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Showing 6 results for Ozone
Bahman Masoomi, Neamatollah Jaafarzadeh, Tayebeh Tabatabaie, Esmaeil Kouhgardi, Sahand Jorfi, Volume 6, Issue 1 (2-2019)
Abstract
Background: Ozone can be used as a single technology or in combination with other processes to improve the coagulation- flocculation or biodegradability in order to remove pollutants in natural water treatment.
Methods: In this study, the effects of pre-ozonation with coagulant substances on the quality parameters of drinking water were investigated using humic acid, kaolin, clay, and green algae in a pilot scale. This study was conducted under laboratory conditions (at both acidic and alkaline pH in different dosages of ozone and coagulant at ozone contact time with simulated water sample (5-20 minutes) in different scenarios).
Results: The highest removal efficiency of parameters in the state of pre-ozonation alone and preozonation with a coagulant was observed at contact time of 20 minutes, ozone dosage of 5 g/h, coagulant dosage of 25 mg/L, at alkaline pH along with a decrease in temperature. So that, the average removal rate of turbidity, total organic carbon (TOC), color, and chlorophyll a in contact time of 20 minutes was 76.9%, 52.8%, 66.6%, and 85%, respectively. However, compared to ozonation under similar conditions, the reduction in turbidity, TOC, color, and chlorophyll a was 36.13%, 24.4%, 32.13%, and 79.6%, respectively. Also, it was revealed that pre-ozonation with coagulant could effectively improve the removal of parameters.
Conclusion: However, since pre-ozonation can be effectively used to improve the coagulation efficacy in the drinking water treatment, the pre-ozonation combined with coagulation is proposed as an alternative to conventional coagulation to improve the process of drinking water treatment plant.
Marie Albert, Mohamed Lemdan, Damien Cuny, Patrick Duriez, Joséphine Escutnaire, Pierre-Yves Gueugniaud, Eric Wiel, Hervé Hubert, Christophe Di Pompeo, Volume 6, Issue 4 (12-2019)
Abstract
Background: Air pollution is increasingly associated with cardiovascular events. As for ozone (O3) pollution, results are inconsistent though O3 levels are associated with hospital admissions, global mortality, and respiratory, and cardiovascular mortality.
Methods: In this time-stratified case-crossover study, the associations between short-term exposure to O3 (on an hourly and daily scale) and out-of-hospital cardiac arrests (OHCA) were investigated. Specific subgroups were explored by sex, age, diabetes status, for OHCA during non-holiday periods. Data were collected in the Nord-Pas-de-Calais region, France, in 2015. Data were statistically analyzed using conditional logistic regression (CLR).
Results: The study included 1039 cases of OHCA. Significant negative associations were found between OHCA and O3 levels measured in 3 or 4 days before the arrest for all the people, and 1, 2 or 3 days before the arrest for men. As for OHCA during non-holiday periods, there was no significant negative associations but a positive association was revealed for women between OHCA and O3 levels measured in 5 days before the arrest (OR=1.53, P = 0.008).
Conclusion: According to the results, OHCA should be investigated during non-holiday periods to control potential confounders that would lead to negative associations. Women might be a susceptible subgroup to O3 pollution.
Farid Rahal, Salima Rezak, Noureddine Benabadji, Volume 7, Issue 4 (10-2020)
Abstract
Background: The effect of confinement due to the coronavirus disease 2019 (COVID-19) pandemic on air pollution has been investigated in several cities. Indeed, the concentration of the main air pollutants have decreased significantly due to the decline in activities consuming fossil fuels. However, it was
found that the concentration of ozone (O3) has increased in Nice, Rome, Valence, Barcelona, Turin, and Wuhan. The main objective of this study was to assess the impact of the COVID-19 pandemic on photochemical pollution in Oran, Algeria.
Methods: In Oran, a port city in the north-west of Algeria, the level of tropospheric ozone pollution was measured automatically every 15 min for 10 days at the same location before and after the confinement period, using an electronic nose, called APOMOS (air pollution monitoring system). This electronic circuit is equipped with an electrochemical sensor (MQ131) as well as a temperature and humidity sensor. Sampling was carried out in the central part of the Oran agglomeration from May to June 2020. The data related to the direction and intensity of the wind were processed to find a correlation between these parameters and the concentration of ozone in the studied area.
Results: The impact of confinement on the increase of the ozone pollution levels in Oran, was estimated to be 52%. On the other hand, the statistical study of the pollution levels, the intensity and direction of the wind indicates that the important part of the downtown is involved in the generation of tropospheric
ozone.
Conclusion: The confinement due to the COVID-19 pandemic in Oran led to the reduction of the road traffic and pollutants emissions and the increase of ozone levels in urban area. Thus, ozone was less degraded because there were low levels of nitrogen oxides (NOx) in the atmosphere of this city during the confinement period.
