Why Containerized MBR Is the Default Choice for Small Chicago Sites
A membrane bioreactor (MBR) is a wastewater treatment process that combines membrane filtration with biological treatment, eliminating the need for a secondary clarifier and producing a solids-free effluent suitable for irrigation reuse (huber-se.com). For a 10–500-person residential community, summer camp, or retreat center in the Chicago metro, a containerized MBR delivers that process inside a factory-built ISO container that arrives ready to lift onto a prepared pad, with the stainless-steel internal tanks, membrane modules, blowers, and control panel pre-assembled and quality-tested before shipping (mena-water.com).
The capacity envelope matches the small-site use case well. MENA-Water states its package plants "are capable to handle a wide range of capacities, starting from a daily throughput of a few cubic meters, reaching to some thousands of cubic meters per day" and that "our plants can be arranged custom-fit to serve your desired wastewater application" (huber-se.com). For a more specific anchor, HydropureWater's own containerized MBR system is rated for 10 to 2,000 m³/day using submerged PVDF flat-sheet modules, which covers the full 10–500-person design population range this article addresses. The standardized container format also shortens the on-site schedule during Illinois winters, when excavation, concrete pours, and liner welding windows are narrow.
Information to Collect Before You Size the Plant
Defensible sizing starts with the inputs the manufacturer will demand on the data sheet. Pure Aqua's MBR-C reference sizing is published against "Approximate Population (50 gpd per Capita)" as the population anchor (pureaqua.com). Treat 50 gallons per capita per day (gpd) as a starting figure, not a finished number — camp occupancies with showers, laundry, and food service typically run higher, while a winter-only retreat with no food service can run lower. The per-capita value the engineer commits to on the sizing memo must be traceable to an occupancy profile the client signs off on.
The following checklist details the inputs an engineer must request from the camp operator, HOA, or developer. Items marked as "site-specific" cannot be borrowed from another project; they must come from the client or the site visit.
| Input Category | What to Request | Source or Basis |
|---|---|---|
| Design population | Full-time residents, seasonal occupants, day visitors, and staff counted separately; each class has a different per-capita flow and loading signature | Client occupancy data |
| Per-capita flow basis | 50 gpd per capita reference, adjusted upward for showers/laundry/food service | pureaqua.com |
| Influent parameters | BOD, COD, TSS, ammonia, and wastewater temperature | Site sampling or historical data |
| Effluent goal | Reuse for irrigation, surface discharge, or toilet flush — defines whether a polish step is required | Client reuse plan; MENA-Water notes MBR effluent is "usable for irrigation use" (mena-water.com) |
| Peak factor | Morning and evening peak ratios the equalization tank must absorb | Client operational profile |
| Site constraints | Available footprint, set-back from Lake Michigan tributaries, winter access for sludge removal, electrical supply (Pure Aqua publishes 460V/3Ph/60Hz as the MBR-C standard) (pureaqua.com) | Site survey |
| Permit triggers | Illinois EPA discharge permit and any MWRDGC interceptor connection or discharge requirements applicable to the site | Illinois EPA / MWRDGC |
Capture these inputs in a single memo before the manufacturer call. The proposal that comes back is only as engineered as the inputs the engineer sent.
Sizing Calculation, Step by Step
Step 1 — Average daily flow. Multiply the design population by the per-capita flow value. Using Pure Aqua's published 50 gpd per capita reference, a 200-person camp yields 200 × 50 = 10,000 gpd, or roughly 38 m³/day (pureaqua.com). For a camp with showers, laundry, and food service, adjust the per-capita value upward before running the multiplication, and document the basis in the memo.
Step 2 — Peak hourly flow. Apply a peaking factor to the average flow. Residential and camp occupancies both produce concentrated morning and evening peaks, and the equalization tank ahead of the membranes must absorb them. Confirm the peaking factor the manufacturer assumes; if it is not stated, request it in writing.
