A: It can be used in a wide range of buildings, hospitals, hotels, office buildings, shopping centres and industrial plants. However, the system must be designed and the site assessed by specialists before installation, so that it suits the actual operating conditions.

A: When chiller efficiency improves, less electricity is consumed, which in turn reduces the indirect greenhouse gas emissions associated with that electricity use. In this case study, emissions were reduced by approximately 21.1 tonnes CO₂e per year.

A: Yes, ongoing care and maintenance is still required, including checking water quality, cleaning the cooling tower, controlling sunlight exposure at the basin, and monitoring chiller performance, so that the system continues to operate efficiently over the long term.

Managing energy costs in large buildings — particularly hospitals, which must run air conditioning 24 hours a day — represents one of the principal unavoidable costs. One frequently encountered problem is the accumulation of scale, algae and bacteria inside the condenser and the cooling tower, which reduces heat transfer efficiency, causes the chiller to work harder and consume more energy than it should, and drives electricity costs higher.

This case study took place at [CLIENT NAME — see publishing decision 1], which chose to install ECONOWATT’s chemical-free ozone cooling water treatment system, model OZG 120 S, with real operating results recorded over a total of 730 days. The outcomes were clear across energy, financial and environmental dimensions.

Key takeaways

• The ozone cooling water treatment system restored the heat transfer efficiency of the condenser and cooling tower, allowing the chillers to operate more efficiently and consume less energy.
• From real operating results, chiller electricity costs were reduced by over 10 million baht per year, with payback in just 2.86 months — a clear demonstration of commercial value.
• Beyond reducing energy costs, the project also reduced carbon emissions by over 1,367 tonnes CO₂ per year and eliminated chemical use by 100%, supporting the organisation’s ESG and sustainability objectives.

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Before the ozone cooling water treatment system was installed, algae (biofilm) had accumulated within the cooling tower and scale had formed on the tube surfaces in the condenser, preventing heat transfer from operating at full efficiency. The resulting impacts were:

• The chillers had to run harder than normal, consuming more electricity
• Chemicals and a softener were required continuously to condition the water, raising costs
• The condenser had to be taken offline periodically for cleaning, costing time and increasing maintenance expenditure

These problems were a significant cause of the building’s rising energy costs, as well as requiring downtime and the use of water conditioning chemicals with long-term environmental consequences.

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ECONOWATT installed an ozone cooling water treatment system, model OZG 120 S, to control water quality in the system in place of chemicals. The ozone system acts as the oxidant in the cooling water instead of chemical treatment, inhibiting scale formation and eliminating algae and bacteria, while reverting to oxygen and leaving no residual. The system also operates as a closed loop with automatic control, so there is no need to shut down the building’s cooling system.

After the system was running, the building was able to decommission its softener system and reduce the use of water conditioning chemicals by 100% — cutting both chemical costs and the maintenance burden in a single step.

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After installation, chiller electricity costs were clearly reduced, arising from two main factors: removing scale from the condenser, which improved heat exchange efficiency, and reducing the number of chillers that had to operate, which lowered overall system energy consumption. From the condenser cleaning effect alone, electricity savings of 512,460 baht per year were achieved.

In addition, where previously three chillers had to run at full load, after installation this was reduced to just two chillers at approximately 60% load, with one chiller shut down entirely — producing electricity savings of 9,562,635 baht per year. In total, actual electricity cost reductions came to 10,075,095 baht per year, not including additional savings on water, labour and other maintenance.

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The installation of the ozone cooling water treatment system to reduce chiller electricity costs in this project was carried out under an ESCO (Energy Service Company) model on a Shared Savings basis, designed so that the customer does not need to use their own capital investment (CAPEX). ECONOWATT funded the entire system installation, and the client paid a share of the actual savings achieved on a monthly basis.

The investment model can be described as follows:

• The customer makes no initial investment → ECONOWATT funds the entire system installation (2.4 million baht)
• Shared savings contract term → 24 months
• Savings achieved = 840,000 baht/month
• ECONOWATT’s share, 2.4 million baht over 24 months = 100,000 baht/month
• The client receives, net and immediately = 740,000 baht/month

On the sharing of benefits: total savings across the two years came to 20.15 million baht, of which ECONOWATT’s share was fixed at 2.40 million baht, leaving the client with 17.75 million baht over the two years. From year three onward, the client receives 100% of the savings (10 million baht per year).

The project produced positive cash flow from the first month, with the client paying its share out of “money actually saved”, without affecting the existing budget. Under this model, ECONOWATT carries the performance risk, because its revenue is tied to actual savings rather than to a one-off equipment sale — reflecting the company’s position of delivering “guaranteed results”.

This is a clear example of how a Shared Savings model allows an organisation to begin an energy saving project immediately, without affecting its capital budget.

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Condenser Approach Temperature is the difference between the temperature of the condensing refrigerant and the temperature of the water leaving the condenser. It is a direct indicator of heat transfer efficiency in a chiller system — the lower the value the better, because it means the heat exchange surface is clean and working at full capability. Measurements before and after installation are summarised below:

Machine	Before installation	2 months after installation	10 months after installation
Chiller No.5	10.9°F	1.3°F	0.7°F
Chiller No.6	13.6°F	0.7°F	0.8°F

The Approach Temperature fell by more than 90%, and the system was able to hold the value below 1°F continuously for as long as 10 months, demonstrating that it had returned to full operating efficiency. This is substantially better than ECONOWATT’s own guarantee criterion, which is that the value will not rise more than 2°F from the starting point.

