Separate the wastewater streams before choosing equipment
A Sarajevo data center needs two wastewater plans: one for sanitary sewage and one for cooling-tower blowdown. Sanitary flow may require connection to the municipal sewer or a packaged biological treatment system. Blowdown contains concentrated dissolved solids and may also contain suspended matter, treatment chemicals, metals, and altered pH, so actual flows and chemistry must be sampled before a process is selected. The preferred route depends on sewer capacity, discharge limits, summer peak loads, and reuse opportunities.
Do not combine these streams by default. Sanitary wastewater comes from restrooms, kitchens and employee facilities. Cooling-tower blowdown is the controlled bleed that removes dissolved-material buildup as water evaporates and is replaced by make-up water. Reverse-osmosis reject, softening reject and maintenance drain-downs may create additional streams and must be confirmed during site design.
Black & Veatch’s data-center discharge guide reports a Texas sanitary-sewer estimate of about 30,200 gallons per day, while noting that evaporative-cooling blowdown can be substantially larger. That comparison is not a Sarajevo flow estimate; it shows only why separate inventories are necessary.
Prepare a stream-by-stream register covering average flow, summer peak flow, emergency dump volume and water-reuse demand. Ask the mechanical engineer for the cooling configuration, make-up source, evaporation assumptions, cycles of concentration and operating schedule. See this guidance on sizing and treatment of cooling blowdown for the broader process context.
| Stream | Design inventory required | Initial routing question |
|---|---|---|
| Sanitary sewage | Average and peak flow; employee and visitor basis | Municipal connection or decentralized biological treatment? |
| Cooling-tower blowdown | Average and summer peak flow; emergency dumps; make-up-water chemistry | Accepted into sewer, treated on site or reused? |
| RO or softening reject | Flow, conductivity and contaminant concentrations | Return to a process stream or treat separately? |
| Maintenance drain-downs | Volume, discharge timing and residual chemistry | Equalization or controlled disposal route? |
| Reuse demand | Daily and peak demand by intended use | Does reuse quality justify additional treatment? |
Characterize cooling blowdown and the wastewater it creates
Evaporation removes water while leaving salts and other non-volatile treatment chemicals in the circulating loop, so blowdown is more concentrated than the incoming make-up water. The treatment objective must follow measured composition rather than the assumption that every data center produces the same wastewater.
Build a monitoring program around flow, pH, conductivity or dissolved solids, suspended solids, temperature, hardness, alkalinity and residual treatment chemicals. The supplied research identifies dissolved solids, temperature, pH, suspended matter, biocides, corrosion inhibitors and scale inhibitors as relevant characteristics. Include metals only when the source-water assessment and chemical program justify them: Water Utility Report, last updated 2026-04-14, identifies elevated heavy metals as a possible constituent, not an inevitable one.
Cycles of concentration, or CoC, express how many times water circulates before blowdown becomes necessary. Genesis Water Technologies calculates theoretical blowdown at 25% of make-up water at 4 CoC and 20% at 6 CoC. Moving between those conditions therefore reduces theoretical blowdown volume by 20%, not 50%. This calculation is a useful check on the mechanical design, not a substitute for metering.
Genesis Water Technologies also reports that measured blowdown can exceed theoretical calculations by 15–30% because of unmeasured losses and emergency dumps. Budget for baseline monitoring and do not size equipment around an annual average alone. Black & Veatch’s 2026 guide cites a Santa Clara study of extreme cooling discharges during heat waves, when several facilities can raise discharges simultaneously; that demonstrates why peak conditions matter to utilities and receiving systems.
| Parameter | Engineering purpose | Evidence or basis |
|---|---|---|
| Flow | Separate average, peak and emergency-dump capacity | Genesis Water Technologies reports actual blowdown can exceed theoretical calculations by 15–30%. |
| Conductivity or dissolved solids | Quantify concentration and assess treatment or reuse limits | Genesis Water Technologies; Black & Veatch. |
| pH, suspended solids and temperature | Define chemical, solids and receiving-system constraints | Black & Veatch identifies these as typical discussion points for blowdown. |
| Biocides, corrosion inhibitors and scale inhibitors | Assess residual chemical effects | Black & Veatch and Water Utility Report, last updated 2026-04-14. |
| Metals | Assess source-water and chemical-program risk | Water Utility Report lists elevated heavy metals as possible, not inevitable. |
Equipment specifications can support this assessment, including available water-treatment parts, valves and media, but the sampling plan should precede procurement.
