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Natural coagulants from a crude water extract of common bean seed showed very good efficiency of turbidity removal from water of ~89 % under optimal coagulation conditions, which were determined using response surface methodology (RSM). However, they also increased the content of organic matter in treated model water by ~66 %, which is the main drawback of usage of natural coagulants, in general. Thus, ultrafiltration was applied for processing of the crude water extract in order to separate biomolecules, which exhibit the coagulation activity. Four fractions obtained by ultrafiltration were applied in coagulation tests under the same conditions as the crude extract, and the 4th fraction (molecules with molecular weights >30 kDa) with the predominant content of proteins with molecular weights 50 - 60 kDa, achieved almost as high efficiency of turbidity removal (75 %) as the crude extract. At the same time, the content of organic matter in treated water increased just for 16 % in comparison to the blank (model water processed in the same way but without coagulant). After optimization of process parameters by RSM for usage of the 4th fraction, the coagulation activity increased further to 80 %. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 451-03-68/2020-14/200134]

Natural coagulants are of organic nature and can increase the organic load of treated water and thus, they require purification in order to remove compounds that do not have coagulation activity. In this work, natural coagulant was extracted from 50 g L-1 of ground common bean with 0.5 mol L-1 NaCl. Proteins from this crude extract were precipitated by addition of ammonium sulphate. After the precipitation, separation and resolution of proteins, further purification was performed using the anion-exchange resin Amberlite IRA 958 Cl in a batch process. Partially purified coagulant eluted with 2 mol L-1 NaCl solution achieved the highest coagulation activity of 53.3 % at a dose of 1 mL L-1 although it contained the lowest amount of proteins, but a slightly lower coagulation activity of 49.8 % was achieved at more than 5 times lower dosage of the same fraction. The organic load in treated water when the purified fraction was applied as coagulant was almost 4 times lower than in case of the crude extract as coagulant.

In this paper adsorption kinetic of Cr(VI) ions onto biochar from brewer’s spent grain was studied. The same study was performed on biochar activated by KOH and H3PO4. Non-activated biochar showed a greater ability to bind Cr(VI) ions at the same initial concentration and 10 times lower dose compared to the brewer’s spent grain. The investigation of activation effect showed that it did not improve the adsorption properties of biochar. The analysis of kinetic data showed that the best description provided pseudo-second order equation and that adsorption takes place as chemisorption on all investigated adsorbents. Diffusion study showed that pore diffusion occurs only on biochar activated by phosphorus acid. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 43005 and Grant no. OI 172059]

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]

The present work studies the effect of operating parameters (pH, feed flow rate, and transmembrane pressure) on microfiltration of distillery stillage. Experiments were conducted in the presence of a Kenics static mixer as a turbulence promoter, and its influence on the flux improvement and specific energy consumption was examined. Response surface methodology was used to investigate the effect of selected factors on microfiltration performances. The results showed that response surface methodology is an appropriate model for mathematical presentation of the process. It was found that the use of a static mixer is justified at the feed flow rates higher than 100 L/h. In contrast, the use of a static mixer at low values of feed flow rate and transmembrane pressure has no justification from an economic point of view. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 31002]

Water reuse and recycling, wastewater treatment, drinking water production and environmental protection are the key challenges for the future of our planet. Membrane separation technologies for the removal of all suspended solids and a fraction of dissolved solids from wastewaters, are becoming more and more promising. Also, these processes are playing a major role in wastewater purification systems because of their high potential for recovery of water from many industrial wastewaters. The aim of this work was to evaluate the application of micro and ultrafiltration for distillery wastewater purification in order to produce water suitable for reuse in the bioethanol industry. The results of the analyses of the permeate obtained after micro and ultrafiltration showed that the content of pollutants in distillery wastewater was significantly reduced. The removal efficiency for chemical oxygen demand, dry matter and total nitrogen was 90%, 99.2% and 99.9%, respectively. Suspended solids were completely removed from the stillage.

Distillery wastewaters have a great pollution potential, and pollution caused by them is one of the most critical environmental issues. This study is concerned with the coagulation efficiency of a new, environmental friendly, natural coagulant extracted from common bean seeds in the primary treatment of distillery wastewater in the bioethanol production from sugar beet juice. Active coagulation components were extracted from ground seeds of common bean with 0.5 mol/L NaCl. The obtained raw extract was used as a coagulant. The coagulation efficiency was measured by jar test at different pH values of wastewater, and a decrease in organic matter content was determined. The experiments confirmed that natural coagulant from common bean could be successfully used for the treatment of extraction juice distillery wastewater. The highest coagulation efficiencies were achieved at the pH 5.2 with a coagulant dose of 30 mL/L, and at the pH 8.5 with a coagulant dose of 5 mL/L, and they were 64.71% and 68.75% respectively. These encouraging results indicate that natural coagulant from common bean seeds is a potential alternative to conventional chemical coagulant/flocculant agents for treatment of wastewaters.[Projekat Ministarstva nauke Republike Srbije, br. III 43005]

Adsorption kinetics is of great significance to evaluate the performance of adsorption process. The kinetics of copper ions adsorption onto different sized sugar beet shreds has been considered. Sugar beet shreds are very promising adsorbents due to their convenient chemical composition and availability in relatively large quantities in many countries. Experimental data were fitted with pseudo-first and pseudo-second-order kinetic models. Also, we used the intraparticle diffusion model for further analysis of kinetics. The coefficient of determination indicates that, the pseudo-second-order equation obtained by using non-linear least square method, was the most appropriate model for the description of copper ions adsorption onto sugar beet shreds. The adsorption capacities at equilibrium, for a particle size of 224 - 400 μm, 400 - 750 μm and 750 - 1000 μm, are 10 mg/g, 9 mg/g and 8.6 mg/g, respectively. By using intraparticle diffusion model proposed by Weber and Morris, it was obtained that there exist two different stages in adsorption: fast initial adsorption which is further limited by intraparticle diffusion. [Projekat Ministarstva nauke Republike Srbije, br. 174009]

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]

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.

