ICI’ Hydecat’ Process for the Catalytic Destruction of Hypochlorite Effluent Streams

Abstract

The concern about the environmental impact of chlorinated caustic effluent streams and the problems associated with the removal of volatile organic carbons from such effluents has encouraged ICI to research and develop “HYDECAT” technology.

The paper will address the environmental impact of contaminated waste hypochlorite, the chemistry of hypochlorite and the current international legislative scene. The traditional methods employed for the destruction of chlorinated caustic wastes will be critically reviewed in the light of current practice and the likely impact of the restructuring of the chlorine producing and consuming market.

The ICI “HYDECAT” process employs proprietary heterogeneous catalyst and a unique reactor design to accelerate the decomposition of hypochlorite thus producing oxygen gas and brine for disposal or recycle. A typical “HYDECAT” hypochlorite destruction unit will be described and experience to date reviewed. Developments to aid removal of low levels of volatile organic carbons from such streams will be discussed. Advantages of the new process include:

• + lower capital costs than conventional treatment

• + operational simplicity and reliability

• + low labour and maintenance costs

• + safer and cleaner operation

• + continous oxygenation of the waste stream

The potential applicability of the “HYDECAT” process to major chlorine utilising processes will be illustrated with references to vinyl chloride monomer, titanium dioxide and organic chlorinations. The adoption of the “HYDECAT” treatment process will strengthen the environmental compatibility of the chlorine industry.

’HYDECAT’ is a Trade Mark of ICI Chemicals & Polymers Ltd