Biosorption of copper(II) and chromium(VI) by modified tea fungus

The tea fungus was found to have good adsorption capacities for heavy metal ions. In this work it was treated with HCl or NaOH at 20°C or 100°C, with the aim to improve its adsorption ability. The sorption of Cu(II) and Cr(VI) ions from aqueous solutions by raw and treated tea fungus was investigated in the batch mode. The largest quantity of adsorbed Cu(II), of about 55 mg/g, was achieved by tea fungus modified with NaOH at 100°C. For Cr(VI), the largest quantity of adsorbed anions, of about 58 mg/g, was achieved by the adsorbent modified with NaOH at 20°C. It was shown that acid modification of tea fungus biomass was not effective. [Projekat Ministarstva nauke Republike Srbije, br. III 43005 i br. TR 31002

Characterization and utilization of the permeate and retentate obtained after “dead-end” ultrafiltration

In the recent years, with the increase in bioethanol production, the increasing amounts of distillery wastewater are generated. Such wastewater (stillage) is one of the most polluted waste product of the food and beverage industries. The present study evaluates the treatment of distillery wastewater by ultrafiltration (UF), in order to reduce its pollution and evaluate the composition of the permeate and retentate. Polyethersulfone ultrafiltration membrane with molecular weight cut-off (MWCO) 30000 Da, was used for the experiments. The UF was carried out in dead-end mode. The results of the analyses of the permeate and retentate obtained after ultrafiltration were considered as well as different ways for their further utilization. The pollutant level in the permeate was decreased significantly in comparison to the raw stillage, and suspended solids were completely removed from the stillage. [Projekat Ministarstva nauke Republike Srbije, br. TR 31002

Ispitivanje koagulacione aktivnosti prirodnih koagulanata ekstrahovanih iz različitih sorti pasulja

Coagulation and flocculation by adding chemicals are the methods that are usually used for removal of water turbidity. This study is concerned with the coagulation activity of extracts of various strains of bean. The aim was to ascertain if bean varieties influence coagulation activity. Active components were extracted from 1 g of ground sample with 100 ml distilled water. Contents of dry matter and nitrogen were specified in the solid samples, and the content of soluble nitrogen was determined in the extracts. These data were used to calculate the efficiency of extraction of nitrogen-containing compounds. The coagulation activity was assessed by jar test using synthetic turbid water, of the initial pH 9 and turbidity 35 NTU. The jar test was carried out by adding different amounts of extracts to model water, and stirring the content. After sedimentation for 1 h, residual turbidity was determined by turbidimeter and coagulation activity was calculated. The increment of organic matter concentration after the coagulation was also determined. These experiments confirmed that extracts of all investigated strains of bean could be used successfully as natural coagulants.Koagulacija i flokulacija predstavljaju najčešće primenjivane metode za bistrenje vode, i uglavnom se izvode dodatkom hemijskih koagulanata. U ovom radu je ispitivana koagulaciona aktivnost ekstrakata dobijenih iz semena različitih sorti pasulja, a s ciljem da se utvrdi mogućnost njihove primene kao prirodnih koagulanata za uklanjanje mutnoće vode, i da se utvrdi uticaj sorte pasulja na koagulacionu aktivnost. Ekstrakcija aktivnih komponenti je izvedena sa 100 ml destilovane vode iz 1 g samlevenog uzorka. U čvrstim uzorcima je određen sadržaj suve materije i azota, a u ekstraktima sadržaj rastvorljivog azota, na osnovu čega je određena efikasnost ekstrakcije jedinjenja sa azotom. Za određivanje koagulacione aktivnosti ekstrakata izveden je džar-test, dodavanjem različitih doza ekstrakata model vodi, čiji je pH 9 i početna mutnoća 35 NTU. Nakon mešanja u određenom vremenskom intervalu, čaše su ostavljene da se njihov sadržaj istaloži, a zatim je u bistrom delu određivana mutnoća, i preko nje koagulaciona aktivnost. Takođe je utvrđen doprinos svakog od ekstrakata porastu sadržaja organskih materija u vodi nakon njenog bistrenja u odnosu na slepu probu, a preko permanganatnog broja. Ovim eksperimentima potvrđeno je da se ekstrakti svih ispitivanih sorti pasulja mogu uspešno primeniti kao prirodni koagulanti

Microfiltration of distillery stillage: Influence of membrane pore size

Stillage is one of the most polluted waste products of the food industry. Beside large volume, the stillage contains high amount of suspended solids, high values of chemical oxygen demand and biological oxygen demand, so it should not be discharged in the nature before previous purification. In this work, three ceramic membranes for microfiltration with different pore sizes were tested for stillage purification in order to find the most suitable membrane for the filtration process. Ceramic membranes with a nominal pore size of 200 nm, 450 nm and 800 nm were used for filtration. The influence of pore size on permeate flux and removal efficiency was investigated. A membrane with the pore size of 200 nm showed the best filtration performance so it was chosen for the microfiltration process

Effect of different conditions on Cu(II) and Cr(VI) biosorption by dried waste tea fungal biomass

