Production of Drinking Water from Highly Contaminated Surface Waters: Removal of Organic,Inorganic, and Microbial Contaminants Applying Mobile Membrane Filtration Units

In military out of area missions of the Bundeswehr, it can be necessary to produce drinking water even from highly polluted surface waters containing a variety of organic, inorganic, and microbiological contaminants. Thus, mobile drinking water purification systems must be able to remove such contaminants as far as possible to meet the requirements of the German and European drinking water regulation/directive. Presently, two novel drinking water purification units applying membrane filtration undergo intensive long‐term trials carried out by the Bundeswehr. If these trials positively proof the functionality of these units and their ability to remove all possible contaminants they shall substitute so far available devices which use large amounts of chemicals and charcoal filtration for water purification.In the course of a research project, the functionality of the new devices and their efficacy to remove high amounts of algae, microbes, and organic and inorganic pollutants are additionally tested in “worst‐case” field studies. In September 2000, the first mobile drinking water purification unit was tested at the Teltowkanal in Berlin, Germany.This canal was chosen because it carries high burdens of municipal sewage effluents. The results from the fatigue test confirmed the ability of the water purification unit to reduce the concentrations of all contaminants meeting the maximum tolerance levels set by the German/European drinking water regulation.The pre‐filtration device was very effective in removing algae and solid particles to protect the membranes from clogging and to enable an almost maintenance‐free operation. Residues of pharmaceuticals and some other organic contaminants have almost totally been removed from the surface water where they were detected at individual concentrations up to the μg/L‐level.     

Elimination of Swimming Pool Water Disinfection By‐products with Advanced Oxidation Processes (AOPs)

Ozonation is a treatment step which was first applied in the 1960s in pool water treatment for disinfection as well as for oxidation of pool water contaminants. Contact time between ozone and pool water was identified to be of significance with an increased elimination efficiency regarding chloramines, trihalogenmethane formation potential and the permanganate index for longer reaction times. Oxidation via OH radicals might be the dominating pathway. In this study ozonation was compared with the ozone based advanced oxidation processes ozone/UV and ozone/hydrogen peroxide regarding the elimination efficiency of both disinfection by‐products (DBPs) and DBP precursors. It was observed that AOPs in comparison to ozonation showed an increased elimination efficiency regarding total organic carbon (TOC), the organically bound halogens adsorbable on activated carbon (AOX) and AOX formation potential. A contact time of 3 minutes between pool water and oxidant turned out to be practically sufficient. Just for the trihalomethane (THM) formation potential ozonation showed a slight advantage compared to the AOPs because ozonation is a highly selective oxidant and OH radical reactions are known to produce small reactive molecules which are easier transformed to THMs. Combination of membrane filtration and AOPs resulted in an elimination of 10 to 90 % of the DBPs and their precursors. The ozone/hydrogen peroxide process is suggested for pool water treatment because of the higher elimination rates compared to ozonation and of economic reasons compared to the ozone/UV process.