EVALUATION OF EFFECTIVENESS OF USE OF COMPLEX COAGULANTS FOR WASTEWATER TREATMENT PROCESSES OF MECHANICAL ENGINEERING

Abstract

In the course of the work, the quantitative and qualitative characteristics of the wastewater of the machine-building enterprises of the Moscow and Penza regions were investigated. It was found that in most cases the most difficult to remove contaminants are oil products entering the wastewater from metal processing operations, as well as heavy metal ions. Due to the lack of separation of stormwater, industrial and domestic sewage systems, the effluent under study had high concentrations of dissolved organic compounds (Biological Oxygen Demand BOD/chemical oxygen demand COD) and suspended solids. Laboratory tests of experimental samples of complex coagulant on waste water of real production were carried out. Normal aluminum sulfate and aluminum sulfate modified with hydrolysis products of titanium tetrachloride (complex coagulant) were used as reagents. It has been established that complex titanium-containing reagents are effective in the processes of coagulation sewage treatment of machine-building enterprises. The process of flocculation and sedimentation proceeded at a high rate due to flocculation reactions on the surface of titanium hydroxo-complexes, as well as nucleation phenomena on the surface of titanium hydroxide particles. The increased efficiency of samples modified by hydrolysis products of titanium coagulant compounds with respect to traditional aluminum sulfate has been proved. The consumption of complex coagulant compared with aluminum sulfate was about 1.25 - 1.5 times lower, while its efficiency is about 5 - 10% higher. The increased efficiency of complex coagulants with respect to the indicators of oil products, COD and color (organic pollutants) was noted, which is due to the developed adsorption surface of titanium hydroxide flakes in comparison with aluminum hydroxide.