Vízügyi Közlemények, 2003 (85. évfolyam)

1. füzet - Somlyódy László: Az értől az óceánig - a víz: a jövő kihívása

94 •Somlyódy László regions, which are poor in water (in many countries the population was doubled in 20 years) this ratio can be increased to ten-fold by the year 2025, depending also on the effect of climate change (Figure 5). In Europe presently we use about daily 0.24-0.25 m

3 water per capita in a prodigal way. Of this the so called physiological water use (WC) is about 0.05 m

3/cap/day, while 0.11 m

3/cap/day is used in the bathroom and in the kitchen. To this conies about 0.08 nvVcap/day water loss, depending on the site (for example seepage from the distribution network). A characteristic of the present households is that they use the best quality water, regardless of whether it is used for drinking, cooking, or toilette flushing (Figure 6). Water consumption could be reduced by 50% without any special difficulty (Figure 7) by improving the maintenance of the distribution networks, supporting the use of water-saving facilities and by using an appropriate price policy. Results of investigations indicate that the above partial uses could be reduced to 0.025, 0.055 and 0.025 m

3/cap/day values, respectively. Drinking water consumption could be lowered to 0.05 m

3/cap/day, if it is confined solely to kitchen and bathroom uses. In this case one would distract the physiological water use from the rest, naming the former the "black sewage", while the rest is named "grey sewage". For flushing of the toilette (if this remains in use) one could use treated "grey sewage" or precipitation water. This, however, would require dual piping within the buildings. The flushing type toilette transports various substances and pollutants into the water phase in a uniform manner, although only 2 sources represent pollutants which must be carried away by water, as the only possible solution (Figure 8). Departing from the use of the traditional "English" WC, the various substances could, along with the decrease of water consumption, be diverted to various directions, taking into account the requirements of easy treatment, the recycling and reuse of water, the closing of the material cycles. The result of all these would be the sustainability. Here only two basic solutions are mentioned (which do not exclude each-other): (I ) Using the present systems with the inclusion of "biological wastes": and (2) separation of the physiological waste and its treatment together with the biological wastes. Thus we state that our present knowledge would allow, in principle, sustainable water saving solutions, which require less energy consumption and carbon dioxide emission and is based on closed cycles. Evidently these solutions depend on the type of the settlements, on the climate and the infrastructure, on the legal regulation of environmental protection, on the flexibility of the environmental industry and on several other factors. In a real situation the options are much richer, depending also on local circumstances. Namely, we could divert the waters, together with their plant nutrient content, from the settlements towards the industry and/or agriculture (in function of the demand and the options of reuse), producing with this a water quality, which is (unlike the case of the flushing toilette) just tailored to the demand of the water use in concern. A part of the water would be spent and the portion which is not recycled (this amounting only to a fraction of the present sewage quantity) would be discharged into recipient water bodies, after appropriate treatment. This line of thoughts leads as to the integrated water management of the future (Figure 9) in which the principles of prevention, cautiousness, that of the "Polluter Pays", the full recovery of costs and the efficiency of the operations are the characteristic ones. The water policy of the EU is based on these principles. As contrasted to the present solutions, the problems of water quality and quantity would not be trans-located neither in time nor in space (Figure 10). This would curtail or even eliminate transboundary impacts. Evidently, technological renewing could only lead to success if it happens along with the alteration of our own attitudes. The precondition of the latter is to improve public education and awareness from the kindergarten until old age.