Circular settling tank with a blue rotating bridge

Representative photo. Your order is made to your specification by a verified seller. Photo: “ČBu, wastewater treatment plant 05” by Czeva, CC BY-SA 4.0.

Water and wastewater · Wastewater treatment plant

Clarifier supplier in Bangladesh

Roptan is a clarifier supplier in Bangladesh for scraper bridges, conveyor collectors and lamella packs. Send the tank drawing and the flows: we source the mechanism from a verified seller, check it against the drawing and deliver it to site.

Verified sellers
Checked before it ships
Delivered by Roptan

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

Buying clarifiers in Bangladesh

A clarifier is a settling tank with mechanical removal of the settled solids. It works twice in most plants: as a primary clarifier after screens and grit, and as a final clarifier after the biological stage, where it separates the biological floc from treated water.

Most buyers order the mechanism for a tank their contractor builds. A clarifier supplier in Bangladesh has to fit it to that tank exactly, so we source scraper bridges, drives, weirs, baffles and plate packs from verified sellers and check them against your drawing. The seller installs and commissions them.

Kinds of clarifier

Circular bridge clarifiers

A bridge rotates about the centre, carrying scraper and skimmer arms that push sludge to a central hopper. Usually chosen for larger single tanks in town and industrial plants.

Rectangular clarifiers

Long tanks cleared by conveyor-type collectors. Choose them where the plot shape or shared walls favour a row of tanks side by side.

Lamella plate settlers

Inclined plates give a large settling area in a small footprint, with no moving parts in the pack. Common at industrial sites short of space; the plates need regular cleaning.

Plate or tube pack retrofits

A bundle of inclined plates or tubes fitted in the clear water zone of an existing clarifier to raise its capacity without a new tank.

Dissolved air flotation instead

For oil, grease and light solids in industrial effluent, micro bubbles float the solids up rather than letting them sink. Compare it with settling where the solids do not settle well.

How to brief a clarifier supplier in Bangladesh

Position in the plant: Primary or final clarifier, and the process ahead of it: activated sludge, trickling filter or none. The solids and sludge volumes differ between the two.
Peak flow: Give peak as well as average flow. If flow through the tank is too high, particles have no time to settle and leave with the treated water.
Monsoon load: In a combined sewer catchment, stormwater raises the hydraulic load on clarifiers in the monsoon. State the wet weather peak and how long it lasts.
Inlet and weirs: Ask for the inlet baffle and overflow weir arrangement on the drawing, not only the diameter: they stop entry velocity carrying across the tank and keep settled solids down.
Sludge removal: State the scraper drive, the hopper position and the sludge pump duty, since the scraper pushes sludge to the hopper and a pump takes it to sludge treatment.
Materials: Name the material of the scraper, weirs and baffles, and for a lamella pack the plate angle and spacing. Plates are usually inclined at 50 to 70 degrees so they clean themselves.

Standards and tests for a clarifier

EN 12255-4:2023: The European part on primary treatment, replacing the withdrawn 2002 edition. Part 6:2023 covers the activated sludge process a final clarifier serves, and Part 1:2024 general design.
ECR 2023 Schedules 3 and 4: The clarifier must deliver the limit after it. The gazette lists suspended solids at 100 mg/L for treated sewage and for industrial effluent to inland surface water.
EN 872:2005 and ISO 5667-10:2020: Test effluent suspended solids by glass fibre filtration to EN 872 and sample to ISO 5667-10; the 1999 edition of EN 872 is withdrawn.

What moves the price of a clarifier

Tank size: a smaller tank at a higher overflow rate saves civil cost but raises the risk of solids carry-over at peak flow.
Mechanism type: a rotating bridge, a conveyor collector or a plate pack, and the span it must cover.
Materials of the scraper, weirs and baffles, and of the plates in a lamella pack.
A standby tank or a bypass, so one clarifier can be drained and desilted while the plant keeps running.
Cleaning access for plate packs, which add upkeep that open tanks do not.

Lead times and delivery

No fair figure covers every clarifier. Time grows with large spans, special materials, drives imported by sea and drawing changes after the tank is cast. A plate pack for a standard tank moves faster than a bridge built to a new diameter. Roptan confirms dates and any minimum in the quote.

We deliver the mechanism to site anywhere in Bangladesh, timed to when the tank walls are ready, with long bridge sections lifted by crane. The seller installs and commissions it and runs the scraper before handover. Handover includes the general arrangement drawing, O&M manual, drive data, warranty and a VAT invoice (Mushak 6.3).

What we check for this order

Drawing check before dispatchWe check the bridge or plate pack against the drawing: materials of scraper, weir and baffles, drive rating, plate angle and spacing.
Rated for peak flowWe confirm the offer is sized for your peak and monsoon flow, not average flow alone.
Inlet and weir layoutWe check the inlet baffle and weir arrangement is shown and matches the tank, not just the diameter.
Drain and desilt planWe confirm how a tank comes out of service for desilting, with a standby or bypass agreed where there is only one clarifier.

Questions buyers ask

Do we need a secondary clarifier with an MBBR or MBR?

An MBR replaces the clarifier with microfiltration or ultrafiltration membranes. An MBBR has no sludge return line, so its biology does not depend on a secondary clarifier. Ask the seller which solids separation step is in the offer and what it guarantees.

Can we raise the capacity of an existing clarifier?

Often yes. A pack of inclined plates or tubes fitted in the clear water zone of an existing conventional clarifier adds settling area without a new tank. Ask how the pack is supported and how it is reached for cleaning.

Circular or rectangular clarifier?

Circular tanks with a rotating bridge are usually chosen for large single tanks. Rectangular tanks with conveyor-type collectors suit a row of tanks with shared walls on a narrow plot. Land shape and the number of tanks you need usually decide it.

Why do lamella plates need cleaning?

Sludge slides down the plates as it settles and leaves a film behind, so the plates foul over time. Ask for the cleaning method and interval, and make sure the pack can be reached or lifted out.

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.