Why is lime added to a digester?

Lime is added to a digester primarily to raise the pH of the sludge. The addition of lime increases the alkalinity of the digester environment, which facilitates the process of anaerobic digestion. A higher pH can help create more favorable conditions for the microorganisms involved in the digestion process, enhancing their activity and efficiency.

Moreover, raising the pH through lime addition can also contribute to the precipitation of certain heavy metals and other unwanted substances, aiding in the stabilization of the sludge. This stabilization not only improves the overall treatment process but also affects the final quality of the digestate produced.

In summary, the role of lime in raising the pH is crucial in promoting effective anaerobic digestion and improving the overall performance of the digesters in wastewater treatment systems.