Entwicklung betriebssicherer Verfahren zur Arsenentfernung bei kleinen Wasserwerken Schlussbericht

Arsenic appears as arsenate-(III) but mainly as arsenate-(V) in geogene contaminated groundwaters. Beside the oxidation state of the arsenate the pH-value, the phosphate concentration as well as the volume of water which has to be treated plays an important role to choose a reliable treatment process method. To minimize arsenate-(V) coprecipitation on Fe(OH)_3, precipitation with Fe"2"+-ions or adsorption on activated alumina are useable. The loaded aluminium oxide can be regenerated by using NaOH. In special cases a nanofiltration is suitable for arsenic removal, which leads to hygenic safe solutions especially in individual supplies. The use of the granulated iron oxide in fixed-bed-adsorbers developed during the project is especially advantageous, because this material has much higher adsorptive capacity in comparison with the aluminum oxide. If arsenate-(III) appears in the water, an oxidation to arsenate-(V) is required. For oxidation of arsenate-(III) the oxidation agents Fenton's reagent (H_2O_2) and Fe(II)) and potassium permanganate were tested. Furthermore, the following methods were tested: UV-induced oxidation, catalytic oxidation with activated carbon and oxidation with solid #delta#-manganese oxid. (orig.)SIGLEAvailable from TIB Hannover: F95B1074 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman