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Wykorzystanie stałego pola magnetycznego i reakcji Fentona w procesie oczyszczania ścieków pochodzących z produkcji drożdży

Dębowski M., Krzemieniewski M., Jedrzejewska M.

Inżynieria i Ochrona Środowiska

2005

T. 8, nr 2

225-235

Przebadano możliwość obniżenia wartości ChZT w ściekach z zastosowaniem technologii wykorzystującej stałe pole magnetyczne (SPM) oraz reakcję Fentona. Do eksperymentu użyto ścieków pochodzących z przemysłu drożdżowego, wstępnie podczyszczonych w beztlenowym reaktorze typu UASB. Charakteryzowały się one ładunkiem ChZT wynoszącym około 2570 mgO2/dm3. Badania odbyły się w skali laboratoryjnej przy zastosowaniu trzech odmiennych stanowisk badawczych. Określono wpływ wielkości dawki odczynnika Fentona na skuteczność zmniejszenia ChZT oraz efekt wspomagania SPM w procesie oczyszczania metodą pogłębionego utleniania (MPU). Stwierdzono, że MPU pozwala na obniżenie wartości ChZT o 33+60% w zależności od stosowanej dawki reagentów chemicznych. Wpływ SPM na intensyfikacje oczyszczania ścieków drożdżowych z wykorzystaniem reakcji Fentona był widoczny jedynie w przypadku najniższej dawki reagentów chemicznych. W tym wariancie skuteczność oczyszczania wzrosła o 15%.

The advanced oxidation processes (AOP) are efficient at contaminants removing during wastewater treatment. One of the most commonly applied AOP methods is based on the use of hydrogen peroxide (H2O2) · H2O2 may react with pollutants instantaneously or directly after preliminary ionisation or dissociation into free radicals (e.g., the hydroxyl radical, OH). The most frequently used catalyst are Fe(II) or Fe(III). Application of catalysts along with hydrogen peroxide is commonly known as the Fenton reaction. As a result of the catalytic breakdown of hydrogen peroxide by ferrous ions, high-reactive hydroxyl radicals are created with a high oxidizing potential of 2.8 V. The possibility of organic compounds (expressed as COD) oxidation during wastewater treatment by means of constant magnetic field (CMF) and Fenton reaction was investigated. Wastes from the yeast production industry, preliminary pre-treated in upflow anaerobic sludge blanket (USAB) reactor were used in the experiment. COD concentration in the wastes was 2570 mgO2/dm3. The experiment was conducted at the laboratory scale at three different research stations. The impact of the amount of Fenton's reagent on COD removal efficiency and the importance of CMF during AOP was determined. In the first phase, the influence of the applied doses of Fenton's reagent on chemical oxygen demand (COD) in wastewater was determined. Second phase were aimed to assign the quality of the direct impact of CMF to determine its influence on the wastewater parameters when the treatment is opuated without the applied reagents. In the third phase, a thorough observation of the effects of simultaneous application of CMF and AOP was made to distinguish the exact CMF influence over the entire treatment. Particular attention was paid to changes in the course of COD concentration over a period of time, which seemed to be subject to Fenton's reagent and CMF activity. Wastewater treatment processes in the discussed experiment depended primarily on the applied dose of the reacting chemical substances. Together with the increasing amounts of hydrogen peroxide and ferrous ions, a higher percent reduction of COD contained in the wastewater was observed. AOP let obtain COD reduction in the range of 33 to 60% depending on chemical reagents dosage. The impact of constant magnetic field on the intensification of yeast wastes treatment with Fenton reaction was observed merely in case of the lowest chemical reagents dosage. In this variant, wastewater treatment efficiency increased by 15%. In the analyzed wastewater, intense oxidation was observed during the first 3 hours of the process. Longer reaction tune did not increase organic compounds removal. The experiment revealed the possibility of applying smaller doses of the Fenton's reagent, thereby keeping up unchanged treatment efficiency, provided that CMF s is applied.