Water and sewage management in Poland has systematically been transformed in terms of quality and quantity since the 1990s. Currently, the most important problem in this matter is posed by areas ...where buildings are spread out across rural areas. The present work aims to analyse the process of changes and the current state of water and sewage management in rural areas of Poland. The author intended to present the issues in their broader context, paying attention to local specificity as well as natural and economic conditions. The analysis led to the conclusion that there have been significant positive changes in water and sewage infrastructure in rural Poland. A several-fold increase in the length of sewage and water supply networks and number of sewage treatment plants was identified. There has been an increase in the use of water and treated sewage, while raw sewage has been minimised. Tap-water quality and wastewater treatment standards have improved. At the same time, areas requiring further improvement—primarily wastewater management—were indicated. It was identified that having only 42% of the rural population connected to a collective sewerage system is unsatisfactory. All the more so, in light of the fact that more than twice as many consumers are connected to the water supply network (85%). The major ecological threat that closed-system septic sewage tanks pose is highlighted. It is pointed out that they are mainly being replaced by household wastewater treatment systems with ineffective filtering drainage. Furthermore, recommendations were also made for the future development of selected aspects of water and sewage management, including the legal and the political.
Nickel composites doped by chromium and calcium fluoride were produced by powder metallurgy. The friction coefficient of the samples containing 20% of the CaF2 was lower at elevated temperatures (600 ...°C) than the friction coefficient for the Ni-50%NiCr(80/20) composite (0.14 vs. 0.20). Sample surfaces were analyzed by the scanning electron microscope (SEM). EDS analysis proved tribofilm formation on the surface of the sample with CaF2 addition. A laser confocal microscope (LCM) was used to investigate the surface condition of the counter-sample after wear tests. The presence of the tribofilm reduced the wear of the frictional pair, and because of that the wear tracks were smooth. Tribofilm limited the abrasive wear and ploughing. Therefore, the tribofilm protected the sample and counter-sample from wear.
This paper presents changes in water and sewage management in the cross-border Oder River basin in the period since the post-communist political and economic system transformation, including the ...period after Poland's accession to the European Union. The Oder River basin, with an area of 124,000 km
, is the second largest basin in the Baltic Sea Basin, and therefore requires particular protection. It was emphasised that in the years 1989-2017, water withdrawal for production purposes considerably decreased (by 42%), as well as water withdrawal for exploitation of the water supply system (by 33%). The amount of sewage discharged to rivers was also reduced (by approximately 50%), and treatment technologies considerably improved. Changes in water and sewage management were presented in spatial form, i.e. by hydrographic regions of the Oder River basin. Particular attention was paid to changes in sewage management in cities. They involved among others the liquidation of mechanical treatment plants and a considerable increase in the number of cities with treatment plants with increased nutrient removal. The analysis of the effect of the changes in water and sewage management on the quality of the Oder River and Baltic Sea was also performed, and the rate of decrease in loads of contaminants most harmful to water ecosystems was determined. The role of European Union funds and national funds in the implementation of investments in the scope of water management was emphasised. Finally, attention was drawn to the need to intensify works for protecting waters in agricultural areas, which currently constitute the primary threat to their quality. Several top-priority tasks were also specified that should be implemented in the near future for the purpose of obtaining a good ecological state of waters in the Oder River basin pursuant to the Water Framework Directive.
