Arsenentfernung mit Ultra-Low-Pressure Ultrafiltration (ULPUF)-Kombinationsverfahren zur Wasseraufbereitung in Entwicklungsländern

This dissertation deals with the development of extended ultra-low pressure ultrafiltration (ULPUF) with the aim of providing arsenic-free drinking water in the economically weak regions of the world. To remove arsenic to the WHO guideline value of 10 μg/L, the combination of ULPUF with adsorption on clay (C-ULPUF) and electrocoagulation (EC-ULPUF) were investigated. Firstly, the investigations on the ULPUF without expansion were carried out. An amount of 20 m³ of arsenic-containing water with an average arsenic concentration of 100 μg/L was treated. As a first result, ULPUF without expansion cannot be applied for the selective removal of dissolved arsenic. However, ULPUF allows complete removal of particulate arsenic compounds. In the following investigations of the combined C-ULPUF process, 50.5 m³ of arseniccontaining water (avg. 100 μg/L) were treated. In continuous operation with a clay dosage of 16 g/L, the C-ULPUF pilot plant provides an As(V) removal from drinking water of average 90.7 % and an As(V) effluent concentration of average 9.0 μg/L. In supporting laboratory tests, the arsenic adsorption capacity of different clay mineral based adsorbents was determined and a mathematical model approach was set up, which allows the estimation of arsenic adsorption capacity and clay dosage. In the investigations of the combined EC-ULPUF process, 47 m³ of arsenic-containing water (avg. 100 μg/L) were treated. The performance of the electrocoagulation cell with aluminum electrodes was investigated and a model approach was developed to estimate the required charge dosage for arsenic reduction in drinking water. In continuous operation with a charge dosage of average 125 C/L or an electrical energy demand of about 500 Wh/m³ provides the EC-ULPUF pilot plant an As(V) removal from drinking water of average 96 % and an As(V) effluent concentration of average 6.5 μg/L. The comprehensive studies verified the ability of both C-ULPUF and EC-ULPUF combined processes for selective arsenic removal. Both processes are capable of providing potable water that meets WHO requirements regarding arsenic and bacteria. Cost of the process were found to be in the range of 0.60 €/m³ to 2.20 €/m³ for C-ULPUF and 0.50 €/m³ to 1.60 €/m³ for EC-ULPUF and are within the willingness-to-pay range for households in economically weak regions of the world.