Abstract: The invention includes a method for the optimization of the soluble CO2 concentration in the aeration basin of an activated sludge system, which significantly improves the specific growth rate of the nitrifying bacteria. The result is a reduction in capital and energy costs for municipalities. The rate of nitrification is a product of the nitrifying bacteria biomass concentration and the specific growth rate of the bacteria. In the activated sludge system, the biomass concentration is maintained at high concentrations by reducing the wasting rate. The specific growth rate is a function of the ammonium concentration and the environmental conditions. Here, the inventors show that growth of nitrifying bacteria is inhibited when the soluble CO2 concentration is elevated beyond certain parameters. Elevated soluble CO2 concentration also reduces the pH, which also impacts the rate of growth of nitrifying bacteria.

Abstract: The invention includes a method for the optimization of the soluble CO2 concentration in the aeration basin of an activated sludge system, which significantly improves the specific growth rate of the nitrifying bacteria. The result is a reduction in capital and energy costs for municipalities. The rate of nitrification is a product of the nitrifying bacteria biomass concentration and the specific growth rate of the bacteria. In the activated sludge system, the biomass concentration is maintained at high concentrations by reducing the wasting rate. The specific growth rate is a function of the ammonium concentration and the environmental conditions. Here, the inventors show that growth of nitrifying bacteria is inhibited when the soluble CO2 concentration is elevated beyond certain parameters. Elevated soluble CO2 concentration also reduces the pH, which also impacts the rate of growth of nitrifying bacteria.

Abstract: A method of stimulating nitrification at low SRT by elevating pCO2 during aeration is disclosed. The improvement on solids settling performance when elevated pCO2 was supplied after 2 hours within the React cycle is consistent with the previous results that identified inorganic carbon as a potential remedy to poor settling and bulking sludge problems in activated sludge systems. Elevated pCO2 increases the concentration of carbon dioxide and lowers the pH, which improve nitrification. The specific growth rate of nitrifying bacteria is sensitive to pCO2, pH, and dissolved oxygen (DO). The DO is a function of the aeration rate. Elevating the pCO2 and lowering the aeration rate provides conditions for nitrification rates that are comparable to conventional systems. However, the lower aeration rate yields significant energy cost savings.