The following graph shows the Approach Temperature values actually recorded throughout the operating period (under real operating load), demonstrating consistently stable performance at a low level.

In addition to the two machines still operating, the improved heat rejection efficiency also made it possible to shut down Chiller No.2 entirely after the ozone system was installed — which is the principal source of the 60% electricity cost saving, or approximately 9.56 million baht per year.

Another of the most tangible results is the condition of the cooling tower basin: from a state where algae had accumulated until the water was cloudy and the drain openings were blocked, it returned to being clean and clear after the ozone system began operating.

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The results of this project reflect not only reduced energy costs but also a clear positive environmental impact. From actual operating data, electricity consumption was reduced by 2.88 million kWh per year, as a result of the chiller system operating more efficiently and being able to reduce the number of machines running from three to two on a continuous basis.

Calculated using Thailand’s Grid Emission Factor (Scope 2) of 0.4750 kgCO₂e/kWh, this is equivalent to a greenhouse gas emission reduction of approximately 1,367 tonnes CO₂ per year, and 2,735 tonnes CO₂ across the full 730-day operating period — comparable to taking approximately 297 private cars off the road for a year.

This still does not count the environmental benefit of eliminating chemicals and the softener system, which reduces both chemical residue and the wastewater arising from blowdown.

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This case study clearly demonstrates that an ozone cooling water treatment system can genuinely improve cooling tower efficiency and reduce the workload on chillers, resulting in chiller electricity cost reductions of more than 10 million baht per year, payback within 2.86 months, an Approach Temperature improvement of more than 90%, and carbon reductions of more than 1,300 tonnes per year.

Combined with an ESCO Shared Savings model requiring zero investment, monthly payment of a share of the savings actually achieved, and receipt of 100% of savings after the two-year contract term, all of this rests on 730 days of real operating results, with continuous monitoring and guaranteed performance.

For those seeking to manage energy costs efficiently, Econowatt is pleased to provide energy management and water treatment solutions for air conditioning systems, delivered by a team of specialist engineers and committed to delivering “guaranteed results” to customers in industry, commercial buildings, hospitals and organisations seeking to improve cooling system efficiency.

Get in touch

• Line: @econowatt
• Facebook: Thai Energy Conservation — Econowatt Water Treatment & Energy Conservation Systems
• Tel: +66 2 809 1601
• Email: sales@econowatt.co.th

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Q: How does an ozone cooling water treatment system reduce chiller electricity costs?

A: It reduces the accumulation of scale, algae and biofilm in the condenser and cooling tower, improving heat transfer, which in turn allows the chiller to consume less energy.

Q: Can an ozone system genuinely replace chemicals in a cooling tower?

A: Yes. Ozone has the properties to inhibit scale, eliminate bacteria and control biofilm, which has allowed many systems to eliminate the use of chemicals and softeners entirely.

Q: What is an ESCO Shared Savings model?

A: It is a model in which the service provider funds the system up front, the customer requires no initial investment, and repayment is made from the energy savings actually achieved — making a project easy to start and reducing budget risk.

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Publishing decisions required ⚠️

Decision 1 — the client name. The Thai original names the Faculty of Medicine, Khon Kaen University. I have left a [CLIENT NAME] placeholder in the English version rather than making the call for you.

• To publish anonymously: replace the placeholder with “a leading university teaching hospital in Thailand” and the article works exactly as written.
• To name them: insert the name, but obtain written confirmation first that the institution is comfortable being named in English-language and international marketing. Consent for a Thai-language page does not automatically extend to that.

Decision 2 — the ESCO commercial terms. The Thai original discloses the full structure: 2.4M investment, 840,000 baht/month saving, ECONOWATT’s share 100,000 baht/month, client’s net 740,000 baht/month.

• Keep it: this transparency is the most persuasive part of the article and is very difficult for a competitor to answer.
• Remove it: delete the bulleted breakdown and the benefit-sharing paragraph, keeping only “zero customer CAPEX, payment from actual savings, 100% of savings from year three”. The article still works, with roughly 70% of the persuasive force.

This is a commercial call for you and the sales team. My recommendation is to keep it — but the decision should be made deliberately, not by default.

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Translation notes

1. Project dates omitted — the Thai original states 1 January 2013 to 31 December 2014. I have retained “730 days” throughout but left the years out, since a 2013–2014 date on an English page in 2026 raises the question of whether there is anything more recent. If the system is still in service, adding a single line — “the system has been in continuous service since 2013” — converts the age from a liability into the strongest proof of durability in the entire set. Worth confirming with the service team.
2. The two “60%” figures — the Thai original uses 60% in two different senses: two chillers running at approximately 60% load, and a 60% electricity cost saving. Both have been translated faithfully here, but they read as contradictory in English. Recommend clarifying in the Thai original and updating both versions.
3. 1,367 vs 1,368 tonnes — 2.88M kWh × 0.4750 = 1,368,000 kg. The Thai article states 1,367 tonnes. Immaterial; source figure retained.
4. “Chiller No.2” appears only in the section on shutting down a machine, while the results table covers Chillers No.5 and No.6. This is faithful to the Thai original, but a reader may wonder about the numbering. Consider adding one clarifying sentence in both versions.
5. The graph referenced in the text (“the following graph shows…”) needs the actual image placed on the English page too, or the sentence should be removed.
6. Currency kept in THB. For international readers, 10,075,095 THB ≈ USD 304,000 at 33.14 THB/USD (28 Aug 2026).
7. British English spelling used, consistent with the other website translations in this set.

