This study justifies the use of biotesting methods to assess the level of toxicity in aquatic environments contaminated with pharmaceutical substances (PSs) of various origins, including diclofenac, streptocide, and paracetamol. To determine overall toxicity, we used Daphnia magna, a cladoceran crustacean, and Brachydanio rerio, a representative vertebrate aquatic organism. To assess cytotoxicity, the blood cells of zebrafish were tested. The biotesting results showed that the tested pharmaceuticals exerted varying degrees of toxicity on aquatic organisms, depending on their concentration in the water, and caused pathological changes in fish blood cells. Aqueous solutions of the pharmaceuticals at concentrations from 0.1 to 10.0 mg/dm3 caused acute toxic effects in Daphnia and chronic toxic effects in fish. In addition, cytotoxicity in the blood cells of Brachydanio rerio was detected after 10 days of exposure to the studied compounds, well before the onset of mortality in the test organisms. According to the European Directive EC 93/67/EEC, these effects correspond to “very toxic,” “toxic,” and “harmful” classifications for aquatic life. These findings indicate negative trends in the ecological status of natural water bodies that are continuously polluted by pharmaceuticals and their metabolites. Excessive contamination may lead to irreversible degradation of aquatic ecosystems.
The widespread application of pharmaceutically active compounds all over the world and the imperfection of traditional water treatment technologies lead to the appearance of these preparations and their metabolites in purified waste and surface waters. Contemporary advanced oxidation processes (AOPs) based on the generation of powerful OH radicals from environmentally friendly oxidants (O2, O3, H2О2) under UV radiation and the application of titania as a photocatalyst are able to provide the complete destruction of many ecotoxicants to CО2, H2О, and inorganic ions, i.e., their mineralization. A promising trend in expanding the capabilities of heterogeneous AOPs is the use of titania, which is deposited (immobilized) on solid supports to avoid the terminal nanosized powder separation stage. The kinetics of photocatalytic and heterogeneous photocatalytic destruction with hydrogen peroxide has been studied for popular cheap drugs, such as aspirin, salicylic acid, and analgin, in an aqueous medium in a reactor with TiО2 immobilized on a large-pore ceramic support under UV-C irradiation. It has been shown that the Н2О2/TіО2/UV photocatalytic system is able to provide the almost complete (96–100%) primary destruction of salicylic acid and aspirin (C0 = 0.2 mM) and analgin (C0 = 0.1 mM) at a maximum degree of mineralization of 85, 84, and 71%, respectively, for 3 h at an oxidant utilization rate ≥90%. The direct photolysis of all three preparations for 3 h has led their molecules only to slight initial transformation (≤41% according to spectrophotometric data) accompanied by a low degree of mineralization (≤6%).
Extracellular polymers (EPS) are critical for microbial metabolism in wastewater biological treatment processes. This study examined the impact of bisphenol A (BPA) on microbial EPS within a biological denitrification system. Results indicated that low concentrations of BPA (0.1, 0.5, and 1.0 mg/L) had minimal effects on denitrification performance. In contrast, high concentrations (3.0 and 5.0 mg/L) significantly impaired denitrification. As the concentration of BPA increased, tyrosine-like proteins content in loosely bound EPS (LB-EPS) increased while tryptophan-like proteins and humic acids content decreased. The C–(C,H) content in LB-EPS initially increased and then decreased, whereas the C–(O,N) content continuously increased. Conversely, in tightly bound EPS (TB-EPS), tyrosine and tryptophan-like proteins content decreased while humic acids content increased. The C–(C,H) content in TB-EPS continuously increased, whereas the C–(O,N) content initially increased and then decreased. The C–O–C and C=O peaks of polysaccharides and carboxylates in both LB-EPS and TB-EPS shifted, whereas the peaks corresponding to protein peptide bonds remained unchanged. BPA primarily binds to C–(C,H) and C–(O,N) components in EPS.
