REMOVAL OF DYEWASTE COLOR FROM SEWAGE EFFLUENT - THE USE OF A FULL-SCALE OZONE PLANT

Textile dyeing within the Severn Trent Region produces highly coloured wastewater. This dyewaste is usually discharged untreated to foul sewer. Conventional treatment at the receiving sewage treatment works removes little colour resulting in colouration of effluents and rivers in certain areas, The regulatory body (N.R.A.) has set strict colour standards on 5 of S.T.W.L. sewage works. These standards are based on a River Quality Objective (R.Q.O.). Methods of removing colour are reviewed. The full scale ozone colour removal plant at Leek S.T.W. is described and early operating data is given. Good colour removal has been obtained, but compliance with the consent has been 89.7% and not the 100% required. Data is presented to indicate that the R.Q.O. does not adequately take natural colour into account. Target aborbances at 400 and 450 nm are thus too low to be practicable for the derived sewage effluent consents.