Uklanjanje arsena iz vode adsorpcijom na nekonvencionalnim materijalima

This paper deals with arsenic removal from water by adsorption with unconventional materials: natural materials (zeolite, bentonite, sepiolite, limonite, pyrolusite), waste materials (waste iron slag, waste sand filter) and modified materials (neutralized waste iron slag, iron(III)-hydroxide coated sand and activated carbon). Under the same conditions are investigated commercial sorbents to compare results. Arsenic removal by adsorption with unconventional materials is investigated in the batch reactor. The best results in batch reactor are obtained with waste materials. Waste iron slag and waste filter sand exhibited equilibrium sorption capacities of 50 μg/g and 30 μg/g, respectively, which is nearly equal to values obtained for the commercial sorbents. Due to the high content of CaO waste iron slag increases significantly water pH (pH=11). In order to minimize its deteriorating impact on the initial water quality, the waste iron slag was neutralized. The new, modified waste iron slag exhibited the highest sorption capacity, 55.U ovom radu su prikazani rezultati istraživanja efikasnosti uklanjanja arsena iz vode sorpcijom na nekonvencionalnim materijalima: prirodnim (zeolit, bentonit, sepiolit, limonit, piroluzit), otpadnim (otpadna šljaka, otpadni filtarski pesak) i modifikovanim (modifikovana otpadna šljaka, kvarcni pesak i aktivni ugalj impregnisani gvožđe(III)-hidroksidom). Pod istim uslovima paralelno su ispitivani komercijalni sorbenti radi poređenja rezultata. Uklanjanje arsena iz vode sorpcijom je ispitivana u šaržnom sistemu Najbolji rezultati u šaržnom sistemu dobijeni su sa otpadnim materijalima: za otpadnu šljaku i 30 μg/g za otpadni filtarski pesak (za Co=0,5 mg/L), što je u nivou vrednosti koje su dobijene za komercijalne sorbente za uklanjanje arsena. Zbog visokog sadržaja CaO, otpadna šljaka značajno povećava pH vrednost vode (pH= 11). Neutralizacijom otpadne šljake dobijen je nov materijal, modifikovana otpadna šljaka, većeg sorpcionog kapaciteta: 55

A Novel Semi-Analytical (Inertial) Solution for Determining Permeability of Highly Pervious Porous Materials Using the Two-Reservoir Laboratory Setup

Two conventional experimental procedures for determination of the water permeability of saturated porous medium are the constant and the falling head permeability tests. The first one is more applicable on more permeable materials where the outflow from the sample is measured at variety of constant water heads, while the second one is more convenient for low permeable materials, utilizing the continuous measurements of the water head falling due to filtration through the saturated sample. However, neither of the two is useful for materials of high permeability and large cross-sectional area. The constant head permeability test faces technical issues since a significant and continuous water discharge is required, while the falling head permeability test has limitations due to neglection of the Forchheimer's high-velocity flow through the sample, but also the influence of inertia on the fluid mass. Here we proposed an approach for determination of the water permeability of saturated porous medium based on the agreement between the measured water level change in two connected reservoirs containing a porous sample and the new semi-analytical expression describing that change by accounting for the mentioned theoretical deficiencies. This efficient approach has been tested on four pervious paver samples, and results showed satisfactory agreement with the constant head permeability data. It has been also confirmed the proposed semi-analytical solution is more accurate than the falling head permeability approach in case of highly pervious materials, while for low permeable materials it reduces to the conventional approach

A New Approach in Regression Analysis for Modeling Adsorption Isotherms

Numerous regression approaches to isotherm parameters estimation appear in the literature. The real insight into the proper modeling pattern can be achieved only by testing methods on a very big number of cases. Experimentally, it cannot be done in a reasonable time, so the Monte Carlo simulation method was applied. The objective of this paper is to introduce and compare numerical approaches that involve different levels of knowledge about the noise structure of the analytical method used for initial and equilibrium concentration determination. Six levels of homoscedastic noise and five types of heteroscedastic noise precision models were considered. Performance of the methods was statistically evaluated based on median percentage error and mean absolute relative error in parameter estimates. The present study showed a clear distinction between two cases. When equilibrium experiments are performed only once, for the homoscedastic case, the winning error function is ordinary least squares, while for the case of heteroscedastic noise the use of orthogonal distance regression or Margart's percent standard deviation is suggested. It was found that in case when experiments are repeated three times the simple method of weighted least squares performed as well as more complicated orthogonal distance regression method

Integral water management including rainfall runoff harvesting and wastewater recycling and reuse

Integrated water management is ucertain since is based on atmospheric phenomenon and hydrology aspects, such as stage and flow rates at rivers and streams and water demands of people and industry in order to quenching the thirst and to protect people and habitat ftom water and pollution it is necessary to understand and to measure / monitor particularities of the so called "hydrology cycle". In modem times global and/or climate change added uncertainty in management, and also possibilities lor improvement ol water management and rainfall harvesting and waste water reuse and recycling aiming to mitigalion of the global and climate change.Proc. 2nd Caspian International Aqua Technologies - Conference Materials; 11. April 2014. Azerbaijan, Baku; Mutarjim, 640pp