5 Factory WWTP

Website English Translation — 5 Factory Wastewater Problems Modern Treatment Solves

Source (TH): https://econowatt.co.th/blog/wastewater-treatment-in-factories-how-it-solves-pollution/ Purpose: English version for the ECONOWATT website · faithful to the Thai structure Created: 31 Aug 2026 · rev-01

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Meta title (57 chars)	5 Factory Wastewater Problems Modern Treatment Can Solve
Meta description (152 chars)	Odour, oil and grease, heavy metals, suspended solids and overflow — the five wastewater problems in Thai factories, and the technology that fixes each.
Primary keyword	wastewater treatment system
Secondary keywords	industrial wastewater treatment · BOD COD standard · MBR · MBDAF · ultrafiltration · water recycling · Thailand effluent standard
Schema	Article + FAQPage

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Article

What is a wastewater treatment system?

A wastewater treatment system is the process of removing contaminants from wastewater generated by use in an industrial plant. Applying wastewater treatment technology produces clean, good-quality water before it is discharged into natural watercourses, or prepares it for a water recycling system. Wastewater can be treated by a number of methods — physical, biological and chemical — depending on the wastewater problem in question.

Why an industrial plant needs a wastewater treatment system

Beyond turning wastewater into clean water, installing a wastewater treatment system in an industrial plant has a number of other advantages:

• Legal compliance: meeting the effluent standards currently in force
• Reduced environmental impact: less pollution, and less accumulation of toxic substances in watercourses
• Economic value: recycling water back into use, reducing water costs and corrosion-related maintenance costs
• Improved reputation: demonstrating responsibility towards society and the environment

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1. Wastewater with a foul odour, and BOD/COD above standard

The problem of foul-smelling wastewater usually arises when there is too much organic matter in the water, requiring the microorganisms used in treatment to consume large amounts of oxygen for decomposition — producing hydrogen sulphide (H₂S) and ammonia. This results in BOD (Biochemical Oxygen Demand) and COD (Chemical Oxygen Demand) values above standard. Normally, BOD must not exceed 20 mg/L and COD must not exceed 120 mg/L.

Under the Ministry of Industry Notification on the control of effluent standards from factories, B.E. 2560 (2017), if discharged water has BOD and COD values above the standard, legal penalties apply — for example, financial penalties, an order to cease discharging wastewater, or the licence being considered for revocation.

2. Wastewater contaminated with oil and grease

Food and beverage processing plants, and plants manufacturing metal components, frequently encounter the problem of discharged water contaminated with oil, grease and residual chemicals. Without good wastewater treatment technology, this leads to floating sludge, blockages in drainage pipes, and wide-ranging environmental damage — because grease adhering to the water surface obstructs the transfer of oxygen from the air into the water, reducing dissolved oxygen and affecting aquatic animals and the aquatic ecosystem.

3. Wastewater contaminated with minerals and heavy metals

Wastewater containing large quantities of minerals results in severely polluted water. When it escapes and contaminates natural watercourses, the environmental impact is severe. It can be removed by chemical stabilisation to precipitate the contaminants, together with filtering out remaining highly charged ions through an Electro Conductivity Reducer (ECR) system or RO, before discharge to the public environment — or the mineral-filtered effluent can be recovered for reuse. The minerals separated from the wastewater must then be crystallised into a solid form.

4. Wastewater with high sediment and suspended solids

Wastewater with large quantities of sediment and suspended solids arises from raw material washing, or from production processes contaminated with organic and inorganic matter such as gravel, clay, sand and material fragments. Without appropriate wastewater treatment technology, suspended solids remain high, causing blockages within the treatment system. If discharged into public watercourses, this creates turbidity, reduces oxygen levels in the water, endangers aquatic life, and ultimately accumulates as bottom sediment.

5. Wastewater accumulating faster than it can be treated

Many plants have a problem with large volumes of wastewater accumulating, particularly during periods when production must be accelerated. If an unsuitable wastewater treatment system is in use, wastewater overflows the treatment tanks and the system blocks easily. Wastewater must then be released from the plant into natural watercourses — which may lead to financial penalties or a legal order to cease discharging.

