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Wpływ chemicznego kondycjonowania na własności grawitacyjne osadu czynnego nadmiernego

Grübel Klaudiusz, Duda Marta

Polish Journal of Materials and Environmental Engineering

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2023

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Vol. 5 (25)

23--31

EN

The formation of sludge is an inevitable consequence of wastewater treatment processes and their disposal and utilization requires knowledge, technology and engineering. Sulfate radical-based advanced oxidation processes (SR-AOPs) are gaining popularity as a fea-sible alternative for sludge conditioning and removing recalcitrant pollutants in an aqueous environment. Application of the pretreatment processes/conditioning allows to obtain better mechanical properties of sludge. In the last decade can be noticed a lot of research from around the world focused on new methods of conditioning of sludge, i.e. the processes of disin-tegration, of which the destruction of the mechanical, chemical and biological. Nowadays, advanced oxidation processes (AOPs) has been proposed as one of the most promising technology over conventional water treatment processes to destroy persistent or-ganic contaminants, as well as better sludge conditioning. Persulfate-based AOPs have attracted significant interest in the AOPs due to the following merits: 1) lower costs of storage and trans-portation; 2) easy availability of persulfate salts; 3) high yield of sulfate radicals formation and their longer half-life compared to other reactive oxygen species in AOPs. Persulfates, namely peroxydisulfate (PDS), are the most common sulfate radical donors. In order to generate them the peroxide bonds of persulfates can be cleaved homolytically or heterolyt-ically by various activation methods. SR-AOPs activation by heat is considered feasible due to the high concentration of radicals produced as well as the lack of catalysts leaching. The research focuses on determining the impact of activated PDS on the gravitational surplus activated sludge properties. Characteristic parameters were determined in sludge sedimenta-tion processes, i.e. the rate of descent and compaction, sludge density index and sludge volume index, and changes in the supernatant liquid. Conditioned sewage sludge with PDS activated by microwaves changes its sedimentation parameters: the sludge volume index de-creased with the dose of PDS and was dependent on it, the settling of the conditioned sludge occurred with the highest intensity in the first minutes of gravitational thickening, the oxidation efficiency of the formed radicals caused a decrease in the turbidity and color of the supernatant liquid.

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Przyjazne środowisku, skuteczne środki wspomagające rozwłóknianie odpowiedzią na nowe regulacje prawne

Grigoriev Vladimir, Hannuksela Tea

Przegląd Papierniczy

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2019

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R. 75, nr 9

554--556

PL

Wodotrwałe gatunki papieru często wymagają zastosowania utleniających substancji wspierających rozwłóknianie. Tradycyjny podchloryn jest niepożądany, ze względu na jego szkodliwość i wpływ na ulegające adsorpcji organiczne chlorowce (AOX). Nowe, surowsze przepisy, szczególnie w Europie, jeszcze bardziej ogranicząjego stosowanie. Alternatywny nadsiarczan w postaci proszku jest bardziej przyjazny dla środowiska, ale często ma ograniczoną skuteczność i pewne wady, np. alkaliczne zażółcenie masy. Kemira opracowała nowy ekologiczny środek pomocniczy do rozwłókniania - FennoSpec 9368. Ten produkt jest oparty na nadwęglanie sodu i stanowi ekonomiczną alternatywę oraz nie posiada znaczących wad. W artykule omówiono korzyści, zalety i doświadczenia przemysłowe związane z zastosowaniem FennoSpec 9368.

EN

Wet-strengthened paper grades often require a use of oxidative repulping aids. Traditional hypochlorite is undesirable due to its hazardous nature and a contribution to AOX. New stricter regulations, especially in Europe, will restrict its use even further. Alternative persulfate powders are more eco-friendly, but often limited in their effectiveness and have some drawbacks, e.g., alkaline yellowing of pulp. A new eco-friendly repulping aid, FennoSpec 9368, was developed by Kemira. This product is based on sodium percarbonate chemistry and provides an economic alternative without significant drawbacks. The benefits, advantages and industrial experiences with FennoSpec 9368 are reviewed in this paper.

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Chemical degradation of PCDD/F in contaminated sediment

Hrabák P., Homolková M., Wacławek S., Černík M.

Ecological Chemistry and Engineering. S

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2016

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Vol. 23, nr 3

473--482

EN

Due to the extreme toxicity of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F), the remediation of PCDD/F aquifer source zones is greatly needed; however, it is very difficult due to their persistence and recalcitrance. The potential degradability of PCDD/F bound to a real matrix was studied in five systems: iron in a high oxidation state (ferrate), zero-valent iron nanoparticles (nZVI), palladium nanopowder (Pd), a combination of nZVI and Pd, and persulfate (PSF). The results were expressed by comparing the total toxicity of treated and untreated samples. This was done by weighting the concentrations of congeners (determined using a standardized GC/HRMS technique) by their defined toxicity equivalent factors (TEF). The results indicated that only PSF was able to significantly degrade PCDD/F. Toxicity in the system decreased by 65% after PSF treatment. Thus, we conclude that PSF may be a potential solution for in-situ remediation of soil and groundwater at PCDD/F contaminated sites.