Gyorgy Patzay

Abstract The separation of inorganic ions by membrane filtration of aqueous solutions through NF-membranes was investigated. The single and binary salt solutions of NaCl, MgCl2, Na2SO4 and MgSO4 were used in this study. These salts are the most commonly ...

Abstract The separation of inorganic ions by membrane filtration of aqueous solutions through NF-membranes was investigated. The single and binary salt solutions of NaCl, MgCl2, Na2SO4 and MgSO4 were used in this study. These salts are the most commonly ...

Geothermal conditions are extremely favourable in Hungary. Thermal water is accessible in 70% of the territory of the country, with a lowest temperature of 30°C. For energetic purposes, it can be utilized in two different ways: for supplying heat or generating electricity. In relation to utilization, one of the most serious problems derives from the chemical composition of thermal water. The present paper investigates the opportunities of preventing scaling by nanofiltration. Experiments were performed on a Thin Film NF DK membrane, thermostated at 50°C and at a pressure of 3.5 MPa with four different samples (from four Hungarian cities - Eger, Mezőkövesd, Bogács, Miskolc-Tapolca) using batch plant. Reproducibility of experiments was also investigated using water samples from Komárom at 50 and 60°C. The results showed that NF DK could achieve high retention of divalent ions. The results of the second phase of the experiments proved that water flux and rejections were very stable. After filtration, the scaling properties of thermal water were simulated with the help of chemical equilibrium modelling software, called Visual MINTEQ 3.0. The results of the permeate samples prove that nanofiltration is a successful process in preventing scaling of thermal water for further use.

Geothermal conditions are extremely favourable in Hungary. Thermal water is accessible in 70% of the territory of the country, with a lowest temperature of 30°C. For energetic purposes, it can be utilized in two different ways: for supplying heat or generating electricity. In relation to utilization, one of the most serious problems derives from the chemical composition of thermal water. The present paper investigates the opportunities of preventing scaling by nanofiltration. Experiments were performed on a Thin Film NF DK membrane, thermostated at 50°C and at a pressure of 3.5 MPa with four different samples (from four Hungarian cities - Eger, Mezőkövesd, Bogács, Miskolc-Tapolca) using batch plant. Reproducibility of experiments was also investigated using water samples from Komárom at 50 and 60°C. The results showed that NF DK could achieve high retention of divalent ions. The results of the second phase of the experiments proved that water flux and rejections were very stable. After filtration, the scaling properties of thermal water were simulated with the help of chemical equilibrium modelling software, called Visual MINTEQ 3.0. The results of the permeate samples prove that nanofiltration is a successful process in preventing scaling of thermal water for further use.

ABSTRACT A wastewater treatment system has been developed by using a mixture of ammonium-insoluble tannin (TANNIX, this is the trademark of an adsorbent made by Mitsubishi Nuclear Fuel Co. Ltd) and mixed (strong acid cation exchanger and strong base anion exchanger) ion exchange resin (MIX) for the selective separation of transuranium isotopes, including Pu, Am, Cm, and U, as well as fission and radioactive corrosion products from boric acid solution (pH ∼ 4.1). The equilibrium and fixed bed sorption experiments resulted in K<sub align="right"> d values of 10<sup align="right"> 4 –10<sup align="right"> 5 ml/g, and decontamination factors of 1,000, with a breakthrough point between 1500 BV and 5000 BV of accumulated volume.

It is well known that in the Hungarian PWR-type nuclear power plant Paks the radioactive waste waters are collected in common tanks. These water streams contain radioactive isotopes in ultra-low concentration and inactive compounds as major components (borate 1.7 g/dm3, sodium-nitrate 0.4 g/dm3, sodium-hydroxide 0.16 g/dm3, and oxalate 0.25 g/dm3). These low salinity solutions were evaporated by adding sodium-hydroxide, until

A solubility equilibrium program GEOPROF was applied to the determination of the bubble-point depth, pressure and temperature, as well as the partial pressure profiles of the gases CO2, CH4 and N2 between the bubble-point depth and the wellhead, in two high enthalpy geothermal wells, NSZ-2 and FAB-4 in southern Hungary. The pH, alkalinity, total carbonates, and equilibrium solubility for CaCO3, CaSO4, BaSO4, and SrSO4 along the well depth profile in the Na–K–Mg–Ca–H–Ba–Sr–Cl–Br–SO4–OH–HCO3–CO3–CO2–H2O system were also determined and the concentrations of Ca2+, Ba2+, Sr2+, H+, OH−, HCO3−, CO32−, and H2CO3* were computed at the actual temperature and CO2 pressure using the Davies and Pitzer activity calculation methods. The calculated amounts of CaCO3 scaling along the wells and at the surface were used in estimating service life. The results for well FAB-4 contain high uncertainties because of the estimated gas separation analysis data.

