Abstract
Iron in titanium-dioxide plant industrial wastewater is removed by limestone in the dune sand into which the waste is disposed. A pilot scale laboratory column experiment to investigate the interactions between the waste and the sand showed that the iron was removed from solution as iron carbonate just beyond the acid neutralization zone. As the acid front progresses the iron is redissolved and redeposited ahead of the slow moving acid neutralization zone. The net effect is that the iron is deposited in a narrow band which is moved along by the advancing acid front. Management conclusions for disposal of the waste into the dune sand are derived, based on the results of the investigation.