Rectangular treatment tanks with steel railings beside a brick building

Representative photo. Your order is made to your specification by a verified seller. Photo: “Trout Run Sewage Treatment Plant II” by Montgomery County Planning Commission, CC BY-SA 2.0.

On site built STP supplier in Bangladesh

Roptan acts as your on site built STP supplier in Bangladesh. Send the flow, the users and the building drawings: we source a seller who designs the tanks and equipment, check the design and each tank test, and deliver the equipment to site.

Verified sellers
Checked before it ships
Delivered by Roptan

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

Buying on site built STP in Bangladesh

An on site built STP is a sewage treatment plant whose tanks are cast in reinforced concrete, or welded from steel sections, at your site. The seller then fits the blowers, diffusers, pumps and control panel. Developers, hospitals, housing projects and factories in Bangladesh choose it for flows too large for a packaged unit, or where the tanks are designed into the building itself.

An on site built STP supplier in Bangladesh carries two jobs, civil work and process equipment, and the line between them must be clear. We have verified sellers quote both to one design basis, check the tank design and each tightness test, and deliver the equipment. The seller installs and commissions it. You can also post the requirement on our board.

Kinds of on site built plant

Concrete extended aeration plant

Rectangular or circular concrete tanks with a long aeration time, typically 24 to 48 hours, so the volume is large. Choose it for large, steady flows on a site with room to excavate.

Tanks built into the building

The tanks form part of the basement or foundation, designed with the structure. Choose it for new buildings. Adding tanks to an existing building can mean significant structural change.

Field-welded steel tank plant

Steel sections are brought to site and welded into tanks. Choose it where a large concrete pour is hard to arrange, and ask for the coating system that protects the steel.

MBBR retrofit in existing tanks

Plastic carriers are added to existing concrete aeration tanks to raise capacity without a larger footprint. Choose it when a building already has tanks that no longer cope.

How to specify an on site built STP

Flow and population: State users and daily flow. One common definition takes 1 PE as 60 g of BOD and 200 litres a day; the seller should state the figures it used.
Tank design code: Ask which code the liquid-retaining tanks are designed to. EN 1992-3 is the European code for concrete liquid-retaining structures; others may be used.
Groundwater and uplift: An empty buried tank in wet or flooded ground can float. Ask for the uplift check for desludging and maintenance, when the tank is empty.
Tightness test: Each tank is filled with water, held, and the drop in level measured before equipment is fixed. Ask for the method and the record.
Scope split: Say who digs, casts, waterproofs and backfills, and who supplies the equipment. Write the hand-over point between civil and process work.
Sludge route: Leave room for a drying bed or tanker access. Dewatered sludge is taken off site for disposal, so plan the route.

Standards and papers for on site built plants

ECR 2023 limits and DoE clearance: The plant must meet the ECR 2023 limits, stated in the design basis. Your consultant should confirm the project's green, yellow, orange or red category.
EN 1992-3: Eurocode 2, Part 3, for liquid-retaining and containment concrete structures. A designer may use it or another code; the drawings should say which.
EN 12255-6 and EN 12255-10: European parts on activated sludge design and on safety principles, covering access, covers and gas around tanks. Not Bangladesh rules.
ISO/IEC 17025 and ISO 5815-1: Outlet samples go to an accredited lab, with BOD measured to ISO 5815-1. Each BOD result takes five days.

What moves the price of an on site built STP

Excavation depth, groundwater and the anchoring or ballast against uplift.
Concrete volume, reinforcement and waterproofing for the tank walls and slabs.
Process equipment: blowers, diffusers, pumps, controls and the standby units for each.
Whether civil work sits with the seller or your own contractor.

Lead times and delivery

Time depends on the job, so Roptan quotes dates for each order rather than a standard figure. Excavation in the monsoon, high groundwater, casting and curing, and a failed tightness test all add time. Imported equipment takes longer for sea freight and customs clearance at Chattogram. Work in an occupied building is slower again. Roptan confirms the dates and any minimum in the quote.

We deliver the process equipment to your site anywhere in Bangladesh once the tanks have passed their tightness tests. The seller installs it, seeds the plant and runs it until the outlet meets the agreed limits. Handover includes the tank test records, as-built drawings, lab reports, operating manual and a VAT invoice (Mushak 6.3).

What we check for this order

Tank designWe ask for the structural drawings, the design code and the uplift check before casting starts.
Tightness test recordWe confirm each tank was filled, held and measured for leaks before any equipment is fixed.
Civil and process scopeWe check that excavation, waterproofing, equipment and commissioning each have an owner in the contract.
A running plantWe ask for a working on site plant of similar size by the same seller, and arrange a visit.

Questions buyers ask

Who builds the concrete tanks?

Either the STP seller or your own civil contractor, working to the seller's drawings. Both work, but the hand-over point must be written down: who answers for a leak, and who answers for the outlet. We get that split agreed before the order is placed.

How is a concrete tank tested for leaks?

Each tank is filled with clean water, left to stand, and the drop in level is measured over a set period. A tank that loses water is repaired and tested again. Ask the seller for the method and keep the record in the handover file.

Can we add an STP to an existing building in Gulshan?

Possibly, but plan for structural work. A Dhaka Tribune report of 31 July 2026 described a government directive requiring buildings in Gulshan, Banani, Baridhara and Niketan to install septic tanks, soak wells and, in some cases, STPs. Owners quoted in the report raised retrofit cost and structural change, so start with a structural survey.

Can existing concrete tanks be upgraded?

Often. MBBR carriers are commonly added to existing activated sludge tanks to raise capacity without a larger footprint. The seller has to check the tank, the aeration grid and the outlet sieves first, and show the new design load in writing.

How soon will I hear back about STP?

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.