Some industrial wastewaters contain high quantities of non-toxic salts besides heavy metal ions. The presence of salt ions leads to a high ionic strength of water, which may significantly affect the performance of the biosorption process, so that the effect of salts on the biosorption of heavy metal ions should be investigated. In this study the effect of different salts concentrations (0.1; 0.5 and 1 mol L-1) and dosage of tea fungal biomass (0.15; 0.25 and 0.5 g L-1) dried at different temperatures: 20°C, 70°C, 80°C, 105°C and 125°C on Cu(II) and Cr(VI) biosorption was studied in a batch system. Biosorption at an ionic strength of 0.1 mol L-1 of all salts investigated had a decreasing effect on Cu(II) and Cr(VI) removal. It was observed that (NH4)2SO4 at the concentrations of 0.5 mol L-1 and 1 mol L-1 was more efficient than other salts for metal ions removal. In case of Cr(VI) the most efficient removal was obtained for the water with K2SO4 at a concentration of 0.5 mol L-1. The lowest biosorbent dosage (0.15 g L-1 tea fungal biomass dried at 20°C in the case of Cu(II) biosorption and at 80°C in the case of Cr(VI) biosorption) resulted in the highest metal uptake of 38 mg g-1 in case of Cu(II) and 33 mg g-1 in case of Cr(VI)

The kinetics of chromium(VI) adsorption from water on some natural materials

This paper is concerned with the kinetics of chromium(VI) adsorption by wood sawdust, pulp, and Kraft lignin. In our previous works we determined adsorption efficiency of these adsorbents. In this paper we focused our attention on the influence of contact time on chromium(VI) adsorption from water by the same adsorbents. The analytical data were approached from the following kinetic models: First-order kinetic model, Parabolic diffusion model, Elovich model, and Modified Freundlich model. Elovich model was shown to be the best fit for the description of chromium(VI) adsorption. It was found that adsorption was the fastest on pulp and slowest on Kraft lignin

The impact of calculation on the value of thermodynamic parameters of copper adsorption on poplar sawdust

The adsorption of Cu(II) onto poplar sawdust as an adsorbent is analyzed. The experimental data were fitted by the Langmuir isotherm using four linearized forms at the isotherm along with the original one. The least squares regression method was applied. Using the obtained Langmuir constants by each at methods, the enthalpy, entropy and Gibbs free energy at adsoption were calculated. A comparison of the used linear and non-linear regression methods in view at the goodness of the fit is presented. The coefficient of correlation was adopted as a criterionn to select the best method. The impact of the choice at regression model on the resulting estimates of the thermodynamic parameters is discussed. The best fit of the experimental data is obtained by the nonlinear regression. Thus, it is recommended to use the Langmuir parameters calculated by the nonlinear regression for estimating the thermodynamic parameters of adsorptin. The differences in the values obtained by different models are not so large to change the basic conclusion that the adsorption of copper ions on poplar sawdust is a spontaneous endothermic process i.e. that tested adsorbent has an affinity for copper ions

Investigation of coagulation activity of natural coagulants from seeds of different leguminose species

The ability of seeds of plants: Phaseolus vulgaris, Robinia pseudoacacia Ceratonia siliqua and Amorpha fruticosa, to act as natural coagulants was tested using synthetic turbid water. This water was prepared by adding kaolin into tap water, just before the test. Active components were extracted from ground seeds with distilled water. The coagulation ability of this extract was assessed by the use of standard jar test measurements in water with various initial turbidity. Investigation of these natural coagulants was confirmed their positive coagulation activity. Of all plants that have been examined, the seed extract from Ceratonia siliqua appeared to be one of the most effective coagulants for water treatment. A dose of 20 mg/l of this coagulant resulted in 100% coagulation activity for clarification of water with 17.5 NTU initial turbidity

Secondary pollution of water during the biosorption of heavy metal ions by pristine and sugar beet shreds from bioethanol production

When biomaterials are used as adsorbents, some compounds present in their structure can be extracted and cause secondary pollution of the treated water. Depending on the type and amount of the secondary pollution, some materials can be unacceptable as adsorbents despite of their good adsorption capacity. Although, it is not a newly discovered phenomenon and it is recognized as a problem, leaching from adsorbents is neglected. The aim of our study is to investigate the secondary pollution of the water during the biosorption of heavy metal ions by pristine and modified sugar beet shreds from bioethanol production. The presence of different elements in the mentioned adsorbents, secondary pollution of the water during the adsorption of heavy metal ions and amount of reducing sugars in the water treated by pristine sugar beet shreds were characterized by the SEM-EDS method, the amount of the leached inorganic and organic matter from the adsorbents (atomic absorption spectroscopy and permanganate index) and Bertrand's method, respectively. Furthermore, the obtained results were compared to the available literature data. Our results showed that according to the valid regulations of emission limit values of the polluting substances in the water and adsorption capacity, the investigated adsorbents have a great potential as biosorbents for practical treatment of wastewaters which contain high concentrations of heavy metal ions. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 43005

Isotherms for the adsorption of Cu(II) onto lignin: Comparison of linear and non-linear methods

Equilibrium studies were carried out for the adsorption of Cu(II) onto Kraft lignin as an adsorbent. The experimental data were fitted to the Freundlich, Langmuir and Redlich-Peterson isotherms by linear and non-linear method. Comparison of linear and non-linear regression method was given in selecting the optimum isotherm for the experimental data. The coefficient of correlation r2 and Chi-square test χ2 was used to select the best linear theoretical isotherm. The best linear model is Redlich-Peterson isotherm model, where r2=0,985 and χ2=0,02. In order to predict the error ERRSQ, HYBRD, MPSD, ARE and EABS were used. Moreover, by minimizing these error functions the optimal values of parameters and also the optimum isotherm was found. The Redlich-Peterson isotherm was found to be the best representative for adsorption of Cu(II) on the adsorbent in the cases when ERRSQ, HYBRD, MPSD functions were used. There coefficients of determination are 0.986, 0.985, 0.984, respectively and Chi-square is 0.02 in all cases. Freundlich isotherms which were obtained by minimization of the ERRSQ, HYBRD, MPSD, ARE and EABS function showed very good agreement with experimental data. In all cases the coefficients of determination are greater than 0.91. Besides, it was observed that non-linear isotherm models were better for representation of equilibrium data than linearized models