Evaluation of the impact of wastewater from separate oil refining units on biological treatment process

Summary

The composition and kinetic characteristics of biochemical oxidation of separate wastewater flows from oil refining process units is determined. The study subject was wastewater of the Novokuibyshevsk oil refinery – fuel and lube refiner. In order to evaluate separate wastewater flows with different biological degradability, a kinetic method under contact conditions was used, i. e. the method of recording variations in time of dissolved oxygen concentration followed by determining the oxygen uptake rate depending on the concentration of substrate or other factors. It was stated that the significant part of wastewater from oil refining process units was inhibiting the process of biological treatment of the entire wastewater flow of the refinery. The experimental determination of the inhibition constants of enzyme kinetics equations is of great practical interest because it provides for evaluating the toxic flow impact on the process rate, and what is more determining the type of inhibition. Knowing the inhibition type the ways of eliminating inhibition can be determined which is equally important in biologcal treatment of toxic wastewater. The general methods of eliminating any type of inhibition in the process of oil refinery wastewater biolological treatment is decreasing the toxic flow part in the total flow, i. e. flow rate equalization and activated sludge concentration increase in the facilities. Flow and pollution concentration equalization will prevent from the disturbance of biological treatment processes related to volleys of such wastewater. The last confirms the technological expediency of using membrane bioreactors for biological treatment of oil refinery wastewater that allow operating under the conditions of complete activated sludge retention the the reactor.

Key words

wastewater , biological treatment , oil refinery , kinetic constants and coefficients , competitive inhibition , uncompetitive inhibition , substrate inhibition