Daily Archives: March 19, 2013

USEPA to delay drinking water decisions until science questions resolved

Peter Grevatt, director of EPA’s Office of Ground Water & Drinking Water, has indicated that USEPA is delaying key drinking water decisions until officials can resolve scientific questions. This includes its pending health goal for perchlorate and a determination whether to regulate hexavalent chromium (Cr6).

The proposed maximum contaminant level goal (MCLG) for perchlorate will be delayed until the final recommendations of its Science Advisory Board (SAB) can be evaluated. The SAB is scheduled to review their latest draft of its perchlorate panel’s report on March 29. Grevatt says that the agency’s number one priority on perchlorate is to get the science right, but time will tell whether this is a smoke screen or a sincere intention.

USEPA is still developing the science on Cr6, and is trying to ensure that any drinking water regulations does not get out in front of the science.

The drinking water office has also had difficulty updating its Lead and Copper Rule because of policy and economic concerns, not scientific issues.

Lastly, the agency is attempting to resolve scientific issues related to its plan to regulate up to 16 carcinogenic volatile organic compounds (VOCs) as a group.

GA bacteriophage superior surrogate to MS2

Nicolas Boudaud, Claire Machinal, Fabienne David, Armelle Fréval-Le Bourdonnec, Jérôme Jossent, Fanny Bakanga, Charlotte Arnal, Marie Pierre Jaffrezic, Sandrine Oberti, Christophe Gantzer. Removal of MS2, Qβ and GA bacteriophages during drinking water treatment at pilot scale. Water Research, Volume 46, Issue 8, 15 May 2012, Pages 2651–2664.

The removal of MS2, Qβ and GA, F-specific RNA bacteriophages, potential surrogates for pathogenic waterborne viruses, was investigated during a conventional drinking water treatment at pilot scale by using river water, artificially and independently spiked with these bacteriophages. The objective of this work is to develop a standard system for assessing the effectiveness of drinking water plants with respect to the removal of MS2, Qβ and GA bacteriophages by a conventional pre-treatment process (coagulation–flocculation–settling-sand filtration) followed or not by an ultrafiltration (UF) membrane (complete treatment process). The specific performances of three UF membranes alone were assessed by using (i) pre-treated water and (ii) 0.1 mM sterile phosphate buffer solution (PBS), spiked with bacteriophages. These UF membranes tested in this work were designed for drinking water treatment market and were also selected for research purpose.

The hypothesis serving as base for this study was that the interfacial properties for these three bacteriophages, in terms of electrostatic charge and the degree of hydrophobicity, could induce variations in the removal performances achieved by drinking water treatments.

The comparison of the results showed a similar behaviour for both MS2 and Qβ surrogates whereas it was particularly atypical for the GA surrogate. The infectious character of MS2 and Qβ bacteriophages was mostly removed after clarification followed by sand filtration processes (more than a 4.8-log reduction) while genomic copies were removed at more than a 4.0-log after the complete treatment process. On the contrary, GA bacteriophage was only slightly removed by clarification followed by sand filtration, with less than1.7-log and 1.2-log reduction, respectively. After the complete treatment process achieved, GA bacteriophage was removed with less than 2.2-log and 1.6-log reduction, respectively.

The effectiveness of the three UF membranes tested in terms of bacteriophages removal showed significant differences, especially for GA bacteriophage. These results could provide recommendations for drinking water suppliers in terms of selection criteria for membranes.

MS2 bacteriophage is widely used as a surrogate for pathogenic waterborne viruses in Europe and the United States. In this study, the choice of MS2 bacteriophage as the best surrogate to be used for assessment of the effectiveness of drinking water treatment in removal of pathogenic waterborne viruses in worst conditions is clearly challenged. It was shown that GA bacteriophage is potentially a better surrogate as a worst case than MS2. Considering GA bacteriophage as the best surrogate in this study, a chlorine disinfection step could guaranteed a complete removal of this model and ensure the safety character of drinking water plants.

Click here for full paper (fee).