Membranes, on the other hand, allow for complete retention of biomass,
enabling MBRs to not only operate with significantly higher MLSS
concentrations (10–20 g L − 1 ) but also produce higher quality effluents. Other benefits of increased MLSS concentrations include: (a) operation at higher loading rates, (b) smaller reactor volumes and
footprint due to decoupling of hydraulic and solids retention times
(HRT and SRT, respectively), (c) development of specialized, slowgrowing microorganisms, and (d) reduced excess sludge production
due to longer SRT