Ozonation of Landfill Leachates: Treatment Optimization by Factorial Design

Author(s):  
Zacharias Frontistis ◽  
Nikolaos P. Xekoukoulotakis ◽  
Evan Diamadopoulos ◽  
Dionissios Mantzavinos

AbstractThe ozonation of landfill leachates in a bubble column was investigated concerning the effect of operating parameters, such as initial organic loading (from 550 to 5500 mg/L dissolved COD), reaction time (from 60 to 360 min) and ozone gas phase concentration (from 19 to 38 mg/L) on treatment efficiency implementing a factorial experimental design. All three parameters tested, as well the second order interaction between initial COD and ozone had a statistically significant, positive impact on COD removal. At increased COD loadings and a maximum ozone concentration of 38 mg/L, COD was the single most important factor affecting both COD and phenols removal. Treatment of the raw leachate (5500 mg/L COD) for 360 min and maximum ozone concentration led to 50% COD removal with a first-order kinetic constant of 2.2 10

2020 ◽  
Vol 58 (3A) ◽  
pp. 1
Author(s):  
Hu Tap Van

Catalytic ozonation is one of the promising treatment methods for removal of persistent organic compounds from water and wastewater. In this study, some metal slags such as: iron slag, lead slag, zinc slag, cadmium slag and copper slag originated from solid waste of Thai Nguyen Non-ferrous Metals Limited Company, Vietnam were used as heterogeneous catalysts for ozonation process to remove organic compounds from pulp wastewater. The effects of the initial pH (pHi) of pulp wastewater and the metal slag dosage on efficiency of decolorization and mineralization of pulp wastewater, in term of COD were investigated. The results indicated that iron slag was the most suitable catalyst for treatment of pulp wastewater by ozonation process with the highest removal efficiency of COD, namely, after 120 min of ozonation (with flowrate of O3 of 3.038 g/h) of the pulp wastewater (initial COD 1809 mg/L), COD removal efficiency, respectively, reached 91,16%; 84%; 83,83 %; 83,91%; 83,41% and 83,14% in the presence of iron, copper, zinc, lead, cadmium slag and ozone alone. Simultaneously, the color was almost completely removed (95.55 – 98.79%) by ozonation processes with using all before-mentioned metal slags as heterogeneous catalysts and ozone alone. Maximum COD and color removal efficiency obtained at pH 7 for ozonation alone and its combinations with iron slag. Moreover, an increase in the iron slag dosage from 0.125 g/L to 2.0 g/L for O3/iron slag could enhance COD and color removal of pulp wastewater. The K values (apparent first-order rate constant values) showed that the COD removal rate followed the pseudo-first-order kinetic model. This study also indicated that the main constituent FeO presence in iron slag reaction with O3 in heterogeneous catalytic ozonation system enhances removal efficiency of color and COD of pulp wastewater.


2019 ◽  
Vol 79 (10) ◽  
pp. 1977-1984
Author(s):  
W. Liamlaem ◽  
L. Benjawan ◽  
C. Polprasert

Abstract Thailand has adopted the concept of eco-tourism as a protocol to protect environmental resources. One of the key factors in enabling the achievement of this goal is the improvement of the quality of effluent from those homestays and resorts which still lack efficient on-site wastewater treatment. This research utilized case studies of subsurface flow constructed wetlands (SFCWs), planted mainly with the Indian shot (Canna indica L.), which were designed to treat wastewaters at three resorts located in Amphawa District, Samut Songkram Province in central Thailand. The results showed that the treated effluent was of sufficient quality to meet the building effluent standards Type C, which require the concentrations of biological oxygen demand (BOD), total Kjeldahl nitrogen (TKN) and suspended solids (SS) to be less than 40, 40 and 50 mg/L, respectively. In addition, the first-order kinetic constants for the design and operation of SFCWs were determined. For treating wastewater containing organic substances, with no prior pre-treatment, the first-order kinetic constant of 0.24 1/d can be applied to predict effluent quality. For treating other types of domestic wastewater, a first-order kinetic constant in the range 0.40–0.45 1/d can be used when sizing and operating SFCWs. This research highlights the great potential of SFCWs as a sustainable wastewater management technology.


2003 ◽  
Vol 48 (4) ◽  
pp. 21-28 ◽  
Author(s):  
S. Mace ◽  
D. Bolzonella ◽  
F. Cecchi ◽  
J. Mata-Alvarez

The results of the start-up of two digesters in mesophilic and thermophilic conditions, together with its steady results at several organic loading rates are described. A kinetic study is also carried out which allows one to estimate the ultimate methane production, together with the first-order kinetic constant. Operation at thermophilic temperature yields better results as it allows a more loaded reactor and the methane production is slightly higher.


