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Improvements to the quality of underground water by introducing carbon dioxide
Mojca Poberžnik, Ludvik Trauner, Albrecht Leis, Aleksandra Lobnik, 2008, izvirni znanstveni članek

Opis: The presented research work is focused on the development of an innovative way of economically improving the quality of underground water by the application of carbon dioxide. The basic pilot plant was developed with the idea of applying carbon dioxide in order to maintain the carbonate equilibria in water, pumped from under the ground. The optimal content of this natural component in underground water, used in urban areas for different purposes (e.g. drinking water, heating systems etc), simultaneously prevents corrosion and precipitated mineral deposits. The adaptation of an existing pilot plant started with operational testing and preliminary measurements. An appropriate sensor system for the online monitoring of the tap waterćs heating process measuring parameters such as the temperature, the concentration of dissolved carbon dioxide, the conductivity and the pH value was built in. Different amounts of carbon dioxide were applied during the two experimental stages. The composition of the water was regularly analysed using automatic titration and ionic chromatography. The gas-dosing control in the first phase was volumetric. Due to an observed inaccuracy in the gasdosing system, the volumetric dosing control was replaced with a system for the mass control of the introduced gas. Closing the system was considered to be suitable, as the water composition remained almost constant during the entire experiment. Improvements to the gas-dosing control and the closing of the system were carried out in the final phase of the pilot plant's adaptation. Further measurements were made in different seasons to test the seasonal influences on underground water's composition and the efficiency of the carbon dioxide supply.
Ključne besede: underground water, drinking water quality, pilot plant, carbonate equilibria, carbon dioxide, precipitation, scale
Objavljeno: 05.06.2018; Ogledov: 549; Prenosov: 41
.pdf Celotno besedilo (661,89 KB)
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The efficiency of a membrane bioreactor in drinking water denitrification
Aleksandra Petrovič, Marjana Simonič, 2015, izvirni znanstveni članek

Opis: The membrane bioreactor (MBR) system was investigated regarding its nitrate removal capacity from drinking water. The performance of a pilot-scale MBR was tested, depending on the operational parameters, using sucrose as a carbon source. Drinking water from the source was introduced into the reactor in order to study the influence of flow-rate on the nitrate removal and denitrification efficiency of drinking water. The content of the nitrate was around 70 mg/L and the C/N ratio was 3:1. Nitrate removal efficiencies above 90% were obtained by flow-rates lower than 4.8 L/h. The specific denitrification rates varied between 0.02 and 0.16 g/L NO3/ (g/L MLSS.d). The efficiencies and nitrate removal were noticeably affected by the flow-rate and hydraulic retention times. At the maximum flow-rate of 10.2 L/h still 68% of the nitrate had been removed, whilst the highest specific denitrification rate was achieved at 0.2738 g/L NO3/ (g/L) MLSS.d). The maximum reactor removal capacity was calculated at 8.75 g NO3/m3.h.
Ključne besede: capacity, denitrification, drinking water, efficiency, membrane bioreactor, sucrose
Objavljeno: 19.07.2017; Ogledov: 631; Prenosov: 294
.pdf Celotno besedilo (123,62 KB)
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A kinetic study on drinking water denitrification using a membrane bioreactor
Aleksandra Petrovič, Andreja Goršek, Marjana Simonič, 2015, izvirni znanstveni članek

Opis: This study determines the basic parameters of Monod kinetics for microbial growth within a membrane bioreactor using the Zenon ZeeWeed 10 MBR system. The influent nitrate concentration was kept at 70 ± 2 mg L-1 NO3ˉ. During the experiments a constant concentration of activated sludge was maintained at approximately 0.76 g L-1 under anoxic conditions. Sucrose was added to the activated sludge as a carbon source. The Monod kinetic parameters were calculated by numerical interpolation, by considering experimental data. The maximum specific growth rate of the biomass was determined to be 0.31 h-1, half-saturation constant 5.4 mg L-1, and yield coefficient 0.35 mg biomass mg-1 COD. Afterwards, a dynamic simulation was performed within the calculated parameters. The dynamic concentration profiles for substrate and biomass were determined at different dilution rates within the range of 0.8 to 5 d-1.
Ključne besede: kinetics, denitrification, drinking water, membrane bioreactor, sucrose
Objavljeno: 03.04.2017; Ogledov: 859; Prenosov: 303
.pdf Celotno besedilo (1,68 MB)
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Removal of arsenic from drinking water
Marjana Simonič, 2007, izvirni znanstveni članek

