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  2. Article: Screening for the good cause - Engelsmann builds prototype for the International Water Aid Organization


Screening for the good cause

ENGELSMANN is supporting the International Water Aid Organization with the development of an Emergency Water Kit

Screening technology is not only used in industrial processes, it can also save lives. This is proven by a current project led by the International Water Aid Organization and the Hochschule Mannheim University of Applied Sciences, which was also supported by Engelsmann. The common goal: an emergency water kit that makes it possible for victims of natural disasters to produce their own hygienically perfect, potable water during the first three days following the disaster.

Natural disasters, such as tsunamis, flooding or hurricanes usually destroy electricity cables, water pipes, streets and bridges. They can also bury wells or contaminate them with water containing sewage. In remote areas, aid organizations cannot bring mobile drinking water treatment systems, and the necessary energy supply systems, by lorry. So as not to die of thirst, the affected population resort to drinking surface water, which is often contaminated with sewage or earth, in emergencies. They are then commonly infected with pathogens causing diarrhea.

The IWAO has thought about this problem and about how they could help people suffering from extreme water shortages. This is how the Emergency Water Kit was born. It should be able to treat highly polluted river water and provide 20 people with 3 liters of hygienically perfect, potable water per person for 3 days, without the people treating the water having to know how to read an instruction manual. However the emergency kit had to meet certain requirements. For example, the river water must be able to be treated without an external energy supply. Chlorine tablets or granulates are not included as this could lead to improper use, for example there is a risk of the product being swallowed or an incorrect dosage may be used.

The specific requirements for this kit were:

  • Energy-free treatment of 200l of highly polluted river water in 72 hours
  • Reduction of turbidity from 400 NTU to < 1 NTU
  • Removal of bacteria, decreasing levels from 108 KBE / 100ml to 0 KBE / 100ml
  • Conservation of the treated surface water for over 72 hours
  • Must be able to be dropped from an airplane / helicopter
  • Must be operable without any educational background (e.g. no reading of the operational manual)

Design of the Emergency Water Kit

The idea was to take tried and tested systems for water treatment and to combine them and, if necessary, to develop them further in such a way that they correspond to the requirements mentioned above. The Institute of Biological Engineering project team, in collaboration with the scientific-technical advisory board, came up with a 3-level concept as to how and with what elements the solutions to the requirements named above should be found. The researchers from the Hochschule Mannheim University of Applied Sciences thought that having three levels, including:

  • A standard commercial filter bag (embedded in a “salad spinner”-type construction)
  • An active charcoal filler, like you see in water filters in the kitchen
  • A metal filter mesh

all fitted under each other in a cylindrical vessel, which you can hold tight under your arm, would solve the problem.

In order to test the process for this prefilter system, a prototype had to be made. They quickly found the perfect partner in the screening technology specialists J. Engelsmann AG, based in Ludwigshafen, who developed a functioning filter system using the ideas and specifications from the Hochschule Mannheim University of Applied Sciences. The research team's project was met with wide support from the Engelsmann designers and so there was a particularly high level of motivation to develop a suitable prototype and to optimize it further using Engelsmann's screening technology know-how. The screening specialists placed a particular focus on good accessibility to all parts of the filter system. For this purpose, the three-level filter system was made in modules which could be easily disassembled. This modular construction method allows the users to clean the filter systems without a significant effort and to keep it free from foreign objects, such as leaves.

In the first filter level, right at the top, the contaminated water flows through a filter basket and initially the largest solids are separated off from the water. With the help of a gearwheel and a crank handle, an interior, uninterrupted shaft, which is fitted with a paddle in the upper area of the first filter, is driven. When operating the crank handle, the paddle begins to rotate and helps to separate solids, such as leaf debris, from the water by using centrifugal force   similar to the functional principal of a salad spinner. The water, which is now free from the coarsest particles of dirt, now flows from above into the second screening level, where it is passes through the active charcoal filler and is filtered again. In the second level, in the middle area, of the filter, the shaft is fitted with a longer paddle than in the first level. The paddles rotate directly beneath the first level's screen floors so that the prefiltered water flowing through here can be optimally distributed on the entire active charcoal surface below. In the third and final level, after passing through the active charcoal level, the water flows through a further screen basket which has a much finer screen mesh than the screen used in the first level. In this way, the smaller solid particles that remain in the water can be separated off in the last step of the procedure. Adjustable wiping strips free the fine mesh from large deposits and ensure that the water passes through the mesh. By the end of the process, the filtered water should only have a turbidity of 10 NTU.

Along with the given manual method for filling the filter system, the Engelsmann designers also developed an “automatic” variation. For this purpose, a fourth module in the form of a tank was built onto the first filter level. A water supply connected to this supplies the tank with water. An adjustable float gauge measures the level so that optimal water intake is guaranteed and the user can avoid overfilling the filter system. In this way, the collected river water can be filtered overnight, for example, and can be used the next morning as safe potable water.

The Engelsmann designers really enjoyed taking part in this unusual task and experimenting with different components. During the process, many everyday objects, such as a basket for a deep fat fryer or a toilet flush, were used to simulate the procedure in as realistic a way as possible. On June 20th the presentation of the emergency kit took place at a press conference at the Engelsmann premises. If you missed the resulting television broadcasts, you can still watch them in the media centres, by clicking on the following links: