Churning brown water in a long concrete aeration tank beside a walkway

Representative photo. Your order is made to your specification by a verified seller. Photo: “Activated sludge sewage treatment plant aeration tank” by Marcos von Sperling, CC BY-SA 4.0.

Water and wastewater · Wastewater treatment plant

Aeration system supplier in Bangladesh

Roptan is an aeration system supplier in Bangladesh for diffuser grids, blowers and surface aerators. Send the flow, the BOD and ammonia loads and the tank depth: we source from verified sellers, check the oxygen figures and deliver to site.

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Delivered by Roptan

Prefer to deal with suppliers yourself? Post it on the requirement board

Buying aeration systems in Bangladesh

An aeration system does two jobs in a biological plant: it supplies oxygen to the microorganisms and mixes them with the organic matter. It is either subsurface, with diffusers on the tank floor fed by blowers, or mechanical, with aerators that draw air from the atmosphere. Sewage plants and factory ETPs across Bangladesh buy both.

Aeration usually takes the largest share of an activated sludge plant's power, so an aeration system supplier in Bangladesh should be judged on oxygen per unit of energy, not on purchase price. We take your loads and tank layout to verified sellers, check their transfer figures and the correction to wastewater, and deliver the equipment. The seller installs and commissions it.

Kinds of aeration system

Fine bubble diffusers

Discs, tubes, domes or plates in ceramic, plastic or perforated membrane, giving small bubbles and high oxygen transfer. The usual choice for activated sludge tanks; they need cleaning as they foul.

Coarse bubble diffusers

Fixed or valved orifices and static tubes. Their larger bubbles transfer less oxygen, so compare the air they need against fine bubble for the same demand.

Surface aerators

Cone aerators on the surface of an activated sludge tank, or fixed and floating units on lagoons. No blower house or air pipework is needed.

Brush and disc aerators

Horizontal rotors in an oxidation ditch that both aerate and drive the mixed liquor round the loop. Suited to sites with more land and simple operation.

Jet aerators

Air and liquid forced through a nozzle near the tank floor, submerged or floating. Used in lagoons, basins and deep tanks.

How to brief an aeration system supplier in Bangladesh

Loads: Oxygen demand follows the influent flow, the BOD load and the ammonia-nitrogen load. Give all three, average and peak.
Diffusers: Ask for airflow per diffuser and the number of diffusers, not only total air. US EPA data puts disc diffusers at about 18 to 24 cm across and 0.25 to 1.5 L/s each.
Water depth: Depth drives transfer: the deeper the diffusers sit, the more of the oxygen in each unit of air usually dissolves before the bubbles reach the surface. State the depth over the diffusers.
Correction to wastewater: Clean water figures must be corrected with the alpha factor, the ratio of transfer in process water to clean water. Ask for the alpha value used and its basis.
Mixing air: Fine pore diffusers are efficient at low airflow, so at the effluent end mixing, not oxygen, may set the air. Ask the seller to show both demands.
Air intake and material: On dusty sites, specify blower intake filters. For industrial effluent, check that the membrane material suits the chemistry, since membranes can be attacked.

Tests and standards for aeration equipment

EN 12255-15:2004: The European clean water test of oxygen transfer in activated sludge aeration tanks. Ask for results at your diffuser density and water depth.
ISO 1217:2009: Usually the acceptance test for positive displacement blowers; Amendment 1:2016 adds specific energy. Turbo blowers are usually tested to ISO 5389:2005.
EN 12255-6:2023 and 12255-12:2024: The current European parts on the activated sludge process and on control and automation, which frame aeration design and dissolved oxygen control.

What moves the price of an aeration system

Power: the US EPA puts aeration at about 50 to 65 percent of the net power of a typical activated sludge plant, so efficiency outweighs purchase price over the plant's life.
Diffuser type: fine bubble usually needs less air than coarse bubble for the same oxygen, but fouls and needs cleaning.
Cleaning and replacement, which depend on how easily diffusers come out and how quickly the basin can be drained.
Blower type, standby units and intake filtration.
Control: airflow and dissolved oxygen meters that let the blowers follow demand.

Lead times and delivery

No fair figure covers every system. Time grows with large or imported blowers, membranes in a special material, a grid laid out to an unusual tank and changes after the layout is approved. Standard diffusers for a common tank size move faster. Roptan confirms dates and any minimum in the quote.

We deliver to site anywhere in Bangladesh, with blowers lifted onto their bases. The seller lays and levels the grid, checks it before the tank is filled, commissions the blowers and trains your staff. Handover includes test reports, blower data, O&M manuals, warranties and a VAT invoice (Mushak 6.3).

What we check for this order

Clean water test basisWe check the oxygen figures come from an EN 12255-15 test at your diffuser density and depth, not a brochure value.
Wastewater correctionWe check the alpha factor and the corrected oxygen demand appear in the calculation, with peak load covered.
Material for your effluentWe confirm the membrane or diffuser material suits your wastewater, which matters more for industrial effluent than for sewage.
Cleaning method and intervalWe ask for the seller's diffuser cleaning method and interval, and for blower filter and meter calibration routines.

Questions buyers ask

Fine bubble or coarse bubble diffusers?

Fine bubble for most activated sludge tanks, because smaller bubbles transfer more oxygen for the same air. Coarse bubble transfers less, so it needs more air and blower power for the same demand. Ask both sellers for the air each needs at your load and depth.

Why do fine bubble diffusers lose performance?

They foul. Particles in the air, metal hydroxides and carbonates clog the pores, and a biofilm grows on the surface. Cleaning is by acid or alkaline washing, gas injection, high-pressure water jetting or air bumping. Good blower intake filters cut the air-side fouling.

How do I compare two aeration offers fairly?

Put both on the same basis: the same loads, depth, alpha factor and dissolved oxygen set point. Then compare oxygen delivered per kWh and the cleaning and replacement plan, not only the price of the equipment.

Does tank depth change blower choice?

Yes. A deeper tank transfers more oxygen for each unit of air, but the blower must push against a higher water head. Give the seller the depth over the diffusers so the blower pressure and the air volume are sized together.

How soon will I hear back about wastewater treatment plant?

Within 48 hours of a complete requirement, with a price and a delivery date. A requirement is complete when it has the capacity, where it is needed and by when.

Who do I deal with?

With Roptan, when Roptan manages the order: we buy from the verified seller and deliver to you. With the supplier directly, when you post on the requirement board and choose a quote yourself.