How to Size a Containerized MBR STP in Chiang Mai, Thailand (2026 Guide)

Why a Containerized MBR Makes Sense in Chiang Mai

A containerized membrane bioreactor arrives in Chiang Mai as a 20' or 40' high-cube ISO unit with bioreactor tanks, blowers, pumps, submerged hollow-fibre UF modules and a PLC pre-assembled and factory-tested. Pure Aqua ships containerized MBR systems in 40' and 20' HC ISO containers with built-in drum screening, fine-bubble aeration, submerged PVDF hollow-fibre UF modules, and an integrated air-scour membrane cleaning system (Pure Aqua, 2025). MENA-Water's containers use stainless internal tanks, are quality-tested in the factory and target plug-and-play start-up, with more than 1,200 m³/day filterable inside a single 40' ISO unit (MENA-Water, 2025). For remote estate sites in Hang Dong, Mae Rim or Doi Saket where civil works should be minimised, that factory build is the main reason to choose the containerized MBR architecture at all.

Reuse is the second reason. The ultrafiltration stage on a containerized MBR retains virus and bacteria by 99.9999% (MENA-Water) and operates at nominal pore sizes of 0.04 µm (Pure Aqua) or, more generally, in the 2–100 nm ultrafiltration range that HUBER describes. On a Chiang Mai estate that wants to reuse treated water for landscape irrigation without a separate tertiary filter, the MBR's UF stage already does the work that a sand filter or disc filter would otherwise have to do. The operating envelope, however, is not generic: Pure Aqua states a design temperature of 20°C and an operating window of 20–30°C. Chiang Mai's cool-season nights can fall toward 15°C, so insulation and blower turn-down need to be confirmed in the RFQ rather than assumed from a datasheet.

A worked example using a HydropureWater integrated MBR membrane bioreactor system in the 10–2,000 m³/day range is the natural place to start the sizing calculation, and that is what the rest of this guide does.

The Five Sizing Inputs You Must Define First

Before any container count is meaningful, five inputs must be locked. None of them can be left to a manufacturer's "typical domestic sewage" assumption without inviting a redesign later.

1. Design population. For residential estates, count occupied units and apply the design occupancy per unit. For camps, use peak headcount including shift overlap. Pure Aqua's containerized MBR is benchmarked at 50 gallons per person per day (≈190 L/p/d), and that basis should be carried into the camp calculation unless fixture counts justify a different number.
2. Peak factor. Residential and camp sewage in Thailand is normally sized at 2.0–2.5× the average daily flow for hydraulic peak. The number to check is the membrane tank's acceptable peak instantaneous flux, not the daily average.
3. Influent load. Typical Thai domestic sewage carries around 200–250 mg/L BOD and a similar-order TSS, but camps with canteens, laundries or worker showers run higher. The manufacturer needs measured BOD, COD, TSS, NH₃-N and FOG, not a textbook value.
4. Effluent target. Reuse for landscape irrigation, surface discharge to a khlong, or reuse for toilet flushing each change the post-treatment train. Containerized MBR effluent is already <1 µm filtered, so disinfection is the variable step, not solids removal.
5. Site constraints. Available footprint, vehicle access for the 20'/40' HC unit, floor loading, and power supply. Pure Aqua's standard is 460V/3Ph/60Hz; Thailand is 380V/3Ph/50Hz, so a transformer or a Thai-spec motor set is mandatory. The 1.5 mm drum screen should also be located upstream of the container in the inlet works.

Worked Sizing Example for a 200-Person Resort in Mae Rim

The same five inputs can be turned into a defensible container count for any project. Take a 200-occupant resort in Mae Rim with mixed tourist and staff occupancy.

Step 1 — Average daily flow. 200 people × 190 L/p/d = 38,000 L/day, or 38 m³/day, using Pure Aqua's 50 gpd per capita reference.

Step 2 — Peak flow. Applying a 2.0–2.5× peak factor gives 76–95 m³/day peak. The membrane tank and equalisation must absorb this number, not the 38 m³/day average.

Step 3 — Organic load. At ~200 mg/L BOD, 38 m³/day carries roughly 7.6 kg BOD/day. That load is well inside the HydropureWater 10–2,000 m³/day integrated MBR range and is comfortably handled by a single submerged PVDF hollow-fibre UF train.

Step 4 — Container count. MENA-Water states that more than 1,200 m³/day is treatable in one 40' ISO container. A 38 m³/day average / 95 m³/day peak project fits easily in a single 20' high-cube unit, with margin for equalisation, the built-in 1.5 mm drum screen, and the air-scour cleaning system Pure Aqua lists as standard.

Step 5 — Membrane flux check. Cross-check instantaneous flux (L/m²·h) at peak flow against the chosen module. For the HydropureWater DF-series PVDF flat-sheet MBR membrane modules, the published per-module throughput range is 32–135 m³/day per module, and the module count falls out of that check. The same cross-check applies to hollow-fibre UF modules against the sizing chart the chosen manufacturer publishes. Do not assume a flux value without this check.

The same five-step logic scales to a 1,000-person worker camp in Mae Sot (≈190 m³/day average, 380–475 m³/day peak — still a single 40' HC) and to a 50-room boutique hotel in Doi Saket (≈19 m³/day average — a single 20' HC, or a buried package plant if the owner prefers).

Containerized MBR vs Buried Package Plant for Small Communities

For flows under about 50 m³/day, the architectural choice is not automatic. A buried A/O package plant and a containerized MBR both have a defensible place, and the right answer depends on reuse, mobility and operator model.

