Effect of phosphate availability on biofilm formation in cooling towers.

Ingrid S M Pinel, Lan Hee Kim, Vitor R Proença Borges, Nadia M Farhat, Geert-Jan Witkamp, Mark C M van Loosdrecht, Johannes S Vrouwenvelder

Biofouling 2020 Aug

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Phosphate limitation has been suggested as a preventive method against biofilms. P-limited feed water was studied as a preventive strategy against biofouling in cooling towers (CTs). Three pilot-scale open recirculating CTs were operated in parallel for five weeks. RO permeate was fed to the CTs (1) without supplementation (reference), (2) with supplementation by biodegradable carbon (P-limited) and (3) with supplementation of all nutrients (non-P-limited). The P-limited water contained ≤10 µg PO4 l-1. Investigating the CT-basins and coupons showed that P-limited water (1) did not prevent biofilm formation and (2) resulted in a higher volume of organic matter per unit of active biomass compared with the other CTs. Exposure to external conditions and cycle of concentration were likely factors that allowed a P concentration sufficient to cause extensive biofouling despite being the limiting compound. In conclusion, phosphate limitation in cooling water is not a suitable strategy for CT biofouling control.

Citation

Ingrid S M Pinel, Lan Hee Kim, Vitor R Proença Borges, Nadia M Farhat, Geert-Jan Witkamp, Mark C M van Loosdrecht, Johannes S Vrouwenvelder. Effect of phosphate availability on biofilm formation in cooling towers. Biofouling. 2020 Aug;36(7):800-815