Implementation of biological filtration for simultaneous removal of arsenic, iron and manganese from groundwater in Asian countries

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We have developed the biological filtration system for simultaneous removal of iron, As, manganese and ammonia from water after 7 years of pilot test in Japan. It can be used in drinking water treatment plant as well as in individual household. Recently, the technique was successfully applied to treat As containing well water in Hanoi, Vietnam. In average, the raw water at the Hanoi site contained 9.6±3.1 mg/L of Fe and 59±8 μg/L of As during the term of the experiment. Ca. 90% of the total arsenic was As(III). The average As removal in the operation from Nov. 4, 2009 to Sep 27, 2010 was 84±6%, during which the flow rate was changed from 100 m/day to 400 m/day. Raw water feeding was continuous for the first 5 months, and was changed to intermittent mode (operate for 1 hr and stop for 3 hrs) because of the reduced groundwater level. When the flow rate was increased to 600 m/day after Sep 27, 2011, the removal was decreased to 67% probably because the filter bead height was small (less than 1 m) compared to the pilot test conducted in Japan (1.5m bead height). The results of the pilot-test showed that the biological filtration technology could efficiently remove As in groundwater from Hanoi.