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Comparative study of different ultrasound based hybrid oxidation approaches for treatment of real effluent from coke oven plant
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Treatment of real textile industry effluent using photocatalysis, sonocatalysis, sonophotocatalysis and H2O2 assisted sonophotocatalysis have been studied based on the use of Ce-TiO2 nanocatalyst synthesized using sonochemical co-precipitation method. Characterization studies of the obtained catalyst revealed crystallite size as 1.44 nm with particles having spherical morphology. A shift of the absorption edge to the visible light range was also observed in UV-Vis diffuse reflectance spectra (UV-DRS) analysis. The effects of different operational parameters viz catalyst dose (0.5 g/L-2 g/L), temperature (30 °C-55 °C) and pH (3-12) on the COD reduction were studied. The reduction in the COD was higher at lower pH and the optimum temperature established was 45 °C. It was also elucidated that the required catalyst dose was lesser in combined sonophotocatalysis when compared with individual photocatalysis and sonocatalysis. Combination of processes and addition of oxidants increased the COD reduction with the sonophotocatalytic oxidation combined with H2O2 treatment showing the best results for COD reduction (84.75%). The highest reduction in COD for photocatalysis was only 45.09% and for sonocatalysis, it was marginally higher at 58.62%. The highest reduction in COD achieved by sonophotocatalysis was 64.41%. Toxicity tests coupled with Liquid Chromatography Mass Spectrometry (LC-MS) analysis revealed that there were no additional toxic intermediates added to the system during the treatment. Kinetic study allowed establishing that generalized kinetic model fits the experimental results well. Overall, the combined advanced oxidation processes showed better results than the individual processes with higher COD reduction and lower requirement of the catalyst.
Synthesis of Fe‐TiO2 and Ce‐TiO2 catalysts using conventional, and ultrasound assisted (US) homogeneous coprecipitation method has been investigated. Effects of ultrasonic irradiation time and ultrasonic power on catalyst synthesis were studied and it was elucidated that best conditions were 140 W and 60 min, respectively. Characterization using FE‐SEM revealed spherical particles with the size range from 36.4 to 49.4 nm whereas XRD analysis affirmed a mixture of anatase, rutile, and brookite TiO2 phase with crystallite size ranging from 4.18 to 12.99 nm. BET analysis revealed highest specific surface area (211.59 m2/g) for the sonochemically synthesized Ce‐TiO2. The process intensification benefits demonstrated in catalyst synthesis were better crystallinity, lower particle size, and higher surface area. The application of catalyst efficacy was tested for photocatalytic, sonocatalytic, and sonophotocatalytic oxidation where maximum decolorization as 71.97% was obtained for sonochemically synthesized Ce‐TiO2 applied in the sonophotocatalytic approach. Studies related to regeneration, stability, and leaching of Ce and Ti ion from the sonochemically synthesized Ce‐TiO2 catalyst were also performed. It was observed that the catalyst can be regenerated easily and there were no structural changes in the catalyst after regeneration with negligible leaching of the ions from the catalyst into the solution. Overall, an improved process for catalyst synthesis with intensified decolorization application was demonstrated based on the use of ultrasound.
BACKGROUND
Chemical industry wastewater is challenging to treat because of the various chemicals they contain. In this study, the treatment of chemical industry wastewater, which produces a wide variety of chemical aids, such as foam control agents, and silicones used in the textile, food and cosmetics industries, by coagulation combined with Fenton or photo‐Fenton oxidation processes was investigated. In coagulation studies, optimum pH and coagulant dose were determined with polyaluminum chloride (PAC), polyaluminum chloride hydroxide sulfate (PACS) and FeCl3 coagulants, while Fe²⁺, H2O2, pH and oxidation time were optimized in Fenton studies.
RESULTS
In the coagulation, higher wastewater treatment was achieved with PAC compared to PACS and FeCl3 coagulants, and 62.6% chemical oxygen demand (COD) and 44.3% total organic carbon (TOC) removal were obtained at 500 mg L⁻¹ PAC and pH 8. In the coagulation and Fenton oxidation, 92.4% COD, 79.7% TOC, 99.8% turbidity, and 96.7% total soluble solids (TSS) were achieved. The application of photo‐Fenton oxidation instead of Fenton oxidation did not cause a significant change in chemical industry wastewater. The cost of chemical industry wastewater treatment by coagulation and Fenton oxidation was calculated as $19.16 m⁻³, and the cost per kilogram of CODremoved was determined as $2.89 kg⁻¹.
CONCLUSION
In chemical industry wastewater treatment, high TSS and turbidity removal can be achieved by coagulation with PAC, and the wastewater load subjected to Fenton oxidation can be reduced. Efficient wastewater treatment was provided by Fenton oxidation after coagulation. The application of the photo‐Fenton oxidation process instead of Fenton oxidation did not show the expected effect. However, toxicity studies should be performed in treated wastewater using coagulation–Fenton oxidation processes in future studies. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).
In recent years industrialization has caused magnificent leaps in the high profitable growth of pharmaceutical industries, and simultaneously given rise to environmental pollution. Pharmaceutical processes like extraction, purification, formulation, etc., generate a large volume of wastewater that contains high chemical oxygen demand (COD), biological oxygen demand, auxiliary chemicals, and different pharmaceutical substances or their metabolites in their active or inactive form. Its metabolites impart non-biodegradable toxic pollutants as a byproduct and intense color, which increases ecotoxicity into the water, thus this requires proper treatment before being discharged. This study focuses on the feasibility analysis of the utilization of ultrasound cavitation (20 kHz frequency) together with a persulfate oxidation approach for the treatment of complex pharmaceutical effluent. Process parameters like pH, amplitude intensity, oxidant dosage were optimized for COD removal applying response surface methodology-based Box–Behnken design. The optimum value observed for pH, amplitude intensity and oxidant dosage are 5, 20% and 100 mg/L respectively with 39.5% removal of COD in 60 min of fixed processing time. This study confirms that a combination of ultrasound cavitation and persulfate is a viable option for the treatment of pharmaceutical wastewater and can be used as an intensification technology in existing effluent treatment plants to achieve the highest amount of COD removal.
