RESEARCH OF PROCESSING TECHNOLOGY OF N-CONTAINING LIQUID WASTE OF AMMONIUM SULPHATE PRODUCTION BY THE REAGENT FLOTATION

Abstract

Coke wastewater is characterized by a significant content of bound nitrogen in various forms, therefore, can be considered as N-containing liquid waste. The main polluting agents of this type of waste are resinous substances. The presence of surfactants also characterizes the total coke-chemical effluent as a stable emulsion system. Flotation methods for cleaning liquid waste from resinous substances have significant technological advantages (simplicity of instrumentation, high productivity, lack of regeneration stage). Increase the depth of de-oiling of liquid waste during flotation is possible due to the coagulation of particles of a colloidal degree of dispersion - emulsified resinous substances. This is achieved by using flotation, in particular, when inorganic electrolytes (often FeSO4) are added to the wastewater. The process of reagent flotation of sewage waters of PJSC Dniprodzerzhynsk Coke Plant with a tar content of 394 mg/dm3 with the addition of coagulants (AlCl3, FeSO4, Al2(OH)5Cl) and flocculants based on polyacrylamide (A3330, CW3279) was investigated. It has been experimentally proved that the addition of 4 mg/dm3 of the anionic flocculant A3330 in reagent flotation with the use of Al2(OH)5Cl at a dose of 25 mg/dm3 allows recovery of resinous substances to 15 mg/dm3 and shortens the duration of the cleaning process by 30 % method of pressure flotation. The regularities of the effect of water temperature in the interval 284-323 K on the efficiency of flotation removal of resinous substances are established. In this interval, an increase in the temperature of the wastewater reduces the duration of the pollutant recovery to the normative content from 30 min to 15 min with the use dose of 25 mg/dm3 Al2(OH)5Cl and anionic flocculant A3330 in the amount of 4 mg/dm3. The possibility of saving the coagulant Al2(OH)5Cl by replacing part of its dose during flotation with cheap FeSO4 without reducing the efficiency of purification is shown.