The exacerbated production of solid residues represents a major problem in the management and handling of urban wastes. The by-product of stored municipal and industrial solid waste production is landfill leachate. Leachate is characterized by a high concentration of organic compounds, ammonia, and the presence of heavy metals. Because of its composition, this kind of wastewater can cause serious environmental pollution and should be treated to reduce its toxic effects. Increasingly, the interest is directed to the application of the ANAMMOX (anaerobic ammonium oxidation) process for the landfill leachate treatment. In this study, for the first time, the effect of treatment with the ANAMMOX process on the toxicity of leachate was investigated. Based on the research performed in this study, it could be stated that the untreated landfill leachate from the municipal landfill and the influent of the ANAMMOX reactor present phytotoxicity to Lemna minor, due to a correlation of high concentrations of organic compounds, heavy metals, such as Cd 2þ , Cu 2þ , Zn 2þ , and the presence of an unionized form of ammonia (NH 3 ). The results of the Allium cepa test demonstrated that the treatment was not efficient in eliminating the genotoxic substances that are responsible for the mutagenic potential in the effluent. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying, adaptation and redistribution, provided the original work is properly cited

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The widespread use of the nanomaterials increases the emission of nano-pollutants into the water. Carbon nanomaterials are particularly interesting. They are characterized by relatively stable structure, which makes them able to migrate and accumulate in the environment. Therefore, the aim of this study was to determine the potential toxicity at the different trophic levels of four selected carbon nanostructures: graphene oxide (GO), reduced graphene oxide (rGO), multi-walled carbon nanotubes (MWCNTs) and oxidized multi-walled carbon nanotubes (f-MWCNTs) on indicators at three trophic levels. Producers was represented by Lemna minor in growth inhibition test. The ecotoxicological effect for consumers was estimated by acute tests on Artemia franciscana, Brachionus calyciflorus and Thamnocephalus platyurus, while the acute toxicity on decomposers was studied on bacteria Escherichia coli. Results show that the short-term exposure on MWCNTs, f-MWCNTs, GO and rGO can be toxic at three trophic levels. The influence of the tested materials was much higher for the consumers, than for the producers. The lowest toxicity from all researched carbon-based nanomaterials was presented by GO. Moreover, generation of high reactive form of oxygen, mechanical damage of cell wall and membrane is one of the main toxicity mechanism; thus, the toxicity depends heavily of the dose and the shape of the nanomaterials.

Anaerobic ammonium oxidation (anammox) is one of the most promising processes for the treatment of ammonium-rich wastewater. It is more effective, cheaper, and more environmentally friendly than the conventional process currently in use for nitrogen removal. Unfortunately, anammox bacteria are sensitive to various substances, including heavy metals and organic matter commonly found in the wastewater treatment plants (WWTPs). Of these deleterious substances, antibiotics are recognized to be important. For decades, the increasing consumption of antibiotics has led to the increased occurrence of antibiotics in the aquatic environment, including wastewater. One of the most important issues related to antibiotic pollution is the generation and transfer of antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARGs). Here, we will discuss the effect of short- and long-term exposure of the anammox process to antibiotic pollutants; with a special focus on the activity of the anammox bacteria, biomass properties, community structures, the presence of antibiotic resistance genes and combined effect of antibiotics with other substances commonly found in wastewater. Further, the defense mechanisms according to which bacteria adapt against antibiotic stress are speculated upon. This review aims to facilitate a better understanding of the influence of antibiotics and other co-pollutants on the anammox process and to highlight future avenues of research to target gaps in the knowledge.

The anammox (anaerobic ammonia oxidation) process is one of the most efficient processes of nitrogen removal from wastewater. Although there are some applications of anammox-based technologies, it is still difficult to apply this process widely because of the high optimal temperature around 30-40°C. Thus, the main objective of this study was to evaluate the short-term effects of MnO 2 on the anammox and nitrification process activity at a wide range of temperatures between 10 and 30°C, using statistical methods based on the central composite design (CCD). The influence of MnO 2 on anammox and nitrification activity, suspended biomass from the laboratory-scale sequencing batch reactor (SBR), and activated sludge from WWTP, respectively, was used. MnO 2 concentration range was set between 15 and 85 mg/L, and the temperature range was set between 10 and 30°C. Anammox and nitrification process activity was measured based on the batch test and oxygen uptake rate (OUR), respectively. The results were statistically analyzed. Results revealed that nanoparticles can slightly improve anammox activity by several percent, by up to 10%, but in most cases MnO 2 influence was insignificant. The optimal concentration for the anammox stimulation at temperatures below 20°C was evaluated between 40 and 60 mg/L, corresponding to 36 and 56 mg/g VSS. Manganese oxides contribution in the nitrogen removal processes was proved and they should be considered in the field of the anammox process. Thus, further studies are suggested to investigate the long-term effects of MnO 2 on the low-temperature anammox process, overcoming possibility of inhibition.