HIGHLIGHTS
Synergistic effect of ultrasonication and persulfate oxidation studied on pharma wastewater.;
Box–Behnken method applied for process parameter optimization.;
Significant reduction in the COD from the pharma wastewater within one hour of the reaction.;
Potential choice for the implementation of the process as a pre-treatment option for wastewater treatment.;
Nowadays, increased human activity, industrialization, and urbanization result in the production of enormous quantities of wastewater. Generally, physicochemical and biological methods are employed to treat industrial effluent and wastewater and have demonstrated high efficacy in removing pollutants. However, some industrial effluent and wastewater contain contaminants that are extremely difficult to remove using standard physicochemical and biological processes. Previously, electrochemical and hybrid advanced oxidation processes (AOP) were considered a viable and promising alternative for achieving an adequate effluent treatment strategy in such instances. These processes rely on the production of hydroxyl radicals, which are highly reactive oxidants that efficiently break down contaminants found in wastewater and industrial effluent. This review focuses on the removal of contaminants from industrial effluents and wastewater through the integration of electrochemical and advanced oxidation techniques. These processes include electrooxidation, electrocoagulation/electroflocculation, electroflotation, photo-Fenton, ozone-photo-Fenton, sono-photo-Fenton, photo-electro-Fenton, ozone/electrocoagulation, sono-electrocoagulation, and peroxi/photo/electrocoagulation. The data acquired from over 150 published articles, most of which were laboratory experiments, demonstrated that the hybrid process is more effective in removing contaminants from industrial effluent and wastewater than standalone processes.
Coking wastewater poses a serious threat to the environment due to the presence of a wide spectrum of refractory substances such as phenolic compounds, polycyclic aromatic hydrocarbons and heterocyclic nitrogenous compounds. These toxic substances are difficult to treat using conventional treatment methods alone. In recent years much attention has been given to the effective treatment of coking wastewater. Thus, this review seeks to provide a brief overview of recent developments that have taken place in the treatment of coking wastewater. In addition, this article addresses the complexity and the problems associated with treatment followed by a discussion on biological methods with special focus on bioaugmentation. As coking wastewater is refractory in nature, some of the studies have been related to improving the biodegradability of wastewater. The final section focuses on the integrated treatment methods that have emerged as the best solution for tackling the highly unmanageable coking wastewater. Attention has also been given to emerging microwave technology which has tremendous potential for treatment of coking wastewater. HIGHLIGHTS
Cost-effective treatment of coking wastewater is a challenge.;
A brief overview of recent developments that have taken place in the treatment of coking wastewater.;
Discussion on integrated treatment methods.;
The conventional biological treatment has been replaced with more efficient and practical solutions.;
Technical and economic viability studies related to treatment methods.;
The magnetic MgFe2O4 nanoparticles (NPs) were fabricated via a facile co-precipitation technique and was comprehensively characterized by XRD, FTIR, SEM, EDX and VSM. The prepared NPs were used as catalyst in presence of ultrasound (US) irradiation to activate persulfate (PS) for generation of sulfate radicals (SO4·-) for boosted degradation of toxic Brilliant Green (BG) dye. Preliminary experiments revealed that highest BG dye degradation efficiency of 91.63% was achieved at MgFe2O4 catalyst dose of 1.0 g/L, PS dose of 300 mg/L, and initial dye concentration of 70 ppm within 15 min of US irradiation. However, only US, US in presence of PS oxidation and US in presence of MgFe2O4 catalyst have shown 20.2%, 83.6% and 45.0% of BG dye removal, respectively. Furthermore, response surface methodology (RSM) based central composite design (CCD) was executed to investigate the effect of interaction between independent variables such as MgFe2O4 catalyst dose (0.5–1.5g/L), PS dose (150–350mg/L), initial BG dye concentration (50–150 ppm) and US irradiation time (4–12 min). The RSM based quadratic model was used to predict the experimental data, and the prediction accuracy was confirmed by analysis of variance (R² = 0.98). The established RSM model has predicted the optimum experimental conditions as MgFe2O4 catalyst dose of 0.75 g/L, PS dose of 300 mg/L, initial dye concentration of 75 ppm and sonication time of 10 min. Subsequently, the treatment cost analysis was performed for all thirty experimental runs of CCD, and the RSM predicted response was found to be evidently optimum as this has delivered best economic condition (140 $/kg of BG removed) with respect to relative dye removal (%). COD removal and residual sulfate analysis have demonstrated satisfactory reduction of COD (90.31%) as well as sulfate ions (42.87 ppm) in the dye solution after treatment. Results of degradation pathway analysis portrayed the transformation of BG molecule (M/Z ratio 385) into simpler fractions with M/Z ratio of 193, 161, 73, and 61. Moreover, the toxicity analysis revealed that sono-catalytically activated PS system has efficiently reduced the toxicity level of BG dye from 93.9% to 5.13%.
The present work demonstrates the significant role of ultrasound (US) in intensifying the efficacy of the combination with Fenton reagent and/or ozone for the treatment of real textile industrial effluent treatment procured from the local industry. Initial part of the work focused on analysing the literature based on combination approaches of US with different oxidants applied for the treatment of real and simulated effluents focusing on the dyes. The work also provides guidelines for the selection of optimal operating parameters for maximizing the intensification of the degradation. The second part of the work presents an experimental study into combined approaches of ultrasound with ozone (O3) and Fenton’s reagent for treatment of real effluent. Under optimized conditions (100W, 20 kHz and duty cycle of 70%), maximum COD reductions of 94.79% and 51% were observed using a combined approach of US+Fenton oxidation followed by lime treatment for the treatment of effluent-I and effluent-II respectively at H2O2 loading of 17.5 g/L, H2O2/Fe²⁺ ratio of 3, pH of 4, CaO dose of 1 g/L and an overall treatment time of 70 min. US+Fenton+O3 followed by lime was also applied for treatment under ozone loading of 1g/h for the treatment of effluent-I and it was found that maximum COD reduction of 95.12% was obtained within 30 min of treatment time, indicating use of ozone did not result in significant value addition in terms of COD reduction but resulted in faster treatment. HC (inlet pressure: 4bar) + Fenton + Lime scheme was successfully replicated on a pilot-scale resulting maximum COD reduction of 57.65 % within 70 min of treatment time. Overall, it has been concluded that the hybrid oxidative processes as US+Fenton followed by lime treatment is established as the best approach ensuring effective COD reduction at the same time obtaining final colourless/reusable effluent.
