U. S. EPA: Struvite Products May Be Regulated by Part 503...
...but case-by-case exemptions are possible.
(Thanks to NACWA for this information & work on this issue.)
U.S. EPA has decided that struvite fertilizers and other products made for land application are, by default, "derived from sewage sludge" and, thus, subject to the requirements of 40 CFR Part 503. However, the Agency "is willing to consider on an individual case-by-case basis whether a particular product recovered from sewage sludge is beyond the scope of Part 503."
In an early-January 2017 letter to NACWA, the Office of Water acknowledged that "some products originating from sewage sludge could conceivably be so heavily refined or processed that a significant transformation or change in quality has occurred to the extent that it would be unreasonable to describe those products as "material derived from sewage sludge.... [S]uch products...would be outside the scope of Part 503."
Initially, U. S. EPA was inclined to categorically declare all such products as subject to Part 503, according to NACWA. "This is a significant win for the Utility of the Future program, and for those NACWA members exploring resource recovery opportunities," NACWA wrote to its members. "NACWA will continue to build on this success to further enhance the ability to recover and reuse the valuable materials in wastewater."
For a few years, producers of struvite fertilizers, NACWA, NEBRA, and others have discussed with U. S. EPA the question of 503 applicability. Struvite fertilizers are generated by engineered precipitation from thickened and/or digested solids or centrate/filtrate. Such processes are increasingly important in protecting treatment facility equipment from struvite (and/or vivianite) build-up and reducing total phosphorus (P) in the final biosolids product.
The Metropolitan Water Reclamation District of Greater Chicago has installed a large-scale struvite removal system, and resolution of the 503 applicability question affects that project's economics. Under the new U. S. EPA determination, Chicago will need to provide EPA with arguments and supporting data regarding why their struvite product is not subject to Part 503.
As part of its determination, which the Agency stresses is subject to change, U. S. EPA does make it clear that products "extracted" from sewage sludge that are not land applied, land disposed, or incinerated are not subject to Part 503. An example used in the letter is an element (e.g. silver).