Mathematical models for biomass in membrane-BNR process for wastewater treatment

Abstract

The equation of biomass is related to the mass-balance equation of substrate. This equation of substrate is expressed according to a model using the Monod equation, which indicates some limits for calculating the amounts of VSS in the MBR process. Some degradation of biomass which is caused by long SRT might result in the generation of substrate based on COD. Research was conducted by lab-scale tests with two membrane-BNR (Biological Nutrients Removal) processes. These were composed of multi-reactors as anaerobic, anoxic, aerobic tank and oxygen exhauster. The aerobic tank was also divided into 3 reactors, which were oxic for nitrification, oxic-media containing fluidized sponge typed media for simultaneous nitrification and denitrification, and oxic-membrane for submerged membrane. This membrane-BNR process could remove most of the organics, suspended solids and nutrient substances like nitrogen thus satisfying the reuse guidelines issued by the Korean Ministry of Environment. The value measured of VSS (X(v)) through the experiment with SRT of 35 days was similar to the biomass using the conventional equation while the one with SRT of 60 days was close to the concentration of VSS calculated by a revised equation which considered the biomass degraded with long SRT.