The hydrogen peroxide role in photocatalytic degradation of an anionic azo dye, Acid Orange 7 (AO7), was investigated in a slurry reactor. Commercial ZnO nanoparticles with an average size between 10 to 30 nm were used as catalysts. Optimum conditions for different parameters, including dye concentration (10–100 mg/L), catalyst concentration (0.1–0.5 g/L), and pH (5–10), were determined first in the absence of H2O2. Changes in the COD were measured for the optimum condition. The impact of adding hydrogen peroxide at different concentrations to the system operating at optimum conditions was investigated. It was observed that 0.416 mM hydrogen peroxide increased the system's efficiency and decreased reaction time by 40 min. The reaction followed first-order kinetic. Hydrogen peroxide alone did not contribute to oxidizing the contaminant, and its positive impact was attributed to decreasing electron-hole recombination in the photocatalytic process. Not only can the hydrogen peroxide-assisted photocatalytic process decrease retention time in treatment units, but it can also result in more contaminant degradation. Therefore, it can reduce the treatment cost. HIGHLIGHTS
Improving the efficiency of the slurry photocatalytic process by adding H2O2.;
Promoting the process's rate and reaction kinetics’ constants four times by adding 2.5 mM of H2O2.;
Determining optimum concentration using energy consumption reaction in order to conduct the research in the minimum energy usage condition.;
Micropollutants such as endocrine disruptors are one of the most important group of chemicals polluting water resources. Conventional treatment systems may not be effective for the removal of endocrine disrupting chemicals (EDCs), and the fate of these chemicals should be carefully monitored in the effluent of wastewater treatment plants (WWTPs). Additional treatment methods such as advanced oxidation processes can be used for the removal of endocrine disruptors. This study presents the existence of endocrine disruptors in 4 different effluents; (i) municipal WWTP effluent, (ii) textile industry WWTP effluent, (iii) organized industrial zone (OIZ) WWTP effluent and (iv) pharmaceutical industry discharge and also presents their removal efficiencies by ozonation and peroxone oxidation. A broad spectrum of removal efficiencies was observed for the EDCs present in the samples since the oxidation efficiency of wastewaters containing EDCs mainly depends on the wastewater matrix and on the type of the EDCs. Ozonation was found to be a low-cost option than peroxone oxidation at the investigated conditions.
Recalcitrant wastewater from a combined effluent treatment plant of heterogeneous industrial sector is very complex and often possess intense colour and fluctuating characteristics. In this work, the treatment of such complex effluent using photo-catalysis and Fenton processes is investigated. Studies on the treatment of combined wastewater are scarce. The reduction in colour and COD with photo-catalysis was 10% and 5%, respectively; and with Fenton process it was 80% and 72%, after 2 h. Fenton process appears to be more promising in comparison to photo-catalysis. Optimization of H2O2 & Fe²⁺ concentrations revealed that maximum reduction in colour and COD occurred at ratio of H2O2:Fe²⁺ (30:1).
Ozonation followed with a polishing moving bed biofilm reactor (MBBR) was implemented in pilot and laboratory to removal the residual pharmaceuticals and toxicity in wastewater effluent, which was from a pilot hybrid system of MBBR and activated sludge receiving municipal wastewater. The delivered ozone dosages achieving 90% pharmaceutical removal were determined both in pilot and laboratory experiments and they were normalised to dissolved organic carbon (DOC), illustrating our findings were comparable with previously published literatures. During wastewater of ozonation, the intensity of natural fluorescence was found to be greatly associated with the concentrations of the studied pharmaceuticals. In pilot experiments, toxicity, measured by Vibrio fischeri, increased after ozonation at delivered ozone dosages at 0.38-0.47 mg O3/mg DOC and was completely removed by the subsequent polishing MBBR. Laboratory experiments verified that the polishing MBBR was able to remove the toxicity produced by the ozonation.
Different types of photolytic and photocatalytic advanced oxidation processes (AOPs) were used for treatment of refinery effluents from bitumen production. The treatment efficiency was evaluated by analyzing chemical oxygen demand (COD), biological oxygen demand (BOD5), volatile organic compounds (VOCs) and sulfide ions concentration. The studies revealed a synergistic effect of application of external oxidants (O3, H2O2, O3/H2O2) with TiO2 and UV applied for improved COD and BOD5 reduction as well as the degradation of the VOCs present in the effluents. Among studied processes a photocatalytic process combined with peroxone (TiO2/UV/O3/H2O2) was the optimal and the most economical technology. It allows to reduce 38 and 32% of COD and BOD5 respectively and degrade 84% of total VOCs in 280 min of treatment. At this conditions the reduced COD exceeds over 30% a theoretical value based on the dose of oxidants, which proves the importance of photocatalysis in the developed technology. The sulfide ions were completely depleted in all experiments in the first 30 min of treatment. The addition of TiO2 in the AOPs technology revealed a decrease in the process cost using less amount of chemicals achieving similar treatment efficiency when comparing with photolytic and non-catalytic technologies. The application of these technologies can be conducted in two alternative scenarios; whether to deplete the sulfides ions concentration or to maximize the treatment efficiency. In both options, the technologies studied are promising as a pre-treatment before other types of AOPs effective at neutral/acidic pH values or before a biological treatment stage. Further studies should be developed, by scaling up the process to a pilot scale in a real case scenario to check the possibility of its implementation in the industrial practice.
