No abstract

Neural networks (NNs) were used to predict the onset of filamentous bulking, as described by trends in stirred sludge volume index, in a pulp and paper activated sludge treatment system. Variables related to activated sludge biomass viability, namely specific oxygen uptake rate (SOUR) and adenosine triphosphate (ATP), were used as inputs to the NN. ATP data were shown to improve NN performance in providing an early warning signal for bulking, both in terms of accuracy and prediction delay. A warning signal system was developed to provide operators with enough time to react and further investigate the causes of bulking."Des réseaux de neurones (RN) ontété utilisés pour prédire le début de problèmes de foisonnement filamenteux, tel que décrit par des tendances dans l'indice de volume des boues agitées, dans un système de traitement par boues activées d'une usine de pâtes et papiers. Des variables liéesà la viabilité de la biomasse des boues activées, c'est-à-dire le taux spécifique d'utilisation de l'oxygène (TSUO) et l'adénosine triphosphate (ATP), ont eté utilisées comme entrées au RN. Il aété démontré que les données d'ATP amélioraient la performance du RN en fournissant un signal d'alerte pour le foisonnement,à la fois en termes d'exactitude que du délai de prédiction. Un système fournissant un signal d'alerte aété développé pour donner suffisamment de temps aux opérateurs pour réagir et s'enquérir plus en détail les causes du foisonnement."

No abstract

A research project was undertaken at an integrated thermomechanical pulp and paper mill in Canada to evaluate the use of adenosine triphosphate (ATP) monitoring methods in order to identify the potential for operational problems related to microbiological aspects of activated sludge. The specific filamentous bulking ATP (fbATP) ratio is an emerging measurement technique that measures the proportion of flocs that have bulking potential by filtering a sample through a 250 microm mesh and measuring the ATP in the retentate. For the host mill in this study, the specific fbATP measurement provides early warning signs of bulking, at 1.0 to 1.5 times the sludge age, before poor settling occurs. A possible bulking scenario was identified in which the initiator was the overflow of an upstream tank containing high BOD whitewater, resulting in spikes of organic acids to the treatment and promoting the proliferation of certain types of filamentous bacteria. A storage response by filamentous bacteria to these high readily biodegradable substrate conditions was monitored with fbATP. By predicting the onset of bulking conditions, this technique can potentially assist operators to make corrective actions proactively.