(a) This subpart applies to each new, reconstructed, or existing “affected source” that produces Saccharomyces cerevisiae at a nutritional yeast manufacturing facility.

(b) The affected source is the collection of equipment used in the manufacture of the nutritional yeast species Saccharomyces cerevisiae. This collection of equipment includes fermentation vessels (fermenters), as described in paragraph (c) of this section. The collection of equipment used in the manufacture of the nutritional yeast species Candida utilis (torula yeast) is not part of the affected source.

(c) The emission limitations in this subpart apply to fermenters in the affected source that meet all of the criteria listed in paragraphs (c)(1) and (2) of this section.

(1) The fermenters are “fed-batch” as defined in §63.2192.

(2) The fermenters are used to support one of the last three fermentation stages in a production run (i.e., third-to-last stage, second-to-last stage, and last stage), which may be referred to as “stock, first generation, and trade,” “seed, semi-seed, and commercial,” or “CB4, CB5, and CB6” stages.

(d) The emission limitations in this subpart do not apply to flask, pure-culture, yeasting-tank, or any other set-batch (as defined in §63.2192) fermentation, and they do not apply to any operations after the last dewatering operation, such as filtration.

(e) The emission limitations in Table 1 to this subpart do not apply to fermenters during the production of specialty yeast (defined in §63.2192).

(f) An affected source is a “new affected source” if you commenced construction of the affected source after October 19, 1998, and you met the applicability criteria in §63.2131 at the time you commenced construction.

(g) An affected source is “reconstructed” if it meets the criteria for reconstruction as defined in §63.2.

(h) An affected source is “existing” if it is not new or reconstructed.