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]

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.

Coagulation and flocculation are the most used methods for removal of turbidity of water. Recently, many studies have focused on the investigation of natural coagulants for this purpose. In view of the fact that extracts of common bean have coagulation activity, this study is concerned with the chemical composition of these extracts and their influence on the coagulation activity. Extraction was conducted with distilled water, 0.5M NaCl and 1M NaCl and total sugars content, proteins, phytic acid and total phenolics content and their coagulation activity were determined in the obtained extracts. These experiments confirmed that an extraction time of 10 minutes is sufficient for the extraction of active coagulant components from common bean seeds and that water is satisfactorily efficient and most economical solvent.

This paper analyzes some chemical pretreatments of sugar beet shreds concerning generated waste flows and yield of reducing sugars obtained by enzymatic hydrolysis of pretreated material. Waste flows produced in pretreatments of sugar beet shreds originated from pectin and lignin removal from raw material. Suitability of substrates prepared in single and two-step pretreatment procedure for enzymatic hydrolysis was determined based on the yield of reducing sugars released by cellulase action on them, while different possibilities of processing of wastewaters were discussed based on the characteristic of waste flows.

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.

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.

The possibility of treatment of wastewater from bioethanol production by aluminium sulfate and natural coagulant extracted from common bean seed was studied. The highest coagulation activity at pH 6.5 is reached with analum dose of 1 g/l, but only a little lower coagulation activities were obtained by the dose of 0.05 and 0.10 g/l, which is more favorable for economic and environmental reasons. When natural coagulant from common bean was applied the highest coagulation activity, 14.3%, at pH 6.5 is reached with a dose of 0.5 ml/l. However, when common bean natural coagulant was used simultaneously with alum, the highest turbidity removal resulting in 24% coagulation activity was achieved and this was more efficient than when alum or natural coagulant were used.

Investigation of an extraction procedure of protein coagulants from common bean seed regarding concentration of NaCl and pH was performed. High values of protein concentration and coagulation activity in crude extract (9.19 g/l and 23.9%, respectively) were obtained when the extraction was performed using 0.5 mol/l NaCl and water as solvent, which represents an advantage for economic and environmental reasons. Crude extract of common bean seed was purified by precipitation at two different percentages of (NH4)2SO4 saturation, followed by batch ion-exchange chromatography. The highest obtained coagulation activity, 45%, was determined in fraction that was eluated at 1.75 mol/l NaCl from resin loaded with proteins precipitated upon 80-100% (NH4)2SO4 saturation. High values of coagulation activity showed by some eluates suggest their application as natural coagulant for water purification. .

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).

An active coagulation component was extracted from common bean seed by NaCl solution and the obtained crude extract was partially purified through a sequence of steps that included precipitation of protein by ammonium sulphate, desalting by dialysis and anion exchange. A turbid water was treated by protein fractions obtained in the anion- exchange elution process by stepwise increase in NaCl concentration. The jar tests were conducted at various dosages of eluates. Different mode of relation between coagulation activity and applied coagulant dose for each protein fraction indicated the existence of different mechanisms of coagulation/flocculation, depending of characteristics of different proteins in the fractions.

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.

Bioethanol can be produced from various feedstocks, including lignocellulosic materials, such as sugar beet shreds. In the case of sugar beet shreds, at first, it is necessary to extract pectin, which itself can be used for different purposes. As a result of that the cellulose becomes more accessible for enzymes degradation to simple sugars, and obtained sugars could be fermented to ethanol. The aim of this study was to evaluate the chemical composition of the raw beet shreds, beet shreds without pectin and solid residue after enzymatic hydrolysis in order to identify whether these materials can be used as animal feed. On the base of the obtained results for dry matter, ash, total Kjeldahl nitrogen, total, soluble and insoluble fibers, it can be concluded that all these materials can be used as animal feed. This would considerably contribute to profitability of bioethanol production from sugar beet shreds.

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.

Combination of 'green' coagulation and powdered activated carbon adsorption was tested for removal of benzophenone (BP), benzophenone-3 (BP-3) and caffeine (CF) from treated municipal wastewater at realistic concentration levels (1–2 µg/L). At the same time it was tracked how the process affected effluent organic matter (EfOM) by measuring chemical oxygen demand (COD). Green coagulant was produced from dry common bean seed in laboratory. Combined coagulation-adsorption experiments were performed by applying different dosing sequences of process materials. Removal of hydrophobic BP and BP-3 by separate adsorption (from 79 to 98%) was not significantly hindered by the addition of the coagulant (activated carbon dose of 5 or 20 mg/L). However, in some cases negative effects were observed for hydrophilic caffeine, depending on the carbon dose, dosing sequence and presence of total suspended solids (TSS). Thus, when coagulant was firstly added into water without TSS before low activated carbon dose of 5 mg/L, caffeine removal dropped from 26% to 5%. Conversely, when TSS were present in the water sample, the removal of caffeine was not hindered under the same PAC dose and dosing sequence. The importance of the process optimisation related to removal of organic micropollutans of different hydrophilicity has been shown in this paper. Removal of around 30% of COD regardless of the dosing sequence was achieved. [ABSTRACT FROM AUTHOR]