News and Views

Sodium sulphate recycle loop is closed The problem with by-product sodium sulphate - and the processes which generate it - is that it is often difficult to sell or reprocess into something useful. This is particularly pertinent to sulphate based Flue Gas Desulphurisation Processes, such as the Soxal process, featured in the News section of our June issue. A treatment for gaseous pollution which merely generates a liquid or solid waste for disposal is only half a solution; and glib assertions that, for example, sodium sulphate by-product can be sold deserve closer scrutiny.

The truth is that industries such as pulp and paper, viscose, detergents and fine chemicals manufacture often have sodium sulphate coming out of their ears! These days such industries which generate large amounts of by-product sodium sulphate are finding it increasingly difficult to manage and dispose of - never mind selling it - under mounting environmental pressure. An economic means of recycle would therefore be helpful.

Such a solution now appears at hand with the announcement by ICI that it has developed an electrochemical process for treating waste sodium sulphate, interestingly based on the company's well known membrane cell technology.

According to Sarah Galbraith, product development manager with ICI's Electrochemical Technology group, the process enables operators to

regenerate acid and alkali for re-use, and ICI is able to customise the process to suit individual needs.

The Soxal process, developed by Aquatech and currently being tested at Florida Power & Light, uses sodium sulphite to scrub SO 2 out of flue gas, followed by a membrane based ion exchange procedure to regenerate the scrub solution and produce a sodium sulphate stream laden with the S% removed from the flue gas. The process is one of an increasing number of applications for Aquatech's membrane water splitting technology, which was features in the Launch issue of Membrane Technology, published in March 1990.

Subsequent recovery of the SO_ as a concentrated gas stream leaves sodium sulphate solution still to deal with, either by commercial sale, disposal or further reprocessing.

New chlor-alkali technology in demand Large investments are needed in eastern Europe to bring chlor-alkali production facilities up to western standards, according to reports at the recent Tecnon Chlor-alkali conference held in London. Environmental standards and outdated technologies are of major concern. Practically all the countries in the region have chlor-alkali production, which is

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