Comparison of Nitrogen Removal in an AN/AO and an AO Submerged Membrane Bioreactor in Treating Bathing Wastewater

Simultaneous nitrification and denitrification (SND) and traditional nitrification and denitrification (TND) were studied in lab-scale and the full-scale submerged membrane bioreactor (MBR) tests for the bathing wastewater treatment under the same condition. As a result, the removal of the nitrogen was not only the contribution of the anoxic (AN) tank, but also the aeration (AO) tank because of its SND effect. From the two tests, it can be drawn that there would be two methods to remove the nitrogen. One was nitrification and denitrification in the AO tank and AN tank, which contributed mainly in nitrogen removal. The other was simultaneous nitrification and denitrification occurred in the AO tank, although its effect was not very significant. The contribution ratios of the two kind´s nitrogen removal ways in treating the bathing wastewater were about 70% and 30%, respectively. At the same time, the main pollutions in bathing wastewater such as COD and LAS were also studied systemically in the two scale tests. As a result, there had a good removal (over 95%) to the pollutions, in which the microorganisms played a greater role than membrane.