268 J Health Popul Nutr Sep 2006 Sancha AM Fig 1. Name and location of water-treatment plants for removal of arsenic, Chile Chile Chuquicamata Chuquicamata Salar Del Carmen Antofogasta Cerro Topater Calama 600-900 150-350 100-250 <50 600-900 150-350 140-250 70-90 80-90 60-80 that use the same process have been built in the north- ern zone in subsequent years (6-9). Experience has confirmed that the coagulation process is a good device for both quality of water (Table 2) and volumes of water to be treated. Recent- ly, the WHO identified the coagulation process as be- ing the most appropriate technology to remove arsenic in large volumes (10). Numerous researchers are cur- (11-16). Some new knowledge became apparent during Chile’s long experience with full-scale arsenic-removal treatment plants. The Chilean drinking-water standard permitted a maximum arsenic concentration of 50 µg/L until 2004. Currently, the Chilean drinking-water standard has been modified to reach a goal of 30 µg/L in 2010 and 10 µg/ L in 2015 (17). The WHO recommended that water for coagulation (5). The first plant was built and began op- erations in 1970. Four arsenic-removal plants (Table 1) rently investigating the coagulation process, and their results indicate that further improvements are viable Table 1. Water-treatment utilities for removal of arsenic in Chile. Chuquicamata is owned by a mining company and has limited availability of public data Utility Capacity (L/sec) Water source Arsenic range (µg/L) Salardel Carmen Complex* Old plant (1970) New plant (1978) Cerro Topater* (1978) Chuquicamata* (1989) Taltal** (1998) *Surface water; **Groundwater 500 520 500 210 32 Toconce Lequena Quinchamale Siloli Polapi Toconce Lequena Quinchamale Colana Inacaliri Agua Verde