Clean-soil Air Water最新文献

Contaminants of emerging concern (CECs) such as phthalic acid esters (PAEs) are ubiquitous, toxic and persistent in aquatic environments. Current study explored mixed metal oxide catalysts derived from magnesium aluminium (MAH), magnesium aluminium ruthenium (MAR-H), magnesium aluminium nickel (MANH) hydroxides and copper aluminium hydroxides of ammonium (CAM-Am) and sodium molybdate (CAM-Na) to remove dibutyl phthalate (DBP) and di-2-ethyl hexyl phthalate (DEHP) from water. Powder X-ray diffraction (XRD) studies of the catalysts before and after the treatment showed that their structures were stable and robust. During Fourier Transform Infrared (FTIR) studies, vibrational bands or peaks of ester and alkane functional groups of DBP and DEHP were observed at all the catalysts after treatment. Thermogravimetric analysis (TGA) confirmed phthalate adsorption at the five catalysts. Hydrolysis of DBP and DEHP was observed during treatment using CAM-Am and CAM-Na that was analysed and quantified using total organic carbon (TOC), high performance liquid chromatography (HPLC) and high-resolution mass spectrometry (HRMS). From TOC analyses, optimal conditions of 500 mg L⁻¹ catalyst dosage and 30 h treatment time were deduced for catalytic hydrolysis of DBP and DEHP. Present study illustrated that the catalysts MAH and MANH can adsorb PAEs while CAM-Na can adsorb and hydrolyse them.

In this study, artificial neural networks (ANNs) were employed to analyze the complex interactions between electro-Fenton (EF) process variables (plate spacing, current intensity [CI], initial pH, aeration rate) and the Fe(II) and Mn(II) removal efficiency from wastewater. After experimenting with 69 different ANN architectures, the 4-8-8-2 architecture was identified as more efficient, achieving higher accuracy (adj. R² of 0.93 for Fe(II) and 0.96 for Mn(II)) than the published model. The research provides valuable insights into the correlation between EF process parameters and removal efficiency, guiding the optimization of wastewater treatment processes. Sensitivity analysis revealed that CI significantly affects Mn(II) and Fe(II) removal efficiency. A user-friendly graphical interface was created based on the synaptic weights of the best model to enable practical predictions. It is designed to be accessible even to users without programing experience.

Short-circuiting in secondary clarifiers is a well-known problem that can occur through up-flow or underflow routes. The underflow short-circuiting is not as visible as up-flow short-circuiting but can affect clarifier performance. The energy-dissipating inlet (EDI) is a type of inlet structure that is used in secondary clarifiers to dissipate the energy of larger influent volumes, allowing clarifiers to operate at higher treatment capacities. The underflow short-circuiting is encountered particularly in clarifiers equipped with EDIs. As influent volume increases, conventional draw-off pipes cannot handle high sludge capacities, deforming the sludge blanket and leading to lower concentration of solids being withdrawn. Retrofitting the design of draw-off pipes is an effective way to mitigate underflow short-circuiting and enhance treatment performance. In this study, a snail-shaped sludge draw-off pipe was designed and tested in two types of EDIs using computational fluid dynamics tools, showing a 20% increase in withdrawn sludge concentration and mitigating underflow short-circuiting potential. The optimal retrofit option was identified as equipping the clarifier with a snail-shaped draw-off pipe and an innovative EDI, known as multilayer EDI column, which would save almost half of the energy and operational costs of the biological processes while meeting discharge limits.

In Unare and Píritu Coastal Lagoons, a study was carried out to assess the effect of C, N, and P load contributions on the capability of the sediments to immobilize phosphates. To achieve the later, the geochemical data of the sediments were coupled to the P-sorption index of Bache and Williams (IBW). In both lagoons, the sediments showed a pH > 7 because of calcareous sedimentation. The inorganic carbon values in the lagoons displayed a spatial distribution with higher concentrations toward the shores, that is defined by the carbonate lithology. On the contrary, the inner part of the lagoons was characterized by the presence of organic materials associated to the clay. The phosphorus content in the Unare Lagoon ranged from 290 to 625 mg kg⁻¹, whereas in the Píritu Lagoon the values fluctuated between 213 and 1013 mg kg⁻¹. The highest concentrations of phosphorus in both lagoons could be linked to sewage and runoff input from agricultural and livestock activities around the lagoon systems. The IBW displayed adsorption average values of 21.97 and 27.42 for Unare and Píritu Lagoon, respectively, corresponding to a rather low P sorption. In Unare Lagoon, the IBW showed positive correlations with C, N and Fe_labile but negative with P. However, in the Píritu Lagoon, despite the analogous lithology of the lagoons, a slightly positive non-significative correlation between IBW and IC was only found. Although the sediments adsorb P with a rather low capacity, they can mitigate the eutrophication process in the studied lagoons.