NUMERICAL MODELLING AND SIMULATION OF WASTEWATER TREATMENT PROCESSES IN SEWAGE SYSTEM

摘要

The sewage network acts like a physical, chemical and biological reactor where microbial transformations occur, being a complex and extremely dynamic system. The mass transfer occurs between all the sewage subsystems: wastewater, sewage atmosphere, biofilm and sewage sediment. Using the sewage network as a 'pre-treatment step' contributes to improving both the efficiency of the treatment plant and the sewage network design in order to control the treatment process in wastewater treatment plants. This study presents the numerical modelling and simulation of complex treatment processes in the sewage system, considering, in the equation of organic matter degradation, the term of consumption, in the form of growth rate of heterotrophic biomass in the aqueous phase, in the aqueous phase and biofilm. Modelling and simulation were also been achieved by introducing the term of organic matter consumption, in the form of the Monod relation, considering the equation of re-aeration and heterotrophic biomass growth in the aqueous phase and biofilm. Results obtained for the studied cases reveal a decrease of 14.2, 26 and 35.44%, respectively, of the organic matter, considering a sewage system having a 5 km-length.