What a Containerized MBR STP Actually Delivers
A containerized MBR STP is a pre-engineered membrane bioreactor assembled inside a standard 20 ft or 40 ft high-cube (HC) shipping container, integrating biological treatment with submerged ultrafiltration at a nominal pore size of 0.04 µm (Pure Aqua MBR-C datasheet, S3; S2). The fixed process train runs feed through a 1.5 mm drum screen, into an anoxic/aerobic biological stage, then through a submerged PVDF UF membrane tank before disinfection. Stock expected permeate from the MBR-C envelope is BOD <10 mg/L, COD <50 mg/L, TSS <5 mg/L, and NH4-N <2 mg/L (Pure Aqua MBR-C datasheet, S3). A single 20 ft HC unit typically handles up to ~50 m³/day, while a 40 ft HC unit covers ~50–200 m³/day, with multiple containers parallelable for larger flows (Pure Aqua MBR-C datasheet, S3; Pure Aqua MBR-C product page, S4; S2).
For La Paz and El Alto, the format is well suited to small residential developments (50–300 homes) and 100–400-person construction or mining camps because the unit arrives on a flatbed, drops onto a concrete pad, and needs only mains power and piped influent to start. No reinforced basins, no long civil schedule. For camps with 2–5 year horizons or phased housing, the container can be lifted out and redeployed. A containerized MBR membrane bioreactor system with built-in PLC control covers the full process train in a single skid (S2). The following steps detail how to calculate the specific requirements for these high-altitude environments.
Step 1 — Fix the Design Population and Per-Capita Flow
Design starts at 190 L/c/d — the 50 gpd per-capita baseline used in Pure Aqua's MBR-C datasheet (Pure Aqua, S3) — and adjusts up or down against an on-site water-use survey. That figure is a baseline, not a universal rule. Lift it to 200–250 L/c/d for labour and construction camps with shared showers, kitchen messes, and laundry. Use 130–180 L/c/d for steady residential developments where occupants are full-time and water fixtures are limited (S2).
Get the occupancy profile right before you commit. Full-time residential is steady; seasonal construction is peak for 3–6 months; a shift-worker camp produces a sharp daytime peak that affects the next step. Add 5–10% to the design headcount for visitors and guests, and confirm whether the camp is single-shift, double-shift, or 24-hour, because the morning shift-changeover surge on a single wash block is the single most common cause of under-sized equalization (S2). Worked example for a 250-person mining camp: 250 × 220 L = 55,000 L/day ≈ 55 m³/day average. If the camp has full showers and a canteen, lift the per-capita value to 220 L; if the camp is light on fixtures, drop to 190 L. Either adjustment changes Qavg and propagates into the next two steps.
Step 2 — Apply a Peak Factor and Derive Qpeak
A membrane bioreactor is rate-limited at the membrane cassette, so size for peak hourly flow (Qpeak) rather than Qavg. Apply a peak factor (PF) of 2.0–2.5 for camp occupancies and 1.5–1.8 for steady residential developments; Qpeak = Qavg × PF (S2). The factor matters because the membrane tank's internal equalization volume is finite — if the buffer is too small, influent surges push transmembrane pressure (TMP) up, shorten cleaning intervals, and risk compliance excursions during peak windows.
Worked example for a 250-person mining camp at 220 L/c/d: Qavg = 250 × 220 L = 55,000 L/day ≈ 55 m³/day. With PF 2.2, Qpeak = 55 × 2.2 / 24 = 5.04 m³/h. If the camp has an extreme profile — for example, a single morning wash block serving the workforce in 90 minutes — specify external buffer storage of 4–6 hours of Qpeak rather than relying on the container's internal equalization. A conservative engineer sizes for the worst observed 4-hour window, not the 24-hour average (S2).
Step 3 — Match Qpeak to the Container Flow Envelope
Translating Qpeak into a specific container size requires adding 20–30% spare capacity above Qpeak for population growth, seasonal load spikes, and future reuse upgrades (S2). Stock envelope: 20 ft HC containerized MBR units handle up to ~50 m³/day; 40 ft HC units cover ~50–200 m³/day; multiple containers can be paralleled for larger flows (Pure Aqua MBR-C datasheet, S3; Pure Aqua MBR-C product page, S4; S2).
