A pH drop in an aerobic digester can be caused by _________

A pH drop in an aerobic digester is primarily influenced by the balance of carbon dioxide (CO2) and bicarbonate buffering in the system. When nitrification occurs, it involves the conversion of ammonia into nitrates, which can produce acids as byproducts. This acid production leads to an increase in hydrogen ions (H+) in the solution, causing the pH to decrease.

Additionally, CO2 buildup can occur when there is insufficient removal of CO2 from the system, contributing to acidity. As CO2 dissolves in water, it forms carbonic acid, which further lowers the pH. The combination of these two processes—nitrification and carbon dioxide accumulation—can significantly contribute to a lowering of pH levels in an aerobic digester.

In contrast, organic underloading may not immediately cause a pH drop, as it can reduce the metabolic activity and the related acid production since there is less substrate available for microbial growth. Hydraulic overloading can dilute the active biomass and affect the process efficiency but isn't directly responsible for a drop in pH. Clogging of diffusers can hinder oxygen transfer, impacting microbial respiration but does not directly lower pH as nitrification and CO2 buildup would. Thus, the dynamics of nitrification