Patent ID: 8308947

Claim:
A method for providing an aerobic medium in a bioreactor compartment comprising: a) measuring the NH 4 + concentration, dissolved oxygen concentration, medium flow rate, and mixed liquor suspended solids of the medium in the compartment and the airflow into the compartment; b) selecting reference values for the NH 4 + concentration, dissolved oxygen concentration, medium flow rate and mixed liquor suspended solids of the medium in the compartment and the airflow into the compartment; c) selecting a reference time period; d) comparing the reference values for the NH 4 + concentration, medium flow rate, and mixed liquor suspended solids for the medium in the compartment to the measured NH 4 + concentration, medium flow rate, and mixed liquor suspended solids for the medium in the compartment; e) comparing the reference value for the dissolved oxygen concentration and the airflow into the compartment to the measured dissolved oxygen concentration and airflow into the compartment if the measured NH 4 + concentration, medium flow rate, and mixed liquor suspended solids for the medium in the compartment are not equal to the reference value for the NH 4 + concentration, medium flow rate, and mixed liquor suspended solids for the medium in the compartment; f) determining the airflow set point value for the compartment, if the reference values for the dissolved oxygen concentration and the airflow into the compartment and the measured dissolved oxygen concentration and airflow into the compartment are equal, according to the formula: Airflow sp , i = Airflow M ⁢ ⁢ 1 + Airflow M ⁢ ⁢ 2 2 where Airflow M ⁢ ⁢ 1 = ( Airflow cur , i · ( β · C s - D ⁢ ⁢ O cur , i ) ) 2 ( β · C s - D ⁢ ⁢ O sp , i ) · Airflow prev , i · ( β · C s - D ⁢ ⁢ O prev , i ) and Airflow M ⁢ ⁢ 2 = Airflow cur , i · ( β · C s - D ⁢ ⁢ O cur , i ) ( β · C s - D ⁢ ⁢ O sp , i ) · D ⁢ ⁢ O sp , i · ( K DO + D ⁢ ⁢ O cur , i ) D ⁢ ⁢ O cur , i · ( K DO + D ⁢ ⁢ O sp , i ) when the reference value for the dissolved oxygen concentration in the compartment is unchanged during the reference time period; and g) adjusting the airflow into the compartment to be equal to the airflow set point value; whereby an aerobic medium is provided in the bioreactor compartment.