Aniline is an aromatic hydrocarbon discharged into the environment through certain industrial
effluents, which thereby contaminate water resources. In this study, the performance ofan oxidizing agent, hydrogen peroxide (H2O2) with ultrasound (US) for the removal of aniline from its aqueous solution was examined. The treatability of contaminated effluent using US/H2O2 with a frequency of 50Hz for the treatment of aniline-contaminated water was investigated. The effects of operational parameters such as H2O2 concentration (0.01-0.07mol/L), initial aniline concentration (20-120 mg/L), contact time (15-90 min) and pH (3- 11) on the degradation of aniline was examined. Optimal H2O2 concentration, initial aniline concentration and contact time were obtained as 0.01 mol/L, 20 mg/L, and 45 min. The degradation process was more efficient at pH of 3. Removal
efficiency of 95.91% was achieved at these optimum conditions. The results indicate that the combined US and H2O2 process at optimal conditions can be applied for the degradation of aniline with great efficiency.
This chapter describes the use of ultrasound in remediation of wastewater contaminated with organic pollutants in the absence and presence of other advanced oxidation processes (AOPs) such as sonolysis, sono-ozone process, sonophotocatalysis, sonoFenton systems and sonophoto-Fenton methods in detail. All these methods are explained with the suitable literature illustrations. In most of the cases, hybrid AOPs (combination of ultrasound with one or more AOPs) resulted in superior efficacy to that of individual AOP. The advantageous effects such as additive and synergistic effects obtained by operating the hybrid AOPs are highlighted with appropriate examples. It is worth to mention here that the utilization of ultrasound is not only restricted in preparation of modern active catalysts but also extensively used for the wastewater treatment. Interestingly, ultrasound coupled AOPs are operationally simple, efficient, and environmentally benign, and can be readily applied for large scale industrial processes which make them economically viable.
This chapter describes the use of ultrasound in remediation of wastewater contaminated with organic pollutants in the absence and presence of other advanced oxidation processes (AOPs) such as sonolysis, sono-ozone process, sonophotocatalysis, sonoFenton systems and sonophoto-Fenton methods in detail. All these methods are explained with the suitable literature illustrations. In most of the cases, hybrid AOPs (combination of ultrasound with one or more AOPs) resulted in superior efficacy to that of individual AOP. The advantageous effects such as additive and synergistic effects obtained by operating the hybrid AOPs are highlighted with appropriate examples. It is worth to mention here that the utilization of ultrasound is not only restricted in preparation of modern active catalysts but also extensively used for the wastewater treatment. Interestingly, ultrasound coupled AOPs are operationally simple, efficient, and environmentally benign, and can be readily applied for large scale industrial processes which make them economically viable.
Gamma-radiation-induced degradation of ciprofloxacin (CIP) in aqueous solution and the factors affecting the degradation process have been investigated. The results showed that CIP (4.6 mg/L) was almost completely degraded at an absorbed dose of 870 Gy. The kinetic studies of aqueous solutions containing 4.6, 10, 15 and 17.9 mg/L indicated that the decomposition of CIP by gamma irradiation followed pseudo-first-order kinetics and the decay constant (k) decreased from 5.9 × 10−3 to 1.6 × 10−3 Gy−1 with an increase in CIP initial concentration from 4.6 to 17.9 mg/L. The effect of saturation of CIP solution with N2, N2O or air on radiation-induced degradation of CIP was also investigated. The effects of radical scavengers, such as t-BuOH and i-PrOH, showed the role of reactive radicals towards degradation of CIP in the order of
. The apparent second-order rate constant of
with CIP was calculated to be 2.64 × 109 M−1 s−1. The effects of solution pH as well as natural water contaminants, such as
,
,
and
, on CIP degradation by gamma-irradiation were also investigated. Major degradation products, including organic acids, were identified using UPLC-MS/MS and IC, and degradation pathways have been proposed.
The aim of the presented study was to determine the toxicity of wastewater from the production of coke. The wastewater was treated with advanced oxidation involving ultrasonic field with Fenton’s reagent (the amplitude was 61.5 μm and sonication time 8 min). Two doses of iron and four doses of hydrogen peroxide were used. The amount of hydrogen peroxide was proportional to the value of the chemical oxygen demand of raw wastewater, ranging from COD/H2O2 ratio of 1:2.5 to 1:20. Two tests were used to determine the toxicity (algae growth inhibition test and Lepidium test). It was found that more toxic to algae was wastewater treated by Fenton’s reagent containing a higher dose of iron. A similar inhibitory effect was observed on the germination of cress seeds.
Advanced oxidation processes (AOPs) were first proposed in the 1980s for drinking water treatment and later were widely studied for treatment of different wastewaters. During the AOP treatment of wastewater, hydroxyl radicals (OH·) or sulfate radicals (SO4 ·−) are generated in sufficient quantity to remove refractory organic matters, traceable organic contaminants, or certain inorganic pollutants, or to increase wastewater biodegradability as a pre-treatment prior to an ensuing biological treatment. In this paper, we review the fundamental mechanisms of radical generation in different AOPs and select landfill leachate and biologically treated municipal wastewater as model wastewaters to discuss wastewater treatment with different AOPs. Generally, the treatment efficiencies rely heavily upon the selected AOP type, physical and chemical properties of target pollutants, and operating conditions. It would be noted that other mechanisms, besides hydroxyl radical or sulfate radical-based oxidation, may occur during the AOP treatment and contribute to the reduction of target pollutants. Particularly, we summarize recent advances in the AOP treatment of landfill leachate, as well as advanced oxidation of effluent organic matters (EfOM) in biologically treated secondary effluent (BTSE) for water reuse.
