With the increase in use and application of carbon nanomaterials and the frequent presence of fluoroquinolones and tetracyclines antibiotics in the aquatic environment, their interactions have attracted extensive attention. In this study, adsorption of two antibiotics: oxytetracycline (OTC) and ciprofloxacin (CIP) by four carbon-based nanomaterials (graphene oxide, reduced graphene oxide, multiwalled carbon-nanotubes, oxidized multiwalled carbon-nanotubes) affected by pH was investigated. The experiment was performed in two steps: (i) adsorption of OTC and CIP at different pH values, (ii) adsorption isotherm studies of both antibiotics on four carbon-based nanomaterials. Both steps were conducted using the batch equilibration technique. The results showed that the adsorption of both antibiotics on studied adsorbents was highly pH-dependent. The highest adsorption was obtained at pH 7.0, implying the importance of the zwitterionic antibiotics forms to adsorption. Antibiotics adsorption isotherms at three given pH values followed the order of pH 7.0 > 1.0 > 11.0, which confirmed zwitterionic species of OTC and CIP as having the greatest ability to adsorb on carbonaceous nanomaterials. Electrostatic interaction, π-π EDA interaction, hydrophobic interaction for both antibiotics, and additionally hydrogen bond for CIP were possible mechanisms responsible for OTC and CIP adsorption onto studied nanomaterials. These results should be important to understand and assess the fate and interaction of carbon-based nanomaterials in the aquatic environment. This study can also be important for the use of carbon nanomaterials to remove antibiotics from the environment.

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

There are certain well-known methods of diminishing concentrations of nitrogen compounds, but they are ineffective in case of nitrogen-rich wastewater with a low content of biodegradable carbon. Partial nitritation followed by anaerobic ammonium oxidation (Anammox) process appear to be an excellent alternative for traditional nitrification and denitrification. This paper presents the feasibility of successful start-up of Anammox process in a laboratory-scale membrane bioreactor (MBR). It was shown that the combination of membrane technology and Anammox process allowed to create a new highly efficient and compact system for nitrogen removal. It was possible to achieve average nitrogen removal efficiency equal to 76.7 ± 8.3%. It was shown that the start-up period of 6 months was needed to obtain high nitrogen removal efficiency. The applied biochemical model of the Anammox process was based on the state-of-the-art Activated Sludge Model No.1 (ASM 1) which was modified for accounting activity of autotrophs (nitrite-oxidising bacteria and nitrateoxidising bacteria) and anammox bacteria. In order to increase the predictive power of the simulation selected parameters of the model were adjusted during model calibration. Readjustment of the model parameters based on the critically evaluated data of the reactor resulted in a satisfactory match between the model predictions and the actual observations.