Impact of side stream crossflow filtration on water quality in a HVAC circuit

This study evaluates the impact of a VORTISAND® Crossflow Microsand Filter (CMF) on the water quality and operational efficiency of a cooling tower system in a large hospital building. Data was collected over 18 months, comparing periods when the filter was active versus inactive. Results demonstrated that the filter reduces turbidity, total suspended solids, and particle counts by 20%, 25-30% and 69%, respectively. The filter was effective particularly for particles >1 μm . Filtration also decreased the concentration of iron and calcium ions by 15% and 25%, indicating its effectiveness in managing particulate and scaling components. While the filter improves water quality and stabilizes system operations, it increases water consumption by 20.7 % due to backwashing. These findings highlight the potential of integrating physical filtration into cooling tower management to optimize performance and reduce chemical use, although further strategies are needed to minimize water losses. This study offered a unique opportunity to successfully shut down the CMF in a full-scale operating system with high maintenance standards and assess the actual impact of the filtration on water quality and operability of the HVAC system. • Long-term use of a side stream crossflow filtration system improves water quality • Removal of all particles improves system efficiency and mitigates fouling issues • Side stream filtration improves process stability and reduces chemical consumption • The daily filter backwash system requires large volumes of water • Increased human resources were required to operate the system without filtration