Can a large cooling system run with no chemical dosing at all? A pilot at Tecnológico de Monterrey in Mexico set out to answer that question. Over several months, three Elgressy EST units treated the cooling water of three 1,000 TR towers (3,000 TR in total) without chemicals, and the university measured the result against its previous chemical-and-softener programme.

The project at a glance

• Site: Tecnológico de Monterrey (Tec de Monterrey), Monterrey campus, Mexico
• Cooling load: 3 cooling towers of 1,000 TR each, 3,000 TR in total
• Technology: 3 x Elgressy EST-25 electrochemical cooling tower treatment systems
• Pilot period: started February 2023 and was extended through August 2023
• Partners: Tec de Monterrey, Graco (Mexican water treatment company) and Elgressy Engineering, as part of the IFC TE SCI programme

The challenge: Mexican water, chemicals and softeners

The campus plant relied on softened make-up water and a regular chemical programme to hold back scale, corrosion and algae. That meant buying chemicals and salt, running water softeners, and sending treated blowdown to waste. The university wanted to reduce water, chemical and salt consumption, support its sustainability goals, and see whether the blowdown could be reused for irrigation.

The goals of the pilot

• Eliminate chemical dosing (sulfuric acid for pH control was the only exception)
• Remove the softeners and use the well water directly as make-up water
• Keep the towers in a non-scaling, non-corrosive state (LSI between 1.0 and 1.6)
• Stop algae forming in the cooling tower basin
• Run at higher cycles of concentration to cut make-up and blowdown water
• Keep the blowdown chemical-free so it can be reused for irrigation

The results

This is water treatment without chemicals in practice. The measured results over the pilot, expressed per year:

• Chemicals: 100% eliminated. About 7,800 litres of treatment chemicals no longer needed, worth around $30,000 USD per year.
• Salt: 100% eliminated. 60,840 kg of softener salt avoided, worth around $20,000 USD per year, plus roughly $35,000 USD of softener renewal avoided.
• Make-up water: 15% less, or 8,836 m³, worth about $5,125 USD per year. Cycles of concentration rose from about 3.0 to between 4.5 and 5.5.
• Softening water: 100% eliminated, 9,000 m³ less per year, worth about $5,520 USD. Together with make-up water this is 17,836 m³ of water saved per year.
• Scale, corrosion and algae: the towers were kept in a non-scaling, non-corrosive state, and no new algae formed in the basin.
• Heat exchanger performance: chiller approach temperatures stayed low without cleaning, instead of rising as they did under the chemical-and-softener programme.
• Blowdown: kept chemical-free and suitable for irrigation.

The financial case

Gross annual savings were about $60,645 USD. After the EST running cost of about $9,500 USD per year (around 70,000 kWh of electricity plus operating costs), the net saving was about $51,145 USD per year for the three towers.

On top of this, the pilot’s theoretical analysis estimated a potential chiller energy reduction of about 6% (360,000 kWh, roughly $53,000 USD and 156 tonnes of CO2e per year). The report is clear that this energy figure is a best-case theoretical estimate, not a metered result, so we treat it as upside rather than a guaranteed saving.

Lessons learned

The pilot was also a real-world test, and it taught useful lessons for any new installation:

• Adapt the equipment to the local standard voltage and follow local electrical regulations
• Use schedule 80 PVC piping
• Plan logistics, packaging and import documentation carefully when shipping from Israel
• Automate pH control and conductivity-based purge, both of which were added during the pilot
• Keep internal cleaning of the EST tanks on a regular schedule

Some technical issues came up during the pilot (including minor leaks, a transformer replacement and the extra attention needed for piping), and Graco supported the system closely throughout. Tec de Monterrey concluded that the system is viable and could be replicated in its other cooling plants.

What this means for your facility

Tec de Monterrey’s cooling water is a demanding, hard-water application, and chemical-free treatment still cut costs, water use and salt. If your cooling towers have the same scale, corrosion or chemical-cost problems, see how non-chemical and chemical treatment compare, read how chemical-free water treatment works, or check the 5 signs your cooling tower needs non-chemical treatment.

Water Treatment Asia is a subsidiary of Aerial Lift Asia, the exclusive Elgressy distributor for South-East Asia. Contact us for a free assessment of your cooling towers.