ABSTRACT At the PWR Paks (Hungary) the diluted radioactive waste water is converted to a concentrate by evaporation and the concentrate is stored in tanks. The most important radionuclides in these solutions are Cs-134, Cs-137 and Co-60. In this research we studied granular potassium nickel hexacyanoferrate(II) as a Cs-selective ion-exchanger. Its capacity depended on the preparation method, temperature of pretreatment and age of the ion exchanger. We investigated also the effect of metal ions (Fe2+, Fe3+, Mn2+, Mg2+, Ca2+, Co2+, Ni2+, Cu2+) on the Cs-capacity in the presence of complex forming compounds citrate, oxalate and EDTA. The cesium ion exchange capacity increased with addition of inactive cobalt or nickel salts. Additionally we studied filtration, adsorption and ultrafiltration separation processes for cobalt removal. The results showed that only adsorption by active carbon could be successfully used for the cobalt removal from evaporation concentrates. Experiments were performed both in the laboratory and at the PWR Paks.

Prediction of scaling in geothermal systems is important in order to be able to take preventive action. Scaling and corrosion processes are correlated in geothermal systems so that the factors influencing both processes are discussed in this paper. Pilot-scale equipment to model dissolution and scaling, and investigate corrosion, has been constructed. The construction of the pilot-scale equipment and the design of the experiments were based on the results of earlier laboratory model experiments. In order to check the measurement results we used a computer programe that was developed earlier, and which is suitable for the calculation of the equilibrium solubilities. Based on the results of the equilibrium experiments, we developed a modelling method for scaling in the pilot-scale equipment, and studied corrosion during scaling on the surfaces of five different structural materials.

At the PWR Paks diluted low-level radioactive waste water (LLW) contains the long-lived 60Co isotope in EDTA complex form, which has no simple separation procedure. In this research nanofiltration(NF) was studied for selective removal of the cobalt(III) EDTA complex from a drain waste water model solution, which contains mainly sodium borate at an alkaline pH. A suitable NF membrane was chosen to separate the cobalt complex from the borate solution. The NF experiments were performed at constant temperature (25°C) and pressure range 1–10 bar. The cobalt complex and the borate ion rejection (R) as well as the permeate flux of the membrane was investigated as a function of pH. The rejection of the cobalt(III) EDTA complex ion and especially the borate were strongly pH dependent. The rejection of the complex ion and the borate was increased at alkaline pH (at pH 8, R = 73%; at pH 11.5, R = 96% for the cobalt complex; at pH 8, R = 7%; at pH 11.5, R = 59% for borate). NF seems to be a suitable separation method for the removal of the Co(III) EDTA complex from nuclear power plant waste streams. The removal of the cobalt complex ion from an alkaline borate solution by NF is possible in two ways: at slightly alkaline pH by a two-step separation, or at a more alkaline pH (pH > 9.5) by a one-step separation.

A simplified solution for multispecies ion exchange kinetics based on the Nernst-Planck model has been developed. The numerical solution has been tested by simple isotopic exchange and binary ion exchange kinetic solutions as well as with the Hwang's computed three-component ion exchange kinetic curves. All of these tests resulted in good agreement. The computational algorithm has been built in a program for the computation of multicomponent fixed bed ion exchange breakthrough and co- and counter-current elution curve. The details of this program will be reported elsewhere.

