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Emerging Implications of Balancing Disinfection and Primary Treatment as an Element in CSO Control: Model Requirements. A presentation.
Citation:
Rowney, A. C., R. I. FIELD, AND T. OCONNOR. Emerging Implications of Balancing Disinfection and Primary Treatment as an Element in CSO Control: Model Requirements. A presentation. Presented at EWRI 2008 World Environmental and Water Resources Congress, Honolulu, HI, May 12 - 16, 2008.
Impact/Purpose:
EPA's national CSO policy requires primary treatment plus disinfection, depending on state and policy context. These technologies and the design considerations involved in their implementation are among the best known of available treatment options, a fact that can be gleaned from a quick review of any basic textbook on wastewater treatment. Nevertheless, the linkages between them have not been fully addressed in US practice in that they are clearly interdependent physically but are not positioned in current policy and regulation to account for that fact. Thie interdependence is potentially significant, because the interactions between the two are a net determinant of treatment efficiency and ultimately cost. Increasing pressures to deliver improved receiving water quality at a time when implementation and operational funds are not inexhaustible and must increasingly compete with other national interests makes a deeper understanding of performance and cost containment related to these factors advisable. Given the tonnages of disinfectants used annually nationwide, and the focus on aging infrastructure that currently prevails, beneficial results of improved practice in these root areas of wastewater tratment could be considerable in terms of economic impact and receiving water protection.
Description:
This paper describes early results and directions arising from ongoing research into factors that affect the preferred balance between primary treatment and disinfection in a conventional wastewater treatment plant during periods of wet weather overflow. Despite the fact that national policy and regional regulations have required or implied use of these elements of treatment for decades, there remain some basic issues that are unresolved. In the context of a wet weather overflow event, the selection of an optimum point and manner for disinfection as it relates to the degree solids removal is one such issue. The factors that affect the choice of this point, particularly as reflected by the current state of microbiological understanding of quantification methods and of the influences of water chemistry on disinfectant behavior and indicator bacteria partitioning between solid and liquid phase components of the flow stream, are examined. Potential avenues for improved treatment practices are noted, and research directions are discussed.