Wastewater treatment is an important option to reclaim treated water for countries that are facing water shortages. The availability of technical and financial factors influences the selection of treatment technology. Therefore, it is very important to choose the best-fit technology for the treatment of wastewater. The objective of this investigation was to optimize the anaerobic digestion for the treatment of slaughterhouse wastewater and to evaluate the bioenergy production potential, and chemical oxygen demand (COD) removal efficiency of residual matter. The anaerobic digestion setup was combined with the electro-coagulation technique to enhance the process optimization and recovery of bioenergy from waste. The performance of the lab scale anaerobic digester was evaluated under mesophilic environmental conditions (29 ± 1.40°C). Experimentation showed the COD removal efficiencies and methane yield of lab scale treatment system in the ranges of 58.92 to 94.54% with the maximum volumetric production of 0.158 ± 0.17 m3/day. The proposed system is efficient enough to cater not only to the high-strength slaughter-house wastewater, but it will also act as a source of generating bioenergy. Consequently, combined processes are inferred to be superior to individual techniques, for the removal of both organic and inorganic compounds from slaughterhouse wastewater.
Groundwater has been depleted much faster in recent decades due to anthropogenic activities. Many pollutants enter water bodies through domestic sewage and industrial wastewater, lowering water quality. The health risks associated with water quality are critical for long-term water management in coastal regions of India. This study analyzed groundwater quality, seawater intrusion, hydrogeochemical processes (Piper trilinear graph and Gibbs plot), and statistical data in Tiruvallur district, Tamil Nadu, India. Water quality data were collected at 58 sampling stations. The water quality index (WQI) results showed that water in 12 stations was unsuitable for drinking. 20 stations exhibited poor water quality, while 20 were very poor. The extent of seawater intrusion into the study area was calculated using the seawater mixing index (SMI), and the results indicated that only one station had an SMI value of >1. A human health risk assessment (HHRA) was performed based on the nitrate and fluoride concentrations. The results showed that 39.65% of stations posed nitrate risks to children, while 20.68% posed risks to adults. By comparison, fluoride-related risks affect 34.48% of the stations in children, but only one station in adults.
Two samples of Algerian clay were collected for preparing ceramic membranes that can be used for water filtration. The membrane support was prepared from mountain clay from El Outaya mountains, Biskra province, Algeria, using calcium carbonate and methocel additive via extrusion method. The membrane was deposited using slip-casting method and the precursor slurry was based on polyvinyl aniline (PVA) and clay from Constantine mountains. The supports exhibited proportional evolution of mechanical resistance with sintering temperature, so the 1150°C support was selected for membrane deposition due to its porosity, which yielded optimal mean flux values (30 002.082, 21 559.54, and 16 511.71 L h–1 m–2 for 3 × 104, 6 × 104, and 9 × 104 Pa pressure, respectively). The selected support possessed optimal permeability suitable for membrane deposition (factor k = 0.25679 L h–1 m–2 Pa–1) because of necks and bridges formation made of mainly Gehlenite–Anorthite with some traces of Mullite. The cast membrane displayed low porosity and very high filtration performance since the Scanning electron microscope (SEM) image revealed a clean side section of the membrane with good homogeneity and low porosity rate. Moreover, the application of the cast membrane for filtration resulted in a very good filtration rate under high-pressure filtration when comparing the polluted water sample and the filtrate, showing the applicability of the designed membrane for microfiltration.
