The paper describes some studies on the influence of water flow rates through water-supply networks on drinking water quality. Water residence time in pipelines for more than seven days in buried pipes and two days in above-ground pipes promotes the development of biochemical systems when the flow rates are low and very low having detrimental consequences on drinking water quality. These shortcomings are due to the residual chlorine decrease below the allowed technical limits (0.5 m/s) as a consequence of the fact that in distribution pipes, fittings and drain junctions the water flows at low rates reaching far to stagnate over the admitted residences. The case study was conducted on the water-supply network in the city of Timişoara using the EPANET program. The hydraulic parameters (flow, diameter, flow rate, loss of head) of EPANET are correlated with the water stagnation periods (residents) on pipe sections with residual chlorine allowed at every point of consumption. After analyzing the distribution of water flow rates in the network, it was concluded that in almost all situations these were between 0.3-0.9 m/s. For a safe disinfection, the residual chlorine in drinking water must be at least 0.3 mg/L.

Generally, in Romania, the water treatment aimed at removing the classic compounds of iron, manganese, ammonium, nitrates / nitrites, etc. by the known classical technologies (chemical coagulation, precipitation, decantation, slow / fast filtration with free / under pressure, disinfection). When in the raw water, besides the classical compounds, heavy metals semi-metals are also found, together with the classical treatment technologies, advanced technologies are required combined, known as hybrid processes (Electro-coagulation / EC, oxidation, adsorption / exchange ions, membrane filtration -UF / NF / RO), which can lead to the desired results. Along with iron, manganese, ammonium, nitrites / nitrates, arsenic is a naturally occurring element in the Earth’s crust. Arsenic in drinking water is a global problem affecting the population worldwide because the arsenic and its components have carcinogenic properties. Regarding the elimination of arsenic (As) found in the water especially collected from the underground, the studies and researches applied were much more restricted and the applications completely isolated, at present the subject being more intensely approached. This situation is also caused by the fact that the Water Framework Directive no.98_83_CEE, transposed into national legislation, lowered the Arsenic (As) chemical indicator limit to 10 μg As / L (from 50 μg As / L). An alternative / complementary technology with low maintenance costs for underground treatment is Electro-oxidation/coagulation (EC), which has been of increasing interest in the last decade. The use of pilot stations / equipment for studying potential treatment technologies is essential for optimizing the treatment schemes and in order to avoid the implementation of costly technologies that cannot work for various reasons. In this case study, it was analysed comparatively from the efficiency point of view combining and optimizing oxidation-coagulation-filtration technologies in a pilot station for water treatment with iron, manganese and arsenic content, coming from the medium depth underground source (western Romania). In the initially provided technological flow (oxidation with ozone, multimedia filtration and disinfection with hypochlorite for the remanence), an electro-coagulation / oxidation (EC) cell was introduced upstream of the multimedia filter. This process aimed at eliminating the use of chemicals (ferric chloride) from the coagulation process that would have caused the rapid alteration of the multimedia filter and consequently increased operating costs. The results showed that compared to conventional technologies, the EC advantage includes high disposal efficiency, a compact treatment plant and the possibility of complete automation.

In this age of urbanization, sustainable development requires good sewerage concepts for the future - not only in growing cities, but also in rural areas. Efficient stormwater management has become an increasingly important national and international concern. Soil waterproofing is oriented to a large extent by land use planning decisions. Land use is a compromise between social, economic, and environmental needs, such as housing, transport infrastructure, energy production, agriculture, nature protection. Limiting soil waterproofing can be done by reducing land use, or by continuing soil waterproofing, but using land already occupied, for example, industrial sites, decommissioned. Keeping water in the city by allowing it to seep into the soil and accumulate in water bodies offers many benefits, including recreational space for people living in the area and creating a cooling effect during heat waves. The use of green infrastructure is a tested component of nature capitalization, to obtain environmental, economic, and social benefits. As an example, instead of building flood protection infrastructure, a green solution can be used to capitalize on the functions (services) of nature: restoring wetland to be able to take over excess water, protecting communities in the areas at risk of flooding. The best way to develop green infrastructure is to take a carefully integrated approach to land management and strategic land use planning. All land users and all policy sectors need to be involved early in the process of developing green infrastructure, with some of them taking responsibility. The purpose of this article is to present some effective measures for urban stormwater management that can be adopted both in cities and in rural areas, and secondly to present the importance of the concept of “Green Infrastructure” (G.I.). In this article is shown that just by simply reorganizing the territory by proposing vertically arranged parking lots and by proposing bioretention solutions, a series of benefits appear such as the cooling effect during heat waves, flood control, clean water and air, and attractive recreation areas, etc.

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