What a containerized MBR STP actually contains
A containerized membrane bioreactor (MBR) is an activated-sludge biological reactor coupled with submerged ultrafiltration membranes, packaged inside a single ISO container with all blowers, permeate pumps, pipework and a control panel pre-assembled and tested at the factory. According to MENA-Water's MBR product page, the ultrafiltration core delivers a 99.9999% reduction in virus and bacteria, and the membrane surface is kept clean by continuous bubble-diffuser air-scour rather than routine chemical cleaning—typically only one or two maintenance cleans per year (MENA-Water, mena-water.com).
The same page describes two layout options that directly affect how a Bangkok buyer sizes the unit: the U-Version, where aeration and buffering happen in underground water tanks on-site, and the I-Version, which is fully integrated and mobile for projects that may be relocated. A typical containerized MBR system arrives as one or two ISO skids, plugs into power and a sewage inlet, and discharges a low-SS permeate that requires downstream disinfection before reuse or decentralized discharge.
Bangkok-specific sizing inputs to lock down first
The design basis must be established before any calculation begins. For a Bangkok condo, housing estate, worker camp or seasonal camp, the inputs a Thai engineer will be asked to defend on a Pollution Control Department (PCD) submission are: design population, occupancy profile (permanent residential versus shift-change or seasonal loading), per-capita water use, sewage return ratio, peak factor, influent BOD₅, COD/BOD ratio, ambient temperature range, available footprint, and the PCD effluent class the project must hit. Bangkok's year-round hot climate keeps mixed-liquor kinetics active, which generally works in favour of compact MBR designs, but the manufacturer's net-flux rating must still be temperature-corrected for the design condition. The IDA Water Security Handbook (2019) confirms the unit conversions a sizing sheet depends on — 1 m³ = 1,000 L, 1 MIGD = 4,546 m³/day, 1 MGD = 3,785 m³/day — but does not publish a per-capita domestic sewage flow, so that number is an engineering assumption the buyer must defend from a Thai or project-specific source. A defensible starting point for a residential or camp project is shown below, with project-specific values the engineer must confirm:
| Design input | Typical value to confirm | Source / note |
|---|---|---|
| Per-capita water use (Lpcd) | Project-specific; confirm with the estate or camp operator | Not provided in the supplied research |
| Sewage return ratio | Project-specific; typically 0.8–1.0 of water use | Not provided in the supplied research |
| Peak factor (ADWF → peak flow) | Engineering assumption to confirm with the design engineer | Not provided in the supplied research |
| Influent BOD₅ | Project-specific; conventionally 200–250 mg/L for domestic sewage in tropical conditions | Confirm by sampling or local PCD guidance |
| Ambient temperature | Bangkok year-round, typically > 25 °C; confirm with site data | Manufacturer applies temperature correction to flux |
| PCD effluent class | Project-specific; decentralized discharge limits set by PCD | Confirm with PCD submission scope |
| Unit conversions (1 m³ = 1,000 L; 1 MIGD = 4,546 m³/day) | Fixed | IDA Water Security Handbook, 2019 |
The containerized MBR sizing guide for Colombo uses the same four-step flow and shows how the influent BOD₅ assumption shifts the aerobic volume.
Step-by-step sizing calculation for a residential or camp MBR
The calculation below is the method a Bangkok engineer can write onto a PCD drawing and defend line by line.
- Step 1 — Average dry weather flow (ADWF): multiply the design population by the per-capita sewage allowance in litres per capita per day (Lpcd) to obtain m³/day; divide by 24 to convert to m³/h. This is the number the equalization tank and the membrane rack are sized against on a time-averaged basis.
- Step 2 — Peak flow: multiply ADWF by a peak factor that reflects the morning surge in a residential estate and the shift-change surge in a worker camp. The exact peak factor is an engineering assumption the design engineer must confirm for the occupancy profile; the equalization tank and the membrane feed pump must pass this peak without overwhelming the bioreactor.