Gamma radiation-induced degradation of ciprofloxacin (CIP) in aqueous solution and the factors affecting the degradation process have been investigated. The results showed that CIP (4.6 mg/L) was almost completely degraded at an absorbed dose of 870 Gy. The kinetic studies of aqueous solutions containing 4.6, 10, 15 and 17.9 mg/L indicated that the decomposition of CIP by gamma-irradiation followed pseudo-first order kinetics and the decay constant (k) decreased from 5.9×10-3 Gy-1 to 1.6×10-3 Gy-1 with an increase in CIP initial concentration from 4.6 to 17.9 mg/L. The effect of saturation of CIP solution with N2, N2O or air on radiation-induced degradation of CIP was also investigated. The effects of radical scavengers, like t-BuOH and i-PrOH showed the role of reactive radicals towards degradation of CIP in the order of •OH > eaq‒ > •H. The apparent second order rate constant of •OH with CIP was calculated to be 2.64 × 109 M-1s-1. The effects of solution pH as well as natural water contaminants, like HCO3‒, CO3‒, NO3‒, and NO2‒ on CIP degradation by gamma - irradiation was also investigated. Major degradation products, including organic acids were identified using UPLC-MS/MS and IC and degradation pathways have been proposed. - See more at: http://www.tandfonline.com/doi/suppl/10.1080/09593330.2015.1075597#.VbMf8fm3uW4
Amantadine wastewater is quite recalcitrant to biological treatment because of the quite stable adamantine backbone. To improve amantadine wastewater biodegradability, the combined advanced oxidation process, such as Fenton/ultrasonic process, was proposed to treat amantadine industrial wastewater. The efficiency comparisons for the treatment of amantadine wastewater using Fenton oxidation, ultrasonic process, and Fenton/ultrasonic process were conducted. The results of wastewater treatment with Fenton/ultrasonic process indicated that the TOC removal reached 65.6 %, showing almost 4 times of the degradation rate by individual oxidizing action of hydrogen peroxide. Kinetic study revealed that degradation of amantadine wastewater fitted first order kinetics for the three processes under investigation. The synergistic index (f) for the combined process was calculated as 2.24, indicating an obvious synergy effect. The energy consumption for hydrodynamic cavitation-based process has been analyzed on the basis of cavitational yield. Fenton and combined processes reduced the toxicity of wastewater by 50 and 55 %, respectively, while ultrasonic process showed no obvious effect on toxicity reduction. The monitoring of treated wastewater by EEM and GC-MS showed that the Fenton/ultrasonic process effectively removed the organic matters in the wastewater, especially the biodegradation-resistant matters containing benzene ring.
Sonolysis with bubble cavitation is an effective tool for the degradation of complex, recalcitrant organic compounds. Thermal and cavitation effects are additive to the breaking of complex bonds in organic contaminants by hydroxyl radicals. Strong oxidants such as persulfate (PS) and hydrogen peroxide (H 2 O 2), with their high redox potentials (2.01 and 1.8 V, respectively), are coupled with ultrasound energy for the degradation of contaminants. PS and H 2 O 2 generate SȮ 4 and Ȯ H radicals, respectively with higher redox potentials (2.6 and 2.8 V, respectively). Consequently, the radicals are even more active at breaking the strong covalent bonds of the contaminants. Coupled methods in different combinations of coagulation-flocculation, chemical oxidation, and sonication are investigated for the treatment of organic content dairy wastewater. The doses of PS and H 2 O 2 are optimized at 0.75 g/L and 25.5 g/L, respectively. The kinetic study reveals that pseudo-second-order kinetic fits experimental data with a R 2 value of 0.99. The oxidation by PS and H 2 O 2 , along with ultrasound application, facilitates the removal of COD up to 84.3 % at an economically feasible treatment cost of $5.635 per kg of COD removal. Coupled process is found able to qualify dairy wastewater as dischargeable at a feasible cost of treatment.
Rubber processing industry consumes huge quantity of water, uses chemicals and produces enormous quantity of toxic wastewater with high level of chemical oxygen demand (COD), solids and turbidity. In this study, treatability of rubber processing industry effluent using a sequential coagulation-flocculation (CF) followed by sonolytic oxidation was studied with the real wastewater collected from a rubber processing industry located near to Agartala, Tripura, the second largest rubber producing state in India. Initially aluminium sulfate was used as coagulant in the CF process to reduce the COD of the wastewater followed by only ultrasonication (CF + US), sonolytic oxidation using persulfate (CF + US + PS), sonolytic oxidation using hydrogen peroxide (CF + US + H2O2) and sonolytic oxidation using both persulfate and hydrogen peroxide (CF + US + PS + H2O2) as oxidants. Real rubber processing wastewater was also treated with only sonication (US). Firstly, the only CF process (aluminium sulphate dose: 500 mg/L) could reduce the COD of wastewater from 18267 mg/L to 12800 mg/L (COD removal: 29.93 %). Thereafter, CF + US (sonication time: 30 min), CF + US + PS (PS dose: 500 mg/L), CF + US + H2O2 (H2O2 dose: 0.75 mmol/L), and CF + US + PS + H2O2 (PS dose: 500 mg/L and H2O2 dose: 0.75 mmol/L) resulted to effluent COD value to ∼ 6800 mg/L, 4200 mg/L, 3200 mg/L and ∼ 1600 mg/L, respectively. The CF + US + PS + H2O2 process was the best option among the considered combination of treatment techniques to treat the real rubber processing industry effluent in terms of COD removal (%). Kinetic analysis for the degradation of COD in various treatment processes were found to be consistent with pseudo second order kinetic model. The treatment cost analysis revealed that COD degradation by CF + US + H2O2 process cost ∼ 2.5 USD/kg of COD removal with 82.48 % of COD removal.
Over the past decade there has been an increasing concern on the presence of cytostatics (also known as anticancer drugs) in natural waterbodies. The conventional wastewater treatments seem not to be effective enough to remove them, and therefore new processes must be considered. This work investigates the performance of ozonation (O3), catalytic ozonation (O3/Fe²⁺) and peroxone (O3/H2O2) processes, under dark or UV radiation conditions, for the degradation of cytostatics of worldwide concern. The degradation of bicalutamide (a representative of recalcitrant cytostatics) was firstly assessed in batch and then in a tubular column reactor (continuous flow mode runs) using a wastewater treatment plant (WWTP) secondary effluent. Bicalutamide removal ranged between 66% (O3) and 98% (O3/H2O2/UV) in continuous flow mode runs, the peroxone process being the most effective. The performance of these processes was then assessed against a mixture of twelve cytostatics of worldwide concern spiked in the WWTP effluent (25-350 ng/L). After treatment, seven cytostatics were completely removed, whereas the five most recalcitrant ones were eliminated to an extent of 8–92% in O3/H2O2, and 44–95% in O3/H2O2/UV. Phytotoxicity tests revealed a noticeable reduction in the effluent toxicity, demonstrating the feasibility of these processes in realistic conditions as tertiary treatment.
