Experimental comparison between MBBR and activated sludge system for the treatment of municipal wastewater

The aim of the described experimentation was the comparison of a low cost MBBR and an activated sludge system (AS). The MBBR applied system consists of the FLOCOR-RMP® plastic media with a specific surface area of about 160 m2/m3 (internal surface only). The comparison with activated sludge (AS) was performed by two parallel treatment lines. Organic substance removal and nitrification were investigated over a 1-year period. Comparing the results obtained with the two lines, it can be observed AS totCOD removal efficiencies were higher than MBBR ones; the average efficiencies for totCOD removal were 76% for MBBR and 84% for AS. On the contrary, the solCOD removals resulted alike (71% for both systems). In spite of the remarkable variations of wastewater temperature, mainly in winter (range of 5–21°C), the average ammonium removal efficiency resulted 92% for MBBR and 98% for AS. With an ammonium loads up to 1.0 g m2 d−1 (up to 0.12 kg m−3 d−1), nitrification efficiencies in MBBR were more than 98%. At higher loads decrease in the MBBR efficiency was registered; that is related to the increase in the applied COD load.