The conventional process used to treat waste acids from the stainless steel
pickling baths is a direct neutralization with alkali. However, this proce
ss requires a high consumption of chemicals, produces a large amount of sol
id wastes, and furthermore, does not meet the recent European Waste Treatme
nt Regulation because of the nitrogen contained in the final effluent. This
paper presents an alternative treatment method based on a diffusion dialys
is process for the free acid recovery and a neutralization process, followe
d by a salt splitting process, for the chemical recovery. This alternative
eliminates waste disposal problems and, at the same time, it regenerates an
d recovers valuable by-products, which contributes to the economic feasibil
ity of the process. Therefore, the work presented is focused on the technic
al and economical feasibility of electromembrane processes for the European
spent pickling baths. Furthermore. bipolar electrodialysis and membrane el
ectrolysis systems are compared for the salt splitting process. At the mome
nt, there is a partial process in Washington Steel based on salt splitting;
however, the recovery of free acid is not considered, and furthermore, the
different concentration of the European pickling baths makes this process
unsuitable for European stainless steel producers.