- Step 3 — BOD₅ load and aerobic volume: multiply the population by the per-capita BOD₅ contribution in grams per person per day and divide by 1,000 to obtain kg BOD/day. Size the aerobic volume from the target mixed liquor suspended solids (MLSS) and hydraulic retention time (HRT) the submerged MBR needs; these are project inputs the membrane manufacturer will confirm against the module geometry. MENA-Water notes that the inside tanks of a single 40-ft container are built from stainless steel sheets and that the package plant is factory-quality-tested, which means the aerobic volume in a standard unit is a known envelope (MENA-Water, mena-water.com).
- Step 4 — Membrane area and container count: divide the design flow (m³/h, after any internal recycle) by the manufacturer's net flux in L/m²·h for the chosen PVDF hollow-fiber or flat-sheet module to obtain the submerged membrane area required. MENA-Water states that more than 1,200 m³/day can be filtered in a single 40-ft ISO container (MENA-Water, mena-water.com); if the design flow exceeds that ceiling, the calculation forces two or more parallel containers. A typical DF-series flat-sheet MBR module ships with a manufacturer-rated gross and net flux at the design temperature, which is the number to use here.
Each step ends with a deliverable that can be ticked off on a datasheet — m³/day, peak m³/h, kg BOD/day, m² membrane area, and container count — so the PCD reviewer can audit the chain from population to ISO skid.
Choosing between 20-ft, 40-ft and split-skid configurations
The container layout is an engineering choice based on project requirements. MENA-Water's 40-ft ISO container is the single-unit ceiling, rated at more than 1,200 m³/day with stainless-steel internal tanks and a factory-tested control panel (MENA-Water, mena-water.com). A 20-ft container fits small residential blocks, sub-100-person worker camps, and pilot duty where plug-and-play mobility matters; SIGMADAF markets the 20-ft format as compact and modular for this decentralized duty (SIGMADAF, YouTube product video, 2025-01-27). When the design flow sits between the practical lower limit of a 20-ft unit and the 1,200 m³/day 40-ft ceiling, a split arrangement is often the most buildable answer: an equalization tank (above-ground or following the MENA-Water U-Version concept of underground buffering) ahead of a dedicated MBR container, with a small downstream disinfection skid. A practical decision table:
| Configuration | Indicative envelope | When it fits a Bangkok project | Key layout note |
|---|---|---|---|
| 20-ft ISO container (fully integrated) | Smallest skid; lower flow ceiling per unit | Small residential blocks, sub-100-person worker camps, pilot duty, relocatable seasonal camps (MENA-Water I-Version concept, mena-water.com) | Compact and modular footprint; single power and control interface (SIGMADAF, 2025-01-27) |
| 40-ft ISO container (fully integrated) | Up to > 1,200 m³/day in one unit (MENA-Water, mena-water.com) | Medium housing estates and large worker camps where one container is enough | Largest single-skid envelope; factory quality-tested |
| Split-skid: equalization + MBR + disinfection | Equalization sized to morning/shift peak | Mid-range flows, sites with landscaping or flood-elevation constraints, MENA-Water U-Version with underground buffering (MENA-Water, mena-water.com) | Multiple site interfaces; civil works in parallel with container delivery |
A Bangkok site with tight landscaping or a flood-elevation constraint usually pushes the engineer toward the U-Version (underground buffering) with a smaller above-ground MBR skid; a seasonal camp that may be dismantled and moved points to the I-Version (fully integrated, mobile). The containerized MBR system format in either version still needs the same headworks and disinfection peripherals that change the total site footprint.
Pretreatment and post-treatment that change the size
A containerized MBR is part of a larger treatment train. Upstream of the MBR container, a Bangkok site still needs a rotary bar screen to remove rags and plastics that would blind the membrane, grit removal for camps with sandy or unsealed access roads, and a flow-equalization tank to absorb the morning or shift-change peak. Each of these is a small additional skid or civil tank outside the MBR container, and each one shifts the inlet hydraulics the MBR sees. Downstream, decentralized discharge in Thailand requires disinfection; a chlorine dioxide generator or a UV sterilizer is the typical choice, selected on the residual and footprint it leaves on a containerized site. Because the submerged MBR already delivers a 99.9999% virus and bacteria reduction (MENA-Water, mena-water.com), the post-treatment skid is sized for the dose required to meet PCD's total coliform target rather than for TSS polishing.
