As a result of anthropological activities, various pollutants, for example heavy metals, enter the environment in significant quantities. They have the potential to accumulate in living organisms and are not biodegradable in the environment. This poses a major threat to the health and life of living organisms and the environment. Therefore, the search for effective technologies to reduce anthropic pollutants in the environment is so important. Currently, membrane techniques, chemical precipitation, electrolysis, coagulation, ion exchange and adsorption, among others, are used to remove heavy metal ions. The most versatile method is adsorption on adsorbents. It is a relatively simple method, but very expensive. This prompts a constant search for new, effective and inexpensive adsorbents. Coffee is one of the most important foodstuffs and agricultural commodities in the world. From the point of view of the circular economy, by-products from the processing of coffee beans have become a valuable raw material in other areas of life. An important way to manage waste from the coffee bean processing industry is to produce adsorbents using it. There are data from laboratory studies indicating that it is possible to produce effective and low-cost adsorbents using by-products from the agro-food industry to remove pollutants from the aquatic environment and wastewater. Laboratory studies prove the high efficiency of heavy metal removal when using coffee-processing waste as adsorbents. However, data from real-world studies are still lacking. In addition, there is a lack of data from analyses on the impact of alternative adsorbents on economic, environmental and social aspects.

Biological metal leaching is a technology used in the mining and biohydrometallurgy industries where microorganisms mediate the dissolution of metals and semi-metals from mineral ores and concentrates. The technology also has great potential for various types of metal-rich waste. In this study, bioleaching was used for sludge from water treatment. In addition to checking the applicability of the process to such a substrate, the influence of experimental conditions on the effectiveness of bioleaching of metals with sludge from water treatment was also determined, including sample acidification, addition of elemental sulfur, incubation temperature, and Acidithiobacillus thiooxidans-isolated strain. The measurement of metal concentration and, on this basis, the determination of bioleaching efficiency, as well as pH and oxygen redox potential (ORP), was carried out during the experiment at the following time intervals: 3, 6, 9, 12 days. After the experiment was completed, a mass balance was also prepared. After the experiment, high efficiency of the process was obtained for the tested substrate. The effectiveness of the process for most metals was high (Ca 96.8%, Cr 92.6%, Cu 80.6%, Fe 95.6%, Mg 91%, Mn 99.5%, Ni 89.7%, Pb 99.5%, Zn 93%). Only lower values were obtained for Al (58.6%) and Cd (68.4%).

Among the methods used to remove metals and their compounds from landfill leachates with low application costs and high efficiency are bioleaching and biosorption. The most effective bacteria used in the metal removal process are Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. The aim of the study was to determine the usefulness of the A. ferrooxidans and A. thiooxidans population in removing heavy metals from landfill leachate. In addition, development opportunities for bacterial population using landfill leachate as growth medium were identified. The substrate for the research was the raw leachate before the reverse osmosis process. In order to increase the efficiency of trace elements removal and recovery from leachate, variable combinations have been used which differ by the addition of sulfuric acid, A. ferrooxidans culture, A. thiooxidans culture, mixed culture containing populations of both bacteria, and elemental sulfur. Based on the research, it was found that the removal of heavy metals from leachate was a selective process. High bioleaching efficiency, from 80% to 90%, was obtained for all metals for which the sample acidification or sulfur addition was used. The simultaneous combination of both these additives turned out to be the most advantageous. The A. thiooxidans culture was the most effective in bioleaching reverse osmosis effluents. For the A. ferrooxidans culture used, much lower efficiencies were obtained, while by contrast, the use of mixed culture of two bacterium species had no significant effect.

The growing production of coke and, consequently, coke wastewater is a significant problem for the environment. Coke wastewater, because it contains high amounts of toxic substances, is classified as an extremely hazardous industrial wastewater. The treatment of such wastewater requires a combination of advanced physicochemical and biological methods. The aim of the research was to investigate the effectiveness of the application of the ultrasonic disintegration of coke wastewater in a sequencing batch reactor (SBR). The tests were conducted in two stages, wherein the first stage involved determining the most favorable sonication conditions, that is, time and amplitude. The authors used the following amplitudes: 31 µm; 61.5 µm; 92 µm; 123 µm and times: 120 s; 240 s; 480 s; 960 s. The second stage focused on treating coke wastewater in SBRs (Reactor A—a proportion of coke wastewater in the mixture: 5%, 10%, and 20%; reactor B—sonicated coke wastewater, proportion in mixture: 5%, 10%, 20%). The efficiency of the treatment process was determined based on the rate of removal of selected parameters: chemical oxygen demand (COD), total organic carbon (TOC), inorganic carbon (IC), ammoniacal nitrogen (N-NH₄), total nitrogen (TN), the course of pH changes. The study revealed that sonication of coke wastewater increased biodegradability and reduced its toxicity. The use of the preliminary sonication of coke wastewater before biological treatment improved the degree of removal of the tested parameters by approximately 10%. The volumetric ratio of coke wastewater in the mixture had the greatest impact on the obtained results. The use of an ultrasound field allows the treatment process to be executed with a coke wastewater addition exceeding 10%. In addition, it was found that in order to increase the coke wastewater treatment efficiency, one should optimize individual phases in the SBR and the pollution load.