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Lavallee B.,Direction des politiques de leau | Lessard P.,Laval University | Vanrolleghem P.A.,Laval University
Biotechnology Progress | Year: 2011

An experimental protocol to evaluate the structured biomass model proposed by Lavallée (Lavallée, Lessard, and Vanrolleghem, J Environ Eng Sci 2005;4:517-532) is presented. The protocol was devised to induce transient behavior and characterize the evolution of several internal biomass components. The proposed model is based on biochemical principles, and was fitted to the collected data. In these experiments, it was observed that filling the storage capacity of cells leads to special transient behavior, including a temporarily reduced metabolic activity. The model-based interpretation of the results showed that the observed transient behavior can be explained by cross-regulation of carbon and nitrogen metabolism. Hence, according to an extensive literature review, the cross-regulation of carbon and nitrogen can be used to model some observed transient behaviors and regulation of the storage process in activated sludge. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011 © 2011 American Institute of Chemical Engineers (AIChE).

Zamyadi A.,Ecole Polytechnique de Montreal | Dorner S.,Ecole Polytechnique de Montreal | Sauve S.,University of Montreal | Ellis D.,Direction des politiques de leau | And 3 more authors.
Water Research | Year: 2013

Accumulation and breakthrough of several potentially toxic cyanobacterial species within drinking water treatment plants (DWTP) have been reported recently. The objectives of this project were to test the efficiency of different treatment barriers in cyanobacterial removal. Upon observation of cyanobacterial blooms, intensive sampling was conducted inside a full scale DWTP at raw water, clarification, filtration and oxidation processes. Samples were taken for microscopic speciation/enumeration and microcystins analysis. Total cyanobacteria cell numbers exceeded World Health Organisation and local alert levels in raw water (6,90,000 cells/mL). Extensive accumulation of cyanobacteria species in sludge beds and filters, and interruption of treatment were observed. Aphanizomenon cells were poorly coagulated and they were not trapped efficiently in the sludge. It was also demonstrated that Aphanizomenon cells passed through and were not retained over the filter. However, Microcystis, Anabaena, and Pseudanabaena cells were adequately removed by clarification and filtration processes. The breakthrough of non toxic cyanobacterial cells into DWTPs could also result in severe treatment disruption leading to plant shutdown. Application of intervention threshold values restricted to raw water does not take into consideration the major long term accumulation of potentially toxic cells in the sludge and the risk of toxins release. Thus, a sampling regime inside the plant adapted to cyanobacterial occurrence and intensity is recommended. © 2013 Elsevier Ltd.

Zamyadi A.,Ecole Polytechnique de Montreal | Dorner S.,Ecole Polytechnique de Montreal | Ndong M.,Ecole Polytechnique de Montreal | Ellis D.,Direction des politiques de leau | And 3 more authors.
Environmental Sciences: Processes and Impacts | Year: 2014

The increasing presence of potentially toxic cyanobacterial blooms in drinking water sources and within drinking water treatment plants (DWTPs) has been reported worldwide. The objectives of this study are to validate the application of in vivo probes for the detection and management of cyanobacteria breakthrough inside DWTPs, and to verify the possibility of treatment adjustment based on intensive real-time monitoring. In vivo phycocyanin YSI probes were used to monitor the fate of cyanobacteria in raw water, clarified water, filtered water, and chlorinated water in a full scale DWTP. Simultaneous samples were also taken for microscopic enumeration. The in vivo probe was successfully used to detect the incoming densities of high cyanobacterial cell number into the clarification process and their breakthrough into the filtered water. In vivo probes were used to trace the increase in floating cells over the clarifier, a robust sign of malfunction of the coagulation-sedimentation process. Pre-emptive treatment adjustments, based on in vivo probe monitoring, resulted in successful removal of cyanobacterial cells. The field results on validation of the probes with cyanobacterial bloom samples showed that the probe responses are highly linear and can be used to trigger alerts to take action. This journal is © The Royal Society of Chemistry 2014.

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