The HydropureWater WSZ underground A/O package sewage treatment plant is the right choice for a housing estate, small school or temple site where the flow is steady, reuse is not required, and the owner wants the tank out of sight. The containerized MBR wins above ~50 m³/day, wherever reuse for irrigation is a project requirement, and on any mobile or temporary project — worker camps, construction sites, event venues — because Pure Aqua's 20'/40' HC ISO format is seaworthy and relocatable, whereas the buried plant is permanent.

Container Count Lookup by Project Size

The bands below are derived from MENA-Water's published benchmark of more than 1,200 m³/day treatable in one 40' container and from the HydropureWater 10–2,000 m³/day integrated MBR range. They are sizing envelopes, not model numbers, and any RFQ should still be cross-checked against the chosen manufacturer's module sizing chart.

For a 100 m³/day worker camp, the answer falls in the 50–250 m³/day band: one 40' HC container with parallel modules is the starting configuration, sized against the same per-capita flow, peak factor and influent load the worked example above uses.

Cold-Season and Camp-Specific Risks to Check Before Ordering

The risks below are exactly the ones a generic equipment datasheet will not surface for a Chiang Mai site, and they are the most common reasons a containerized MBR underperforms in its first cool season.

• Cool-season temperature drop. Pure Aqua's design temperature is 20°C and the operating window is 20–30°C. Below 20°C, biological kinetics slow and membrane fouling risk rises. Specify insulated container walls (Pure Aqua lists insulated walls as standard) and confirm the blower can turn down for low-load night periods.
• Camp peak loads. Shift-change showers, canteen FOG spikes and weekend departures all produce hydraulic peaks well above residential patterns. The equalisation tank should be sized for at least 8–12 hours of average flow, not 2–4.
• Power and control. The Pure Aqua standard is 460V/3Ph/60Hz; Thailand is 380V/3Ph/50Hz. Confirm the manufacturer is supplying a Thai-spec motor set or a step-up transformer, and that the PLC supports remote monitoring for off-site estates.
• Sludge handling. Specify a sludge withdrawal line and a downstream dewatering plan — a plate-and-frame filter press or bagging — rather than letting the membrane tank act as a sludge store. Otherwise MLSS drift will choke the membranes within months. A rotary mechanical bar screen at the inlet works also reduces the solids load on that drum screen.

What to Send the Manufacturer in Your RFQ

To get a like-for-like quote, the RFQ has to carry the same five inputs that drove the sizing, plus a list of options the manufacturer should price in or out. A complete package is:

• Population, occupancy profile (residential vs camp) and applied peak factor.
• Influent BOD, COD, TSS, NH₃-N, FOG and design temperature — request these from the project hydraulic consultant if not already measured.
• Effluent target: reuse for irrigation, surface discharge to a khlong, or toilet flushing reuse.
• Site constraints: container footprint, vehicle access, available voltage and frequency, sound limits, and the membrane cleaning strategy preferred (Pure Aqua lists built-in air-scour cleaning as standard, with chemical cleaning as a maintenance step).
• Required options list: anoxic zone for denitrification, standby pumps, and remote monitoring (all three are listed by Pure Aqua as available options).

For a reader who wants a second opinion on the same calculation under tropical conditions, the containerized MBR STP sizing guide for Colombo walks through an equivalent worked example in a different grid and climate. For a deeper cost and ROI discussion under different power and tariff conditions, the MBR engineering guide with costs and ROI for the Middle East covers the financial side. If the plant is already built and underperforming, the article on seven common wastewater treatment failure modes and fixes is a useful diagnostic companion.

Frequently Asked Questions

What daily flow per person should I use to size a containerized MBR in Thailand?

Use 50 gallons per person per day, or about 190 L/p/d. Pure Aqua's containerized MBR sizing tables are explicitly built on that 50 gpd per capita reference (Pure Aqua, 2025). For camps with canteens, laundries or worker showers, ask the hydraulic consultant to confirm the number against measured fixture data before issuing the RFQ, because the per-capita flow will run higher than the residential benchmark.

How many containers do I need for a 100 m³/day worker camp?

One 40' high-cube ISO container, with parallel membrane modules and a standby pump for redundancy. MENA-Water's published benchmark is more than 1,200 m³/day treatable in a single 40' container (MENA-Water, 2025), and the HydropureWater 10–2,000 m³/day integrated MBR range covers the same band. Confirm the module count against the manufacturer's per-module throughput range, and ask the vendor to price an anoxic zone for denitrification if surface discharge limits apply.

Is a containerized MBR or a buried package plant cheaper for a small community?

Below about 50 m³/day, a buried A/O package plant is generally the more economical option because the civil works are simple and the plant runs unattended. Above about 50 m³/day, or wherever reuse for irrigation is a project requirement, the containerized MBR is the practical choice because it produces UF-grade effluent without a separate tertiary filter. Neither option has a published unit price in the research, so request a written quote for both architectures at your actual flow band before deciding.

What is the lead time for a containerized MBR delivered to Thailand?

The research does not publish a specific Thailand delivery window, so request a written lead time from each vendor covering factory build, sea freight, customs clearance and on-site commissioning. Items that consistently slow delivery to Thailand are the 380V/3Ph/50Hz motor or transformer re-spec, any added anoxic zone, and the membrane cleaning options — confirm each of these is on the order confirmation rather than left to be added later.

Related Equipment

• DF-series PVDF flat-sheet MBR membrane modules — specifications, capacity range, and technical data