Choose the legal discharge route for a Sarajevo site
The discharge route must be established in writing before detailed equipment selection. Confirm with the Sarajevo sewer authority whether cooling blowdown is accepted into the municipal network, whether an industrial-user or commercial wastewater permit is required, and which local discharge limits apply.
Request written confirmation of sewer capacity, connection conditions, sampling duties, permitted parameters, surcharge rules and restrictions covering cooling water and treatment chemicals. The supplied research contains no Sarajevo-specific numeric discharge limits, so none can be stated defensibly.
Do not transplant US thresholds into Bosnia and Herzegovina. Black & Veatch’s 2026 guide describes US pretreatment screening tests including average industrial-user flow of 25,000 gallons per day or more and process flow equal to 5% or more of plant capacity. Those are US screening concepts, not Sarajevo permit criteria. The relevant local authority must determine classification and applicable conditions.
Pass through and interference remain useful engineering tests regardless of jurisdiction. Treatment should prevent contaminants from impairing the receiving plant or preventing it from meeting its discharge obligations. If surface-water discharge is considered, obtain the applicable Bosnian permit, receiving-water and temperature limits, monitoring requirements and any ecological assessment before selecting equipment.
Model average and peak flows against conveyance constraints, not treatment-plant capacity alone. Black & Veatch describes one data-center project that included a 2.5-mile pipeline and permit modification, illustrating that connection infrastructure can become a major project component.
| Route | Question to resolve | Evidence needed before commitment |
|---|---|---|
| Municipal sewer | Will the authority accept the stream and peak load? | Written acceptance, permit class, local limits, sampling duties, capacity and charges |
| On-site treatment | Can the treated water meet the approved discharge route? | Treated-water specification, receiving authorization and treatment train |
| Surface water | Is direct discharge permissible? | Bosnian permit, receiving-water limits, temperature limits and monitoring plan |
| Reuse | Is the intended use legally and technically acceptable? | Application-specific water quality, local reuse rules and operating controls |
The data-center discharge-route framework illustrates why sewer acceptance, infrastructure and permitting must be evaluated together.
Build the treatment train around the intended water quality
Each stream needs an outlet-specific process train. For sanitary wastewater, compare municipal sewer discharge with an installed biological package. The WSZ series combines anoxic/aerobic contact oxidation, sedimentation and disinfection in one buried unit for flows from 1–80 m³/h; local electrical requirements, siting, discharge authorization and sludge handling still need confirmation.
For cooling blowdown, begin with equalization and controlled pumping. Add solids separation and filtration according to measured suspended solids and downstream quality requirements. A DAF system for cooling-blowdown solids separation can address floatable material, suspended solids, oil and grease, and colloidal matter. The catalog DAF range covers 4–300 m³/h across 13 standard models, but the selected capacity must follow measured flow and contaminant loading.
Use an ultrafiltration system for blowdown pretreatment and reuse where bacteria, colloids and suspended solids must be removed without chemical addition. HydropureWater’s hollow-fiber range is 2,000–40,000 L/h with 0.03-micron PVDF membranes, automatic backwash and air scour. These are equipment specifications, not a guarantee of site performance.
Where reuse requires very low dissolved solids, evaluate the industrial reverse-osmosis system after appropriate pretreatment. Its stated recovery rate is up to 95%; feed chemistry, scaling, pretreatment and operating schedule determine the actual recovery.
Disinfection is a separate objective. A chlorine dioxide generator can provide on-site microbial control for industrial cooling loops and process wastewater, but residual and chemical acceptance must be verified with the sewer authority before application. For decentralized sanitary treatment, the MBR system provides near-reuse-quality effluent with filtration below 1 micron and handles 10–2,000 m³/day. Its added process complexity is justified only when the required effluent quality and decentralized operating model justify it.
| Target or stream | Potential process step | Selection evidence |
|---|---|---|
| Sanitary sewer discharge | Equalization, biological treatment and disinfection | Measured flow, required outlet quality and local acceptance |
| Sanitary on-site reuse | MBR followed by any application-specific polishing | Reuse specification, footprint, operation and residuals |
| Cooling blowdown pretreatment | Equalization, solids separation and filtration | Suspended solids, floatables, flow profile and downstream requirements |
| Low-dissolved-solids reuse | UF followed by RO where required | Feed water, scaling analysis, recovery target and pretreatment performance |
| Microbial control | Disinfection as a separately specified stage | Receiving-system criteria, residual limits and chemical acceptance |
Decide whether blowdown reuse justifies the extra treatment
Start with lower-risk reuse applications, such as toilet flushing, outdoor equipment washing or irrigation where local rules permit. Cooling-tower make-up demands a more demanding comparison because scaling, corrosion, microbiological risk and treatment-chemical effects must remain inside the cooling system’s operating envelope.
