operational approach is important because it ensures that the feedstock provides the necessary organic material needed for the anaerobic microbial community to thrive and effectively degrade the organic matter within the digester. The mass of volatile solids is crucial because these solids are the organic fraction that can be broken down by anaerobic bacteria to produce biogas, which is the primary purpose of the digestion process.

Feeding by volume of water or a fixed flow rate does not adequately account for the organic content, which can vary widely between different wastewater sources. Additionally, simply counting the number of bacteria does not provide a reliable or relevant metric for feeding the digester since the bacteria will adjust to the organic load and not be a direct indicator of the volatile solids available. Therefore, focusing on the mass of volatile solids ensures an optimal balance of feed material, allowing for efficient digestion and biogas production.