Evaluation of greenhouse gas emissions from membrane bioreactors: development of a new mathematical model

A mathematical model for quantifying greenhouse gas (GHG) emissions from a Membrane Bioreactor (MBR) is presented. The main aim is to provide an useful tool (a process-based dynamic model ) for the evaluation of GHGs emission from MBR. The influence of the sludge retention time on the GHG emissions is also presented. The GHG model is an extension of a previously developed MBR integrated model which is able to simulate jointly biological and physical processes as well as their mutual interactions. For simulating the GHG emissions, new biological processes have been introduced partially modifying some already existing ones of the integrated model. The new GHG-MBR model is also able to quantify the emissions of carbon dioxide (CO2) and nitrous oxide (N2O). The model has been applied to a University Cape Town –MBR pilot plant. The results show that the model is able to adequately reproduce the main processes occurring inside the system. Moreover, the model results in terms of N2O and CO2 emissions highlight the importance in the assessment of the emissions predictions by means of a process-based dynamic model