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Installing a wastewater treatment system to address these problems generally divides into three treatment stages:

Preliminary treatment

A physical treatment stage that separates large, water-insoluble contaminants using screens, passing them into a settling tank. Some plants may add a grease removal system to reduce problems with grease accumulation in the wastewater. Preliminary treatment methods include:

• Trapping contaminants with separation screens
• Settling to prevent pump blockages
• Grit and sand removal
• MBDAF (Micro Bubble Dissolved Air Flotation), which uses micron-scale air bubbles to separate sludge, oil and grease from the water
• Biomicrogel®, a bio-based oil capture agent that is environmentally friendly and captures oil more effectively than general chemicals

Secondary treatment

Treatment at this stage focuses on reducing the contaminant load of the wastewater by chemical or biological means. The method must be considered against the characteristics of the wastewater in each case. Wastewater treatment systems used at the secondary stage include:

• Aeration systems, such as the activated sludge process, which uses microorganisms to help decompose organic matter
• MBR (Membrane Bioreactor), which combines biological processes with membranes, producing clearer water and reducing odour more effectively than before

Advanced treatment

Advanced wastewater treatment is a process for removing suspended solids that are difficult to settle, along with nutrients and colour that cannot be removed at the intermediate stage. In most cases, installing wastewater treatment technology at this stage is intended to bring water quality to the highest level so that it can be safely reused. Systems used at this stage include:

• UF (Ultrafiltration) filtration, filtering to as fine as 0.01 micron
• ECR (Electro Conductivity Reducer), a technology that reduces ionic content in water by using electricity to separate charged particles without chemicals, in order to reduce TDS and the true colour caused by dissolved minerals
• EHR (Electro Hardness Removal), using electric current to separate calcium and magnesium from water without chemicals, in order to reduce water hardness
• Ozone wastewater treatment (Ozone Water System), which helps disinfect and reduce colour and odour
• Automatic control systems, monitoring water quality in real time

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An industrial wastewater treatment system is an innovation that delivers real value to industrial plants today. Beyond complying with Department of Industrial Works requirements, it also helps improve production efficiency and establishes long-term sustainability standards for the plant.

For plant owners looking to install a quality wastewater treatment system suited to real-world operation, Econowatt designs wastewater treatment systems and advises on installation to solve wastewater problems, with more than 30 years of experience. We are ready to be the partner that raises your production and wastewater treatment standards to meet requirements and move towards genuine sustainability.

Get in touch

• Line: @econowatt
• Facebook: Thai Energy Conservation — Econowatt Water Treatment & Energy Conservation Systems
• Tel: +66 2 809 1601
• Email: sales@econowatt.co.th

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Q: How does an activated sludge wastewater treatment system work?

A: The system uses microorganisms to help decompose organic matter in wastewater, with aeration added so the microorganisms can work at full efficiency. This helps reduce BOD and COD values to within standard levels.

Q: Do small factories need to install a wastewater treatment system?

A: Yes. Every factory producing discharged water from its production process must comply with environmental law, in order to help reduce the impact on surrounding communities.

Q: Do modern wastewater treatment systems use a lot of energy?

A: New technologies such as MBDAF and EHR use less energy than older wastewater treatment systems and can be configured to operate automatically, helping to reduce costs over the long term.

Q: Can treated water be reused?

A: Yes, provided the water recycling system has been properly designed. However, the water should be filtered and its quality checked before every use.

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Translation notes ⚠️

1. Buddhist era converted — พ.ศ. 2560 → B.E. 2560 (2017). Both forms kept, since Thai regulations are usually cited by their Buddhist-era year and an international reader needs the Gregorian equivalent.
2. BOD 20 / COD 120 limits — explicitly attributed to the Thai Ministry of Industry notification, so an international reader does not assume these limits apply in their own jurisdiction.
3. “Department of Industrial Works” (กรอ.) — the accepted English name of the Thai regulator. Consider adding “(DIW)” on first use.
4. Biomicrogel® — registered trademark symbol added, as this is a product ECONOWATT carries. Confirm the correct trademark treatment for English-language use.
5. “More than 30 years of experience” — taken directly from the Thai original. Please confirm this is current, as it is a claim that dates.
6. A typo in the Thai original — “ปนเปือน” in problem 2 should be “ปนเปื้อน”. Worth correcting in the Thai version.
7. Structural note — the Thai original lists the five problems and then separately lists the three treatment stages, so a reader has to connect them mentally. The structure has been kept faithful here for the website. The companion LinkedIn version attaches each solution directly to its problem, which reads better. If the English page is ever restructured, that pairing is the improvement worth making — and it would improve the Thai original too.
8. British English spelling used, consistent with the other website translations in this set.

5 Retail Branches Ozone CT

Website English Translation — Condenser Approach Below 4°F, 5 Retail Branches

Source (TH): https://econowatt.co.th/blog/condenser-approach-chiller-ozone-case-study/ Purpose: English version for the ECONOWATT website · faithful to the Thai structure Created: 31 Aug 2026 · rev-01 Companion file: 31082026-LinkedIn-Article-Condenser-Approach-Ozone-EN-rev-01

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Meta title (59 chars)	Condenser Approach Below 4°F for 24 Months: Ozone Case Study
Meta description (156 chars)	Five large retail branches held condenser approach below 4°F for 24 months on ozone water treatment, with no condenser tube cleaning. Full data and method.
Primary keyword	condenser approach temperature
Secondary keywords	chiller efficiency · cooling tower water treatment · ozone water treatment · condenser fouling · kW/Ton
Schema	Article + FAQPage

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Article

In the air conditioning systems of large buildings, chiller efficiency does not depend on the chiller alone. It also depends on the cleanliness of the heat rejection system, particularly the condenser and the cooling water system connected to the cooling tower. If scale, algae or biofilm begin to accumulate on the heat exchange surface — even in small amounts — the chiller can consume more energy than necessary.

