METHOD FOR PURIFYING OF CONCENTRATED ALKALINE SULPHIDE CONTAINING LIME WASTE WATERS WITH RECUPERATION OF SULPHUR CONTAINING COMPOUNDS AND INSTALLATION FOR ITS IMPLEMENTING

摘要

The method is applied in the leather industry. It provides for a larger effect in purifying suspended substances, dissolved and colloidal organic compounds. It also prevents the emission of toxic hydrogen sulphide in the environment. The method consists in the following: lime sewage water containing sulphides is subjected to preliminary aeration with air for 5 to 15 minutes. This is followed by the addition of sulphuric acid with uniform dispersion for 1 to 10 minutes until pH 4 - 4.5 is reached, then aeration degassing with air or water, sedimentation and absorption of the hydrogen sulphide by sparging of the gas-air mixture in a solution of sodium hydroxide with a concentration of 5 to 15% by volume. The installation for the implementation of the method includes equipment for the purification of the sewage water and a sparging type absorber. This equipment is a hermetically sealed vessel, which is composed of a cylindrical and a conical part where the ratio of the working height of the cylinder and its diameter is 1 to 2. The air distributor is located at a distance of 0.5 - 1.0 m from the lower end of the cylindrical part, while the distributor for the acid feeding is 0.2 - 0.9 m above the air distributor. The absorber is a column, equipped with perforated plates and inert material is poured over it.