Disinfection Strategies to Keep Pace with Reuse Trends

Sunday, October 19, 8:30 am – 4:30 pm
1 day, 0.6 CEUs

Wastewater disinfection is becoming increasingly complicated as a result of the growing number of end uses that many treatment facilities must now accommodate.  The one-size-fits-all disinfection strategy no longer applies, and economics may not be the key factor in selecting the reuse and disinfection technologies.  In addition protecting the public from the risk of acute pathogen infection, removal of microconstituents and avoiding adverse impacts on the aquatic environment of the receiving water bodies, some municipalities must now develop strategies that minimize disinfection byproduct formation while also complying with other reuse and recharge standards.  As we move into a new era of wastewater treatment requirements, reuse and disinfection strategies must respond to a variety of site-specific issues in a cost-effective manner. 

Design of disinfection systems for reuse and recharge applications has become challenging. Owners and operators of facilities with more than one discharge point need to consider how to cost-effectively implement multiple disinfection strategies while meeting the varied needs of multiple end users.  In addition, there is the need to avoid aquatic toxicity, which can be in the form of chlorine or, if chloramination is used, chlorine or ammonia.  Effluent for irrigation and reuse is usually subject to low bacteria limits. In combination with high-quality effluent, a chlorine residual is desirable for pipe maintenance and prevention of bacteria re-growth. 

Historically, chlorine has been the most common means of disinfection. It has come under scrutiny as a result of concerns over the hazards associated with transporting it from the chemical manufacturer to the point of use: chlorine gas can be toxic, hypochlorite solution is corrosive, chlorine residual in treatment plant effluent can harmful to aquatic life and adding chlorine to wastewater can result in formation of undesirable disinfection byproducts (DBPs).  Alternative disinfectants such as ultraviolet (UV) light, ozone, chlorine dioxide,  chloramines, peracetic acid, and hydrogen peroxide alone or in combination are often considered in reuse and recharge applications to eliminate the need to deal with chlorine residual and/or DBP issues.

This workshop will address the regulatory issues related to the removal of emerging microconstituents and their impact on disinfection processes. Attendees will be challenged throughout the workshop to insure the highlights of the materials being presented are understood.  A final workshop exercise, which is taken from an actual case history, will be completed to help the participants understand the challenges of implementing various reuse and disinfection strategies.

Chair
Brad Hemken, Black & Veatch

Co-Chair
Craig Riley, Washington Department of Ecology

Speakers
Gary L. Hunter, Black & Veatch
James Crook, Consultant
Craig Riley, Washington Department of Ecology
Jöeg Drewes, Colorado School of Mines
Andrew Salveson, Carollo Engineers
Gasper Lesznik, Ozonia
Morteza Abbaszagegan, Arizona State University
Jim Coughenour, City of Phoenix, Arizona
Doug Drury, Clark County Water Reclamation District