Ion exchange for effective separation of 3-nitro-1,2,4-triazol-5-one (NTO) from wastewater

Ecotoxicological evaluation of urban wastewater treatment plants: a Sicilian study

(1) Background: Ecotoxicological screening evaluates the acute toxicity of WWs. The Vibrio fischeri ecotoxicological assay analyses inlet and outlet wastewater samples from two urban wastewater treatment plants in Catania, Sicily, Italy. (2) Methods: The APAT CNR IRSA 8030 Man 29 method was used as method; (3) Results: The results showed toxicity values below the limit of the Italian Legislative Decree 152/06; (4) Conclusions: This monitoring study allows to verify the efficacy, and the outlet quality of WWs discharged to sea water. This ecotoxicological assay is a valuable tool for evaluating the combined toxicity of various pollutants that underline the total damage of the studied matrices detecting the true effect of complex mixtures on the environment and its fauna.

Anaerobic sequencing batch reactor for concurrent removal of multiple recalcitrant munition compounds

Large-scale production, use, and disposal of munitions has resulted in widespread environmental contamination. A laboratory-scale anaerobic sequencing batch reactor (AnSBR) was initiated in this study to investigate the concurrent removal of multiple energetic compounds that comprise modern munition formulations. The AnSBR achieved high removal efficiencies of 2,4-dinitroanisole (DNAN, >99%) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX, 84 ± 16%), along with the partial removal of 1-nitroguanidine (NQ, 30 ± 27%). Specific DNAN, RDX, and NQ removal rates of 17.0 ± 0.1 µmol DNAN/g VSS/d, 22.0 ± 0.8 µmol RDX/g VSS/d, and 2.0 ± 0.3 µmol NQ/g VSS/d were recorded in the AnSBR under steady-state conditions, respectively. Long-term operation of the AnSBR selected Actinobacteria (2 - 58%) and uncultured Actinomycetaceae (1 - 58%) as the most abundant phylum and genus, respectively. Results from this study provide valuable insights into the development of anaerobic bioreactors for the remediation of sites impacted by modern munitions.

Mechanisms and extended kinetic model of thermal desorption in organic-contaminated soil

Thermal desorption is a preferred technology for site remediation due to its various advantages. To ensure the effective removal of different pollutants in practical applications, it is necessary to understand the kinetic behaviors and removal mechanisms of pollutants in thermal desorption process. This paper explored the thermal desorption processes of five organic pollutants (nitrobenzene, naphthalene, n-dodecane, 1-nitronaphthalene, and phenanthrene) at 50-350 °C in two different subsoils with 6-18% moisture content. The results suggested that the thermal desorption process was well-fitted by the exponential decay model (R2 = 0.972-0.999) and could be divided into two distinct stages. The first stage was relatively fast and highly influenced by soil moisture, while the second stage showed a slower desorption rate due to the constraints imposed by the soil texture and structure. The influence of soil moisture on thermal desorption depended on the octanol/water partition coefficient (KOW) of pollutants. Pollutants with log KOW values lower than the critical value exhibited enhanced thermal desorption, while those with log KOW values higher than the critical value were inhibited. The critical value of log KOW might be between 3.33 and 4.46. Changes in soil texture and structure caused by heating promoted thermal desorption, especially for naphthalene, 1-nitronaphthalene and phenanthrene. The differences in texture and structure between the two soils diminished as the temperature increased. Finally, an extended kinetic model under changing temperature conditions was derived, and the simulation results for the two subsoils were very close to the actual thermogravimetric results, with the differences ranging from -1.28% to 0.94% and from -0.67% to 1.35%, respectively. These findings propose new insights into the influencing mechanisms of soil moisture and structure on the thermal desorption of organic pollutants. The extended kinetic model can provide reference for future kinetic research and guide practical site remediation.

In-situ thermal conductive heating (TCH) for soil remediation: A review

This paper provides a comprehensive overview of research works on in-situ thermal conductive heating (TCH), including heat transfer in soil, desorption behavior of pollutants, and mass transfer mechanism within the site. Each stage influences the effectiveness of subsequent stages. Comparison of simulation and experimental results demonstrates that heat transfer and temperature rise in soil are related to the hydrogeological conditions, wells layout and pollutants contents. Thermal desorption of pollutants from soil particles can be influenced by four aspects: energy input, pollutant properties, soil characteristics, and the binding state of pollutant in soil. The exponential decay kinetic model exhibits better applicability for fitting thermal desorption processes. After desorption, the pollutants migrate in soil driven by high temperature and extraction pressure, while hydrogeological conditions of the site determine the actual migration path and rate. Applying convection-dispersion model allows for quantitatively describing the complex migration behavior of pollutants in heterogeneous sites. Future research should focus more on the composite effects of multiple factors in TCH and develop multi-field coupling models through the combination of numerical simulation and in-situ experiments. Accurate characterization and prediction of entire TCH process can improve remediation efficiency, reduce energy costs, and achieve sustainable low-carbon remediation.

Adsorption of Rhodamine B and Pb(II) from aqueous solution by MoS2 nanosheet modified biochar: Fabrication, performance, and mechanisms

Mediated by polydopamine, MoS2 nanosheets were immobilized on the porous biochar derived from fungus residue, forming a novel biochar-based nanocomposite (MoS2-PDA@FRC) for the removal of Rhodamine B(RhB) and Pb(II) from water. Utilizing MoS2 nanosheets with abundant active adsorption sites, MoS2-PDA@FRC showed higher adsorption capacities than raw biochar, with 2.76 and 1.78 times higher capacities for RhB and Pb(II) respectively. MoS2-PDA@FRC also exhibited fast adsorption kinetics for RhB (120 min) and Pb (180 min) removal, as well as satisfactory adsorption selectivity in the presence of coexisting substances. The underlying removal mechanism was explored via Fourier transform infrared and X-ray photoelectron spectroscopies. Furthermore, during cyclic adsorption-regeneration and the fixed-bed adsorption experiments, the nanocomposite removed RhB and Pb(II) with high effectiveness and stability. Collectively, the results demonstrated the bright prospects of MoS2-PDA@FRC as a highly efficient decontamination agent of RhB and Pb(II) from water.