Assessment of Asbestos Fiber Occurrence and Removal Throughout the Drinking Water Treatment Chain: From Source Contamination to Household Filtration

Asbestos contamination in drinking water remains an underexplored environmental issue despite the widespread historical use of asbestos-cement materials in water infrastructure and buildings worldwide. This study evaluated the occurrence and removal of asbestos fibers throughout the drinking water treatment chain in Cartagena de Indias, Colombia, from source contamination to household filtration. Synthetic asbestos-contaminated water prepared from asbestos-cement roofing materials was treated using coagulation–flocculation with aluminum sulfate, a pilot-scale conventional treatment train, membrane filtration, and household point-of-use filtration systems. Asbestos quantification and mineral identification were performed using transmission electron microscopy (TEM), with results reported as million fibers per liter (MFL). Coagulation–flocculation achieved the highest removal efficiencies, reaching up to 99.8% at aluminum sulfate dosages between 35 and 45 mg/L. The pilot-scale treatment system substantially reduced asbestos concentrations, with granular filtration representing the principal removal barrier. Membrane filtration exhibited moderate and highly variable performance, with an average removal efficiency of 44.7%, whereas household filters showed inconsistent behavior and occasional concentration peaks associated with possible breakthrough or remobilization processes. The results demonstrate that asbestos removal is strongly governed by the treatment mechanism, with particle destabilization and aggregation outperforming technologies relying exclusively on physical retention. These findings support the progressive replacement of asbestos-containing water infrastructure as the primary long-term preventive strategy, complemented by targeted monitoring and optimized asbestos-removal treatment where fiber contamination is detected or a risk of release from legacy materials exists.