Respirometric determination of the readily biodegradable COD produced in the anaerobic stage of a biological phosphorus removal process

A respirometric method for determination of the readily biodegradable chemi cal oxygen demand (COD) concentration in a wastewater was developed, and us ed to study the effect of the anaerobic stage of a biological phosphorus (P ) removal process. The sludge used was obtained from a laboratory scale act ivated sludge A/O (anaerobic/aerobic) process for biological P removal, fed with synthetic wastewater composed by glucose and peptone as carbon source s. Respirometric tests were made in an electrolytic respirometer. Wastewate r short-time biochemical oxygen demands were measured after anaerobic react ions using the sludge from the A/O process, and the readily biodegradable C OD concentrations were then calculated. Several tests were made using diffe rent kinds of synthetic wastewater in order to know the accuracy of the exp erimental technique. These wastewaters were prepared using a constant COD l evel but different organic composition in order to change their biodegradab ility. The method was used to study the effect of the anaerobic period dura tion on the readily biodegradable COD concentration produced from a-starch containing wastewater. A higher anaerobic retention time caused an increase in the readily biodegradable COD concentration. This determination can be useful to know the effectiveness of the anaerobic period and thus, the viab ility of the Biological Phosphorus Removal (BPR) process with slowly biodeg radable wastewater.