Why Ouagadougou Changes the Design
A Lagos, Stockholm, or Kampala design copy-pasted into a 2026 Ouagadougou build will fail on at least one of four non-negotiables. First, Harmattan: the December-to-February dust episodes load the basin with fine particulate that swings inlet turbidity and forces the side-stream filter and UF duty up, not down. Second, ONEA mains and Centre-region shallow borehole feed typically run 200–600 mg/L TDS, with silica at 8–20 mg/L as the conservative design point (HydropureWater field data, 2026, used here as the closest documented West/East African mains envelope — site-specific testing on the ONEA source must be commissioned before FEED).
Third, SONABEL industrial-tariff electricity makes water-treatment energy a material OPEX line: at $1.50–$3.00 per thousand gallons treated (HydropureWater field data, 2026), the OPEX curve favours high-recovery, low-energy unit operations over membrane-heavy imports. Fourth, Burkina Faso is landlocked: there is no marine outfall for brine concentrate, so concentrate handling is a structural cost line that the civil footprint, the EIA scope, and the operating budget all have to absorb from day one. The four-stage train — multi-media filter, side-stream screen, UF, BWRO — still applies, but it has to be re-scoped against Sahel feed and the Burkinabè brine path, not imported.
Feed Water Chemistry and Blowdown Mass Balance
The mass balance is the part most often under-engineered in an early Ouagadougou P&ID. ONEA mains and Centre-region shallow borehole feed run 200–600 mg/L TDS, with hardness-driven Langelier Saturation Index (LSI) sitting in the upper scaling band and silica at 8–20 mg/L as the conservative design point (HydropureWater field data, 2026). Target cycles of concentration (CoC) 5–6 for a 2026 Ouagadougou facility, with LSI and Ryznar Stability Index (RSI) held in the −0.5 to +0.5 band. Raising CoC from 4 to 6 cuts blowdown by roughly one-third (HydropureWater field data, 2026) — the cheapest freshwater-saving move before any membrane capital is committed. The blowdown stream at 1,200–6,000 mg/L TDS carries 10–50 mg/L suspended solids from corrosion products and biofilm fragments, plus accumulated biocides and corrosion inhibitors — the exact load the side-stream filter must knock down before any membrane (Genesis Water Technologies, 2026). For a 50 MW heat load at 80% cooling-tower efficiency, evaporation is approximately 99,537 kg/h; blowdown equals evaporation divided by (CoC − 1), so CoC 4 produces about 33,000 kg/h of blowdown versus about 19,900 kg/h at CoC 6 (HydropureWater field data, 2026).
| Parameter | Design value | Source |
|---|---|---|
| ONEA / Centre-region borehole TDS | 200–600 mg/L | HydropureWater field data, 2026 (West/East African envelope; site-specific testing required) |
| Silica (conservative design point) | 8–20 mg/L | HydropureWater field data, 2026 |
| LSI band | −0.5 to +0.5 | HydropureWater field data, 2026 |
| Target CoC | 5–6 | HydropureWater field data, 2026 |
| Blowdown TDS (CoC 4–6) | 1,200–6,000 mg/L | Genesis Water Technologies, 2026 |
| Blowdown suspended solids | 10–50 mg/L | Genesis Water Technologies, 2026 |
| Blowdown at CoC 4 (50 MW, 80% eff.) | ~33,000 kg/h | HydropureWater field data, 2026 |
| Blowdown at CoC 6 (50 MW, 80% eff.) | ~19,900 kg/h | HydropureWater field data, 2026 |
The Four-Stage Train, Re-Scoped for the Sahel
The four-stage logic is the same one used in coastal and East African builds, but every stage has to be sized against Sahel feed and the SONABEL grid profile.
Stage 1 — Intake pretreatment. A multi-media filter with automatic backwash cuts turbidity below 3 NTU and protects downstream RO; units sized for 10–200 m³/h are the standard first barrier (HydropureWater field data, 2026). During Harmattan episodes, turbidity swings can push above 50 NTU; specify coagulation ahead of the media filter to handle those events rather than treating them as freak conditions.
Stage 2 — Side-stream filtration. Self-cleaning 10–25 µm screen filters handle 1–5% of circulation flow and drop blowdown suspended solids to membrane-friendly levels; CAPEX lands at $50,000–$200,000 for a typical data-center installation (Genesis Water Technologies, 2026). This stage is the cheapest insurance against premature RO membrane fouling and is often under-specified in early P&IDs.
Stage 3 — Ultrafiltration. A PVDF hollow-fiber ultrafiltration skid with 0.03–0.1 µm pores, 90–95% recovery, 10–30 psi, and automatic backwash holds SDI15 below 3 to protect downstream RO and is the standard RO pretreatment on variable Sahel feed (HydropureWater field data, 2026). UF removes the bacteria, colloids, and biofilm fragments the side-stream screen cannot catch.
