MBR building blocks
As with a conventional biological wastewater treatment process, an MBR is a combination of tanks, pipework, pumps and blowers, with the addition of the membrane differentiating it from classical processes.
A simple design of a small MBR has been provided by Lo et al (2015). This is a general design for a municipal wastewater treatment based on an immersed membrane and an MLE (modified Ludzack−Ettinger) process. The specifications of the individual pieces of equipment (power, flow and/or pressure ratings) then depend on the application and assumptions made.
Most MBR installations must also include a control system for regulating flows and pressures.
| Category | Component(s) | ID | Description/purpose |
|---|---|---|---|
| Tanks | Raw water | T1 | Storage tank for inlet wastewater |
| Primary sedimentation | T2 | Removal of gross, settleable solids | |
| Equalisation (EQ) | T3 | Equalisation of flow | |
| Anoxic (Ax) | T4 | Denitrification | |
| Aeration (Ae) | T5 | Nitrification and biological oxidation | |
| Membrane | T6 | Membrane separation | |
| Treated water | T7 | Storage of permeate water | |
| Sludge | T8 | Storage of wasted sludge | |
| Chemicals storage | T9, T10 | ||
| Pumps | Settled sludge transfer | P1 | Submerged, settled sludge to sludge storage tank |
| Feed | P2 | EQ tank through rotary screen | |
| Permeate | P3 | Self-priming, membrane suction filtration | |
| Sludge return/discharge | P4 | Submerged, sludge recirculation and excess | |
| Sludge transfer | P5 | WAS to dewatering | |
| Chemicals | P6, P7 | Cleaning chemicals transfer to membrane, x2 | |
| Blower | Process | B1 | Biological process aeration |
| Membrane | B2 | Membrane scouring | |
| Mixer | EQ tank mixer | X1 | High speed, equalisation tank |
| Ax tank mixer | X2 | Low speed, anoxic tank | |
| Screen | Rotary screen | S1 | Fine screening of feed |
| Membrane | Membrane module | M1 | FS membrane plus frame with built-in aerator |
| Diffusers | Fine bubble diffuser | D1 | Process aeration |
| Coarse bubble diffuser | D2 | Membrane aeration |
Acknowledgements
© Text and image copyright Judd & Judd Ltd
References
Lo, C.-H., McAdam, E., and Judd, S. (2015). The cost of a small membrane bioreactor, Water Sci Technol 72(10) 1739−1746.
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