The powder-pack boriding technique with an open retort was used to form borided layers on X165CrV12 tool steel. The process was carried out at 1123, 1173, and 1223 K for 3, 6, and 9 h. As a result of ...boriding the high-chromium substrate, the produced layers consisted of three zones: an outer FeB layer, an inner Fe
B layer, and a transition zone, below which the substrate material was present. Depending on the applied parameters of boriding, the total thickness of the borided layers ranged from 12.45 to 78.76 µm. The increased temperature, as well as longer duration, was accompanied by an increase in the thickness of the FeB zone and the total layer thickness. The integral diffusion model was utilized to kinetically describe the time evolution of the thickness of the FeB and (FeB + Fe
B) layers grown on the surface of powder-pack borided X165CrV12 steel. The activation energy of boron for the FeB phase was lower than that for the Fe
B phase. This suggested that the FeB phase could be formed before the Fe
B phase appeared in the microstructure. The high chromium concentration in X165CrV12 steel led to the formation of chromium borides in the borided layer, which increased the hardness (21.88 ± 1.35 GPa for FeB zone, 17.45 ± 1.20 GPa for Fe
B zone) and Young's modulus (386.27 ± 27.04 GPa for FeB zone, 339.75 ± 17.44 GPa for Fe
B zone). The presence of the transition zone resulted from the accumulation of chromium and carbon atoms at the interface between the tips of Fe
B needles and the substrate material. The presence of hard iron and chromium borides provided significant improvement in the wear resistance of X165CrV12 steel. The powder-pack borided steel was characterized by a four times lower mass wear intensity factor and nine times lower ratio of mass loss to the length or wear path compared to the non-borided material.
Novel alumina-based materials enriched with vanadia and lanthana were successfully synthesized via in situ modification using a mechanochemical method, and were applied in ammonia-induced selective ...catalytic reduction of nitrogen oxides (SCR process). The synthesis was optimized in terms of the ball milling time (3 or 5 h), vanadium content (0.5, 1 or 2 wt% in the final product), and lanthanum content (0.5 or 1 wt% in the final product). Vanadium (V) oxide was immobilized on an alumina support to provide catalytic activity, while lanthana was introduced to increase the affinity of nitrogen oxides and create more active adsorption sites. Mechanochemical synthesis successfully produced mesoporous materials with a large specific surface area of 279-337 m
/g and a wide electrokinetic potential range from 60 to (- 40) mV. Catalytic tests showed that the incorporation of vanadia resulted in a very large improvement in catalytic performance compared with pristine alumina, increasing its efficiency from 14 to 63% at 400 °C. The best SCR performance, a 75% nitrogen oxide conversion rate at a temperature of 450 °C, was obtained for alumina enriched with 2 and 0.5 wt% of vanadium and lanthanum, respectively, which may be considered as a promising result.
This study presents the structure-property relationship of rotationally molded products made of waste-based polylactide (PLA) pre-processed with different procedures. While the use of recycled ...petrochemical thermoplastics, such as polyethylene, is a current industrial practice, there is no evidence of recycled, biodegradable polymers as a source of material for manufacturing the rotomolded parts. The main problem is the difficulty in grinding low-melting material with a high ability to degrade during the milling process into a powder, which is essential from the point of view of rotational molding. The work describes three types of polylactide pre-treatment from post-consumer disposable cups for applying powders and micropellet as a material for manufacturing rotationally molded purposes. The applied pre-treatments are annealing disposable cups for 24 h at 100 °C and melt processing by extrusion of previously shredded cups. As part of the conducted research, the influence of initial recrystallization of the polymeric material and the impact of additional melt processing on the geometric features of the charge materials and the degree of their degradation was assessed. Complete structural characteristics of particle-shaped materials (powders and micropellets) evaluated using spectroscopic and calorimetric methods (FTIR and DSC) were related to the structure of the final products assessed by the 3D computed tomography (CT) method and resulting mechanical properties. Based on the conducted analyses, the risks and potential paths of development of the technology of shaping rotomolded products with low porosity (void volume 0.53%) and favorable mechanical properties (tensile strength of 48 MPa), made of recycled, biodegradable polyesters, were shown.
•The first attempt to recycle PLA waste in rotomolding has been made.•Disposable PLA cups were successfully processed into rotationally molded products.•Thermal treatment and melt extrusion pre-processing were used to improve PLA milling ability.•PLA preprocessing limit the porosity of rotomolded parts and reduce the degradation rate during processing.