Author(s):  
Matin Parvari ◽  
Peyman Moradi

The hydrodesulfurization of dibenzothiophene (HDS of DBT) in a high pressure batch reactor at 320°C was carried out over CoMo/Al2O3-B2O3 catalysts with different B2O3 contents (4, 10, and 16 wt%). Ethylenediaminetetraacetic acid (EDTA) with different EDTA/Co mole ratios (0.6, 1.2 and 1.8) was used as a chelating ligand during the preparation of CoMo/Al2O3-B2O3. XRD studies, FTIR, TPD of NH3, and BET experiments were used to investigate the catalyst samples. The results showed that the catalyst using the support with 4 wt% B2O3 and an EDTA/Co mole ratio of 1.2 had a hydrodesulfurization activity (in pseudo first order kinetic constant basis) value of ~2.96 times higher than that of the simple CoMo/Al2O3 catalyst.


2009 ◽  
Vol 36 (12) ◽  
pp. 1919-1925 ◽  
Author(s):  
Sonia Arriaga ◽  
Sergio Revah

Mathematical modeling in the biofiltration of volatile organic compounds is a valuable tool for performance prediction and in scaling up. Majority of the published models include parameters obtained from fitting experimental data, thus masking their real influence as they are lumped generally. The present work aims to evaluate experimentally some of the most relevant parameters including kinetic constant, partition coefficient in the biofilm, biofilm thickness, superficial area, and effective diffusivity. For the fungal biofilm, all the parameters mentioned above were obtained experimentally; and for the bacterial biofilm, the biofilm thickness and some intrinsic parameters used to obtain the first-order kinetic constant were taken from the literature. These parameters were then incorporated in a mathematical model to describe the steady-state degradation of hexane in bacterial and fungal biofilters operating under continuous mode. Experimentally, the dimensionless partition coefficients (mG) indicated that hexane was 4 and 35 times more soluble in the bacterial (mG = 9.14) and fungal (mG = 0.88) biofilters, respectively, than in water (mG = 30.4). Comparison of model estimates with experimental concentration profiles of the pollutant along the height of the biofilters proves that the first-order limited by reaction model was appropriate to interpret the experimental results with a small error of ∼1%.


2017 ◽  
Vol 46 ◽  
pp. 111-122 ◽  
Author(s):  
Hosein Ghahremani

Photocatalytic degradation of sulfanilamide (SNM) as a kind of pollutant agent through titanium dioxide nano particles (TiO2) under UV irradiation was evaluated. The effect of different parameters, such as TiO2 and SNM concentrations, amount of pH, inorganic salt and type of light source on the reaction rate was investigated. The results show that SNM was completely removed from the solution after 60 min under UV irradiation. Furthermore, kinetic studied were performed at 25°C over different ranges of SNM concentrations from 100 to 300 ppm, TiO2 concentrations from 0.05 to 1 gL-1 and pH of suspensions from 3 to 11. In this range of concentration of materials, a Langmuir–Hinshelwood kinetic model can describe the process. An overall pseudo-first order kinetic constant was calculated for sulfanilamide conversion. The optimum TiO2 loading, which provides enough surface area for reaction without irradiation loss due to scattering of UV light, was found to be 0.1gL-1, and SNM concentration was100 ppm. Higher degradation efficiency of SNM was observed at pH=9. Finally, the results of this work proved that photocatalysis of SNM is a promising technology to reduce persistent substances even if they are present in low concentrations.


2018 ◽  
Vol 156 ◽  
pp. 03019
Author(s):  
Lieke Riadi ◽  
Andrian Sugiharto ◽  
Hana Gondokusumo

This paper describes the ozonation process in yarn dyed wastewater using continuous stirred tank reactor with the objective to study the kinetic of COD degradation at various volumetric flow rate (30, 50, 70 ml/min) and ozone concentration (2.70 %, 4.25%, 5.86 % mol/mol). The wastewater which was collected from a yarn dying process located in Surabaya area was pretreated by electrocoagulation prior to ozonation process. The electrocoagulation process was carried out to reduce the color intensity and total suspended solid. The pretreated wastewater was then processed using ozonation for 2.5 hours. The result showed that at various concentration of ozone, maximum COD removal was 90.78% which was achieved at 5.86 %mol/mol of Ozon and volumetric flow rate 50 ml/min. It was found that the degradation process followed the pseudo-first order kinetic model. The obtained pseudo-first order rate constants for volumetric rate of 50 mil/min were 0.0307 min-1, 0.0419 min-1 and 0.053 min-1 for ozon concentration of 2.70 %, 4.25%, 5.86 % mol/mol respectively. The residence time were 41 minutes, 31 minutes and 23 minutes for ozone concentration of 2.70 %, 4.25%, 5.86 % mol/mol respectively. These findings offers an alternative treatment for wastewater containing dyes.


