From: Gerald Fisher
Sent: Fri Jun 17 13:57:28 2016
To: gfisher@cityofmolalla.com
Subject: FW: DEQ response to Molalla PAA trial request.
Importance: Normal
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From: Jennifer Cline [mailto:jcline@cityofmolalla.com]
Sent: Friday, June 17, 2016 10:49 AM
To: Gerald Fisher <geraldf@pdgnw.com>
Subject: FW: DEQ response to Molalla PAA trial request.
Jennifer Cline, P.E. | Public Works Director
Licensed in OR, WA
117 N Molalla Ave. | PO Box 248 * |Molalla, OR 97038
O: 503.759.0218 | F: 503.829.3676
From: COLE David [mailto:david.cole@state.or.us]
Sent: Friday, June 17, 2016 10:42 AM
To: Jason Clifford <jclifford@cityofmolalla.com>
Cc: COLE David <david.cole@state.or.us>; Dan Huff <dhuff@cityofmolalla.com>; Jennifer Cline <jcline@cityofmolalla.com>; HYNSON Mark <mark.hynson@state.or.us>; PINNEY Mike <mike.pinney@state.or.us>; BAILEY Randall <randall.bailey@state.or.us>; YELTON-BRAM Tiffany <tiffany.yelton-bram@state.or.us>
Subject: DEQ response to Molalla PAA trial request.
Hello Jason. Earlier this week DEQ staff and management discussed the issue of Molalla using peracetic acid on a trial basis for treating the plant’s wastewater, instead of the existing chlorination/dechlorination system. At this point in time, DEQ recommends that Molalla wait until the results of several studies are available, before committing any resources into your own study.
The following is some background information to consider.
· Clackamas County’s Tri-Cities facility is currently engaged in a pilot study to test the effectiveness of using PAA as a sole means of providing wastewater disinfection for one of their treatment trains. The facility is testing PAA as an alternative to their current method of disinfection (gaseous chlorine). DEQ expects the facility to complete the study no later than June 2017. Currently, DEQ does not have all the information needed to approve the use of PAA for permanent full-time disinfection of domestic wastewater. DEQ approved a trial pilot study, but not permanent permitted use. One of DEQ’s goals with the pilot study is determining PAA’s effectiveness in destroying viruses.
· Sample results to date have shown that PAA use has led to false positive residual chlorine concentrations. It is not yet clear whether methods for testing will change or whether this problem will be dealt with in another way.
· PAA does a good job killing bacteria. However, in wastewater, bacteria is used as an indicator of overall pathogen content. Pathogens include phages and viruses as well as bacteria. Chlorine and UV disinfection have a long track record of broad spectrum of disinfection ability, from bacteria to viruses and phages. The current available documentation brings into question the ability of PAA to deactivate viruses and phages. The trial period at Tri-City WPCP will include virus deactivation testing.
· In September 2012 EPA published a fact sheet on using PAA as an alternative disinfection method. The fact sheet summarized results of two studies. One important finding of the studies is that PAA dissipates rapidly. Neither study involved testing PAA’s effectiveness at destroying viruses.
· The April 2011 issue of Florida Water Resources Journal, summarized a head-to head comparison of PAA and chlorination/dechlorination treatment technologies at the St. Augustine facility. One finding of this full scale study was that the PAA system was 10 percent less expensive compared to the chlorination/dechlorination system because PAA was more efficient, with 1.5 ppm concentration delivering equivalent microbial performance to 7.0 ppm of chlorine. This study did not evaluate PAA’s effectiveness at destroying viruses.
· Even though the Molalla permit has requirements for bacteria, simply destroying the indicator does not assure DEQ that the wastewater is adequately disinfected, and the public health protected. For this reason, we cannot permit the movement to PAA as a wastewater disinfectant until more study is done.
· Additionally, PAA may not be a strong enough disinfectant to keep a Class A qualification on Molalla’s recycled water for pathogen removal, because PAA disassociates quickly, and this could lead to pathogen re-growth in the pipeline, which could cause bacteria violations.
· DEQ is concerned that significantly higher doses of PAA may be required to assure virus destruction, thereby negating any cost savings over the existing chlorination/dechlorination system.
· Currently, there are only about 10 facilities in the United States that use PAA as their sole disinfection method in domestic wastewater treatment. PAA use is prohibited in some states.
· EPA and the Water Environment Federation Research group are both studying PAA as a wastewater disinfectant. Those studies will start being available later this year.
At this point, DEQ does not recommend that Molalla commit resources to PAA testing for wastewater treatment.
We would be happy to discuss this further if you wish, and share additional information.
David Cole, R.G.
Water Quality Specialist
DEQ - Northwest Region & Western Region
700 NE Multnomah Street, Suite 600
Portland, OR 97232
503-229-5011 (P)
503-229-6957 (F)