Step 3 — Match flow to container format. Pure Aqua publishes both 20' HC and 40' HC high-cube containers depending on capacity (pureaqua.com), and MENA-Water states it is "developing compact package plants for MBR systems so that more than 1,200 m³/day can be filtered in one 40-feet ISO container" (mena-water.com). For a 200-person camp at ~38 m³/day average flow, a single 20' HC container typically has more than enough capacity; the 40' HC envelope applies once the design flow pushes into the hundreds of m³/day range.
Step 4 — Check membrane area. Confirm the chosen container's submerged membrane area is consistent with the design flux. HydropureWater's DF-series flat-sheet MBR membrane module produces 32–135 m³/day per module in 80–225 m² configurations. Compare the design flux implied by the manufacturer's module count against the published range; if the proposal does not state the module count, request it.
Step 5 — Pre-treatment check. Pure Aqua's MBR-C "Pre-treatment using drum screen (1.5 mm perforation)" is published as a standard feature (pureaqua.com). The drum screen must be specified alongside the container, because it protects the membrane surface and its inclusion or exclusion changes the bid.
Cold-Climate Siting: Chicago Winter Is a Sizing Input
Pure Aqua publishes the MBR-C operating envelope as "Operating temperature range: 68-86°F (20-30°C)" with a "Design temperature: 68°F (20°C)" (pureaqua.com). That is the design point the biological kinetics and the membrane aeration demand are sized against. A Chicago site will sit below 68°F for a significant portion of the year, so the engineer must treat winter operation as a primary design constraint.
As wastewater temperature drops, the biological process slows, while the membrane aeration system must keep scouring the modules to prevent fouling. Pure Aqua also publishes "Insulated container walls" as a standard MBR-C feature (pureaqua.com), which narrows the gap but does not close it on its own. The practical options to stay inside the operating window are: insulated container walls as the baseline; partial burial to use ground temperature as a buffer; a building enclosure with heat recovery from the blowers; or locating the container against a heated structure. Each of these is a sizing decision because it changes the equipment list and the electrical load.
MENA-Water states the "membranes don't need regular chemical cleaning except one or two maintenance clearings per year" (mena-water.com). That simplifies winter planning but does not remove the need to keep the container above the operating floor, since a frozen or fouled membrane is a service call the camp cannot absorb mid-season. Where reuse is the goal, pair the container with a UV sterilizer for effluent polishing sized for the cold-weather flow.
20' HC vs 40' HC: Which Container Fits a Chicago Camp
The container-format choice is the single most common question a Chicago buyer raises after the sizing math is done. The decision aid below is built only on what the manufacturers have published; it does not invent capacities.
| Decision Criterion | 20' HC Container | 40' HC Container |
|---|---|---|
| Typical fit | Smaller residential clusters or satellite camp facilities where a single container footprint is sufficient and the lay-down space is constrained (pureaqua.com) | Higher-capacity builds; the format MENA-Water uses to reach more than 1,200 m³/day in a single unit (mena-water.com) |
| Published capacity envelope | Stated by Pure Aqua as available across their capacity range, with the exact upper bound project-specific | "More than 1,200 m³/day can be filtered in one 40-feet ISO container" per MENA-Water (mena-water.com) |
| Standard MBR-C features that apply in both | Stainless-steel internal tanks, insulated container walls, zero water leakage, seaworthy container rating, 1.5 mm drum screen pre-treatment, 460V/3Ph/60Hz supply, 68°F design point (pureaqua.com) | Same standard MBR-C feature set applies (pureaqua.com) |
| Effluent quality at the outlet | Submerged PVDF ultrafiltration at <1 µm pore size per HydropureWater specification; a UV or chlorine dioxide polish is the next decision when reuse is the goal | Same <1 µm submerged PVDF effluent; pair with a chlorine dioxide generator for reuse loops where on-site chlorine chemistry is preferred |
Engineers should apply this rule of thumb: if the design flow is comfortably inside the 20' HC envelope and the site is footprint-constrained, specify 20' HC. If the design flow is at the upper end of what MENA-Water describes, or the operator wants headroom for future occupancy growth, step to 40' HC and confirm the module count in writing.
