Evaluation of sodium lignosulphonate for the remediation of chromium-contaminated soil and water

Commercial sodium lignosulphonate, a by–product of sulphite pulp leaching, was evaluated for the remediation of soil and water contaminated with hexavalent chromium. Two series of bench–scale tests were performed: (a) removal of chromium from water using reagent binding and membrane separation; and (b) stabilisation of chromium in the soil using chemical soil flushing. Water treatment tests were performed in a batch mode in stirred ultrafiltration cells. The test results revealed that lignosulphonates can bind hexavalent chromium and facilitate its removal from water when used in conjunction with ex–situ water treatment (membrane filtration). Soil treatment tests carried out in a column revealed that lignosulphonates reduced chromium mobility and helped stabilise it within the soil matrix. These tests showed that lignosulphonate fixation can be used to stabilise chromium in soil with in–situ treatment (soil flushing).