Mineral fillers are mainly utilized in the production of printing and writing papers (P&W) to improve their optical features and their vulnerability to printing. With the high cost of pulp, the aim of their introduction has been to increase mineral loading in paper and reduce the overall cost of production. For many years the only method of paper formation was acid technology, while the only raw material of choice for filling and coating paper and cardboard was kaolin (in the beginning of the 1970s it was 80% of fillers and 94% of coating grades used in Western Europe, while in the USA – 92% and 96%, respectively). The onset on new methods of acid-free (alkaline) paper forming caused a drastic reduction in the kaolin demand for cost-competitive calcium carbonate: GCC – Ground Calcium Carbonate) and PCC – Precipitated Calcium Carbonate. This also resulted from the progressive self-destruction of machine-made acid papers. In 2013, the share of calcium carbonate in the total production of fillers was 83%, while kaolin accounted for 10%, and talc – 7%. The article presents the parameters of principal mineral fillers for the paper industry and the main reasons why they are suitable for particular kinds of paper. Kaolin, due to the platy nature of its main mineral constituent – kaolinite, is preferred in multiple coating papers. The choice of GCC is beneficial because of its low price and properties (especially whiteness). PCC , due to the possibility of shape and particle size modification serves as filler in uncoated woodfree papers, the key features of which are expected to be lightness and opacity. Size distribution is the main difference between PCC and GCC . The article also presents tendencies observed over the last several years in the paper market in Poland, i.e. in a significant growth in coated paper and board for packaging, as well as the decreasing demand for newspaper, which is a consequence of progressive digitalization.

The study objective was to analyse the number of tourists present in the shore zone and bathing areas of lakes with regard to their tourist carrying capacity and the amount of biogenic substances potentially entering the ecosystem from the beach and bathing areas. The procedures from project between the EU and Poland, in the module “Development of the sanitary supervision of water quality” were used in three categories: physiological substances – sweat and urine; water-soluble and insoluble organic compounds; and biogenic elements – nitrogen and phosphorus. The research was conducted in two model mesotrophic lakes, Piaseczno and Zagłębocze, located in the Łęczna- Włodawa Lakeland (eastern Poland). The data were analysed in reference to biological trophic status indices defining the limnological status of lakes in the summer of 2014 and 2016. Analyses of gross primary production of phytoplankton using the light and dark bottles method and the analysis of chlorophyll a concentration were applied using the laboratory spectrophotometric method. The relatively small number of tourists recorded in the shore zone of both lakes did not exceed their tourist carrying capacity, and their potential contribution of biogenic substances to the lake ecosystems was small. Biological trophic indices for both lakes indicated that they had been continually late- mesotrophic for decades. The amount of biogenic substances directly linked to beach tourism usually has a minor effect on the limnological status of mesotrophic lakes. Due to the specific character of lake ecosystems, however, even small amounts of these substances can contribute to the destabilisation of the biocenotic system.

Elaborating composites containing waste materials requires study of basic mechanical properties and assessment of their structure quality. The subject of investigation was PPC concrete where aggregate was substituted with PET remaining after beverages bottles grinding. Substitution was done up to 25% (by volume). Waste material was fractioned and applied in various granulations. The main goal was to indicate the influence of such modification on the composite mechanical properties and to examine composite structure quality at macro level. Since PET and quartz differ greatly in density, to perform such examination it was possible to apply the nondestructive ultrasonic method, one of the most common NDT techniques used in material science and industry. The paper presents the effects of substitution of quartz with PET on ultrasonic wave propagation in PCC. The ultrasonic test results (measurements of wave velocity) compared with results of destructive tests (flexural and compressive strength) showed great correlation.