Vesna M. Vasić

Evaluation of possibility of textile dye removal from wastewater by aqueous two-phase extraction

Abstract Possibility of removal of textile dye from wastewater by extraction in aqueous two-phase system (ATPS) was studied in model solution of Acid blue 9. Partitioning of the dye in ATPSs composed of polyethylene glycol of different molecular weights (1,500, 6,000, and 10,000 g/mol) and several salts (ammonium sulfate, sodium sulfate, and sodium citrate) was investigated. Best results in respect of partitioning coefficient and concentration factor were obtained in polyethylene glycol 1,500/sodium citrate and polyethylene glycol 6,000/sodium citrate systems, respectively. Moreover, in selected ATPSs, the effect of tie-line length and volume ratio on partitioning parameters of Acid blue 9 was evaluated in order to determine conditions at which the highest possible removal of textile dye from wastewater could be achieved.

Application of membrane processes for distillery wastewater purification—a review

Abstract Worldwide environment regulatory authorities are becoming more and more stringent in setting norms for discharge of wastewaters from industries. Distillery wastewaters are highly polluted and their pollution potential is one of the most critical environmental issues of today. For these reasons, distillery industries are forced to look for more effective technologies for wastewater treatment. In recent years, membrane processes have been widely used for various applications, especially for wastewater treatment. The usage of membrane technologies is reflected in high removal efficiency, optimal costs and simple handling with devices. This review presents these membrane processes in the sense of their application on distillery wastewater purification.

Application of membrane and natural coagulants for stillage purification

Abstract Wastewater that remains after bioethanol production (stillage) is a major problem from the viewpoint of environmental protection. Besides the large volume, stillage contains high amounts of organic matter, suspended solids, dead yeast cells and their metabolites, so it should not be disposed in the recipient without previous treatment. In this work the possibility of usage of microfiltration for stillage purification was investigated. Also, the application of natural coagulants was investigated, in order to increase the efficiency of microfiltration for stillage treatment. Results obtained after microfiltration showed chemical oxygen demand (COD) reduction of 35% while the combined use of natural coagulants and microfiltration achieved 50% of COD reduction compared to the initial value. Many published works confirmed the activity of natural coagulants on model water but just few of them investigated the activity of natural coagulants in real samples of waters and wastewaters, which makes this pap...

The fractionation of natural coagulant extracted from common bean by use of ultrafiltration membranes

Abstract In the age of rapid degradation of environment, the use of natural coagulants for water and wastewater treatment represents a promising idea which is in line with the global sustainable initiatives. Since these coagulants are of organic nature and have complex composition, it is important to separate components which show coagulation activity from those which do not show. In this work, ultrafiltration membranes with MW cut off of 10,000 Da and 30,000 Da were used for fractionation of natural coagulant extract obtained from common bean seed. Coagulation efficiency of these fractions was assessed by jar tests in model water. Coagulation conditions (pH and applied dose of coagulant) were optimized for each fraction. The fraction of extract with molecular weight lower than 10,000 Da was showed as the best coagulant with coagulation efficiency more than 40% at pH 10 and applied dose 2.5 ml/l.

A new approach for modelling and optimization of Cu(II) biosorption from aqueous solutions using sugar beet shreds in a fixed-bed column

The potential use of sugar beet shreds for copper ions removal from aqueous solution in a fixed-bed column was investigated. Experiments were performed using Box-Behnken experimental design on three levels and three variables: concentration of the inlet solution (50-150 mg L-1), adsorbent dosage (8-12 g) and pH of the inlet solution (4.0-5.0). The obtained breakthrough curves were fitted with two common empirical models, Bohart-Adams and dose-response. Observing the asymmetric shape of the breakthrough curves, the new mathematical model was proposed. The new model proposes the breakthrough curve composed of two parts, sum of which gives the asymmetrical S-shaped curve, accurately matching experimental data. Regarding the lowest SSer (7.8·10-4) and highest R2 (0.9998), new model exhibited the best fit comparing to the commonly used models. RSM and ANN modelling were employed for process variables evaluation and optimization. The most influential parameter exhibiting negative influence on target response (critical time) was concentration of the inlet solution, while the adsorbent dosage exhibited positive influence. Optimization procedure revealed that the highest critical time (341.4 min) was achieved at following conditions: C0 = 50 mg·L-1, ma = 12 g and pH 4.53 by ANN, while RSM considered pH as insignificant factor and obtained 314.8 min as the highest response.

Possibility of improvement of boiler water treatment process—ion exchange vs. reverse osmosis

The boiler water in certain power plant is produced by chemical decarbonization, sand filtration, and ion exchange. Process ends with mixed bed ion exchange. The current boiler water treatment process is analyzed in terms of achieved water quality, quantity and quality of wastewater, and amount of chemicals needed. The main disadvantage of current process is consumption of large amount of chemicals. Ion exchange process could be replaced with the reverse osmosis, but pretreatment (decarbonization and filtration) should be retained. Since the permeate quality does not meet quality requirements, it would be advisable to use mixed bed ion exchange. If reverse osmosis is used, quantity of water that enters the treatment and wastewater would be for about 17.5 and 150% larger, respectively, but content of salt in wastewater would be about 20–30-fold less. Nevertheless, final decision on which technique to apply should be based on further economical considerations.