Genesis Water Technologies reports that two-stage physical treatment can reduce make-up-water demand by 15–25% when blowdown is reused for non-critical applications. That result supports a staged decision, but it does not establish site-specific savings without measured blowdown, recovered volume and application demand.
Distinguish water usage from consumption. Genesis Water Technologies defines consumption as water permanently removed through evaporation or incorporated into products, while usage includes water withdrawn, used and returned to the source after treatment. A reuse calculation must therefore count what is returned and usable, not only what leaves through evaporation.
Build the business case from total avoided costs: water, wastewater charges, treatment chemicals, energy, maintenance, monitoring and disposal. Raising CoC is not automatically proportional. Genesis Water Technologies calculates theoretical blowdown falling from 25% to 20% of make-up water between 4 and 6 CoC, a 20% volume reduction, while scaling and biological-control risks become harder to manage. Compare treated-water chemistry with each receiving application before committing to advanced reuse.
| Decision | Use when | Required check |
|---|---|---|
| Toilet flushing or equipment washing | Water quality matches the application and local rules permit reuse | Treatment performance, seasonal demand and distribution infrastructure |
| Irrigation | Quality and site conditions are suitable | Local approval, application rate, constituents and runoff controls |
| Cooling-tower make-up | Advanced treatment and operating resources are justified | Scaling, corrosion, microbiology, chemicals, recovery and reliability |
| Higher CoC without reuse | Cooling-system control can safely support it | Blowdown reduction measured against increased chemical and maintenance burden |
The data-center water-reuse treatment routes provide further context for separating water usage from consumption and evaluating recovery applications.
Move from concept to a defensible Sarajevo implementation plan
The first 30 days should establish the design basis: cooling design, make-up source, chemical program, wastewater-flow model, utility correspondence and property constraints. During the next 30 days, collect representative samples across operating conditions and obtain written sewer or receiving-water acceptance criteria, including peak-flow and chemical restrictions.
Pilot the selected route with actual wastewater. Compare observed flow, solids, conductivity, pH, temperature and reuse quality against the design assumptions. A pilot does not replace a formal approval, but it exposes material loads and control problems before a packaged system is ordered.
Before purchase, issue a performance specification covering flow range, peak load, guaranteed outlet parameters, controls, redundancy, monitoring, sludge or concentrate handling, operator training and maintenance support. Include commissioning tests, a sampling plan, bypass or fail-safe provisions and a contingency route for periods when the municipal sewer or reuse system is unavailable.
Keep an auditable compliance file containing baseline flows, authority submissions, permits, test results, chemical inventories, training records and operating logs. Regional experience in regional data-center wastewater planning supports the same sequence: characterize the stream, establish legal acceptance, pilot with real wastewater, then specify and verify.
- Days 1–30: collect design inputs, identify every discharge stream and open authority discussions.
- Days 31–60: complete representative sampling and obtain written acceptance criteria.
- Days 61–90: pilot, issue the performance specification, close compliance risks and place the selected equipment on an approval path.
Frequently Asked Questions
What should a buyer request when budgeting wastewater and cooling blowdown treatment in Sarajevo?
Request a site-specific quotation separated into equipment, installation, connection works, controls, commissioning, monitoring, chemicals, energy, maintenance, sludge or concentrate disposal, and permit-related engineering. Also request the water and wastewater tariff assumptions used in the reuse calculation. The supplied research contains no Sarajevo equipment cost, tariff, site flow or reuse value, so it does not support a universal budget or payback period.
How should treatment equipment be sized?
Size from measured average and peak flows, contaminant loads, required outlet or reuse quality, operating hours, redundancy and available footprint. Do not size from data-center electrical capacity alone. Include emergency dumps and the conveyance route to the municipal sewer or receiving point, because treatment capacity alone does not provide usable discharge capacity.
Which supplier qualifications should be checked?
Require demonstrated performance on representative wastewater, documented guarantees, controls and monitoring details, operator training, maintenance support and a defined method for handling sludge or concentrate. Check whether proposed guarantees are conditional on feed chemistry, operating hours, pretreatment or chemical dosing. The relevant reference for UF evaluation is this ultrafiltration system guide.
Does compliant equipment guarantee permission to discharge?
No. Equipment performance and legal permission are separate. Final discharge acceptance must come from the relevant Sarajevo sewer authority or competent Bosnian authority, including confirmation of the permitted route, local limits, monitoring, peak-flow conditions and restrictions on cooling water and treatment chemicals.