Komparativna sorpcija jona teških metala na različitim tipovima sorbenata

In this master thesis the sorption of heavy metals on activated carbon and zeolite was analyzed. The chosen heavy metals (Ag+, Cu2+, Zn2+) have been analyzed separately and as a mixture in order to check their sorption affinity toward granulated active carbon (GAC) and natural zeolite. These heavy metals are commonly found in some industrial wastewater and they need to be removed from effluent in order to protect environment. Heavy metals in solid phase are treated as solid waste materials that go on other ways of treatment. Granulated active carbon is widely used and efficient, but also expensive, and natural sorbents (such as zeolite) are low-cost and easily found in nature. The idea is to compare and try to change GAC with zeolite, if it proves to be efficient enough. The sorption capacity (efficiency of removal) and kinetics of sorption process (removal efficiency with time period) have been analyzed. Sorption efficiency has been analyzed through sorption kinetics and sorption isotherms. Sorption kinetics has been analyzed by using two models of kinetics: Pseudo-first order model (Lagergren model) and pseudo-second order model. Sorption isotherms have been analyzed by using three different isotherm models: Freundlich model, Langmuir model and Jovanovic model. For processing of results 'DataFit' (Oakdale engineering, USA) was used and data in the fifth chapter, 'Results and discussion', are obtained by using this software. Analysis of samples was carried out in a flame atomic absorption spectrometers in 'Anahem' laboratory and at the Institute of Nuclear Sciences 'Vinca'. Sample preparation, solutions and execution of experiments was carried out in the laboratory of Civil Engineering, University of Belgrade. By analyzing the results of sorption kinetics, it was found that both sorbent have the greatest affinity for silver and that the adsorption of silver occurs at a higher speed than the adsorption of copper and zinc. Competitive sorption showed that 50 % of silver ions from a mixture was adsorbed after 2 min in contact with activated carbon. Using zeolite as a sorbent, this time was increased to 30 min. For the adsorption of the same amount (50%) of copper and zinc ions from the mixture took more than 24 hours. All kinetic models and models of isotherms showed a similar trend. Experiments have shown that zeolite possesses sufficient sorption efficiency to replace the activated carbon in the process of purification of industrial waste water.U okviru ovog rada analizirana je sorpcija teških metala na aktivnom uglju i zeolitu. Analizirana je sorpcija jona Ag+, Cu2+, Zn2+ pojedinačno i u smeši, kako bi se uporedile sorpcione karakteristike i afinitet u odnosu na granulisani aktivni ugalj (GAU) i prirodni zeolit. Odabrani teški metali se često mogu pronaći u industrijskim otpadnim vodama. U cilju zaštite životne sredine, ovi metali moraju biti uklonjeni iz efluenata. Teški metali u čvrstoj fazi se tretiraju kao čvrsti otpad koji se nakon adsorpcije može proslediti na dalji tretman prečišćavanja. Granulisani aktivni ugalj izabran je zbog široke upotrebe i velike efikasnosti. Za razliku od aktivnog uglja, koji je skup, prirodni sorbenti (u koje spada i zeolit) su jeftini i lako se mogu pronaći u prirodi. Cilj rada bio je upoređivanje aktivnog uglja i zeolita i analiza mogućnosti zamene aktivnog uglja zeolitom u slučaju da se zeolit pokaže dovoljno efikasnim. Ispitivan je sorpcioni kapacitet (efikasnost uklanjanja), kao i kinetika (efikasnost uklanjanja u određenom vremenskom periodu). Efikasnost sorpcije analizirana je kroz kinetiku sorpcije i izoterme. Kinetika sorpcije je analizirana pomoću modela pseudo-prvog reda (model Lagergren-a) i modela pseudo-drugog reda. Sorpcione izoterme su analizirane pomoću modela Freundlich-a, Langmuir-a i Jovanović-a. Za obradu rezultata korišćen je program 'DataFit' (Oakdale engineering, USA) i prikazani podaci u okviru rezultata i diskusije su dobijeni korišćenjem ovog softvera. Analiza uzoraka je rađena na plamenim spektrometrima za atomsku apsorpciju u 'Anahem' laboratoriji i Institutu za nuklearne nauke 'Vinča'. Priprema uzoraka, rastvora i izvođenje eksperimenata rađeno je u laboratoriji Građevinskog fakulteta Univerziteta u Beogradu. Analizom rezultata kinetike sorpcije, utvrđeno je da se oba sorbenta imaju najveći afinitet prema srebru i da se adsorpcija srebra odvija većom brzinom nego adsorpcija bakra i cinka. Kompetitivna sorpcija pokazuje da se 50 % jona srebra iz smeše adsorbuje nakon 2 min u kontaktu sa aktivnim ugljem. Korišćenjem zeolita kao sorbenta ovo vreme se povećava na 30 min. Za adsorpciju iste količine (50 %) jona bakra i cinka iz smeše potrebno je više od 24 h. Svi kinetički modeli i modeli izotermi pokazuju sličan trend. Eksperimentima je pokazano da zeolit poseduje dovoljnu efikasnost sorpcije da zameni aktivni ugalj u procesima prečišćavanja industrijskih otpadnih voda