Did you know that in an automatic car-wash, several hundred liters of water are needed, also for just one motor car? Can you imagine, what the water- and especially the sewage costs are for operator? If one cubic meter
nowadays, costs a good bit more than 5 Euros, it could mean up to 30 or more Euros per hour.
It's quite obvious, that a water processing system is of significant value. Of course this also makes sense for ecological reasons. However, one must make a distinction between the various types of car-washes.
Apparently, in the self-service areas less water is used than in the automatic car-wash, it would appear that here the water processing is obviously too expensive. Thus, if you wish to do something for the environment, then
choose the automatic car-wash.
Since this article is about water processing and not about oil-separation, we won't go into the subject of what happens to the water when it leaves the self-service wash. Here we will be dealing solely with washing
facilities for motor cars, trucks and, if you like, for trains. At this point, we would like to explain the three stages of water processing.
In this case, like with the oil-separation, we have to, first of all, concern ourselves with the grit-trap as a part of the 'coarse material separation'. This is a sufficiently large concrete basin, where the waste water from the
system is stored for a while. All the coarse particles sink to the bottom. This is followed by the so-called 'water revitalization', whereby, the respective enriching through compressed air provides sufficient oxygen for the
microbes to do their biological degrading more efficiently. The final, physical process of separating the fine substances, if not already done in stage 1, then takes place. Afterwards, although the water cannot be drunk, it
can again be used for further washing. The manufacturers even guarantee the greatest possible neutrality as far as odour is concerned.
The dimensions of the installation are very important. A part of a side-room, must be able to handle up to 3.000 liters per hour. In those where the cars are washed one after the other, up to 50.000 liters per hour are then
used. If the necessary space, of up to 40 m², is not available, then the installation must be placed underground and must be cased in a concrete jacket, whereby, the stages 2 and 3 might be combined.
Indeed, we've now landed back with the oil-separator, because it is situated directly next to the processing plant. Of course, in connection with the water processing, chemistry also plays a role, the chemicals are
introduced during the circulation. One particular example should be mentioned here, the removal of graffiti from the outside of train coaches.
One might think that the system has now been sufficiently explained. Indeed, the problems lie in the details. In fact, there where one would not expect them to be. Whoever would expect there to be a difference between two
round grit-trap basins and one oval one? Indeed, instead of two round ones, each having the same diameter, one should rather have one oval basin. After all, the excavation work is the same and the effective surface area
is almost doubled.
The time that the particles linger in the basin, has a settling effect on them, on the other hand however, the change from one basin to the other does just the opposite. If the smaller particles are also to sink to the bottom,
then a longer settling phase is helpful. This means a longer settling period at the same flow rate and thus, an increased cleansing effect. 09/12