Stage 4 — Brackish reverse osmosis. An industrial brackish-water reverse osmosis skid at 75–85% recovery produces 10–50 mg/L TDS permeate for cooling-tower make-up; concentrate at 5,000–8,000 mg/L TDS is routed to a side-stream softener or a small mechanical vapor compression (MVC) polisher rather than discharged. A PLC-controlled antiscalant and biocide dosing skid handles pH adjustment, holds LSI neutral, and exports the SCADA logs an ANEVE audit will demand. On the Burkinabè grid, specify the dosing skid, blowers, and SCADA on generator backup — any membrane stage that cannot ride through a SONABEL transfer event is the wrong choice for a 2026 Ouagadougou build.
| Stage | Equipment | Key parameters | Cost / data point |
|---|---|---|---|
| 1 — Intake pretreatment | Multi-media filter with automatic backwash; coagulation ahead of media on Harmattan swings above 50 NTU | 10–200 m³/h; turbidity < 3 NTU downstream | Envelope per HydropureWater field data, 2026 |
| 2 — Side-stream filtration | Self-cleaning 10–25 µm screen filter | 1–5% of circulation flow | $50,000–$200,000 installed (Genesis Water Technologies, 2026) |
| 3 — Ultrafiltration | PVDF hollow-fiber UF | 0.03–0.1 µm; 90–95% recovery; 10–30 psi; SDI15 < 3 | HydropureWater field data, 2026 |
| 4 — Brackish RO | BWRO skid + PLC-controlled dosing skid | 75–85% recovery; 10–50 mg/L TDS permeate | 50,000 GPD skid at $250,000–$500,000 installed (Genesis Water Technologies, 2026) |
Concentrate Handling on a Landlocked Sahelian Site
Burkina Faso is landlocked, and that is the constraint that most often breaks a copy-pasted design. BWRO concentrate at 5,000–8,000 mg/L TDS is non-hazardous but cannot be discharged to ANEVE-regulated storm drains or surface water (HydropureWater field data, 2026, applied to the Burkinabè regulatory stack). The standard path is an on-site buffer tank plus either a licensed hauler to a registered disposal site or a lined evaporation pond sized for the dry-season evaporation rate — site-specific evaporation data must be requested from the Burkinabè meteorological service before FEED. The high-recovery polish option is a small MVC unit at 95–98% recovery producing distillate below 10 mg/L TDS, with CAPEX of $1–3M for 10,000–30,000 GPD capacity (Genesis Water Technologies, 2026); reserve that for water-scarce or ZLD sites, not baseline scope. The concentrate-handling decision must be locked in at FEED because the civil footprint and the EIA scope both depend on it.
Regulatory Stack: ANEVE, ONEA, and the EIA Path
The Burkinabè environmental and discharge regime is built on the Code de l'environnement and ANEVE (Agence Nationale des Évaluations Environnementes) project-level EIA requirements; a 5–20 MW data center crosses the EIA scope by default. Current ANEVE threshold tables and decree references must be confirmed with local counsel before FEED, but the project-level EIA will govern. ONEA (Office National de l'Eau et de l'Assainissement) sewer discharge limits typically cover TDS, TSS, BOD/COD, residual chlorine, pH, and temperature rise; a 2,000 mg/L TDS envelope and ΔT ≤ 5 °C are the conservative design points (HydropureWater field data, 2026, used as the documented West/East African benchmark pending site-specific ONEA permit confirmation). Specify the SCADA and chemical dosing skid to export flow, pH, conductivity, and temperature records automatically — manual logs do not survive an ANEVE audit. If chlorine disinfection is used upstream, a dechlorination stage is required before any sewer or surface-water discharge.
| Parameter | Burkinabè design point (conservative) | Design implication for an Ouagadougou data center |
|---|---|---|
| TDS | ≤ 2,000 mg/L (ONEA-style) | BWRO permeate at 10–50 mg/L is well below; concentrate handling is the design driver |
| pH | 6.0–9.0 | Dosing skid must trim both directions for RO permeate and any neutralized blowdown |
| Residual chlorine | < 0.5 mg/L | Dechlorination stage before discharge if chlorine is used upstream |
| Temperature rise (ΔT) | ≤ 5 °C | Cooling-tower discharge must cool or blend before any outfall |
| TSS | Site-specific | Side-stream filter and UF protect the outfall envelope |
| BOD / COD | Site-specific | Blowdown BOD is low unless biocide breakthrough occurs — monitor on SCADA |
| EIA scope | ANEVE project-level EIA | 5–20 MW build crosses the threshold by default; lock concentrate handling in at FEED |
Reference Cases and CAPEX for a 2026 Ouagadougou Build
Two reference cases cover the 2026 Ouagadougou envelope. Reference case A — a 2–5 MW colocation build at Water Usage Effectiveness (WUE) 1.8 L/kWh implies 36,000–90,000 m³/year of cooling-tower make-up; a 50 m³/day BWRO skid handles blowdown at CoC 5, and a 50,000 GPD RO skid lands at $250,000–$500,000 installed. Side-stream filtration adds $50,000–$200,000, putting the typical 2–5 MW scope at $400,000–$800,000 (Genesis Water Technologies, 2026; HydropureWater field data, 2026). Reference case B — a 10–20 MW hyperscale build hits 1.14–1.70 million L/day of cooling-tower make-up. A 200–300 m³/day BWRO train with side-stream filtration, UF, chemical dosing, and concentrate handling is the typical scope; full installed cost lands at $1.2M–$2.5M (HydropureWater field data, 2026). ZLD polish is reserved for water-scarce sites at $3M–$8M (Genesis Water Technologies, 2026); baseline scope in Ouagadougou is reuse plus landlocked concentrate handling, not full ZLD. OPEX runs $1.50–$3.00 per thousand gallons treated, dominated by energy at SONABEL industrial tariffs; chemical dosing adds another 10–15% (HydropureWater field data, 2026). Cutting ONEA mains draw by 60–70% on a 15 MW site saves roughly 250,000–400,000 m³/year and pulls payback inside 3–4 years once avoided discharge and pumping costs are included.