One of the key indicators building engineers use to track abnormalities in the system is the Condenser Approach Temperature, or approach value, which directly reflects the condenser’s ability to transfer heat. A low value indicates the system is still exchanging heat well. A value that rises steadily is usually a sign that the tube surfaces are becoming fouled, that scale is accumulating, or that fouling is developing inside the system.

This article presents a case study from five large retail branches that changed from conventional chemical water treatment to an ozone water treatment system in the cooling tower’s cooling water circuit, and were able to hold Condenser Approach below 4°F continuously for 24 months.

Key takeaways

• Condenser Approach Temperature is a key indicator reflecting the heat transfer efficiency of a chiller. A rising value usually means the condenser tubes are beginning to accumulate fouling, scale or biofilm.
• For every 1°F increase in Condenser Approach, chiller energy consumption — the kW/Ton value — can increase by approximately 1.5%, directly affecting the building’s electricity cost.
• Conventional chemical water treatment can cause the approach value to fluctuate in line with the tube cleaning cycle, making chiller efficiency inconsistent and requiring downtime for maintenance.
• An ozone water treatment system controls biofilm and fouling in the cooling water system, keeping condenser tube surfaces cleaner without reliance on conventional chemicals.
• Holding the approach value low on a continuous basis maintains chiller efficiency, reduces energy consumption, reduces the maintenance burden, and reduces the impact of chemicals in the cooling tower system.

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Condenser Approach Temperature is the difference between the saturation temperature of the refrigerant in the condenser and the temperature of the cooling water leaving the condenser. It can be defined by the temperature difference as follows:

Condenser Approach = Condenser Saturation Temperature − Condenser Water Temperature Out

This value directly reflects the “resistance to heat transfer” at the condenser tube surface. The cleaner the tubes, the lower the value. In engineering terms, its relationship to efficiency is as follows:

• For every 1°F increase in the approach value, chiller kW/Ton increases by approximately 1.5% (efficiency falls by 1.5%).
• For the best heat exchange, the value should be maintained in the range of 0–2°F, and generally should not exceed 10°F.
• In energy terms, allowing approach to climb from a clean condition to around 10°F before cleaning is equivalent to kW/Ton moving from 100% up to approximately 115%.

The value functions like a “vital sign” for system efficiency that can be read every day, without waiting for the electricity bill. Engineering guidance generally recommends keeping the approach value as low as reasonably achievable, with the appropriate range usually around 0–2°F, and the value should not be allowed to rise close to 10°F — because the higher the approach value climbs, the more chiller efficiency declines.

This principle is consistent with chiller manufacturers’ technical documentation, which states that every 1°F (0.56°C) increase in approach raises electricity cost by an average of approximately 1.5% [2]. Experimental research has found that every 1 K (≈1.8°F) increase in Condenser Approach reduces chiller COP by approximately 3.3–3.6% and increases power draw by approximately 3% [1] (equivalent to approximately 1.5% per °F). Both sources confirm the same quantitative relationship.

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With chemical treatment, what is clearly visible is field data showing a repeating pattern: the approach value climbs continuously as scale and fouling accumulate, until mechanical cleaning of the condenser tubes is required every 5 months to reset the value back down. The consequences are:

• The approach value fluctuates in a sawtooth pattern, with periods where it reaches 10°F before cleaning — during which the chiller consumes more energy than necessary.
• Hidden costs arise from chemical costs, cleaning labour, downtime, and the risk of tube surface corrosion.
• Comparative photographs of condenser tube condition confirm that after 6 months on the chemical system, the tube surface shows clear corrosion and blockage, compared with tubes on the ozone system for 12 months which remained in good condition.
• The effect of fouling is more severe than expected — a film or scale layer just 0.6 mm thicker can reduce chiller efficiency by as much as 34% and increase energy consumption by as much as 21%. Research also indicates that condenser fouling is the most likely cause of chiller damage, with cases found of condenser tubes cracking under heavy scale accumulation.

This pattern of operation causes chiller efficiency to fluctuate cyclically in a sawtooth shape: after the tubes are freshly cleaned, the approach value falls and the chiller performs better, but as time passes fouling accumulates, the approach value rises, and the chiller consumes more energy — until the machine must be stopped for cleaning once again.

The limitations of a conventional chemical system are therefore not only the cost of the chemicals, but also the tube cleaning labour, the downtime, the risk associated with acid cleaning, and the long-term risk of corrosion to the condenser tube surface.

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Ozone water treatment is the use of ozone gas, or O₃, which acts as an oxidant, to help control microorganisms, biofilm and fouling in the cooling water system without reliance on conventional chemicals.

In this case study, the ozone system was installed in the cooling tower’s cooling water circuit. The ozone generator produces ozone gas from oxygen, which is then mixed into the water via a mixing pump before being returned to the cooling water system, so that ozone circulates with the water throughout the system.

The installation configuration in this case study (example from one branch) is: cooling towers 3 × 500 tons, chillers 3 × 400 tons, circulation pumps 3 × 1,200 GPM, with ozone dosed into the system at a rate of approximately 100 L/min, covering a total pipe run of approximately 50 metres.

The distinguishing feature of this system is that it controls the problem at source, particularly by inhibiting biofilm — a key factor that allows scale and sediment to adhere readily to tube surfaces. When biofilm is controlled, condenser tube surfaces stay cleaner, heat transfer becomes more efficient, and the approach value can be held at a low level on a continuous basis.