High-performance water treatment systems based on cavitational processes have received an increasing interest of scientific community in the past few decades. Numerous studies indicated the advantageous application of hydrodynamic cavitation as an alternative, reagent-free treatment method of various pollutants in water. Both approaches were proved as an effective method to achieve mineralization of many organic contaminants as well as a disinfection method, which is able to eliminate pathogenic microorganisms. This makes cavitation-based methods a promising candidate implemented in a post-treatment stage of water treatment facilities. Nowadays, hybrid methods based on combination of cavitation with advanced oxidation processes (AOPs), possessing enhanced oxidation capacity were proposed. Compared to the individual utilization of cavitation and AOPs (e.g., O3, H2O2, Fenton’s process), hybrid processes are capable to degrade even highly persistent contaminants and shorten the operation time reducing the overall consumption of energy and oxidants. The improved performance of hybrid methods is attributed to the synergistic effect occurring between integrated technologies, which is expressed by the synergistic index. In this paper, recent reports focusing on coupling of cavitation and AOPs were reviewed to reveal major principles and mechanisms governing the synergistic effect. The review discusses the effect of process parameters (oxidant type, pH, hydraulic and ultrasonic properties, Kow) on the oxidation effectiveness. Comparative analysis was provided in order to highlight the advantages and limits laying behind the discussed methods. The analysis of the economic feasibility was performed to assess the potential applicability of hybrid techniques in large-scale wastewater treatment.
In this study, the treatment of textile industrial wastewater by Fenton and Photo-Fenton oxidation processes was investigated. For this purpose, the pH, Fe²⁺ and H2O2 concentrations with the best organic matter and color removal were determined in the Fenton process and comparison with Fenton was made by Photo-Fenton oxidation at the optimal Fe²⁺/H2O2 ratio. The influent COD and TOC values of the wastewater used in the study were 848 mg/L and 253 mg/L, respectively. With the Fenton process, the best organic matter and color removal was obtained at pH 3, at 200 mg/L Fe²⁺ and 300 mg/L H2O2 concentrations. Under these conditions, 88.9% COD, 84.2% TOC and over 97% color removal were obtained with Fenton oxidation, and 93.2% COD, 88.9% TOC and 98% color were obtained with Photo-Fenton oxidation. However, when Fe²⁺ and H2O2 amounts were reduced to 50 mg/L and 75 mg/L, both organic matter and color removal were reduced with Fenton process, while higher organic matter removal and color removal were achieved with Photo-Fenton process. The total cost was changed between 9.56-16.88 €/m³ and 13.46–20.13 €/m³ with Fenton and Photo-Fenton oxidation process for all Fe²⁺/H2O2 ratios, respectively. With the Photo-Fenton oxidation process, higher organic matter removal was obtained at optimum Fe²⁺ and H2O2 concentrations. In addition, less Fe²⁺ and H2O2 chemicals were used in Photo-Fenton oxidation process to achieve the same removal efficiency compared to the Fenton oxidation process.
In this study, CaFe2O4 nanoparticles were successfully synthesized by a chemical precipitation technique and applied in persulfate (PS) activated sono-assisted degradation of brilliant green (BG) dye from aqueous medium. Vibrating-sample magnetometer (VSM) analysis revealed that CaFe2O4 nanoparticles have manifested magnetic properties, which aided in effortless separation of nanoparticles from aqua matrix after treatment. More than 99% BG dye degradation was observed under dye concentration of 50 mg/L, catalyst dose of 0.5 g/L, PS dose of 200 mg/L and in an ultrasound (US) irradiation time of 15 min. However, US alone treatment had shown BG degradation of only 40.7% whereas the efficiency was enhanced to ∼89% upon addition of CaFe2O4 in US system. The PS activated sono-catalytic dye degradation (US+CaF+PS) process was optimized using response surface methodology (RSM) with four experimental variables, i.e., CaFe2O4 catalyst dose, PS dose, dye concentration, and sonication time. The quadratic model developed using RSM was found to be successful in optimizing the process variables (R²∼0.983). The scavenging effects observed with sodium chloride and sodium sulphate on US+CaF+PS process have reduced BG removal efficiency from 98% to 93% and 89%, respectively, which affirmed that the free radicals play the fundamental role in BG degradation. In US+CaF+PS process, BG dye (m/z ∼ 385) was degraded to simpler products having m/z ratio of 215, 113 and 73. Moreover, the microtox bioassay results indicated that the formed intermediate products were non-toxic in nature, i.e., toxicity of BG dye reduced from 90.58% to 1.24% after treatment with US+CaF+PS system. The treatment cost of BG dye solution varied between 131.85 to 922.02 USD/Kg of BG dye removed; however, the RSM based model has predicted the optimal BG dye removal of 99.57% with treatment cost of 330.82 USD/Kg of BG dye removed. Finally, the outcome of reusability study revealed that the synthesized nanoparticles were recyclable with a removal efficiency of 80.1% even after five consecutive cycles.
Sulfamethoxazole, one of the most frequently used sulfonamide antibiotics, has been frequently detected in the aquatic environment. The long-term presence of sulfamethoxazole in natural water bodies can easily lead to the development of resistant bacteria, posing a serious threat to the health and safety of aquatic organisms and humans. In this paper, the degradation of sulfamethoxazole by a combined system of ultrasound/PW12/KI/H2O2 was investigated based on advanced oxidation techniques. The effects of different factors, such as ultrasonic power, initial pH, KI concentration, H2O2 concentration, PW12 concentration and initial concentration of sulfamethoxazole, on the degradation effect were discussed. The reactive radicals in the system, the degradation products of sulfamethoxazole and the main degradation pathways were analyzed. The results indicate that the US/PW12/KI/H2O2 system is of great potential application value in removal of organic pollution and environmental purification.
