Human health risk-based life cycle assessment of drinking water treatment for heavy metal(loids) removal.

A human health risk-based life cycle assessment (LCA) framework was developed for selecting low-impact water treatment systems with a focus on heavy metal(loids) removal. The framework comprises three phases, including pilot-scale water treatment, human health risk assessment (HRA), and LCA. The application of the framework was demonstrated by a case study. Two water treatment systems employing ozonation-greensand-ferric hydroxide-based sorbent (OGF) and Birm-ferric hydroxide-based sorbent (BF) processes were used to reduce arsenic and manganese concentrations in the source water of a small municipality in southwestern Canada. The heavy metal(loids) concentration as well as material and energy use data of the two systems were collected to perform HRA and LCA. The results showed that both systems can reduce arsenic and manganese concentrations; however, the removal efficiencies of OGF and BF processes decreased with the increase of treatment volume. At a constant inflow rate, the ferric hydroxide-based sorbent needed to be replaced every 31 and 25 days in the OGF and BF processes, respectively, to ensure that arsenic concentration in the effluent would not pose any significant human health risk. The LCA results indicated that the system using the OGF process generated lower life cycle environmental impacts than the system using the BF process throughout ten years' operation. It was also found that the arsenic removal process was the largest impact contributor in both systems. The manufacturing of ferric hydroxide-based sorbent and disposal of arsenic-contaminated treatment waste accounted for the highest impact in water treatment. Image 1 • A health risk-based LCA framework is proposed for assessing water treatment systems. • Two water treatment systems designed for arsenic and manganese removal are assessed. • Human health risk assessment determines acceptable adsorbent replacement frequency. • System using ozonation-greensand-ferric oxyhydroxide treatment shows lower impacts. • Arsenic removal process generates the highest life cycle environmental impacts. [ABSTRACT FROM AUTHOR]