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This case study collected data from five large retail branches, comparing performance during the period of chemical water treatment with the period after changing to ozone water treatment in the cooling tower’s cooling water circuit. The data collection method was as follows:

• Condenser Approach Temperature was measured continuously on all three chillers at each branch throughout the service period.
• Data was collected both before the system change (chemical) and after the change to ozone, in order to compare under real operating conditions.
• The continuous ozone data collection period was approximately 24 months, covering both the hot season and the rainy season.

The key criterion used to assess results in this case study was holding Condenser Approach below 4°F — a level that reflects that the heat exchange surface remains clean and that the system is able to maintain chiller efficiency on a continuous basis.

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Monitoring after the change to the ozone system found that all five branches were able to hold Condenser Approach below 4°F continuously throughout the 24-month study period, with most approach values in the range of approximately 2–3°F — clearly different from the period of conventional chemical treatment. Comparing the two systems in overview shows the following differences:

Indicator	Chemical treatment period	Ozone system period
Approach trend	Climbs continuously, approaching 10°F	Holds at approximately 2–3°F
Holding below 4°F	Not achieved continuously	Achieved continuously for 24 months
Condenser tube cleaning	Required approximately every 5 months	No tube cleaning required at all
Tube surface condition	Corrosion and blockage found	Tube surfaces clean after continuous service
Effect on chiller efficiency	Efficiency fluctuates with the fouling cycle	Efficiency more stable

At some branches there were periods where the approach value rose above the criterion, but the cause could be clearly identified — for example, the ozone system being shut down for cooling tower maintenance for approximately 1 month, or an abnormality in the chiller itself. Once the system returned to normal operation, the approach value returned below 4°F again.

This data helps confirm the relationship between continuous operation of the ozone system and holding the approach value at a low level — a key factor in maintaining chiller efficiency over the long term.

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Reducing Condenser Approach is not merely an engineering figure. It relates directly to reducing the electricity cost of the air conditioning system, because when the condenser transfers heat more effectively, the chiller does not need to use excessive energy to produce chilled water.

Based on the principle that every 1°F increase in the approach value raises kW/Ton by approximately 1.5%: comparing the chemical treatment period, with an average approach of approximately 6°F, against the ozone period, which held approach at approximately 2.5°F, gives a difference of approximately 3.5°F.

Assessed in engineering terms, this difference translates into a chiller efficiency improvement of approximately 5% on a continuous basis, for as long as the system is able to hold the approach value at a low level.

The actual saving in baht per year, however, depends on chiller load, operating hours and the electricity tariff at each branch, and should be calculated from actual bills on a site-by-site basis. What this case study clearly demonstrates is that holding the approach value low on a continuous basis is one of the methods that concretely reduces energy losses in a chiller system.

Water quality and environmental benefits

Beyond the effects on chiller efficiency and energy saving, the ozone water treatment system also clearly affects water quality in the cooling tower. The case study data found that water in the system after ozone use was clearer and cleaner than during the period of conventional chemical treatment.

The relevant water quality analysis results — such as pH, conductivity, hardness and alkalinity — remained within standard ranges, reflecting that the system is able to control water quality without reliance on conventional chemical dosing.

Environmentally, a chemical-free water treatment system is consistent with the sustainability goals of modern buildings, helping to reduce chemical use, reduce the risk of chemical residue in discharged water, reduce the use of acid for condenser tube cleaning, and support green building approaches as well as sustainable energy management.

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The case study of ozone water treatment across five large retail branches demonstrates that holding Condenser Approach Temperature below 4°F on a continuous basis can significantly help maintain chiller efficiency. After changing from a chemical system to an ozone system, the approach value stayed at a low level throughout 24 months, with no need to stop the machines to clean the condenser tubes with brushes or acid at any point.

Compared with conventional chemical water treatment, where the approach value tends to climb until tubes must be cleaned on a cycle, the ozone system makes cooling water management in the cooling tower more stable, reduces fouling, reduces the maintenance burden, reduces chemical use, and allows engineers to verify the results from the actual approach values occurring in the system.

For businesses seeking to manage energy costs efficiently, Econowatt provides energy management and water treatment solutions for air conditioning systems, delivered by a team of specialist engineers, together with a monitoring system to help control water quality, reduce microbiological risk, and support the continuous and sustainable performance of cooling tower and chiller systems.

Get in touch

• Line: @econowatt
• Facebook: Thai Energy Conservation — Econowatt Water Treatment & Energy Conservation Systems
• Tel: +66 2 809 1601
• Email: sales@econowatt.co.th

References

1. N. Suamir, I N. G. Baliarta, M. E. Arsana and I P. S. Negara, “Condenser–Evaporator Approach Temperatures and their Influences on Energy Performance of Water Cooled Chillers,” Proc. 14th Int. Conf. on QIR (Quality in Research), Lombok, Indonesia, 10–13 August 2015, ISSN 1411-1284, pp. 428–433.
2. Trane (Thailand), a business of Ingersoll Rand, “Exchanger Cleaning Program,” document MUL-SLB021-TH, May 2011.

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Q: What is Condenser Approach Temperature?

