Sequential extraction of chromium from galvanic wastewater sludge

The sequential extraction of chromium from galvanic wastewater sludge was studied. A five-step sequential fractionation scheme was used to partition the chromium into exchangeable (F I), acid-soluble (F II), reducible (F III), organic matter (F IV) and residual (F V) fractions. The results of investigations indicate that 59.5% of chromium occurred in residual fraction, which is permanently immobilized, whereas 40.5% of chromium in galvanic wastewater sludge can be released to ecosystems under changing natural conditions.