Patent ID: 7431840

Claim:
An aqueous denitrification process for a wastewater treatment system having influent and effluent aqueous flows, a filtration bed harboring microbes, and feed forward and feed back control loops, the process comprising: determining influent flow Q, influent dissolved oxygen concentration DO in , influent nitrate concentration NO 3 -N in , and influent nitrite concentration NO 2 -N in ; utilizing a feed forward control loop relationship (1) to determine a feed chemical requirement, FCR, FCR=Q [( X*DO in )+( Y*NO 3 - N in )+( Z*NO 2 - N in )] (1) in which X, Y, and Z are predetermined unitless factors ranging from about 0.7 to about 3.0; determining effluent nitrate concentration NO 3 -N eff , and effluent nitrite concentration NO 2 -N eff ; and utilizing feed back control loop relationships (2), (3) and (4) to determine an adjusted feed chemical requirement, AFCR, utilizing relationship (5), AP = GAIN * ERR ( 2 ) AI ( new ) = AI ( old ) + GAIN * dl TI * ERR ( new ) + ERR ( old ) 2 ( 3 ) A = AP + AI ( 4 ) AFCR = FCR * ( 1 + A ) ( 5 ) in which GAIN is a predetermined unitless action coefficient, ERR is a difference between measured NO x -N eff and set point NO x -N eff , in which the measured NO x -N eff is a sum of NO 3 -N eff ), dl is a sum of microprocessor processing time and a time interval TI between measurements, and references to new and old refer to a current measurement and a prior measurement.