Use of a Nylon Manufacturing Waste as an Industrial Fermentation Substrate

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Abstract
Nonvolatile residue (NVR), a waste stream from the manufacture of nylon 6′6′, contains mainly small carboxylic acids and alcohols, making it a potential fermentation substrate. Above a concentration of 1.3% (wt/vol), NVR inhibited the growth of all microorganisms tested. The most inhibitory of the major NVR components were the monocarboxylic acids (C 4 to C 6 ) and ε-caprolactone. The inhibitory effects of NVR could be avoided by using a carbon-limited chemostat. Microorganisms were found that could use all of the major NVR components as carbon and energy sources. One such organism, Pseudomonas cepacia , was grown in a carbon-limited chemostat with a medium feed concentration of 20.5 g of NVR liter −1 . At a dilution rate of 0.14 h −1 the yield of biomass ( Y x/s , where x is biomass produced and s is substrate used) from NVR was 18% (neglecting the water content of NVR). It was concluded that NVR would be a suitable carbon source for certain industrial fermentation processes such as the production of poly-β-hydroxybutyric acid.