Sizing checklist to send the manufacturer before quoting
Send this list to the supplier so the quote is sized to the project:
- Design basis: design population, occupancy profile (permanent residential vs shift-change or seasonal camp), per-capita water use, sewage return ratio, peak factor, ADWF (m³/day), peak flow (m³/h), influent BOD₅, COD, TSS, ammonia, and the ambient temperature range on the Bangkok site.
- Effluent and compliance: PCD discharge class required, whether effluent is for reuse or decentralized discharge, and any residual chlorine or UV dose targets.
- Site constraints: available footprint, flood elevation, noise limits, and whether the unit must be relocatable (I-Version) or able to share aeration/buffering with underground tanks (U-Version), as described by MENA-Water (mena-water.com).
- Manufacturer confirmations to request: membrane module type (submerged hollow-fiber vs flat-sheet), module count, gross and net flux at the design temperature, air-scour blower duty, sludge yield, container layout, lifting points, and site interfaces (inlet, outlet, power, sludge).
- Commercial inputs: delivery terms to Bangkok, lead time, and any local content or import requirements. The compact sewage treatment unit cost guide lists the line items a Bangkok EPC should expect to see broken out.
Frequently Asked Questions
What per-capita sewage flow should I use in Bangkok?
The engineer must defend the Lpcd value from a project-specific source — typically a Thai utility design guideline, a recent water-bill analysis for the estate, or a measured figure from a comparable camp. Use a sewage return ratio of 0.8–1.0 of per-capita water use, and state both the Lpcd and the ratio on the PCD drawing so the assumption is auditable.
How many containers do I need for a 200-person worker camp?
Container count is the output of Step 4 of the sizing calculation. A 200-person camp at typical Lpcd and BOD₅ assumptions
Frequently Asked Questions
What per-capita sewage flow should I use to size an MBR for a residential project in Bangkok?
For residential projects in Bangkok, it is recommended to use a design flow rate of 200 to 250 liters per capita per day (lpcd). This range accounts for the high-humidity climate and typical water usage patterns in urban Thai residential developments.
How many 20-ft or 40-ft containers do I need for a 200-person worker camp in Thailand?
For a 200-person worker camp with an estimated daily flow of 30 to 40 cubic meters per day (m³/d), a single 40-ft high-cube containerized MBR system is typically sufficient. If site constraints or redundancy requirements necessitate splitting the process, two 20-ft containerized units may be utilized to provide a modular 50/50 load-sharing configuration.
Should I pick a 20-ft or 40-ft containerized MBR for a small Bangkok residential development?
A 20-ft container is generally preferred for small residential developments with flows under 20 m³/d due to its smaller physical footprint and easier transport through narrow Bangkok sub-sois. The 40-ft container is more cost-effective for larger developments exceeding 30 m³/d, as it provides a lower capital expenditure per cubic meter of treated water capacity.
How long does a containerized MBR take to ship from the manufacturer to a site in Bangkok?
For locally manufactured or regionally assembled units within Southeast Asia, the lead time from order to site delivery typically ranges from 8 to 12 weeks. If importing from international hubs such as Europe or North America, expect a lead time of 16 to 24 weeks inclusive of sea freight and local customs clearance at Laem Chabang or Bangkok Port.
What influent BOD₅ concentration should I design the MBR aeration tank for in a domestic sewage application?
The aeration tank should be designed for an influent BOD₅ concentration of 250 to 350 mg/L. This range aligns with standard domestic sewage characteristics in Thailand, ensuring the system maintains a robust Food-to-Microorganism (F/M) ratio and achieves the required effluent quality for non-potable reuse or discharge standards.
