Contamination of the environment has been a growing problem in recent years. Due to the rapid growth in human population, the expansion of cities, along with the development of industry, more and more dangerous chemicals end up in the environment, especially in soil and water. For the most part, it is not possible to effectively remove chemicals through traditional remediation techniques, because those used in treatment plants are not specifically designed for this purpose. Therefore, new approaches for water remediation are in great demand. Many efforts have been focused on applications of photocatalysis for the remediation of chemical pollutants including drugs. Titanium(IV) oxide nanoparticles have particularly been considered as potential photocatalysts due to their favorable properties. In this article, we present the problem of emerging contaminants including drugs and discuss the use of photocatalysts based on titanium(IV) oxide nanoparticles for their degradation. A wide selection of materials, starting from bare TiO₂, via its hybrid and composite materials, are discussed including those based on carbonaceous materials or connections with macrocyclic structures. Examples of photodegradation experiments on TiO₂-based materials including those performed with various active pharmaceutical ingredients are also included.

Background: Interest in water chemical activity, its content, and its impact on human health has greatly increased throughout the last decade. Some studies suggest that drinking water with high hardness may have preventative effects on cardiovascular diseases. This study aims to investigate the association between drinking water hardness and cardiovascular disease (CVD) mortality. Methods: The study selection process was designed to find the association between drinking water hardness and CVDs mortality. The search included both qualitative and quantitative research and was performed in three databases: Web of Science (Clarivate Analytics, Ann Arbor, MI, USA), PubMed (National Institute of Health, Bethesda, MA, USA), and Scopus (Elsevier, RELX Group plc, London, UK). The project was registered in the International Prospective Register of Systematic Reviews (PROSPERO), registration number: CRD42020213102. Results: Seventeen studies out of a total of twenty-five studies qualitatively analyzed indicated a significant relation between total water hardness and protection from CVD mortality. The quantitative analysis concluded that high drinking water hardness has a significantly lowering effect on mortality from CVDs, however, the heterogeneity was high. Conclusions: This systematic literature review shows that total water hardness could affect CVD prevention and mortality. Due to the many confounding factors in the studies, more research is needed.

Sand filtration is a primary stage of treatment for reuse of greywater. This study aimed at assessing the volatile solid removal efficiency of a sand filter and imitating its performance using analytical simulation. This study used artificial greywater, medium sand as a filtering material, and nine PVC cylinders as filter columns. Samples of the sand were collected after 6, 14 and 21 days, with the aim of specific deposit determination. The vertical distribution of specific deposit (volatile solids) in the sand filters was typical for gravitationally operated sand filters. Relatively high removal efficiency of volatile solids (51–60%) was achieved at relatively low cumulative hydraulic load. The average removal efficiency of organic compounds (detected as chemical oxygen demand) was 26.8%. Maximum specific deposit was achieved for a cumulative hydraulic load of 363.6 m. The filter coefficient was identified empirically for application of the Iwasaki formula. The filter coefficient λ was corrected for a better fit of the modelled values with measured values.

The aim of this study was to characterise conditions and factors affecting fine sand clogging by septic tank effluent on the basis of physical modelling. The physical model consisted of 12 sand columns dosed with sewage from one household (5 persons), preliminary treated in a septic tank. Hydraulic loadings of the sand filters were equal to 82 mm/d. The mean discharge from sand columns, measured as the effluent volume collected during 10 minutes, decreased significantly over the experiment period from 34 cm³/min in August 2000 to 20 cm³/min in August 2001 at the same temperature of about 20°C. First the columns clogged almost completely after 480 days in December 2001, however six columns had remained unclogged till the end of the experiment (March 2002). The temperature had a significant impact on hydraulic conductivity. A vertical distribution of accumulated mass and biomass was investigated in partly clogged sand. Microscopic survey of the clogging layer showed a presence of live micro-organisms, residuals of dead micro-organisms, particularly pieces of small animal armour and many fibres. These particles accelerated the accumulation of solids in the upper clogging layer. The study indicated that temperature impact on the filter hydraulic conductivity was more significant for biological activity, than for sewage viscosity.

The natural environment is constantly under threat from man-made pollution. More and more pharmaceuticals are recognized as emerging pollutants due to their growing concentration in the environment. One such chemical is ibuprofen which has been detected in processed sewage. The ineffectiveness of water methods treatment currently used raises the need for new remediation techniques, one of such is photodegradation of pollutants. In the present study, zinc(II) and copper(II) phthalocyanines were grafted onto pure anatase TiO₂ nanoparticles (5 and 15 nm) to form photocatalysts for photodecomposition of ibuprofen in water. The nanoparticles were subjected to physicochemical characterization, including: thermogravimetric analysis, X-ray powder diffraction, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller surface area analysis and particle size measurements. In addition, they were assessed by means of electron spin resonance spectroscopy to evaluate the free radical generation. The materials were also tested for their photocatalytic activity under either UV (365 nm) or visible light (665 nm) irradiation. After 6 h of irradiation, almost complete removal of ibuprofen under UV light was observed, as assessed by liquid chromatography coupled to mass spectrometry. The reaction kinetics calculations revealed that the copper(II) phthalocyanine-containing nanoparticles were acting at a faster rate than those with zinc(II) derivative. The solutions after the photoremediation experiments were subjected to Microtox^® acute toxicity analysis.

The objective of this study was preliminary identification of heterotrophic and ammonia oxidizing bacteria (AOB) cell concentration in the cross-sectional profile of geotextile filters for wastewater treatment. Filters of thicknesses 3.6 and 7.2 mm, made of non-woven textile TS20, were supplied with septic tank effluent and intermittently dosed and filtered under hydrostatic pressure. The cumulative loads of chemical oxygen demand (COD) and total solids were about 1.36 and 1.06 kg/cm², respectively. The filters under analysis reached a relatively high removal efficiency for organic pollution 70–90% for biochemical oxygen demand (BOD₅) and 60–85% for COD. The ammonia nitrogen removal efficiency level proved to be unstable (15–55%). Biomass samples for dry mass identification were taken from two regions: continuously flooded with wastewater and intermittently flooded with wastewater. The culturable heterotrophic bacteria were determined as colony-forming units (CFUs) on microbiological-selective media by means of the plate method. AOB and nitrite oxidizing bacteria (NOB) were examined using the FISH technique. A relatively wide range of heterotrophic bacteria was observed from 7.4 × 10⁵/cm² to 3.8 × 10⁶/cm² in geotextile layers. The highest concentration of heterotrophic bacteria (3.8 × 10⁶/cm²) was observed in the first layer of the textile filter. AOB were identified occasionally – about 8–15% of all bacteria colonizing the last filter layer, but occasionally much higher concentrations and ammonia nitrogen efficiency were achieved. Bacteria oxidizing nitrite to nitrate were not observed. The relation of total and organic fraction of biomass to culturable heterotrophic bacteria was also found.