| Reference case | Cooling-tower make-up | BWRO scope | Installed CAPEX (water train) | Annual freshwater saved |
|---|---|---|---|---|
| A — 2–5 MW colocation, WUE 1.8 L/kWh | 36,000–90,000 m³/yr | ~50 m³/day at CoC 5 + side-stream filtration | $400,000–$800,000 | Site-specific; sized against ONEA tariff |
| B — 10–20 MW hyperscale | 1.14–1.70 million L/day | 200–300 m³/day BWRO + side-stream + UF + dosing + concentrate handling | $1.2M–$2.5M | 250,000–400,000 m³/yr at a 15 MW site (60–70% mains reduction) |
| ZLD polish option (water-scarce sites only) | — | Adds MVC + crystallizer | $3M–$8M | 95–99% overall recovery |
Frequently Asked Questions
What does a four-stage data center wastewater and cooling-blowdown train in Ouagadougou look like in 2026?
The standard 2026 train is multi-media filtration → side-stream screen filtration → PVDF ultrafiltration → brackish reverse osmosis, sized for 200–600 mg/L TDS feed, 10–50 NTU turbidity swings during Harmattan, and CoC 5–6 operation. Side-stream screen CAPEX lands at $50,000–$200,000; a 50,000 GPD RO skid lands at $250,000–$500,000 installed (Genesis Water Technologies, 2026). On the Burkinabè grid, the dosing skid, blowers, and SCADA must ride through a SONABEL transfer event.
What CAPEX and OPEX should a board expect for a 2–5 MW versus 10–20 MW Ouagadougou data center water train?
A 2–5 MW colocation build with side-stream filtration and a ~50 m³/day BWRO skid lands at $400,000–$800,000 installed; a 10–20 MW hyperscale build with 200–300 m³/day BWRO, side-stream filtration, UF, chemical dosing, and concentrate handling lands at $1.2M–$2.5M (Genesis Water Technologies, 2026; HydropureWater field data, 2026). OPEX runs $1.50–$3.00 per thousand gallons treated at SONABEL industrial tariffs, with chemical dosing adding another 10–15%. Buyers should request a per-kgal OPEX line item including energy, chemicals, membrane replacement, and concentrate disposal before committing to a supplier quotation.
How is BWRO concentrate from a landlocked Sahelian site handled without a marine outfall?
Concentrate at 5,000–8,000 mg/L TDS is non-hazardous but cannot be sent to ANEVE-regulated storm drains or surface water. The standard path is an on-site buffer tank plus a licensed hauler to a registered disposal site or a lined evaporation pond; a small MVC unit at 95–98% recovery producing distillate below 10 mg/L TDS is the high-recovery polish, at $1–3M for 10,000–30,000 GPD (Genesis Water Technologies, 2026). The concentrate-handling decision must be locked in at FEED because the civil footprint and the EIA scope both depend on it — request that the supplier commit to a concentrate path, with a named disposal site, before FEED closes.
What permits and SCADA exports does an Ouagadougou data center need for an ANEVE audit?
A 5–20 MW build crosses the ANEVE project-level EIA scope by default; current ANEVE threshold tables and decree references must be confirmed with local counsel before FEED. ONEA discharge limits typically cover TDS (≤ 2,000 mg/L conservative design point), pH (6.0–9.0), residual chlorine (< 0.5 mg/L), and ΔT (≤ 5 °C) (HydropureWater field data, 2026, pending site-specific ONEA permit confirmation). The SCADA and chemical dosing skid must export flow, pH, conductivity, and temperature records automatically — manual logs do not survive an ANEVE audit. Request proof of automated SCADA export in the supplier proposal and a dechlorination stage if chlorine is used upstream.
