WATER PURIFICATION Composition of water sources on Earth. ©Kärcher Futuretech
module able to cope with all kinds of contamination and designed for a worst-case scenario. If the raw-water quality in the operation area is not known,
the customer can operate the purification system with all modules running. They can also adjust the water purification to real raw-water quality in longer-running missions aſter analysis of raw water quality has been done. The benefits of this approach include reduced running costs and higher yields of drinking water production, as well as a complete system design approach for maximum ruggedness and hygiene.
Clean water in the field KFT’s water purification and drinking water filling systems have been deployed for more than ten years on missions in varying climates and under very different mission parameters, including ISAF in Afghanistan, tsunami disaster relief in the Maldives and Sri Lanka, and the earthquake and tsunami in Japan. For the main treatment KFT uses either ultra-filtration (UF) membranes or reverse-osmosis (RO) membranes. In mobile applications, membranes are mostly used for the main treatment steps as they are compact, use far fewer chemicals for the purification
WAA DECON
In 2012 KFT won a competitive tender from the Federal Office of Bundeswehr Equipment, Information Technology and In-Service Support for the Bundeswehr (German Army) for a new water purification system designed to treat CBRN-contaminated raw waters based on German drinking water legislation (TrinkwV 2001 – the so-called ‘WAA Decon’). The illustration above and right shows the WAA Decon concept with the purification and accessories containers. The system is designed to be easily operated while wearing full CBRN protective clothing; no contami- nation is spread during the changing of pre-filters or RO membranes.
56 CBNW 2013/01
process, and are relatively easy to use compared with classical treatment methods in stationary drinking water production, such as flocculation in combination with rapid sand filtration. RO systems achieved a retention rate of more than 99% for the most relevant chemical contaminants present in natural raw water sources. RO can also remove microbacteria and viruses with more than seven log steps (> 99.99999 %). If the raw water contains a higher particle load – from slit, sand, and in colloid suspensions – a preliminary ultra-filtration membrane stage should be used ahead of the RO stage. KFT’s UF stage can also be used as a stand-alone system as it additionally removes microbacteria and viruses at the same rate as the RO system. Chemical contami- nants cannot be removed by ultra-filtration systems. If the raw water is very badly contaminated with CBRN contaminants – that is, chemical warfare agents (CWAs) of 10 mg/l concentration according to the standards set by FINABEL (the EU organization which aims at developing a joint European under- standing of defence), the very high retention rates of the RO stage may not be sufficient to meet required standards. Normally, such extremely high contaminations are only present in natural raw water sources aſter acts of war, terrorism, and natural disasters.
Double-Pass For such extreme events KFT developed the Double-Pass mode especially for its RO systems. The equipment can be installed in all water purification systems based on KFT RO membrane technology (above and right). Using this option, the system’s elimination rate is doubled while the yield in drinking water is reduced. In the Double-Pass mode, the membranes get hydraulically connected in such a way that each water molecule coming out of the drinking water outlet of the system has passed through two RO membranes. Live-agent testing was conducted to FINABEL standards
at the German Armed Forces Scientific Institute for Protection Technologies NBC Protection (WIS) in Munster, using the trailer-based WTC 1600 system. It met long-term limit values for drinking water according to STANAG 2136 (the NATO standard for drinking water) for most of the tested contaminates that had already made the single pass. The Double-Pass mode was only necessary for a few contaminants to reach values far below the STANAG 2136 limits.
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