Investigation into Ozonation of Coal Coking Processing Wastewater for Cyanide, Thiocyanate and Organic Removal

A laboratory investigation was carried out to establish whether ozonation could be used to oxidize cyanides, thiocyanates and color in wastewater from a coal coking plant to supplement biological and activated carbon treatment (GAC). Ozonation was found to be capable of oxidizing cyanide and cyanate to sufficiently low levels at relatively high stoichiometric ratios as a result of competitive ozone consumption by organic substances in the wastewater. While good color removal was also achieved with ozonation, organic removal could not match GAC in overall organic removal. Ozonation was not found to be economical for the remaining nine years of a build, own, operate and transfer (BOOT) contract period. Ozonation would be competitive over longer operational periods and more environmentally friendly than presently used technology.