For a 250-person La Paz camp with Qavg 55 m³/day and Qpeak ~5 m³/h, a single 20 ft HC unit sits at the upper edge of its envelope with little spare — spec a 40 ft HC unit, or two parallel 20 ft units with one held as standby. For phased projects, install a 20 ft unit now, plumb the second pad, and add the second 20 ft when occupancy hits about 70% of design. The submerged PVDF cassette can be swapped or expanded without replacing the container (S2). All units need a flat 150 mm RC concrete pad, standard flatbed truck access, and mains power plus piped influent at the inlet.
| Parameter | 20 ft HC Unit | 40 ft HC Unit | Multiple Parallel Units |
|---|---|---|---|
| Indicative flow envelope | Up to ~50 m³/day | ~50–200 m³/day | Beyond 200 m³/day |
| Indicative population (at 190 L/c/d) | ~250 people | ~250–1,050 people | Sized to total Qpeak |
| Site access | Standard flatbed truck; tight sites | Standard flatbed; longer clear approach | Reserve space for each pad |
| Pad spec | Flat concrete pad, 150 mm RC typical | Flat concrete pad, 150 mm RC typical | One pad per container |
| Phasing option | Reserve space for a parallel second 20 ft unit | Multiple 40 ft units can be paralleled | Add a unit at ~70% of design occupancy |
| Membrane cassette | PVDF flat sheet membrane module — swappable | Same cassette type, expanded count | Independent cassettes per container |
Step 4 — Verify the Envelope Against La Paz Site Conditions
Site-specific checks prevent the most common integration issues on Bolivian projects. Four factors are critical. First, altitude: La Paz sits around 3,600 m and El Alto around 4,100 m; blower output for the fine-bubble aeration stage drops with atmospheric pressure, so a derating factor must be confirmed with the supplier. Request a numeric curve in writing before quotation. Second, ambient temperature: El Alto winter nights regularly fall below 5°C, outside the MBR-C stock operating range of 20–30°C with a 20°C design point (Pure Aqua MBR-C product page, S4). Enclosure insulation and any heating or heat-recovery option should be specified at quotation, and effluent polishing with a UV sterilizer for effluent polishing should be confirmed against the cold-water disinfection curve. Third, grid: Bolivia's standard supply is 220V/50Hz single or three-phase, which matches the local stock better than the Senegal case — but the 460V/3Ph/60Hz MBR-C stock spec (Pure Aqua MBR-C product page, S4) still requires a step-up transformer or a voltage-matched build for sites using 380–460V industrial supply. Fourth, influent sampling: run on-site sampling for at least 2 weekdays and 1 weekend day before finalizing the design; camp greywater can carry sand, hair, and plastics that overwhelm a 1.5 mm drum screen if upstream grit removal is skipped (S2). For background on the membrane stage itself, see the MBR membrane module design criteria for 2026.
| Parameter | Stock MBR-C Envelope (Pure Aqua MBR-C product page, S4) | La Paz / El Alto Typical Conditions | Action for Quotation |
|---|---|---|---|
| Operating temperature | 20–30°C, design point 20°C | El Alto winter nights below 5°C; daytime up to ~18°C | Specify enclosure insulation; confirm heating or heat-recovery option |
| Altitude effect on blowers | Not stated in stock datasheet | 3,600–4,100 m — reduced atmospheric pressure | Request altitude derating curve in writing from supplier |
| Electrical supply | 460V / 3Ph / 60Hz (Pure Aqua MBR-C product page, S4) | 220V / 50Hz standard Bolivian grid | Specify 220V/50Hz build or step-up transformer; confirm phase |
| Pre-treatment | 1.5 mm drum screen (Pure Aqua MBR-C product page, S4) | Camp greywater may carry sand, hair, plastics | Add upstream grit removal for camps |
| Effluent target | BOD <10 mg/L, COD <50 mg/L, TSS <5 mg/L, NH4-N <2 mg/L (Pure Aqua MBR-C datasheet, S3) | NB 512 series — confirm applicable standard | Match polishing to receiving environment (irrigation / sewer / watercourse) |
Common Sizing Mistakes on La Paz Projects
The failure modes below are the ones that show up most often on Bolivia specifications and that an engineer can audit against their own draft before issuing an enquiry.
- Forgetting visitors and guests — add 5–10% to the design headcount (S2).
- Under-counting a morning shift-changeover surge on a single wash block; a 90-minute peak needs external buffer storage of 4–6 hours of Qpeak (S2).