The analysis of correlations between the quality indicators of water resources is carried out for the Dnipro River representing a strategic water resource of Ukraine as an example. The studies show an increase in the concentrations of contaminants, such as ammonium ions, nitrates, nitrites, and chlorides due to excessive water discharge and climate changes. In particular, significant distinctions in the dynamics of water quality indicators on the left and right banks of the Kremenchuk Reservoir are observed to evidence a nonuniform character of load on the water resources. The objective of this study is to determine the effect of climate changes and anthropogenic load on the quality indicators of surface water in the Kremenchuk Reservoir. Mathematic modeling by means of regression analysis, statistical data processing, and analysis of trends in water quality indicators for the period from 2016 to 2024 are performed. It has been revealed that most of the studied indicators do not correspond to the normal distribution law due to a complex effect of climatic and anthropogenic factors. Correlation analysis results evidence that temperature cycle has an essential effect on the organic water parameters and the seasonal character of their change. At the same time, chlorides and dissolved oxygen remain stable and independent of temperature fluctuations. The conclusions of this papers emphasize importance of adaption to European standards, introduction of advanced water treatment methods, and reformation in the water supply and sewage infractructure. A key problem in attaining the sustainable development and European integration goals of Ukraine is to preserve the qualitative state of water resources.
Among the physicochemical and biological methods of water purification from organic and inorganic contaminants, adsorption is the most suitable and advanced technique due to the high removal efficiency, easy operation, economic availability, and reusability of adsorbents. The removal of organic contaminants from water sources can be improved by using appropriate target adsorbents. Currently, much attention is paid to the production of carbon-containing sorbents from biorenewable raw materials (agro-industrial residues, wood processing products, wastes from various industries). The structural and sorption properties of fruitstone activated carbon from apricot kernels (FAC) and its modified sample obtained by impregnation with iron salts (Fe-FAC) have been studied. It has been shown that FAC modification leads to an increase in the total specific surface area, the surface of meso- and micropores, and the volume of pores. An increase in the static cation- and anion-exchange capacities was observed. The adsorption of p-chloroaniline, p-nitroaniline, and m-nitroaniline was studied under steady-state conditions at temperatures of 5, 20, and 40°C. In all the cases, adsorption is better on the modified adsorbent. The obtained results were described by the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich models. Thermal studies allowed us to calculate thermodynamic parameters, such as the Gibbs free energy change and process enthalpy and entropy. It has been revealed that the adsorption of the studied compounds occurs as a spontaneous exothermal process.
The adoption of water-saving technologies in dairy industry facilities has created a challenge in effectively treating their high-strength wastewater. One approach to addressing this issue involves the implementation of integrated treatment technologies. This study aimed to identify the most effective wastewater pretreatment solutions for discharge into municipal sewer systems or natural water bodies. We analyzed current methods and technologies for treating high-strength effluents generated by dairy plants, proposed, and experimentally validated the performance of a custom-designed aeration-settling tank with increased hydraulic height and jet aeration for use at dairy wastewater treatment facilities. For high-strength effluents with chemical oxygen demand (COD) values ranging from 2000 to 5000 mg/dm3, where discharge into municipal sewer systems is intended, the proposed technology and proprietary infrastructure proved suitable. These include flotation-settling tanks and aeration-settling tanks with increased hydraulic height (6–10 m) equipped with surface jet aeration. When discharging into natural water bodies, a two-stage biological treatment process is necessary, utilizing the same aeration tank configuration followed by post-treatment through polystyrene-based filtration systems. Field testing of the proposed system demonstrated its capacity to increase the concentration of activated sludge in the aeration zone to 5–6 g/dm3 and to efficiently separate sludge mixtures. This results in high oxidative capacity of the treatment infrastructure, with COD removal rates reaching up to 2200 g/(m3 day), and enables effective nitrogen compound removal via simultaneous biological nitrification−denitrification. This is achieved by forming an aerobic zone in the upper part and an anoxic (anaerobic) zone in the lower part of the unit. The authors also investigated the flocculating and disinfecting properties of polyhexamethylene guanidine salts, confirming their applicability at various stages of wastewater treatment. These compounds neutralize potentially harmful microorganisms, promote the sedimentation of suspended solids, and eliminate residual odors and coloration. Based on these findings, the authors propose a treatment technology for high-strength dairy wastewater (COD 2000–5000 mg/dm3) that combines physical and biological methods. This integrated approach ensures efficient treatment before discharge into either municipal sewer systems or open water bodies.
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