FULL-SCALE TREATMENT OF PHENOLIC COKE COKING WASTE-WATER UNDER UNSTEADY CONDITIONS

Phenolic waste water from the largest coke coking plant in Poland is t reated at a full technical scale. From the very beginning it became ev ident that very high qualitative variations in short and long periods are to be expected. For this purpose, the biological treatment giant b ased on activated sludge is protected through preliminary physical-che mical treatment and the results are secured by a final chemical stage of treatment. Nevertheless, improvements in the performance of the tre atment plant have been found necessary to introduce. The experienced g ained over the last five years has been described and developed improv ements have been presented. At the preliminary stage the importance an d necessity of preparation was evaluated. It was found essential to us e dissolved air flotation, instead of a simple pressured air flotation system. Even with an average relatively high retention in the aeratio n tanks, there was an uneven distribution of load, dissolved oxygen co ncentration and oxygen uptake. Dissolved iron or highly dispersed hydr oxide particulates in the over flow of the first chemical treatment st age has had a beneficial effect on activated sludge flocs. As a result not only the physical properties but also the overall effect of treat ment.