How the single-orifice membrane works, how the body pipe and clamp rings are built, where the aerator is mounted, and which figures have to be confirmed for your tank.
← Back to Single-orifice Membrane AeratorA single-orifice membrane aerator is a fine-bubble aeration device used to supply oxygen to aerobic biological treatment, and it is most often found in aerated biological filters (BAF) and other fixed-film reactors, where aeration and biological oxidation take place in the same bed of media. It is also called a single-orifice membrane diffuser or single-hole membrane aerator.
The unit is built around an air branch pipe rather than around a single diffuser head. The pipe is the aerator body, and it carries one or more membrane stations along its length. Each station is an air port in the pipe wall covered by an elastic rubber membrane disc, and that disc has a single orifice at its centre. The membrane is held flat over the port by two moulded toothed clamp rings, one on each side of the port.
Because the membrane stations sit on a pipe, one air connection feeds a whole run of aeration points, and the aeration grid on the tank floor or on a filter plate is assembled from rows of these body pipes. A long-stem version is supplied for filter-plate mounting, with the membrane head standing above the plate.
Air from the distribution main enters the body pipe and passes along it to the air ports under the membranes. The pressure of the air lifts the elastic membrane away from the port, the single orifice opens, and the air is released into the water through that one opening as a stream of fine bubbles. Each station therefore releases from a single point rather than from a perforated area, and the membrane returns to its seat on the port when the pressure falls.
When the blower stops, the membrane relaxes back onto the port and closes the orifice. This self-closing behaviour is the reason this diffuser type is widely used in fixed-film beds: the orifice is shut to the water while the air is off, so wastewater does not drain back into the air main, and the orifice stays clear instead of silting up. The bubble stream produced while the blower runs supplies oxygen to the biofilm and at the same time keeps the bed stirred, so the aerator both oxygenates the water and mixes it.
The body pipe is supported on the tank floor or on the filter plate, and the support foot with its base plate carries the weight of the pipe and keeps the run level so that air is distributed evenly along the row.
A standard body pipe is assembled from the following parts:
The long-stem version is a single-station body: a longer pipe with the membrane head and its grooved barrel at the top end and a slotted foot at the other, for mounting through a filter plate so that the membrane head stands above the plate.
Body pipes and membrane heads are supplied to suit the grid, so station spacing, pipe length and the number of stations per pipe are set by the layout you need.
The membrane is made of EPDM (ethylene propylene diene monomer) rubber. It is chosen for its elasticity and its resistance to heat, ozone and acids and alkalis, which is what lets the membrane open and reseat through many aeration cycles without hardening or cracking.
Each membrane carries one orifice at the centre of the disc, and that single opening is the metering point of the station. Because there is only one opening per membrane, the air leaves each station from one defined point; the membrane itself seals that point when the air is off. Orifice diameter is not fixed across the range — it is chosen with the airflow per station, so it is confirmed for the duty rather than quoted from a table.
The membrane disc is held in place by the two toothed clamp rings rather than by a bonded or screwed fitting, which means the disc can be released and renewed at its own station on the pipe. Clamp rings, membranes and body pipes are all moulded components, and the body pipe is non-metallic, so the assembly is suitable for corrosive wastewater duties.
| Parameter | Value |
|---|---|
| Diffuser type | Single-orifice membrane (rubber-sleeve) fine-bubble diffuser |
| Product form | Air branch pipe with one or more membrane stations |
| Body material | ABS — other grades on request |
| Membrane material | EPDM rubber — other elastomer grades on request |
| Orifice per membrane | One, at the centre of the disc — diameter on request |
| Membrane retention | Two moulded toothed clamp rings per station |
| Stations per body pipe | On request |
| Body pipe bore | On request |
| Overall length per body pipe | On request |
| Air connection type & thread | On request — confirmed with the air main design |
| Airflow per unit | On request |
| Service area per diffuser | On request |
| Bubble diameter | On request |
| Oxygen utilisation | On request |
| Recommended water depth | On request |
| Service temperature | On request |
| Mounting | Rows on the tank floor; long-stem version through a filter plate |
| MOQ / price | On request |
Site performance depends on tank or filter-plate layout, water depth, airflow rate, diffuser density and station spacing, so every dimensional and performance figure is confirmed in writing against the ordered configuration and your tank design.
The aerator is used for aeration and oxygen supply in municipal domestic sewage and industrial wastewater treatment, and its main duty is aerated biological filtration. In a BAF or similar fixed-film bed, the aerator supplies the oxygen that the biofilm needs while the same bed carries out biological oxidation and solids retention, so the aerator is part of the treatment process rather than only a mixing device.
Typical duties include:
These notes describe the standard build of this diffuser type. Confirm bore, length, station spacing, orifice size and airflow against the ordered configuration before detailed engineering.