Ebrahim Shahsavani, Mohammad Hassan Ehrampoush, Mohammad Reza Samaei, Ehsan Abouee Mehrizi, Farzan Madadizadeh, Alireza Abbasi, Parvaneh Talebi, Amin Mohammadpour, Ali Asghar Ebrahimi, Volume 9, Issue 4 (10-2022)
Abstract
Background: Background: Because of the growing population and increasing freshwater consumption, treatment and reuse of greywater have been widely considered. The application of a new and environmentally friendly treatment method for synthetic and real greywater (RGW) is of utmost importance. This study aimed to evaluate the efficiency of the combination of ozonation, biological activated carbon, and ultrafiltration (O3/BAC/UF) in the removal of chemical oxygen demand (COD), turbidity, five-day biochemical oxygen demand (BOD5), and linear alkylbenzene sulfonates (LAS) from synthetic greywater and RGW.
Methods: Bacillus Subtilis, Acinetobacter radioresistens, Pseudomonas aeruginosa, and Ochrobactrum oryzae were selected from nine pure bacterial species and transferred to granular activated carbon (GAC), then, mineral culture medium was added to the reactor for the growth and establishment of bacterial consortium. The SEM method was employed to ensure the formation of a microbial layer on GAC. Then, the continuous flow of synthetic greywater (for six months) at a low: 6.1, medium: 12.2, and high: 18.3 gCOD/L.d organic loading rates as well as RGW (for two weeks) entered the treatment system.
Results: The percentages of COD removal in low, medium, and high organic loads of synthetic greywater and RGW were 85.12%, 79.05%, 85.3%, and 98.65%, respectively. Moreover, the percentages of BOD5 removal were 87%, 82%, 51%, and 92%, respectively. Furthermore, the percentages of turbidity removal were 93.5%, 97%, 96.69%, 73.33%, and the percentages of LAS removal were 91.4%, 88.1%, 84.8%, and 93.7%, respectively.
Conclusion: The treatment system has a remarkable ability to remove pollutants from greywater and can be used as a new method of greywater treatment in Iran.
Samira Djaroud, Zoubir Belmokhtar, Yassine Merad, Kamel Nassour, Malika Belkacemi, Derouicha Matmour, Zakaria Merad, Volume 10, Issue 3 (7-2023)
Abstract
Background: Disinfection is performed in our laboratory using sodium hypochlorite, glutaraldehyde, alcohol, or hydrogen peroxide. All these products are known for their harmful side effects on human and ecological health. As a part of the search for new sterilization methods that respect the environment
much more, we were interested in studying the antifungal activity of ozone gas on the most isolated fungi in our hospital “University Hospital Center Hassani Abdelkader of Sidi Bel Abbes”.
Methods: This study focused on the antifungal activity of gaseous ozone on the most common fungal isolates in the hospital, with consideration of the duration of the exposure to ozone.
Results: The fungicidal effect of ozone gas on molds was more effective compared to its effect on yeasts, it makes it possible to inhibit the reproduction and fungal growth of molds, in particular the filamentous molds and the most commonly isolated dermatophytes. A longer exposure would seem to be more effective.
Conclusion: Ozone gas can be a new alternative for sterilization and disinfection techniques, especially filamentous fungi and dermatophytes.
Zahra Jamshidinasirmahale, Ahmadreza Yazdanbakhsh, Mohamadreza Masoudinejad, Nadali Alavi Bakhtiarvand, Volume 11, Issue 1 (1-2024)
Abstract
Background: Anaerobic co-digestion (AcoD) of various wastes is a suitable method for the removal of contaminants and biogas production. The first aim of this study was to determine the optimal ratio of landfill leachate (LL) and sewage sludge (SS) for AcoD, and the second one was to evaluate the effect of
pre-ozonation of the mixture on AcoD.
Methods: The LL and SS samples were taken from landfill sites and municipal wastewater treatment plants (MWTPs), respectively. In the first step, five reactors were used and named R1 (100% SS), R2(100% LL), R3 (15% LL/85% SS), R4 (25% LL/75% SS), and R5 (45% LL/55% SS). Mesophilic anaerobic digestion (AD) was performed on the reactors and the optimal ratio was determined. In the second stage, the optimal mixtures were subjected to an ozonation process before AcoD.
Results: The results of the first stage showed that the highest efficiency removal of the total solids (TS), volatile solids (VS), and chemical oxygen demand (COD), and the highest biogas production belonged to R3 digester, containing 15% LL and 85% SS. In the second stage, the results showed that the removal efficiency of COD and VS in the ozonated sample at the dosage of 7.6 gO3/h were 29.8% and 36.6% higher than the non-ozonated sample, respectively. Furthermore, in the ozonated sample, the biogas yield and the content of methane in the gas mixture were 27% and 9% higher respectively, compared to the non-ozonated sample.
Conclusion: According to the results, the appropriate ratio of LL to SS and pre-ozonation of LL/SS mixture have a great impact on the performance of AcoD.
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