- Copying a hotel per-capita figure onto a camp with very different fixture counts (S2).
- Sizing for Qavg instead of Qpeak on a flux-limited membrane (S2).
- Quoting a stock 460V/3Ph/60Hz MBR-C unit for a Bolivian site without confirming voltage and phase, and without asking the supplier for an altitude derating curve for blowers and an ambient-temperature check for El Alto winter nights.
Frequently Asked Questions
What is the indicative price range for a containerized MBR STP sized for a 250-person La Paz camp?
The research data does not provide a quotation for a containerized MBR system. Pricing depends on container size (20 ft HC versus 40 ft HC), voltage build (220V/50Hz versus 460V/3Ph/60Hz), altitude derating for blowers, enclosure insulation for El Alto winter nights, and any effluent-polishing step required by the NB 512 discharge standard. Request a written quotation that itemises each of these line items rather than a single lump sum, so the altitude and cold-night allowances are visible.
How do I confirm a supplier can deliver for a 3,600–4,100 m site on Bolivia's 220V/50Hz grid?
Ask the supplier for two documents in writing before issuing a purchase order: an altitude derating curve for the fine-bubble blowers at 3,600 m and 4,100 m, and confirmation that the MBR-C build will be supplied as a
Frequently Asked Questions
What size containerized MBR STP do I need for a 250-person mining camp in La Paz?
For a 250-person mining camp, you should plan for a nominal capacity of approximately 45 to 50 cubic meters per day (m³/day). This calculation assumes a conservative hydraulic loading rate to account for peak flow variations common in mining environments.
Standard containerized Membrane Bioreactor (MBR) units for this capacity are typically housed in a single 40-foot high-cube shipping container. Ensure the selected unit provides a minimum hydraulic retention time (HRT) of 12 to 18 hours to maintain biological stability under variable loading conditions.
How does the altitude in La Paz or El Alto affect the sizing of a containerized MBR?
The high altitude of La Paz (approx. 3,600m) and El Alto (approx. 4,000m) results in lower atmospheric pressure and reduced oxygen transfer efficiency (OTE). You must increase the blower capacity by 20% to 30% compared to sea-level specifications to compensate for the lower partial pressure of oxygen in the process air.
Additionally, the air-cooled heat exchangers and internal combustion components often found in containerized systems require derating factors. Confirm with the manufacturer that all motorized equipment is sized for the lower air density to prevent motor overheating and premature failure.
What is the per-capita wastewater flow I should use to size a camp STP in Bolivia?
For mining camps in Bolivia, a design flow of 180 to 200 liters per person per day (L/p/d) is the recommended standard. This range accounts for typical domestic water usage including showers, laundry, and kitchen facilities found in remote worker accommodations.
It is advisable to apply a peak factor of 2.5 to 3.0 to this daily average when sizing the equalization tank and the membrane filtration module to ensure the system can handle morning and evening peak discharge periods without overflowing.
Do I need a step-up transformer if I install a stock 460V MBR unit in Bolivia?
Yes, a step-up transformer is likely required. Standard industrial power distribution in Bolivia is 380V/220V at 50Hz, whereas many "stock" containerized MBR units imported from North American markets are configured for 460V/60Hz.
Running a 60Hz motor on a 50Hz supply will cause it to run at a lower speed and potentially overheat, while the voltage mismatch will lead to improper torque output. Ensure your electrical design includes a transformer to convert 380V to 460V and a Variable Frequency Drive (VFD) adjustment to recalibrate pump and blower operations for the 50Hz frequency.
What influent and effluent parameters should I confirm with the supplier before buying a containerized MBR for a Bolivian project?
You must confirm that the influent BOD5 (Biochemical Oxygen Demand) design range is between 250 mg/L and 400 mg/L, and that the system is rated to handle Total Suspended Solids (TSS) up to 300 mg/L. These values represent standard domestic sewage loads for remote camps.
For effluent, verify that the MBR is guaranteed to meet Bolivian environmental discharge standards, typically requiring BOD5 < 30 mg/L, TSS < 30 mg/L, and Fecal Coliforms < 1,000 MPN/100mL. If the treated water is intended for dust suppression or irrigation on-site, request a system capable of tertiary-level filtration to ensure effluent turbidity remains below 1 NTU.