The article contains a legal-environmental analysis covering the development and operational aspects of small hydropower plants (SHPs) in Poland. From legal perspective, the paper presents conditions ...that have to be met during the investment process. It was shown that such a process is highly formalized. The need to protect the water and the environment results in necessity to obtain various administration decisions like water permits or decision on environmental conditions. Second discussed law-related field is the support system. In Poland there are three categories of SHPs support system: green certificates, auction system and feed-in tariff (FIT) or feed-in premium (FIP) system. The last one is the most optimal for SHPs and significantly helps to make them profitable. Moving on to an environmental perspective, Polish topography is relatively unfavorable for SHPs because of water resources and significant part of flat lowlands. Taking into account that SHP may have a visible impact on ecosystems and – in most cases – are localized and managed by private entities, it is crucial to use the SHPs potential in Poland as effective as possible. Conducted analysis also shown the legal regulation should be changed to more friendly for SHPs operators.
Application of lignocellulosic fillers in the manufacturing of wood polymer composites (WPCs) is a very popular trend of research, however it is still rarely observed in the case of rotational ...molding. The present study aimed to analyze the impact of wheat bran content (from 2.5 wt.% to 20 wt.%) on the performance of rotationally-molded composites based on a linear low-density polyethylene (LLDPE) matrix. Microscopic structure (scanning electron microscopy), as well as physico-mechanical (density, porosity, tensile performance, hardness, rebound resilience, dynamic mechanical analysis), rheological (oscillatory rheometry) and thermo-mechanical (Vicat softening temperature) properties of composites were investigated. Incorporation of 2.5 wt.% and 5 wt.% of wheat bran did not cause significant deterioration of the mechanical performance of the material, despite the presence of 'pin-holes' at the surface. Values of tensile strength and rebound resilience were maintained at a very similar level, while hardness was slightly decreased, which was associated with the porosity of the structure. Higher loadings resulted in the deterioration of mechanical performance, which was also expressed by the noticeable rise of the adhesion factor. For lower loadings of filler did not affect the rheological properties. However, composites with 10wt.% and 20 wt.% also showed behavior suitable for rotational molding. The presented results indicate that the manufacturing of thin-walled products based on wood polymer composites via rotational molding should be considered a very interesting direction of research.
In this work, in order to produce Cu-MoS2-WS2-Ag-CNT self-lubricating materials, powder metallurgy was used. Several different compositions containing single solid lubricant MoS2, WS2, Ag and CNTs as ...well as multi-component lubricants in the copper matrix were prepared. Friction and wear tests were carried out using the pin-on-disc method at room temperature. Light microscopy (LM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were used to characterize the wear mechanism of sintered materials. The tribofilm on the worn surfaces of sintered materials and counter-specimens was observed. The influence of single solid lubricants and the synergistic interaction of two, three or four solid lubricants on tribological properties of sintered composite materials were determined.
The structure and performance of polyurethane (PU) foams are strongly driven by the stoichiometry of the polyaddition reaction, quantitatively described by the isocyanate index. It determines the ...balance between isocyanate and hydroxyl groups in the reacting system and is affected by the introduction of additional functionalities originated, e.g., from applied fillers. Nevertheless, this issue is hardly taken into account in research works. Herein, the structure and performance of PU/ground tire rubber (GTR) composites differing in their isocyanate index (from 0.8 to 1.2) and prepared with and without considering the GTR functionalities in formulation development were investigated. Incorporating GTR into the PU matrix led to a reduction in average cell diameter (from 2 to 30% depending on the isocyanate index) compared to unfilled foams. However, formulation adjustments did not show a significant impact on cellular structure. The only decrease in open cell content was noted, from 10% for the 0.9 index to 40% for 1.2. Such changes were related to the increasing strength of the PU cellular structure able to maintain inside the increasing amount of carbon dioxide. On the other hand, considering hydroxyl values of GTR noticeably affected the thermomechanical performance of composites. The shift of glass transition temperature (T
), even by 10 °C for 1.2 isocyanate index, enhanced the performance of materials, which was expressed in an 8-62% drop in the composite performance factor, pointing to the enhanced reinforcing effect resulting from filler incorporation. The stiffening of foams, related to the variations in PU segmental structure, also caused minor changes in the course of thermal degradation of PU/GTR composites due to the inferior thermal stability of hard segments. The obtained results provide important insights into the development of formulations of PU composites filled with materials containing reactive functional groups able to disrupt the stoichiometric balance of the polyaddition reaction.
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