Wastewater Treatment Sodium bicarbonate is an ideal pH and alkalinity control agent for wastewater treatment. It provides a reserve buffering ability in sludge to help prevent upsets in the operating systems of secondary treatment plants that depend on various types of microorganisms to digest organic wastes and control odor. Acids produced in the waste breakdown process, along with other conditions prevalent in treatment plants, tend to lower pH. This alters the biological balance and can result in bulking sludge, digester upset and the "rotten egg" or hydrogen sulfide odor that usually mean trouble and expense for the plant. Unlike harsh alkaline chemicals such as lime, caustic soda and ammonia, sodium bicarbonate is buffered and cannot cause pH overrun. It can be slug-fed or added continuously to digesters at the operator's discretion. In aerobic digestion systems, the optimum feed point is the return sludge line or at the head of the aeration basin. Because of low loading at most wastewater treatment plants during nighttime hours, sodium bicarbonate is added in the late afternoon or early evening for best results. With anaerobic systems, application in the wet well or scum pit on the sludge line leading to the digester is recommended. Sodium bicarbonate should be fed in a manner that promotes maximum distribution throughout the digester.