What is the most common cause of high ammonia levels in the effluent of a wastewater treatment plant?

High ammonia levels in the effluent of a wastewater treatment plant are primarily linked to poorly functioning nitrifying bacteria. These bacteria play a crucial role in the nitrogen cycle, where they convert ammonia into nitrite and then into nitrate in a process known as nitrification. If these bacteria are not functioning effectively, whether due to toxicity, insufficient oxygen levels, or other environmental factors, the conversion of ammonia is hindered. This leads to an accumulation of ammonia in the treatment system, resulting in higher levels of ammonia in the effluent.

While inadequate aeration, excessive organic loading, and increased temperature can contribute to other issues in the treatment process or affect bacterial activity indirectly, they do not specifically and directly relate to the failure of ammonia conversion as the key factor causing high ammonia levels. The nitrifying bacteria's health and performance are the central elements determining ammonia removal efficiency in wastewater treatment.