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CASE STUDY

90 m³/hour Automated RO Water Treatment Plant in Tatu City

90 m³/hour Automated RO Water Treatment Plant in Tatu City

Image note: Project photography will be added after client and engineering approval. The current illustration is a placeholder and does not depict the installed plant.

A food-grade manufacturing facility in Tatu City needed a dependable source of drinking and process water despite variations in its municipal and borehole water supplies. Spenomatic designed and commissioned a fully automated reverse-osmosis water-treatment plant with a stated treatment capacity of up to 90 cubic metres per hour.

Project overview

IndustryFood-grade manufacturing
LocationTatu City, Kenya
ApplicationDrinking and process water
Treatment capacityUp to 90 m³/hour, subject to operating and feed-water conditions
Core technologyReverse osmosis
Supporting processesChemical dosing, chlorination, dechlorination, antiscalant dosing and UV treatment
AutomationAutomated process operation and chemical dosing
Monitoring and protectionConductivity monitoring, pressure management, alarms, safety interlocks and automatic shutdown
Water sourcesMunicipal water, supplemented with borehole water when required
Commissioning periodOctober 2017 to January 2018
Continuing supportMaintenance and water-quality monitoring

The challenge

Variable source-water quality

Municipal water was the preferred source, but rationing could interrupt supply. Borehole water therefore had to supplement the municipal supply. This improved availability while changing the concentration of dissolved minerals and other impurities entering the plant. Silica, hardness and conductivity required particular attention because changes can affect membrane scaling and treated-water consistency.

Food-grade water requirements

Water used for drinking and production had to remain within the facility’s required quality parameters. The system needed to manage dissolved salts, hardness-forming compounds, silica, ionic contaminants and microbiological risks as part of a controlled treatment process.

High-capacity, dependable operation

At up to 90 m³/hour, manual monitoring and dosing would make consistent responses to feed-water changes difficult. The project therefore required automated dosing, process monitoring, alarms and safety interlocks suitable for industrial operation.

The Spenomatic solution

1. Raw-water management and blending

The system accommodates municipal and borehole water. When municipal supply is restricted, borehole water can supplement the feed stream while the treatment process manages the resulting changes in mineral content and conductivity.

2. Automated chemical dosing

The pretreatment design incorporates controlled chlorine, sodium metabisulphite and antiscalant dosing. Chlorination supports microbial control, sodium metabisulphite neutralises residual chlorine before chlorine-sensitive RO membranes, and antiscalant helps limit deposits from hardness salts, silica and other scale-forming substances.

3. Reverse-osmosis treatment

High-pressure pumps provide the force needed to overcome osmotic pressure and move the pretreated feed water through semi-permeable membranes. The membranes pass water while rejecting most dissolved salts and many other contaminants, reducing conductivity and dissolved mineral content to meet the facility’s required process-water parameters. The membrane configuration and operating conditions were selected around the raw-water characteristics, required water quality and plant capacity.

4. Conductivity monitoring

Conductivity monitoring provides a rapid operational indication of dissolved ionic content. Measurements at key stages help operators observe changes in incoming water, assess membrane performance and identify unusual conditions. Conductivity is used alongside appropriate chemical and microbiological testing because it does not identify every contaminant.

5. UV disinfection

Ultraviolet treatment provides an additional microbial-control barrier by inactivating susceptible microorganisms. UV does not remove salts, hardness or particles, so it operates as part of the wider treatment process.

6. Reject-water management

The RO process separates purified permeate from a concentrated reject stream. Any recovery, reuse or discharge decision must follow laboratory analysis and applicable environmental requirements because the reject contains higher concentrations of the substances removed from the product water.

Automation and operational control

The control system coordinates pump operation, chemical dosing, pressure management, conductivity monitoring, treatment sequencing, alarms, safety interlocks and automatic shutdown under unsafe conditions. Automation reduces dosing errors, supports membrane protection and helps the plant respond consistently when source-water conditions change.

Project outcomes

  • Treatment capacity of up to 90 m³/hour
  • Drinking and process water aligned with the client’s required quality parameters during commissioning
  • More consistent treated-water quality across blended source-water conditions
  • Reduced conductivity and dissolved mineral content
  • Additional microbial control through pretreatment and UV
  • Reduced scaling risk through controlled antiscalant dosing
  • More stable water quality to support product consistency and protect piping and process equipment
  • Automated monitoring, alarms and safety interlocks
  • Continued maintenance and water-quality monitoring support

Long-term operation

The installation has remained in operation since commissioning in early 2018. Continued monitoring is important because municipal and borehole water characteristics can change over time. Routine review allows the engineering team to assess dosing, silica variation, membrane condition and treated-water performance.

Why this project matters

This project demonstrates why a high-capacity industrial RO installation must be designed around the intended water use, source-water variability, pretreatment, microbial risks, automation, reject-water management and lifecycle maintenance rather than around the membrane equipment alone.

Frequently asked questions

What is the capacity of the Tatu City RO plant?

The plant has a stated treatment capacity of up to 90 cubic metres per hour, subject to operating conditions and feed-water characteristics.

Why was reverse osmosis selected?

Reverse osmosis substantially reduces dissolved salts and conductivity. Combined with suitable pretreatment, disinfection and monitoring, it helps maintain consistent water quality when source-water characteristics vary.

Why are municipal and borehole water blended?

Borehole water supplements municipal supply during rationing or interruptions. Blending improves availability while requiring the treatment system to manage variations in minerals, silica and conductivity.

Why is chlorine removed before the RO membranes?

Chlorine supports microbial control during pretreatment, but residual chlorine can damage many RO membrane materials. Sodium metabisulphite is therefore dosed to neutralise it before the membrane stage.

Does antiscalant remove existing scale?

No. Antiscalant helps inhibit new deposits from hardness salts, silica and other scale-forming substances. It does not replace appropriate membrane cleaning after significant scale has formed.

Does UV remove bacteria from the water?

UV inactivates susceptible microorganisms by disrupting their ability to reproduce; it does not physically filter them from the water. Its performance depends on suitable pretreatment, operating conditions and maintenance.

Why is conductivity monitored?

Conductivity provides a rapid indication of dissolved ionic content and helps operators track changes in feed water and RO performance. It does not measure every impurity, so it is used alongside appropriate chemical and microbiological testing.

Can RO reject water be reused?

Potentially, but only after its composition and the intended application have been assessed. Reject water contains concentrated salts and is not automatically beneficial to soil. Any recovery, reuse or discharge must follow laboratory findings and applicable environmental requirements.

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