AN ADAPTIVE ALGORITHM FOR EXTERNAL CARBON ADDITION TO AN ALTERNATING ACTIVATED-SLUDGE PROCESS FOR NUTRIENT REMOVAL FROM WASTE-WATER

The paper deals with a means to improve nitrogen removal in an alterna ting activated sludge waste water treatment process by automatic contr ol. A control strategy is formulated involving the on demand increase in denitrification rate by the addition of a readily metabolizable car bon source to the point in the process where denitrification occurs. A n algorithm is presented which automatically adjusts the carbon additi on rate to match current process conditions. Two models are employed: a prediction model based on mass balances to determine the needed deni trification rate; and an experimentally determined, empirical relation al model describing the denitrification rate as a function of carbon a ddition rate. An adaptive technique is employed to continually update estimates for the slowly changing parameters of the relational model. The algorithm is illustrated with a simulated example and two pilot pl ant demonstrations.