The main source of sulfate contamination in the fermentation industry is the
use of sulfuric acid for pH control. H2SO4is relatively cheap and can be transported
very concentrated (> 96%). Additionally, many fermentation products (e.g., or-ganic acids such as citric and tartaric acid) are recovered from the process liquid
by precipitation with calcium sulfate (Ehlinger et al., 1992; Colleran et al., 1994).
In addition, sulfur compounds are used for bleaching (sulfur dioxide in sugar
manufacturing) or as oxygen scavenger to prevent colorization (sulfite in starch
production).