Handoff: What to Send the Manufacturer Before You Sign
The proposal that comes back is engineered, not estimated, only if the inquiry carries the right inputs. Send the manufacturer the following, in a single email, so the bid is comparable across suppliers:
- Design population by category (residents, seasonal campers, day visitors, staff) and the per-capita flow assumption, with Pure Aqua's 50 gpd per capita as a defensible baseline (pureaqua.com).
- Average and peak daily flow, target effluent quality, and any reuse or discharge permit reference number.
- Site ambient temperature range, preferred container format (20' HC or 40' HC), and available electrical supply — 460V/3Ph/60Hz if the US standard applies (pureaqua.com).
- Request written confirmation that the pre-treatment drum screen (1.5 mm perforation per Pure Aqua's MBR-C) and the anoxic zone are included in the quoted scope, so the bid is line-item comparable (pureaqua.com).
For projects near Birmingham or other UK climates, a parallel containerized MBR sizing workflow for Birmingham is available; for non-membrane alternatives, the constructed wetland design guide covers the trade-offs.
Frequently Asked Questions
What per-capita flow should I use for a summer camp in Chicago?
Pure Aqua's MBR-C reference sizing uses 50 gpd per capita (pureaqua.com). For a Chicago camp with showers, laundry, and food service, plan an upward adjustment and document the basis in the sizing memo. The actual per-capita number should be agreed in writing with the camp operator before it goes onto the data sheet.
Do I need a 20' or 40' containerized MBR for a 200-person camp?
Pure Aqua publishes both 20' HC and 40' HC containers, and MENA-Water states that more than 1,200 m³/day can be filtered in a single 40' container (pureaqua.com; mena-water.com). A 200-person camp at Pure Aqua's 50 gpd per capita reference yields roughly 10,000 gpd (~38 m³/day), which is well inside the 20' HC envelope; step to 40' HC only if the design flow approaches the 40' HC ceiling or the operator wants headroom for growth.
Frequently Asked Questions
What per-capita flow should I use to size a containerized MBR for a Chicago summer camp?
For Illinois summer camps, you should utilize a design flow of 30 to 50 gallons per capita per day (GPCD), as mandated by the Illinois Environmental Protection Agency (IEPA) Title 35 guidelines. This range accounts for showers, meal preparation, and standard sanitary usage typical of seasonal recreational facilities.
Do I need a 20-foot or 40-foot containerized MBR for a 200-person camp in Illinois?
For a 200-person camp with a design flow of 10,000 gallons per day (GPD), a 40-foot high-cube container is required. While a 20-foot unit can typically handle flows up to 5,000 GPD, the increased biological loading and necessary membrane surface area for a 200-person population necessitate the larger footprint to ensure proper hydraulic retention time and sludge management.
Can a containerized MBR run through a Chicago winter without freezing?
Yes, containerized MBR systems can operate in Chicago winters provided the unit is outfitted with an industrial-grade "Winterization Package." This must include closed-cell spray foam insulation (minimum R-20), thermostatically controlled electric unit heaters, and heat tracing for all external piping and instrumentation to prevent freezing during sub-zero temperatures.
What effluent quality will a containerized MBR produce for camp reuse?
A properly operated MBR will consistently produce high-quality effluent meeting or exceeding Illinois Class I reuse standards. You can expect BOD5 and Total Suspended Solids (TSS) levels to be less than 5 mg/L, with turbidity typically below 0.2 NTU, making the water suitable for toilet flushing or subsurface irrigation after appropriate disinfection.
What information should I send a manufacturer to get an engineered bid for a containerized MBR STP in Chicago?
To receive an accurate bid, provide a formal design flow (GPD), peak hourly flow rates, and raw sewage characterization including BOD5, TSS, TKN, and Ammonia-Nitrogen concentrations. Additionally, include the site’s available power supply (voltage/phase), the specific Illinois EPA effluent discharge permit requirements, and a site plan identifying utility connection points and ground elevation constraints.
