1. Investigation of the influencing parameters of the ▫$H_2O_2-assisted$▫ photochemical treatment of waste liquid from the hydrothermal carbonization process in a microreactor flow systemAleksandra Petrovič, Tjaša Cenčič, Silvo Hribernik, Andreja Nemet, 2025, izvirni znanstveni članek Opis: Due to its complex composition and toxicity, the waste liquid from hydrothermal carbonization (HTC) poses a serious environmental challenge that must be addressed before disposal. In this study, the photochemical treatment of HTC liquid in a microreactor flow system was investigated. The effects of wavelength, the presence of atmospheric oxygen, oxidizing agent (H2O2) and catalyst (FeSO4), residence time and pH on the efficiency of the photo-treatment were investigated. In addition, the influence of the addition of deep eutectic solvent (DES) on photo-treatment was studied. The results showed that the photochemical treatment was more efficient at 365 nm than at 420 nm, and that the acidic conditions gave better results than the basic ones. UV365 treatment in the presence of H2O2 (at a dosage of 1 vol%) resulted in removal efficiencies of 31.6% for COD, 17.6% for TOC, 16.9% for NH4-N and 17.2% for PO4-P. The addition of FeSO4 caused coagulation/flocculation effects, but improved phosphorus removal. The addition of DES resulted in slight discolouration of the liquid and proved unsuccessful in COD removal. The GC-MS analysis and 3D-EEM spectra showed significant changes in the fate of organics and in the fluorescence intensity of aromatic proteins and humic acid-like substances. Photochemical treatment in a microreactor flow system in the presence of H2O2 under the selected operating conditions reduced the content of organics and nutrients in the HTC liquid, but the process liquids still showed toxic effects on the organisms V. fischeri and Daphnia magna.
Ključne besede: hydrothermal treatment, waste process liquid, photochemical treatment, hydrogen peroxide, microreactor flow system
Objavljeno v DKUM: 25.09.2025; Ogledov: 0; Prenosov: 4
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2. Thermal treatment of raw and pre-treated wastes from the paper industryAleksandra Petrovič, Christoph Hochenauer, Matej Zazijal, Lidija Čuček, Darko Goričanec, Danijela Urbancl, 2023, izvirni znanstveni članek Opis: In this study, the thermal treatment of two types of waste from the paper industry was investigated, paper mill sludge and sewage sludge from biological wastewater treatment plants. Hydrothermal carbonisation (HTC) and torrefaction were investigated as sustainable alternatives for solid biofuel production. Untreated samples and samples chemically pre-treated with alcoholic vinegar were subjected to torrefaction at 350 °C in N2 atmosphere, and the exhaust gases were analysed. HTC was performed at 250 °C with a residence time of 4 h. The feedstocks and the biochars produced were characterised by different analytical methods, and the effects of pre-treatment on fuel properties were studied. Both processes, HTC and torrefaction, showed inspiring results in the production of biofuels from paper industry wastes under the tested experimental conditions. A positive influence of pre-treatment on fuel properties (higher heating value, carbon content) of the obtained char was observed, and changes in the gas phase during torrefaction were observed.
Ključne besede: thermal treatment of waste, wastewater treatment, hydrothermal carbonisation
Objavljeno v DKUM: 18.04.2024; Ogledov: 237; Prenosov: 12
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3. Formation of meso- and micro-pores in fly-ash zeolites using a three-step activationBhagwanjee Jha, D. N. Singh, 2014, izvirni znanstveni članek Opis: Researchers have comprehensively characterized alkali- activated fly-ash (the residue) and ascertained its highly zeolitic nature. In order to evaluate its potential for application as an adsorbent for the decontamination of waste water, the decisive parameters have mostly been the cation-exchange capacity, the mineralogy and the morphology of the residue. However, a study of the pore characteristics (e.g., the size and volume) of such residues is still warranted to anticipate their contaminant transport and the diffusion phenomena as a type of geotechnical engineering material. In this situation, the present study demonstrates the evolution of pores in the fly-ash after alkali activation up to three steps, and simultaneously, its effects` on other characteristics (e.g., the specific gravity, specific surface area and the cation-exchange capacity) of three types of similarly synthesized residues (the first, produced by using a NaOH aqueous solution and the other two residues, the result of alkali activation using a NaOH spent solution, the filtrates). Based on N2 gas absorption isotherms and infrared transmittance spectra, residues obtained from the second and third steps, each involving 24 hours of treatment using filtrates of 1.5-M NaOH, are established to be significantly enriched in the finer meso- and micro-pores, respectively, in comparison with a pure and macro-porous zeolite 4A.
Ključne besede: fly-ash, hydrothermal treatment, three-step activation, pore characteristics
Objavljeno v DKUM: 14.06.2018; Ogledov: 1066; Prenosov: 329
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