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Disinfection Byproducts Abstract

Director of Security and Regulatory Affairs, AWWA
 

This presentation will summarize the past Safe Drinking Water Act (SDWA) regulations, going back to the first set of national standards in 1976. This presentation will detail the history of disinfection by-product (DBP) regulations and summarize the treatment technology compliance predictions made by the Environmental Protection Agency (EPA) in those regulations. This presentation will look at the trends in DBP violations from 2000-2008 and will discuss what those violations might mean under EPA’s new enforcement policy. Simultaneous compliance with all of the regulations will be discussed, with the Milwaukee and the District of Columbia used as examples. The Water Research Foundation’s simultaneous compliance tool will be shown as a tool that increases one’s understanding of the potential impacts from typical treatment changes. This presentation will conclude with a discussion of how DBP regulations and other regulations might be revised in the future and how potential chemical security regulations will likely be a consideration.

 

George Budd, PhD
Senior Process Engineer, Black & Veatch

Disinfectant/Disinfection Byproduct (D/DBP) regulations have undergone significant change in the last ten years. Regulations for chlorinated byproducts have been broadened to include haloacetic acids, enhanced coagulation has been specified as a required treatment technique that is applicable for many water plants, new byproducts have been regulated for ozone and chlorine dioxide, and limits have been placed on disinfectant residuals.

New regulations under the soon to be enforced Stage 2 D/DBP will require further measures for compliance by many utilities. A key aspect of these regulations is the requirement that utilities comply with MCLs for THMs and HAA5 on a locational running annual average basis. Compliance monitoring for this rule will begin in 2012 for utilities serving more than 50,000 people, and compliance for the first four quarters of sampling will begin to be determined in 2013. There are indications that the effects of these changes embodied by these regulations will be widespread.
 
Optimizing a system for control of DBPs involves several critical questions that frame the planning approach:

1.  What is the nature of DBP precursors and how do fluctuations in characteristics affect planning?
2.  How will new sampling requirements under the Stage 2 regulations affect compliance in the  
      system?
3.  What are other critical treatment attributes and goals within a plant and how will they be
       affected by changes or process additions to improve DBP compliance?
4.  Can DBP formation be reduced by operational or minor changes within the system?
5.  Can changes be made to oxidant and disinfectant use within the plant?
6.  Are advanced water treatment processes needed?
7.  How can strategies be best integrated and combined to meet new DBP goals while also
       addressing other aspects of plant operation?
8.  How will potential future DBP regulations affect near term strategies?

The presentation describe an overall approach to controlling DBPs within a system that is based on addressing each of these questions.