Ozone for dye waste color removal: Four years operation at Leek STW (Reprinted from The Role of Ozone in Wastewater Treatment, 1997)

The problems caused by discharges of colored dye waste into the sewer are described. Coloration of the River Churnet by the Leek Sewage Treatment Works (STW) effluent necessitated the setting of color discharge consent conditions by the National Rivers Authority (now the Environment Agency). These and other tightened consent conditions led to the planning of a major works extension to give an extensive flow sheet unique to the UK. The conceptual design is described, together with four years operating data. The extended plant has performed extremely well since October 1992, and in particular the ozonation process has given excellent color removal. Resulting improvements in the downstream water quality of the River Churnet have been demonstrated by the lack of public complaint and by the return of trout and chub.