Where the space savings come from
Three things make an MBR plant compact. The secondary clarifier disappears, because membranes do the solids separation. The aeration basin gets smaller, because the biology can run at higher MLSS. And tertiary filters are often unnecessary, because the membrane already delivers low turbidity. Together these can reduce the process footprint substantially compared with a conventional train, though the exact figure depends on loading and effluent limits.
Custom sizing: we cut, weld and assemble in Poughkeepsie, NY, so cartridge and module sizes can often be tailored to your existing tanks. Tell us your tank dimensions, or see custom sizes.
Plan for the supporting equipment
A compact basin still needs fine screens, blowers, permeate pumps, a cleaning chemical skid and electrical space. Good layouts put these in a small building or skid next to the tank. When we size modules we also look at access for lifting, so modules can be lifted out easily for maintenance.
Swing in existing tanks
Swing modules have a footprint close to hollow-fiber designs, so they are often a one-for-one retrofit into an existing membrane tank, and they can also convert a clarifier-based plant to MBR within its current basins. Septic and decentralized users have a smaller drop-in cassette option.
| Mild backwash (special cases only) |
|---|
| Backwashing is not a standard Swing operating mode and is not meant for routine use. Swing has been pressure-tested to 14.5 psi (1 bar) and held without breaking. If a site is in a bind even after relaxation and CIP, contact us; we may be able to work out a special mild-backwash procedure. |
Worked sizing example
Take a tight urban site treating 158,503 gpd (600 m³/day):
| Item | US | Metric | Note |
|---|---|---|---|
| Average flow | 158,503 gpd | 600 m³/day | about 110 gpm (25,000 L/h) |
| Design flux (gross) | 11.8 gfd | 20 LMH | Zyramic design guidance |
| Derate for relaxation and cleaning | ~20% | ~20% | |
| Net flux | ~9.4 gfd | ~16 LMH | |
| Membrane area needed | ~16,819 ft² | ~1,562 m² | average flow ÷ net flux |
| Swing-8 cartridges | ~125 | ~125 | 135 ft² (12.5 m²) each |
| Peak factor | ~2.0 | ~2.0 | |
| Peak flow | ~317,006 gpd | ~1,200 m³/day | extra area, short-term higher flux, or equalization |
This is an illustration only; a real design also checks temperature, MLSS, redundancy and the cleaning schedule.
Tips for a smooth project
- Size for peak hour as well as average flow
- Invest in good fine screening up front
- Use temperature-corrected flux for cold-weather design
- Plan lifting access so modules come out easily
Next step
Most projects start with a short call or an email with flows and a sketch. We send back a preliminary module layout and a quote, then refine it with your engineer once the process design is firm. If you are still comparing processes, we'll help you choose the right approach for your site.
Sizing considerations
To give a useful recommendation we usually need:
- Available site area and tank volumes
- Peak flow and load
- Effluent or reuse limits
- Space for screens, blowers and cleaning skid
- Lifting access for module removal
Most relevant product: Swing MBR. See also replacement membranes, rentals and how to choose.
Why engineers look at Zyramic flat-sheet modules
| Item | Details |
|---|---|
| Smaller sheets, less wear and tear | each sheet flexes less in service, and a damaged unit affects less area. |
| Strong wide membrane welds | designed to resist delamination over the membrane's life. |
| Thick, robust membrane | about 250 microns including support. |
| Assembled in Poughkeepsie, NY | of domestic and imported components. In our Poughkeepsie shop we cut and weld membrane sheets to plates, build module frames and assemble complete modules. For funded projects, tell us your domestic-content requirements and we'll review what we can document. |
| Buy, rent or replace | new modules, rentals and pilots for US projects, and replacement membranes that fit many existing cassettes. |
Performance and life depend on pretreatment, design flux and operation; flux figures are Zyramic design guidance, sized to each project.
Frequently asked questions
How much smaller is an MBR than conventional treatment?
It varies with design, but removing clarifiers and filters and running higher MLSS usually saves a large share of the process area.
Is a compact plant harder to operate?
It needs good screening and a regular cleaning routine, but many operators find MBR effluent quality easier to keep consistent.
Can you retrofit an existing small plant?
Often. Send drawings and we will check whether Swing or Palisade modules fit.
Do you offer a trial?
Rental modules are available for US pilots and interim capacity.
What MLSS do compact MBR plants run at?
Many run several times the MLSS of conventional plants, within the membrane manufacturer's recommended range. Higher MLSS needs more aeration, so blowers must be sized accordingly.
Can a compact plant meet reuse standards?
MBR filtrate is a common basis for reuse after disinfection, subject to local regulations and any additional treatment they require.