A: Condenser Approach Temperature is the difference between the saturation temperature of the refrigerant in the condenser and the leaving condenser water temperature. It is used to indicate the heat transfer efficiency of a chiller.

Q: How does a high Condenser Approach affect chiller efficiency?

A: A higher Condenser Approach requires the chiller to use more energy, because the condenser finds it harder to reject heat. This raises the kW/Ton value and increases electricity cost.

Q: What should the Condenser Approach value be?

A: In general, the approach value should be kept as low as reasonably achievable, with the appropriate range usually around 0–2°F, and should not be allowed to climb close to 10°F.

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Translation notes ⚠️

1. Client anonymity preserved — “five large retail branches”, as in the Thai original.
2. Trane citation — retained as reference [2], as published in the Thai original. See the note in the companion LinkedIn file: Trane is a chiller OEM rather than an ECONOWATT competitor, and the citation strengthens credibility. Confirm whether to keep the name or generalise it to “chiller OEM technical documentation”.
3. Reference [1] numbering — the Thai original lists the Suamir et al. paper without a bracketed number while citing “[1]” in the body. Numbering has been made consistent here. Worth fixing in the Thai original too.
4. “สัญญาณชีพ” → “vital sign” — kept as a metaphor, since it works equally well in English and is a memorable framing for the concept.
5. °F retained throughout — the source uses Fahrenheit for approach, which is standard practice in the chiller industry internationally. The one metric conversion in the original (1°F = 0.56°C) has been retained.
6. British English spelling used, consistent with the other website translations in this set.

Ozone CT FAQ

Website English Translation — Cooling Water System & Ozone Water Treatment

Source (TH): https://econowatt.co.th/blog/econowatt-case-study-cooling-water/ Purpose: English version for the ECONOWATT website · faithful to the Thai structure Created: 31 Aug 2026 · rev-01

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SEO metadata

Field	Value
Suggested slug	/en/blog/cooling-water-system-ozone-water-treatment-case-study/
Meta title (58 chars)	Cooling Water Systems & Ozone Water Treatment: 190-Day Test
Meta description (155 chars)	A 190-day ASTM G4 corrosion study on an ozone-treated cooling tower at a Thai automotive plant. Carbon steel 4.0 mpy, copper 0.28 mpy — both rated Good.
Primary keyword	ozone water treatment
Secondary keywords	cooling water system · cooling tower · condenser water · MIC corrosion · corrosion coupon test · chemical-free water treatment
Schema	Article + FAQPage

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Article

The cooling water system is central to both air conditioning and production processes in industrial plants. Where water quality is not properly managed, scale, biofilm and equipment corrosion can develop — driving up energy consumption, shortening equipment life, and raising maintenance costs.

Many organisations are now adopting Ozone Water Treatment as an alternative approach to managing cooling water: reducing chemical use, controlling microbiological growth, and maintaining the efficiency of cooling tower and condenser water systems.

Key points

• Ozone Water Treatment controls microorganisms and biofilm in the cooling water system, reducing the factors that give rise to microbiologically influenced corrosion (MIC).
• An ozone system reduces the use of water treatment chemicals, along with the associated chemical handling burden and environmental impact.
• Controlling water quality parameters such as pH and alkalinity alongside ozone use further improves the management of cooling tower and condenser water systems.
• Keeping equipment surfaces free of biofilm improves heat transfer efficiency, reduces energy consumption, and extends the service life of equipment in the system.

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A cooling water system transfers heat away from machinery or air conditioning equipment to the outside environment, with the cooling tower and condenser water system as its key components. If the quality of the circulating water is not appropriate, it will affect the performance of the entire system over the long term.

Commonly encountered problems include:

• Corrosion of steel pipework and heat exchange equipment
• Scale formation inside pipes
• Accumulation of biofilm and microorganisms
• Blockage of the circulating water system
• Reduced heat transfer efficiency
• Higher electricity and maintenance costs

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Ozone Water Treatment is the application of ozone gas (O₃) to treat the circulating water within a cooling water system. Ozone is a highly effective oxidant, capable of rapidly eliminating bacteria, fungi, algae and biofilm.

The ECONOWATT system generates ozone from oxygen in the air and injects it directly into the circulating water. Once it has done its work, ozone naturally reverts to oxygen, leaving no residual in the system.

Although ozone does not act directly as a corrosion inhibitor, it can effectively help reduce Microbiologically Influenced Corrosion (MIC) — corrosion caused by microorganisms — because it eliminates the biofilm in which microbial colonies accumulate on metal surfaces.

When the surfaces of pipework and heat exchangers are cleaner, heat transfer becomes more efficient and the likelihood of long-term corrosion is reduced.

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ECONOWATT installed an ozone generation system, model OZG1025N, on Cooling Tower (CT 3-1) at an automotive industry plant in Chonburi province.

The test ran continuously for 190 days (4 November 2025 – 13 May 2026), using corrosion coupons in both carbon steel and copper installed within the circulating water system in accordance with ASTM G4. The results were then used to calculate corrosion rates per ASTM G1 and compared against the criteria of the Association of Water Technologies (AWT).

Water quality during the test

Item	Test start	Test end
Date	4 Nov 2025	13 May 2026
pH	6.62	6.30
Conductivity	360 µS/cm	368 µS/cm
TDS	180 mg/L	183 mg/L
Temperature	30.1°C	28.7°C

The data shows that water quality changed only marginally over the test period, demonstrating that the system was able to maintain cooling tower operating conditions continuously under real operating conditions.

