Piping for Alkalinity Addition
Ideally, facilities should provide piping for adding alkalinity at both the influentequalization basin and the SBR basin. It is also desirable to be able to measure alkalinity at each location. Alkalinity addition should be based on the amount measured during the decant phase, not on incoming flow. Alkalinity should be kept in a range of 40-70 mg/L as CaCO3 prior to the decant phase to be sure the nitrification cycle is complete. Consider implementing a method of alkalinity addition even if a facility is not designed to nitrify.
When nitrification occurs at SBR facilities, it often occurs during periods of diurnal low flow (e.g., very late evening or very early morning) when a plant is not staffed. If no testing or chemical addition is available to compensate for an alkalinity drop, pH in the SBR unit will drop and cause process upsets.