The present work reports the application of cavitation for the real industrial effluent treatment, which was derived from the cellulosic fiber manufacturing sector, individually or in combination with advanced oxidation processes. Cavitation has been applied with the objective of reducing the chemical oxygen demand (COD) of the industrial effluent and to study its simultaneous effect on the total dissolved solids (TDS). A combination of cavitation with different additives/oxidants viz. hydrogen peroxide (H 2 O 2), ozone (O 3), sodium hypochlorite (NaCLO), and Fenton's reagent have been studied. Ultrasonic horn operating at an acoustic power of 120 W with a frequency of 20 kHz and duty cycle of 80% (8 sec ON, 2 sec OFF) was used for treatment based on ultrasound. Under optimized conditions, it was established that a combination of ultrasound (US) with Fenton's reagent using an optimum mole ratio of H 2 O 2 /Fe 2+ of 3 followed by lime coagulation gave a maximum COD reduction of 92% and also resulted in TDS reduction of 31%. Studies were also performed using a hydrodynamic cavitation (HC) reactor (10 L capacity) where slit venturi was used as a cavitating device. It has been observed that a combination of HC with Fenton's reagent at molar ratio of H 2 O 2 /Fe 2+ as 3 gave the maximum COD reduction of 86% and a TDS reduction of 47%. It was also established that lime treatment played an important role in separating the sludge formed during the Fenton oxidation treatment and in converting brownish colored effluent to colorless effluent. Overall, it has been established that cavitation coupled with the Fenton oxidation was most the efficient among all studied combinations giving a good COD reduction as well as TDS reduction with a final colourless nature of effluent.
The discharge of effluent from the pharmaceutical industries is a major source of environmental pollution due to the toxic and at times carcinogenic nature of contaminants. The current work investigates the treatment of pharmaceutical industry effluent (PIE) using ultrasonic horn, operated individually and in combination with oxidants. Under controlled operating conditions, the effect of addition of hydrogen peroxide (ratio of COD of PIE: H2O2 varied over the range from 1:1 to 1:10), ozone (flow rate of 400 mg/h) and Fenton’s reagent (FeSO4:H2O2 ratio of 3:5) was investigated as a possible process intensification strategy. The combined approach of ultrasound, ozone and CuO catalyst (0.3 g/L) as well as US + H2O2 + Ozone was also studied. The combined operation of US with H2O2 and Ozone resulted in a 73 % COD reduction, whereas the combination of the US, ozone and CuO catalyst gave maximum COD reduction of 92 %. The study also focused on identification of intermediate products formed during the PIE treatment. The component analysis of PIE before and after treatment was carried out by high-resolution liquid chromatography–mass spectroscopy (HR-LCMS). The research work has clearly established that cavitation in combination with other AOPs can be effectively used for the treatment of PIE with a significant increase in the extent of COD reduction for the combination approach.
Treatment of wastewater using ultrasound systems is gaining increasing interest due to its effectiveness for a wide range of pollutants and no secondary pollutants production. This paper proposes two ultrasound systems operating at different ranges of electrical power and frequency developed to remove toxic Polycyclic Aromatic Hydrocarbon (PAH) compounds in wastewater. Both light molecular weight (LMW) and high molecular weight (HMW) compounds were degraded using the developed systems. However, HMW compounds were more affected. The experimental results revealed that treatment at high power level is not always a proper approach for large reduction of PAH compounds. While treatment at higher frequencies and lower power can be a suitable alternative to enhance the PAHs removal rate and the system energy efficiency and reduce losses. Therefore, a dual mode ultrasound system with adjustable operating frequency and power is a promising approach for the treatment of industrial wastewater containing toxic PAH compounds.
Studies on the degradation of organic pollutants (phenolic, tannins etc.,) present in the wastewater released from tannery industry have been carried out in this work. The combined effect of cavitation and magnetic stirring with the advanced oxidation processes (AOPs) has been compared. The different parameters that affect the chemical oxidation process of the tannery wastewater, like pH, ultrasound irradiation time and dosage of hydrogen peroxide (H2O2) were studied. The samples were treated by two different approaches by varying these parameters. In the first approach, wastewater was treated in the presence of cavitation using ultrasound probe sonicator and in the second approach in the presence of magnetic stirring using magnetic stirrer was used. In both the cases, the suspended total organic carbon (TOC) was measured before and after varying the parameters to ensure the destruction of organic pollutants present in the wastewater sample. The optimum conditions obtained with ultrasonic cavitation was further used in hydrodynamic cavitation set-up in order to increase the efficiency. The experimental results show that the combination of cavitation and H2O2gives a higher reduction in suspended TOC values of tannery wastewater than with addition of only hydrogen peroxide (H2O2).
Coke making process is strictly connected with formation of coke oven wastewater, highly loaded and contaminated stream, proper treatment and utilization of which requires sophisticated methods and technologies. This wastewater is defined as a mixture of technological streams, which are formed during coke oven gas cleaning and coal-derivatives production, and sanitary wastewater formed at coke oven plant. Due to the composition and specificity of contaminants present in coke oven wastewater, its proper treatment requires the involvement of physical, chemical and biological methods, which are often proceeded with additional polishing. In dependence on its further use (deposition to environment or wet quenching of coke) different types of contaminants are found to be priority substances, removal of which during the stream treatment is especially important. In the article,
a literature review on coke production, coke oven wastewater formation, its parameters, applied technologies of
treatment and utilization methods is presented. The special attention was given to the applied treatment techniques,
which were found to be the key factor in further stream utilization. Additionally, issues related with nowadays
used systems were pointed out.
Article is available online at: http://tchie.uni.opole.pl/PECO17_1/PECO_2017_1_p1.pdf
NOTE: in text, capacity of coke production should be in Tg instead of Gg.
This study provides a comparison between classic and modified (i.e., ultrasound) Fenton process on the industrial textile wastewater. For this purpose, the classic, and ultrasound Fenton process were investigated and compared using the following parameters: pH of solution, amount of ferrous ion (Fe(II)), and hydrogen peroxide as well as reaction time. With these parameters, degrading organic compounds (i.e., decolorization percentage) was calculated. The best decolorization percentage (95% for Pt-Co) was found using 0.10 g L⁻¹ of Fe(II), and 2.20 g L⁻¹ of H2O2 for 90 min at pH 3 for classic Fenton process. Similar experiments were carried out using 35 kHz ultrasonic irradiation, and the best decolorization percentage (99% for Pt-Co) was obtained via 0.05 g L⁻¹ of Fe (II) and 1.65 g L⁻¹ H2O2 for 60 min at pH 3 for ultrasound Fenton process. The results showed that decolorization increased with decreasing amount of chemical for the ultrasound Fenton process. Additionally, the contact time was decreased by comparing performance with classic Fenton process. In light of these results, the ultrasound Fenton process can be used for decolorization of textile wastewater to save reaction time and chemical costs. Also, the decolorized water (e.g., treated water) may be reused in the plant for washing the textile materials after applying ion exchange process.
