Arsenic, iron and manganese removal from ground water in a pilot plant located at a rural school

En el Centro de Ingeniería Sanitaria (CIS) se desarrolló el Proceso BioCIS-UNR® para remoción de hierro (Fe) y manganeso (Mn) y mediante este trabajo, se pretende ampliar su campo de aplicación para remoción de arsénico (As) en presencia de Fe y Mn. Se operó una planta piloto en una escuela en Zuripozo (Provincia de Santiago del Estero, Argentina), en una perforación cuya agua tiene: Fe total 0.35 mg.L-1 , Fe 0.04 mg.L-1 , Mn total 0.16 mg.L-1 , As total 42 g.L-1 y bacterias del Fe. Con las concentraciones naturales las eficiencias de remoción fueron 35% Fe total, 90% Mn total y 10% As (con valores máximos de remoción observados de 40%). Para mejorar el proceso, se agregó sulfato ferroso al agua cruda; las eficiencias fueron 92% Fe Total, 95% Fe2+, 93% Mn Total y 66% As Total. La baja eficiencia de remoción de As inicial podría deberse a la baja cantidad de precipitados biológicos de Fe formados, que da lugar a escasos sitios de adsorción disponibles para el As. Este proceso, de fácil operación, bajos costos de instalación y operación, es una tecnología aplicable a abastecimientos de agua potable con escasos recursos y alejados de centros urbanos.The Process BioCIS-UNR® developed by the Centro de Ingeniería Sanitaria (CIS) for iron (Fe) and manganese (Mn) removal was further developed in this work to remove arsenic (As) in presence of Fe and Mn. We operated a pilot plant located in a school at Zuripozo (Province of Santiago del Estero, Argentina. The plant was connected to a well with water containing total Fe 0.35 mg.L-1, Fe+2 0.04 mg.L-1 , total Mn 0.16 mg.L-1 , total As 42 g.L-1 and Fe bacteria. This element concentration was compared with element concentration in natural water. The efficiency of element removal was 35% of total Fe, 90% of total Mn and 10% of As (maximum 40%). Ferrous sulfate was added to raw water to improve process efficiency. The efficiencies obtained were 92% for total Fe, 95% for Fe2+, 93% for total Mn and 66% for total As. Initial low efficiency of As removal may be due to a low formation of Fe biological precipitates, causing a shortage of available sites for As adsorption. This easily operated process with low installation and operation costs is an affordable technical solution for drinking water supply for rural areas with scarce resource located far from urban centers.Comité de Medio Ambient