Hydrologie: Aktuelle Forschung

This paper aimed to the study of microbiological quality of wastewater effluents issued from a sand filter system used as a secondary treatment; this sand filter was coupled to UV irradiation system as a tertiary treatment to assume their possible application as alternatives to chemical disinfection of municipal wastewater before agronomic utilization. For that reason, an infiltration basin of 100 m² of area equipped with two wells of sampling, in the center and in the periphery, has been constructed on the irrigated perimeter of Dissa in Gabes (south east of Tunisia). A comparative study was undertaken concerning the quality of effluents obtained from the sand filter as secondary effluent and from the UV irradiation disinfection system as a tertiary municipal wastewater treatment. Both the combined systems gave effluent of excellent microbiological quality (almost total absence of E. coli, faecal coliforms and P. aeruginosa). However, if the microbiological quality of effluent remained constant in the case of a sand filter system which depends only on the quality of the influent, while with the UV-disinfection process, microbiological quality of tertiary effluent was shown to depend on the quality of secondary effluent. The monitoring of the UV irradiation device using a UV dose of around 96 mW.s.cm-2 and corresponding to an exposure time of 16 sec, for the secondary effluent at the outlet of Sand Filter, showed that the average bacterial inactivation rate was around 3 U-Log for E. coli, faecal coliforms and P. aeruginosa, respectively. Therefore, the average concentration remaining in the effluent at the output of the UV reactor, was less than a 100 cfu/ 100 ml for E. coli and faecal coliforms, and less than a 100 bacteria/ 100 ml for P. aeruginosa. These values coincided with the range recommended by several standardized international guidelines.

Static headspace coupled with gas chromatography-mass spectrometry was applied to extraction and analysis of volatile organic compounds in water samples. The effects of various factors affecting on the extraction efficiency including: the extraction temperature, extraction time, salt concentration and stirring speed were carried out by means of a 24 full factorial design. It was found that the effects of extraction temperature and salt concentration were signi?cant. Then, a central composite design was performed to optimize the level of these factors. The optimal headspace conditions were achieved when the vials were heated under 88°C and 29% w/w addition of salt. At optimum operating conditions, analytical figures of merit of method such as linearity (0.9962-0.9996), repeatability (1.2-12.13%), detection limits (0.1-4.9 μg.L−1) and linearity dynamic range (10-1000 μg.L−1) were determined. The proposed methods can be used to direct investigation of the presence of Volatile organic compounds in environmental
samples without pre-treatment of samples. Finally the optimized method was used to investigate the existence of volatile organic compounds in Babolroud River in the north of Iran.

Ceramic materials are easy to make using most African soils. They have been used for a long time mainly for cooking and water storage. However, in other low income economies these clay ceramic filters have been shown to have the potential of being improved by being embedded with carbonaceous materials for water purification. In this research we have produced efficient physiological and biological gravity operated smoked pots for water purification. We used well calculated volume ratios of black clay, red and sand soils (B:R:S) and soil balls; All these were baked at different smoke infusing kiln temperatures for efficient water purification. We analyzed water purification efficiencies of the pot ceramics and the trickling rates at different conditions. We isolated the best B:R:S to be the 40:40:20. We found significant reductions in turbidity (99.95%), salinity (21.42%), microbial populations, total dissolved solutes (TDS) (17.19%), pH (1.39%) and electrical conductivity (EC) (16.92%). These ceramics can be crucial for common or nomadic communities in sub-Saharan rural areas and in times of disaster to guarantee a cheap continued supply of clean potable water for better health amongst the low income earning societies.

In developing countries, many of urban water networks are too old where most of them are not designed or expanded by engineering methods. Therefore, it is of high concerns to rebuild or relief them in a way that they can operate best. This will reduce the water loss and the costs of maintenance of the water network for a long time period. Use of evolutionary and meta-heuristic algorithms for optimization of water network is most popular nowadays. Methods such as Genetic Algorithm (GA) and Ant Colony Optimization (ACO) have been used frequently in the literatures. In this research, the new meta-heuristic evolutionary algorithm called Honey Bee Mating Optimization (HBMO) has been used so as to optimize the urban water network of a real town in north of Iran named Langarud. The purpose of this research was replacing adequate pipes for balancing the pressure level at the water network of Langarud city with the lowest cost. The result of optimization were compared with the present situation of network and showed a good effectiveness in the improvement of operational parameters.

Iran is the land of drought, floods and qanats. The ancient Persians discovered that the best place to store water was under ground, and the most appropriate method for its delivery was qanat. Their groundwater resources were sustainable before the importation of motor pumps and construction of large dams. The pumps enabled them to mine water from aquifers a few hundred meter deep and transporting it to mountain summits. The dam builders were either not aware of our geological and climatological settings, or ignored them. Enormous sedimentation, abundant evaporation, large leakage and astronomical costs make dams the most inappropriate technology for the Land of Iran and other dry lands of the world. Floodwater spreading for spate irrigation and the artificial recharge of groundwater (ARG) provides a low cost technology which is environmentally sound, financially viable and socially acceptable. The ARG on 14.9 million ha of our rain-fed farm fields and rangelands not only saves our groundwater for the future generations, but also rejuvenates about 30,000 desiccated qanats. Maintaining a rather constant flow in qanats is tantamount to groundwater sustainability. Our findings in Iran could be safely copied in other water-short regions of the world were wasted floodwater and suitable potential aquifers are available. We summarize results from a long-term ARG project and contrast them with detailed considerations of problems with the current practice of dams. Our results suggest that the rejuvenation of qanats is the better way to a sustainable water use in Iran.