Assoc. Prof. Agata Gąsiorowska of the SWPS University of Social Sciences and Humanities ponders if the Poles know how to manage their money wisely.

Arsenic is one of the most harmful pollutants in groundwater. In this paper, the Nepali bio sand filter (BSF) was modi-fied with different bio-adsorbents, and proved to be an efficient method for arsenic removal from groundwater. Three dif-ferent bio-adsorbents were used to modify the Nepali BSF. Iron nails and biochar BSF, ~96% and ~93% arsenic removal was achieved, within the range of WHO guidelines. In iron nails, BSF and biochar BSF ~15 dm3∙h–1 arsenic content water was treated. In the other two BSFs, rice-husk and banana peel were used, the arsenic removal efficiency was ~83% of both BSFs. Furthermore, the efficiency of rice-husk and banana peel BSFs can be increased by increasing the surface area of the adsorbent or by reducing the flow rate.

Fructification of Stratiotes aloides L. is very rarely recorded at present. In general, there are only one sex representatives in each lake basin, which simply makes generative reproduction difficult. The subfossil seeds of Stratiotes aloides have been found in five localities of biogenic accumulation in northern and central Poland.

The Bulletin of the Polish Academy of Sciences: Technical Sciences (Bull.Pol. Ac.: Tech.) is published bimonthly by the Division IV Engineering Sciences of the Polish Academy of Sciences, since the beginning of the existence of the PAS in 1952. The journal is peer‐reviewed and is published both in printed and electronic form. It is established for the publication of original high quality papers from multidisciplinary Engineering sciences with the following topics preferred: Artificial and Computational Intelligence, Biomedical Engineering and Biotechnology, Civil Engineering, Control, Informatics and Robotics, Electronics, Telecommunication and Optoelectronics, Mechanical and Aeronautical Engineering, Thermodynamics, Material Science and Nanotechnology, Power Systems and Power Electronics.

Journal Metrics: JCR Impact Factor 2018: 1.361, 5 Year Impact Factor: 1.323, SCImago Journal Rank (SJR) 2017: 0.319, Source Normalized Impact per Paper (SNIP) 2017: 1.005, CiteScore 2017: 1.27, The Polish Ministry of Science and Higher Education 2017: 25 points.

Abbreviations/Acronym: Journal citation: Bull. Pol. Ac.: Tech., ISO: Bull. Pol. Acad. Sci.-Tech. Sci., JCR Abbrev: B POL ACAD SCI-TECH Acronym in the Editorial System: BPASTS.

The situation when groundwater considerably rises above the “normal” level, water intake, lowering of groundwater levels and other relevant practical tasks require the drainage facilities. The most effective techniques of numerical studies of the corresponding boundary problems at present time are methods of dealing with inverse boundary value problems (conformal and quasi-conformal mappings). As basis of this research we used the case of combining the fictitious domain methods with quasi-conformal mappings of the solution of nonlinear boundary value problems for the calculation of filtra-tion regimes in environments with free boundary areas (depression curves) and zones of “mountainous” areas. This paper reviews the stationary issue of flat-vertical stationary non-pressure liquid filtration to horizontal symmetric drainage. In the paper a practical methodology for solving boundary value problems on conformal mappings is suggested for the calculation of the filtration process in the horizontal symmetrical drainage. The idea of block iterative methods was used during the creation of the corresponding algorithm which is based on the alternating “freeze” of the anticipated conformance parameter, the internal and boundary connections of the curvilinear area. The results of the conducted numerical calculations confirmed the effectiveness of the suggested problem formulations and algorithms of their numerical solution and the possibility of their use in the modelling of nonlinear filtration processesoccurring in horizontal drainage systems, as well as in the design of drainage facilities and optimizing other hydrosystems. Therefore these results are of great importance.