Author(s):  
Chen-Yan Hu ◽  
Si-Cheng Ren ◽  
Yi-Li Lin ◽  
Ji-Chen Zhang ◽  
Ye-Ye Zhu ◽  
...  

Abstract In this study, we studied the degradation kinetics of a common iodine contrast agent, diatrizoate, by ozone and the formation of disinfection by-products (DBPs) in the sequential chlorination. Effects of ozone concentration, solution pH, and bromide concentration on diatrizoate degradation were evaluated. The results indicate that diatrizoate can be effectively degraded (over 80% within 1 h) by ozone, and the degradation kinetics can be well described using the pseudo-first-order kinetic model. The pseudo-first-order rate constant (kobs) of diatrizoate degradation significantly increased with increasing ozone concentration and decreasing bromide concentration. The kobs kept increasing with the increase of pH value and reached a maximum of 6.5 (±0.05) × 10−2 min−1 at pH 9. As the ozone concentration gradually increased from 0.342 to 1.316 mg/L, the corresponding kobs of diatrizoate degradation increased from 1.76 (±0.20) × 10−3 to 4.22 (±0.3) × 10−2 min−1. The bromide concentration exhibited a strong inhibitory effect on diatrizoate degradation because of the competition for ozone with diatrizoate. Trichloromethane was the only detected DBP in the subsequent chlorination in the absence of bromide. However, in the presence of bromide, six other DBPs were detected, and bromochloroiodomethane and tribromomethane became the major products with concentrations 1–2 orders higher than those of the other DBPs. In order to provide safe drinking water to the public, water should be maintained at circumneutral pH values and low bromine concentrations (<5 μM) before reaching the chlorine disinfection process to effectively control the formation of DBPs.


2020 ◽  
Vol 31 (2) ◽  
pp. 171-179
Author(s):  
Umi Laila ◽  
◽  
Rochmadi Rochmadi ◽  
Sri Pudjiraharti ◽  
Rifa Nurhayati ◽  
...  

Previous study successfully conducted encapsulation of the purple-fleshed sweet potato’s anthocyanin but the study has yet to reveal the stability of encapsulated anthocyanin. Therefore, this research aims to observe the stability of encapsulated anthocyanin regarding the characteristic of low anthocyanin stability, which depends on environmental factors, such as temperature, pH, humidity, and water activity. The kinetic parameters of stability, including kinetic constant (k), reaction order, and half-life (t1/2), were also studied. Stability testing was conducted in high water activity of 0.75 and various in-cubation temperatures at 16, 25, 35, and 45°C. Un-encapsulated anthocyanin extract was also tested for its stability in the same condition in order to be compared with encapsulated anthocyanin. This study re-vealed that the encapsulated anthocyanin had lower stability than un-encapsulated anthocyanin extract. It was proven by higher kinetic constant and lower half-life of encapsulated anthocyanin for every incubation temperature which was induced by higher pH of encapsulated anthocyanin compared with anthocyanin extract. Besides, high water activity reduced glass transition temperature (Tg), in which encapsulated anthocyanin was in rubbery state. Both encapsulated anthocyanin and anthocyanin extract were degraded following the first order kinetic. Using the Arrhenius equation, it was obtained that the degradation kinetic constant of encapsulated anthocyanin was stated as k= 420.44 exp (-23.33/RT). Meanwhile, k= 1.12x106 exp (-46.70/RT) described degradation of kinetic constant of anthocyanin extract. The stability test re-vealed that the application of encapsulated anthocyanin was not suitable for wet-type food product.


2017 ◽  
Vol 19 (4) ◽  
pp. 641-649 ◽  

This study evaluated the effectiveness of solar Photo-Fenton’s technique (H2O2/Fe2+/Solar) to treat the refinery wastewater. The experimental data were analyzed using the first and second-order kinetic models. The results clearly indicated that the pseudo-second-order models gave better prediction than the pseudo-first-order models for IC and COD removals, as indicated by the higher regression coefficients (R2). The degradation rate by this treatment could be expressed as a pseudo-second-order reaction with respect to IC and COD removals. The best operating conditions, as elucidated by kapp values, were pH (2), Fe+2 (0.08 g/L), H2O2 (1 g/L), H2O2/Fe2+ ratio (12.5), and reaction time (300 minutes). The solar Photo-Fenton reaction was very fast and reached a maximum IC and COD removals to 62% and 84%, respectively. This study demonstrated that solar Photo-Fenton oxidation process could be used effectively as a post-treatment to enhance the treatment efficiency of petroleum wastewater.


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