Keywords
biofilm, water distribution systems, object oriented bayesian networks
Start Date
1-7-2012 12:00 AM
Abstract
Biofilms develop in drinking water distribution systems (DWDSs) as layers of microorganisms bound by a matrix of organic polymers and attached to pipe walls. Biofilms are ubiquitous in DWDSs, regardless of the type of treatment or disinfection employed. Many problems in these systems are microbial in nature. Biofilm growth within DWDSs could lead to operational problems such as deterioration of bacterial water quality, generation of bad tastes and odors, and proliferation of macroinvertebrates and other undesirable impacts in DWDSs. The presence of substantial and active attached biomass can protect pathogenic microorganism, create anaerobic zones, lead to the formation of high biocorrosion zones, and consume residual disinfectant. Numerous studies have been carried out on the reasons and effects of the biofilms in DWDSs, both in the microbiological and in the engineering fields. Several factors have been found related to biofilm development in DWDSs, but the complexity of the disinfectant microenvironment under study, and the use of different methodologies and biofilm growth systems lead to ambiguous or not easily comparable results. Our aim is to compile the information available nowadays about biofilm ecology since it has been simplified in practical approaches, softening the biofilms' role. To this purpose, an object oriented Bayesian network (OOBN) is proposed. This framework for knowledge representation uses a Bayesian network to describe the probabilistic relations between the attributes of an object. These attributes can themselves be objects, providing a natural way for managing a pipe, a district area, and a whole DWDS in the same encoding features. Thus, we propose a tool that allows us to identify network areas whose characteristics tend to develop more biofilm.
Assessing variation in biofilms development in a drinking water distribution system by an object oriented Bayesian network approach
Biofilms develop in drinking water distribution systems (DWDSs) as layers of microorganisms bound by a matrix of organic polymers and attached to pipe walls. Biofilms are ubiquitous in DWDSs, regardless of the type of treatment or disinfection employed. Many problems in these systems are microbial in nature. Biofilm growth within DWDSs could lead to operational problems such as deterioration of bacterial water quality, generation of bad tastes and odors, and proliferation of macroinvertebrates and other undesirable impacts in DWDSs. The presence of substantial and active attached biomass can protect pathogenic microorganism, create anaerobic zones, lead to the formation of high biocorrosion zones, and consume residual disinfectant. Numerous studies have been carried out on the reasons and effects of the biofilms in DWDSs, both in the microbiological and in the engineering fields. Several factors have been found related to biofilm development in DWDSs, but the complexity of the disinfectant microenvironment under study, and the use of different methodologies and biofilm growth systems lead to ambiguous or not easily comparable results. Our aim is to compile the information available nowadays about biofilm ecology since it has been simplified in practical approaches, softening the biofilms' role. To this purpose, an object oriented Bayesian network (OOBN) is proposed. This framework for knowledge representation uses a Bayesian network to describe the probabilistic relations between the attributes of an object. These attributes can themselves be objects, providing a natural way for managing a pipe, a district area, and a whole DWDS in the same encoding features. Thus, we propose a tool that allows us to identify network areas whose characteristics tend to develop more biofilm.
