Browsing by Subject "Ozonation"

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Growth of lettuce in hydroponics fed with aerobic- and anaerobic–aerobic-treated domestic wastewater
(2023) Germer, Jörn; Brandt, Christian; Rasche, Frank; Dockhorn, Thomas; Bliedung, Alexa
Reusing water and nutrients from municipal wastewater can conserve resources and reduce wastewater treatment costs. In this study, the suitability of different qualities of treated wastewater for plant production in a hydroponic flow-through system was investigated. Lettuce (Lactuca sativa L.) was grown in hydroponic lines fed with treated wastewater, i.e., conventional effluent from aerobic wastewater treatment by the activated sludge process (CE), ozonised CE (CEO), anaerobically pre-treated and nitrified wastewater (AN) and biological activated carbon filtered AN (ANC) in comparison with a modified Hoagland nutrient solution. In CEO, AN and ANC, the lettuce reached a similar weight and elemental composition as that in HS. The low N and P concentrations in CE and CEO were quickly depleted, resulting in limited plant development at the ends of these lines. The lower water content in the CE shoots was probably related to hypoxia that occurred at higher temperatures. In the CEO line, this condition did not arise due to the constant decay of O3. At lower temperatures, the CEO shoot dry weight was 90% higher than that in CE. This was possibly an effect of residual ozone and/or oxygen supersaturation. AN produced the highest yield, while carbon filtration lowered the content of cations in ANC, inducing deficiency of Fe > Mn > Cu > Zn > K. Coupling wastewater treatment with hydroponics allows for efficient nutrient recovery, and thus could reduce the energy and reactor volume needed for N and P elimination.
Rheological evaluation of wheat dough treated with ozone and ambient air during kneading and dough formation
(2022) Moll, Sarah; Zettel, Viktoria; Delgado, Antonio; Hitzmann, Bernd
The aim of this study is to compare the application of ozone with that of air during the dough kneading process. Experiments were performed on doughs made from two wheat flours of different protein contents by changing the treatment time and oxidative gas. All samples were analyzed by Farinograph, oscillatory rheometer, and dough extensibility test. Farinograph measurements showed that water absorption capacity by ozone treatment during kneading was increased by 1.8% and 2.6%, and dough development time was 47% and 37% higher than of untreated doughs made of lower and higher quality wheat flour, respectively. Dough softening was reduced by 30% and 42% by air. Ozone treatment slightly decreased the dough stability of doughs made from higher quality flour and increased dough softening for both. Ozone treatment increased the force required to break the dough strand after 5 min by 42% and 23% for samples of lower and higher quality wheat flour, respectively. The extensibility of the dough behaved inversely. The frequency sweep test showed an increase in G′ and G″.