Opis: The drinking water well in Slovenska Bistrica, Slovenia, contains arsenic in concentration around 50 ▫$/mu$▫g/L. Therefore it is necessary to implement a technological treatment to make the water suitable for drinking. In order to do so the following technologies were suggested: activated alumina, green sand, granular ferric hydroxide and special goethite media. They were all carried out on a laboratory scale. We managed to remove arsenic below 1 ▫$/mu$▫g/L. Arsenic is usually found as an anion with acid characteristics in the trivalent (III) and pentavalent (V) forms. Chemical analyses of our drinking water showed that arsenic is present in pentavalent form. This means that the water is less toxic as it would be if it contained arsenic in the trivalent form. On the other hand, all the important physical chemical parameters of water remained practically unchanged after the treatment. The hygienic water quality obtained was not an issue. Finally, in addition to capability of arsenic removal, a comprehensive economic analysis of selected technologies is provided.
Ključne besede: pitna voda, arzen, aktivna glinica, goetit, drinking water, arsenic, activated alumina, goethit
Objavljeno: 21.12.2015; Ogledov: 1099; Prenosov: 23
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Water pre-treatment process in food industry
Marjana Simonič, 2009, izvirni znanstveni članek

Ključne besede: drinking water, food industry, pre-treatment, membrane
Objavljeno: 10.07.2015; Ogledov: 829; Prenosov: 15
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Removal of inorganic As [sup] 5+ from a small drinking water system
Marjana Simonič, 2009, izvirni znanstveni članek

Opis: The drinking water from a small drinking water system contained arsenic in a concentration of about 50 ▫$mu$▫g/L. Chemical analyses showed that the pentavalent form of arsenic was present. Since the MCL value is 10 ▫$mu$▫g/L, it was necessary to implement a technological treatment to make the water suitable for drinking. In order to do so, two technologies were suggested: activated alumina and ▫$alpha$▫-FeOOH (TehnoArz, TA) adsorption media. Experiments using both adsorption media were performed on a laboratory scale. It was possible to remove arsenic to below 1 ▫$mu$▫g/L. The maximal adsorption capacity was found to be 12.7 mg of As5+ per gram of ▫$alpha$▫-FeOOH. Moreover, all the important physico- chemical parameters of the water remained practically unchanged after the treatment. Only a slight release of iron from the media was observed. The Fe-As bond was studied by means of chemical analysis and X-ray powder diffraction. Finally, in addition to showing the capability of arsenic removalby ▫$alpha$▫-FeOOH, a comprehensive optimization of the technological parameters of the selected technology is provided.
Ključne besede: drinking water, arsenic, activated alumina, goethite, adsorption
Objavljeno: 01.06.2012; Ogledov: 1306; Prenosov: 31
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Use of a stable carbon isotope to assess the efficiency of a drinking water treatment method with CO[sub]2
Mojca Poberžnik, Albrecht Leis, Aleksandra Lobnik, 2012, izvirni znanstveni članek

Opis: CO2 gas with a special isotopic signature (?13C = -35.2% vs. VPDB) was used as a marker to evaluate the efficiency of a drinking water treatment method and the effect of an ultrasonic (US) stirrer. This treatment was developed to prevent precipitation and corrosion effects in water-supply systems. The research work was performed using a laboratory-scale pilot plant that was filled with tap water. The stable isotope analyses of ?13C-DIC (Dissolved Inorganic Carbon) in the water samples indicated that the maximum content of added CO2 gas in DIC was in the range of 35 to 45%. The use of the US stirrer during the entire experiment decreased the method's overall efficiency by 10%, due to degassing at a late stage of the experiment but accelerated the dissolution process in the early experimental stage.
Ključne besede: 13C stable isotope, carbon dioxide, carbonate equilibrium, corrosion, drinking water, limestone
Objavljeno: 01.06.2012; Ogledov: 1761; Prenosov: 25
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