Waste Effluent Treatment by Ion Exchange

The first large scale application of ion exchange to effluent treatment was in the recovery of water, ammonia, and basic copper sulfate from the waste streams encountered in the cuprammonium rayon process. Originally a phenolic type condensation resin was employed, but more recently carboxylic acid acrylic-based exchangers have been introduced. A similar process exists for zinc recovery from the spinning acids of viscose rayon plants, except that in this operation a sulfonic acid resin is employed. 

Ion exchange methods are established for treating various rinse streams arising from metal finishing processes such as plating and 

The first regeneration of the strong base anion exchange resin with a near stoichiometric quantity of sodium hydroxide converts the loaded dichromate form of the resin to the chromate form whereafter it is able to efficiently take up chromic acid again. The anion column effiuent of sodium chromate may be cation exchanged across a strong acid resin in the hydrogen form to recover chromic acid  

Ion exchange treatments have successfully been applied to the effluent streams arising from paper manufacture, photographic processing, chemical leaching, zinc smelting, and metal pickling. The 

Regeneration is effected with water which through hydrolysis decomposes the anionic complex ions to give a rapid elution of the cations, firstly Fe and then Zn, which are recovered (see also Box 5.2). The severe osmotic cycling between treatment and regeneration stages dictate the use of macroporous resins. 

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