Corrosion test results

Material	Weight loss	Corrosion rate	AWT criterion	Assessment
Carbon steel	0.917 g	4.0 mpy	≤ 5.0 mpy	Good
Copper	0.074 g	0.28 mpy	≤ 0.35 mpy	Good

The results show carbon steel corroding at 4.0 mpy and copper at 0.28 mpy. Both values fall below the AWT standard criteria and are classified as “Good”, reflecting the system’s ability to effectively control corrosion of equipment within the cooling water system throughout the test period.

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Beyond the corrosion results falling within a good range, the water quality data offers further insight into the performance of the Ozone Water Treatment system.

Although pH sat in the range of 6.3–6.62 — below 7, a condition that may increase the likelihood of metal corrosion — and although conductivity of only 360–368 µS/cm and TDS of approximately 180–183 mg/L indicate water with a relatively low dissolved solids content, which engineering principles regard as a condition that may also affect metal corrosion, the corrosion rates for both steel and copper nonetheless remained at the Good level under AWT criteria.

This demonstrates that the ozone system effectively controlled the formation of biofilm and microorganisms — a principal cause of Microbiologically Influenced Corrosion (MIC) — keeping equipment surfaces clean and reducing the factors that accelerate corrosion within the system.

That said, to obtain the greatest benefit from Ozone Water Treatment, water quality should be managed in parallel — particularly controlling pH and alkalinity within an appropriate range, in order to reduce corrosion arising from chemical factors and extend equipment service life over the long term.

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Reduced chemical use

Ozone eliminates bacteria, fungi, algae and biofilm effectively, reducing reliance on disinfectants and multiple water treatment chemicals. This lowers both chemical procurement costs and the burden of chemical management.

Corrosion control

Although ozone is not a direct corrosion inhibitor, it reduces corrosion indirectly by eliminating biofilm — a principal cause of microbiologically influenced corrosion (MIC) — helping to extend the service life of pipework, pumps and heat exchangers.

Improved heat transfer efficiency

When heat exchanger surfaces are clean and free of biofilm, cooling tower and condenser water systems transfer heat more effectively, reducing the workload on equipment and saving energy over the long term.

Environmentally friendly

Ozone naturally reverts to oxygen, leaving no residual in the water. This reduces the load on wastewater treatment systems and supports business operations aligned with ESG principles and sustainable development.

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The real-world results of ECONOWATT’s Ozone Water Treatment system at an automotive industry plant over 190 days demonstrate that the technology can control corrosion rates at 4.0 mpy for carbon steel and 0.28 mpy for copper — both at the Good level under AWT criteria — even while operating under water conditions that would tend to promote corrosion.

Beyond maintaining the performance of the cooling water system, cooling tower and condenser water, the system also reduces chemical use, controls biofilm formation, lowers the maintenance burden, and supports energy saving and sustainable business operation.

For organisations looking to improve cooling water system efficiency while reducing energy costs and environmental impact, ECONOWATT’s Ozone Water Treatment technology is an option that addresses both the engineering and the long-term management case.

Get in touch

• Line: @econowatt
• Facebook: Thai Energy Conservation — Econowatt Water Treatment & Energy Conservation Systems
• Tel: +66 2 809 1601
• Email: sales@econowatt.co.th

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Q: How does Ozone Water Treatment reduce corrosion in a cooling water system?

A: Ozone does not act directly as a corrosion inhibitor. It eliminates microorganisms and biofilm, which are a principal cause of microbiologically influenced corrosion (MIC), thereby reducing the factors that accelerate corrosion and helping preserve the surface condition of equipment in the cooling water system.

Q: What types of cooling tower is an Ozone Water Treatment system suitable for?

A: The system can be applied to cooling towers and condenser water systems in industrial plants, office buildings, hotels, hospitals and large buildings. System design should take into account system size, water quality and operating characteristics in order to achieve the best performance.

Q: How does Ozone Water Treatment save energy?

A: When ozone reduces the accumulation of biofilm and fouling on heat exchanger surfaces, the system transfers heat more effectively. Equipment then operates more efficiently, the load on the cooling system is reduced, and energy consumption falls over the long term.

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Translation notes ⚠️

1. Buddhist era converted — 4 พ.ย. 2568 → 4 November 2025 · 13 พ.ค. 2569 → 13 May 2026. The 190-day duration has been verified against these dates.
2. Client anonymity preserved — “an automotive industry plant in Chonburi province”, as in the Thai original.
3. mpy — mils per year, retained without expansion as it is the standard unit in AWT documentation and will be understood by the technical audience. Consider adding “(mils per year)” on first use if the page targets a general audience.
4. “ต้องบริหารคุณภาพน้ำควบคู่กัน” — rendered as a clear recommendation rather than a caveat. This is a strength of the original: it prevents a reader from concluding ozone removes the need for chemistry control.
5. Phone number converted to international format.
6. FAQ heading — the Thai original’s FAQ heading says “about Condenser Water” while the article is about the cooling water system generally. Retained faithfully, but this looks like a copy-paste artefact in the Thai original and is worth fixing in both versions.
7. British English spelling used, consistent with the other website translations in this set.