Process using DO and ORP signals for biological nitrification and denitrification: validation of a food-processing industry wastewater treatment plant on boosting with pure oxygen

The simultaneous removal of carbonaceous and nitrogenous pollution by the a ctivated sludge process is becoming common in industrial and municipal wast ewater treatment plants. An oxygenation monitoring process has been develop ed, which is based on the dynamic analysis of ORP and DO signals and allows the detection of specific characteristic points at the end of the biologic al nitrification and denitrification. The aim of this study is to validate this process in a food-processing indu stry WWTP (slaughterhouse) to having large variations of carbonaceous and n itrogenous loads. In order to treat during the peak period, pure oxygen is used. The first part of the study provides a precise diagnosis of the WWTP operation by the analysis of the ORP and DO signals. It is particularly eas y to estimate the level of nitrogen treatment actually achieved and the oxy gen requirements, and to detect the over- or under-oxygenated phases. Thanks to the monitoring process, the aerobic period of each cycle is reduc ed to the optimal duration, cn providing a reduction of 30% on the energy c onsumption compared to a traditional schedule. We have co demonstrated that the use of pure oxygen associated with the existing air system is particul arly relevant for the peak period. The revamping of an existing plant to si multaneously treat the carbon and the ammonia in the same basin is now tech nically feasible.