Mechanism of Chromium Separation and Concentration from Tannery Wastewater by Membrane Methods.

The article specifies conditions for a nanofiltration process employing a diafiltration method with a constant volume diafiltration (NF-CVD) for exhausted chromium tannery wastewater treatment and describes a mechanism of the examined process carried out for model wastewater. The authors prove that a decrease in salt concentration in the NF-CVD process is an important factor that enables effective concentration of chromium. Based on the proposed chromium separation and concentration mechanisms, it was found that this effect may be achieved by (1) limiting the formation of an ionic adsorption-polarization layer and (2) reducing the increase in the osmotic pressure caused by a change in the separation properties of the membrane. The article shows that in the analyzed system a higher amount of the solvent introduced at the diafiltration stage and a lower process pressure that ensures a reduction in salt retention translate to a high level of salt removal. In regenerates, after the NF-CVD processes in which at least the same volume of a washing diluent as the volume of the retentate after the pre-concentration step was used, salt concentration below 10 g L-1 and chromium concentration about three times higher than in the case of the feed solution were obtained. Therefore, the proposed solution implements the circular economy strategy in the tannery.

Consequences of the accessibility of the mountain national parks in Poland.

In Poland, mountain national parks are visited by about 8 million tourists annually. As a result, national parks must have a properly developed infrastructure to accommodate such a large number of people. Tourism development in mountain national parks satisfies the needs of tourist participants and should increase the attractiveness of the area, fit into the cultural concepts of a given region, and promote its development. The research aims to determine the consequences of making mountain national parks available in Poland and determine the factors determining the attractiveness of the protected area and the related tourist burden. Nine mountain national parks located in Poland were selected for the research. An interview was conducted with employees of mountain national parks concerning (a) the tourist burden on the national park, (b) the tourist management of the national park and its surroundings, and (c) the impact of tourist traffic on the natural environment. Parameters characterizing the intensity and spatial character of tourist traffic, tourist management, and the influence of tourist traffic on the natural environment of mountain national parks are discussed. The study presents the parameters determining: tourist traffic density, tourist route density, and tourist traffic intensity. A map of the development of the surroundings of national parks was presented, and its influence on tourist traffic was determined. The obtained results were discussed in the context of the consequences of tourist traffic in mountain national parks. The result of the work was the development of a map of the tourist load of mountain national parks in Poland. Tourism is of crucial importance for the proper functioning of national parks. However, if not properly cultivated, it threatens the fauna and flora of such areas. Rational use of natural resources by tourists visiting mountain national parks is crucial to maintain the balance between man and nature. Proper supervision and management in the national park, as well as the collective responsibility of tourists visiting national parks and the community living in their vicinity, is of fundamental importance for the proper functioning of the system in national parks and nearby tourist destinations.

Kinetics of chromium(III) transport through a liquid membrane containing DNNSA as a carrier.

Kinetics of Cr(III) ions transport through a bulk liquid membrane containing dinonylnaphthalenesulfonic acid (DNNSA) as a carrier, flowing over aqueous phases, has been examined. Special attention has been paid to the effect of the membrane's velocity flow on the chromium concentration decrease in a feed phase. For the description of relationships of chromium(III) concentration in particular phases with the time, a model based on the assumption of consecutive first-order reactions was proposed. Satisfactory compatibility of experiments and model results have been obtained both for the membrane flow velocities below 0.0034 m.s(-1) when the interfaces begin to fluctuate slightly and for low initial Cr(III) concentration in the feed phase.