DEVELOPMENT OF A RESPIROMETRIC ASSAY TO MEASURE THE TRANSIENT LOAD RESPONSE OF ACTIVATED-SLUDGE TO INDIVIDUAL ORGANIC-CHEMICALS

This study described a new respirometric technique to monitor the tran sient response of activated sludge systems to individual synthetic org anic compounds (SOCs). The assay used a fed-batch reactor system which contained mixed liquor from the parent reactor and received a biogeni c feed and the target SOC at the same F/M ratio as was applied to the parent reactor. The fed-batch reactor was oxygenated using a hollow-fi ber reaeration module to meet the steady-state oxygen demand. The reae ration module was characterized by means of K(L)a studies. The assay m onitored the dissolved oxygen concentration profile after application of a shock load achieved by switching to a fed-batch feed with the tar get SOC at an elevated concentration. Mathematical descriptions of the transient profiles were derived and the experimentally observed disso lved oxygen profiles were subsequently compared to profiles predicted using extant kinetic parameters for SOC removal measured using an earl ier developed assay. ?he use of the assay were complicated by the diff iculty in maintaining a reaeration capacity at constant and low capaci ty. As a result, the adequacy of the measured extant kinetic parameter s as predictors of the transient response could not be confirmed. Copy right (C) 1996 IAWQ.