A study, using a simulated sea-water, of the disposal of acidic iron effluent at sea

The titanium dioxide pigment industry at present disposes of a large quantity of acid-iron waste by dumping it at sea. The ensuing interactions result in a red discolouration of the environment which is a source of increasing public concern. A study has been made of the reactions that occur when an effluent solution of ferrous sulphate in sulphuric acid is added to sea-water. On addition of the effluent solution there is an initial rapid reaction between the effluent acid and the bicarbonate buffer of sea-water. The ferrous iron content is dispersed, is subsequently oxidised and precipitates as a form of ferric hydroxide. In seawater ferrous iron solubility is controlled by the solubility of ferrous carbonate. Solubility calculations, based on available thermodynamic data at 25 ° C, show that for the composition of typical industrial effluents there is little possibility of ferrous carbonate precipitating on effluent dispersion in sea-water.