Zero tolerance for Legionella and biocides in cooling system at Epiroc
There are several challenges associated with the operation of open recirculating cooling systems. Warm and humid conditions are ideal for the reproduction of disease-causing microorganisms such as Legionella bacteria. To overcome this challenge, toxins such as biocides are often added, which leads to further problems due to strict wastewater regulations.
To ensure that strict requirements for Legionella are met as well as the need for cooling and reduced costs, Epiroc Drilling Tools in Fagersta has installed AquaWorker - a powerful industrial UV system that reduces biological and organic pollutants, especially developed for tough conditions.
AquaWorker at Epiroc resulted in:
- Reduced risk of Legionella outbreaks
- 90% reduction in operating costs and biocide consumption
- Less handling of chemicals and related risks
- Shortened downtime and reduced chemical emissions
- Low and stable bacteria levels beneath recommended action levels
Focus on sustainability at Epiroc
At Epiroc, part of the continuous sustainability work is to reduce the use of chemicals. For the cooling system, the goal was to replace the use of biocides with UV treatment.
Biocides have historically been used to control biological activity in the cooling system but despite this, Epiroc has experienced problems on several occasions with bacteria levels exceeding EWGLI limits. Legionella levels have also exceeded the limits on some occasions. In these cases, they have had to use large volumes of cold tap water to meet the production requirements for process cooling, resulting in high costs.
AquaWorker at Epiroc
Wallenius Water Innovation conducted a system analysis for the cooling system at Epiroc, and AquaWorker was installed and fully operational at the end of August 2022. From September 2022 to May 2023, the amount of biocides was continuously reduced while the system's bacteria levels were measured.
"We wanted to feel sure of not getting legionella growth in our system, but at the same time we wanted to reduce the biocide addition. This product has helped us, and we see the possibility of being able to completely exclude biocide additives and ensure low water consumption"
Elin Stål, Safety & Health Coordinator, Epiroc
Annual savings of SEK 580 000
Epiroc's total annual savings were over SEK 580 000. The largest savings are due to reduced consumption of biocides. The operating cost calculations include costs for biocides, electricity, spare parts and maintenance hours for personnel. The ROI calculation was less than 2 years.
| Biocides only | AquaWorker in operation | |
| System data | Total volume=150 m3, Cooling flow rate=176 m3/h, Operation=360 days, 24h |
|
| Water treatment | Biocides 100% | UV treatment, biocides < 10% |
| Biocide dosage | 90 min/day, 7 days/week | 45 min/day, 1 days/week |
| Bacteria levels | Fluctuating, bacteria levels above 106 CFU/ml | Stable, bacteria levels below 104 CFU/ml |
| Transmittance of water | 24% | 57% |
| Water/system appearance | Fluctuating, foam | Stable, much less foam, clearer water, less system cleaning required |
Want to know more? Read the full case here [PDF]
About Epiroc
Epiroc develops and supplies innovative and safe equipment such as drilling rigs, rock mining and construction equipment and tools for surface and underground applications. Epiroc has approximately 17 000 employees who support and collaborate with customers in approximately 150 countries.