Salt rejection and ion selectivity of NF-255 and NF-45 nanofiltration (NF) membranes were investigated. The rejection of two cations (Na+, Ca2+) and two anions (Cl−, SO42−) which are common in natural and in industrial wastewater, were studied as a function of pH at permanent pressure and temperature. The ion rejection of NF membranes were investigated in single salt solutions like NaCl, CaCl2, Na2SO4, CaSO4, and in multicomponent systems that contained all the previous ions. We found that, there is a minimum rejection of the Na+ and Cl− ions between pH 4–5 in NF-255 and between pH 7–8 in NF-45. The rejection of calcium ions were increased in each case at lower pH in both membranes. However the pH value where the ion rejection behaviour of membranes changed, were different: pH 4 in NF-255 and pH 8 in NF-45. In NF-45 the chloride ion has negative rejection which depends on the quality of ions and the pH. We found that below pH values of 4 the selectivity of mono- and multivalent cations considerable increased in NF-255. This phenomena may be used for separation of calcium ions from sodium ions from weakly acidic (hydrochloric and sulfuric acid) solution, e.g. regeneration solution of sodium form softening ion exchangers.

ABSTRACT At the PWR Paks (Hungary) the diluted radioactive waste water is converted to a concentrate by evaporation and the concentrate is stored in tanks. The most important radionuclides in these solutions are Cs-134, Cs-137 and Co-60. In this research we studied granular potassium nickel hexacyanoferrate(II) as a Cs-selective ion-exchanger. Its capacity depended on the preparation method, temperature of pretreatment and age of the ion exchanger. We investigated also the effect of metal ions (Fe2+, Fe3+, Mn2+, Mg2+, Ca2+, Co2+, Ni2+, Cu2+) on the Cs-capacity in the presence of complex forming compounds citrate, oxalate and EDTA. The cesium ion exchange capacity increased with addition of inactive cobalt or nickel salts. Additionally we studied filtration, adsorption and ultrafiltration separation processes for cobalt removal. The results showed that only adsorption by active carbon could be successfully used for the cobalt removal from evaporation concentrates. Experiments were performed both in the laboratory and at the PWR Paks.

ABSTRACT Under radiolytic conditions at a concentration of 0.1 mmol dm−3 the reactions of sulfamethoxazole, a worldwide used anti-infective sulfonamide antibiotic, were mainly induced by hydroxyl radicals. With a dose of 5 kGy complete degradation of aromatic system was observed. The sulfur of the molecule was entirely transformed to SO42–, while NO3– and NH4+ were formed from the nitrogen content. The chemical oxygen demand and total organic carbon values indicated complete mineralization during irradiation. In pursuance of toxicity tests, the observed increase in mortality of Vibrio fischeri bacteria was mainly due to H2O2 formed during the radiolytic procedure. The results showed that the degradation was effective; therefore, the irradiation technology can be recommended for treatment of wastewater containing sulfamethoxazole.

A solubility equilibrium program GEOPROF was applied to the determination of the bubble-point depth, pressure and temperature, as well as the partial pressure profiles of the gases CO2, CH4 and N2 between the bubble-point depth and the wellhead, in two high enthalpy geothermal wells, NSZ-2 and FAB-4 in southern Hungary. The pH, alkalinity, total carbonates, and equilibrium solubility for CaCO3,

Prediction of scaling in geothermal systems is important in order to be able to take preventive action. Scaling and corrosion processes are correlated in geothermal systems so that the factors influencing both processes are discussed in this paper. Pilot-scale equipment to model dissolution and scaling, and investigate corrosion, has been constructed. The construction of the pilot-scale equipment and the design

At the PWR Paks diluted low-level radioactive waste water (LLW) contains the long-lived 60Co isotope in EDTA complex form, which has no simple separation procedure. In this research nanofiltration(NF) was studied for selective removal of the cobalt(III) EDTA complex from a drain waste water model solution, which contains mainly sodium borate at an alkaline pH. A suitable NF membrane was chosen to separate the cobalt complex from the borate solution. The NF experiments were performed at constant temperature (25°C) and pressure range 1–10 bar. The cobalt complex and the borate ion rejection (R) as well as the permeate flux of the membrane was investigated as a function of pH. The rejection of the cobalt(III) EDTA complex ion and especially the borate were strongly pH dependent. The rejection of the complex ion and the borate was increased at alkaline pH (at pH 8, R = 73%; at pH 11.5, R = 96% for the cobalt complex; at pH 8, R = 7%; at pH 11.5, R = 59% for borate). NF seems to be a suitable separation method for the removal of the Co(III) EDTA complex from nuclear power plant waste streams. The removal of the cobalt complex ion from an alkaline borate solution by NF is possible in two ways: at slightly alkaline pH by a two-step separation, or at a more alkaline pH (pH > 9.5) by a one-step separation.