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AWWA Workshop on cVOC Treatment

This week, AWWA convened a workshop of experts in treatment technologies to discuss the treatment implications of the list of 16 Carcinogenic Volatile Organic Compounds (cVOC) being considered for a group drinking water regulation.  The list includes eight currently regulated VOCs and eight more VOCs from the Contaminant Candidate List.  Some of the discussion focused on defining a VOC, since there is no specific definition of a VOC for drinking water in the SDWA.  Traditionally, the definition has been at least partially based on treatment, with the VOC group effectively removed through air stripping.  Not all the listed cVOCs are adequately treated by that traditional VOC treatment method.  That’s because some of them are not really volatile in the traditional sense.  However, if Granular Activated Carbon (GAC) is added, a few more contaminants can be effectively treated.  Going to Advanced Oxidation Processes (AOP) offers some additional treatment advantages but probably only in certain circumstances.  There is probably not enough field data yet on AOP to include it as a Best Available Technology in a proposed rule.  The experts reviewed various data on treatability using Packed Tower Aeration (PTA), GAC, and AOP.  Although on paper, some of the VOCs appear to be treatable, there are practical limitations on parameters like the height of the tower or the air-to-water ratio.  The group also heard from experts on treatment operations involving additional issues that impact treatment feasibility.

The bottom line was that, based on feasibility of treatment, the workshop participants felt that the existing regulated VOCs are fine for regulation as a group, but all of the additional listed contaminants may not be appropriate for the final cVOC group.  A companion workshop on the analytical methods conducted by EPA last month came to similar conclusions that some of the new VOCs included in the cVOC list may not be appropriate because they are not captured by the same analytical method as the existing VOCs (EPA Method 524.3).  Reports from both workshops will be shared with EPA.  During the workshops, EPA indicated that they appreciated the additional information but could not confirm what the final list of cVOCs would be.  An EPA workgroup is currently considering the future proposed regulation.