The presentation gives a brief introduction to coke production, coke oven wastewater formation, main contaminants and current methods of treatment as well as it shows the main assumptions of INNOWATREAT project.
In this study, treatment of an antibiotic compound amoxicillin by medium-high frequency ultrasonic irradiation and/or ozonation has been studied. Ultrasonic irradiation process was carried out in a batch reactor for aqueous amoxicillin solutions at three different frequencies (575, 861 and 1141 kHz). The applied ultrasonic power was 75 W and the diffused power was calculated as 14.6 W/L. The highest removal was achieved at 575 kHz ultrasonic frequency (>99%) with the highest pseudo first order reaction rate constant 0.04 min⁻¹ at pH 10 but the mineralization achieved was around 10%. Presence of alkalinity and humic acid species had negative effect on the removal efficiency (50% decrease). To improve the poor outcomes, ozonation had been applied with or without ultrasound. Ozone removed the amoxicillin at a rate 50 times faster than ultrasound. Moreover, due to the synergistic effect, coupling of ozone and ultrasound gave rise to rate constant of 2.5 min⁻¹ (625 times higher than ultrasound). In the processes where ozone was used, humic acid did not show any significant effect because the rate constant was so high that ozone has easily overcome the scavenging effects of natural water constituents. Furthermore, the intermediate compounds, after the incomplete oxidation mechanisms, has been analyzed to reveal the possible degradation pathways of amoxicillin through ultrasonic irradiation and ozonation applications. The outcomes of the intermediate compounds experiments and the toxicity was investigated to give a clear explanation about the safety of the resulting solution. The relevance of all the results concluded that hybrid advanced oxidation system was the best option for amoxicillin removal.
The use of hybrid Advanced Oxidation Processes (AOPs) for the removal of pollutants from industrial effluents has been extensively studied in recent literature. The aim of this study is to compare the performance of the photo, Fenton, photo-Fenton and ozone-photo-Fenton processes in terms of color removal and chemical oxygen demand (COD) removal of distillery industrial effluent together with the associated electrical energy per order. It was observed from the experimental results that the O3/UV/Fe2 +/H2O2 process yielded a 100% color and 95.50% COD removals with electrical energy per order of 0.015 kW·h/m³ compared to all other combinations of the AOPs. The effects of various operating parameters such as H2O2 and Fe2 + concentration, effluent pH, COD concentration and UV power on the removal of color, COD and electrical energy per order for the ozone-photo-Fenton process was critically studied and reported. The color and COD removals were analyzed using a UV/Vis Spectrometer and closed reflux method.
TiO2/Montmorillonite (TiO2/MMT) nanocomposite as sonocatalyst was produced by immobilizing synthesized TiO2 on the surface of montmorillonite. The characteristics of produced nanocomposite were investigated using XRD, XRF, FTIR, TEM, SEM, EDX, UV–vis DRS and nitrogen adsorption-desorption analyses. The synthesized TiO2 and TiO2/MMT samples were applied as catalysts for sonocatalytic degradation of ciprofloxacin (CIP). The performance of the TiO2/MMT was greater than pure TiO2 sample in treatment of CIP solution. The degradation efficiency of the CIP by sonocatalytic process was affected by solution pH, catalyst dosage, initial CIP concentrations and ultrasonic power. Degradation efficiency of 65.01% was obtained at the pH of 6, catalyst dosage of 0.2 g L⁻¹, initial CIP concentration of 10 mg L⁻¹ and ultrasonic power of 650 W L⁻¹. It was observed that the presence of inorganic and organic scavengers suppressed the performance of sonocatalytic process. The stability of the nanocomposite was studied in several successive experiments, and the degradation efficiency declined only 61.48% after 4 repeated experiments. The main degradation by-products were recognized by GC–MS method to propose the possible sonocatalytic mechanism for the degradation of CIP.
In this study, the removal of color and COD from landfill leachate, together with the electrical energy per order by the ozonation (O3), sonication (US), O3/H2O2, US/H2O2, O3/Fe²⁺/H2O2, US/Fe²⁺/H2O2 and O3/US/Fe²⁺/H2O2 processes was studied. The experimental results indicated that the color removal, COD removal and electrical energy per order from the landfill leachate were 100%, 95%, and 1.20 kW h/m³, respectively, at the optimum operating conditions. The obtained values were much higher than that obtained in the O3 and US based advanced oxidation processes. The effects of various experimental parameters such as Fe²⁺ concentration, H2O2 concentration, solution pH, COD concentration, ozone production and sonication power were studied to identify the optimum conditions leading to maximum removal of color and COD with minimum electrical energy per order by the O3/US/Fe²⁺/H2O2 process. The synergy index between the O3 and US/Fe²⁺/H2O2 processes was studied and reported. The results indicated that the combination of O3 and US based advanced oxidation processes could effectively treat the industrial effluents and wastewater.
Wastewater generated from coke oven industries contains highly toxic organic and inorganic compounds. In the present study, biological reactors were integrated in sequence of anaerobic-aerobic-anoxic and tested with real coke oven wastewater obtained from a Steel Plant located in India. Among several pretreatment methods, coagulation of raw CWW was found to be effective.COD removal efficiency of 78.5% was achieved by the integrated bioreactor system after coagulation of CWW with 1000 mg/L of alum. The effluent COD, NH4-N and TCN concentration from the integrated bioreactors was 420, 152 and 20 mg/L, respectively. It was observed that 420 mg/L of COD present in the effluent after integrated bio treatment was degraded in less than 4 h to minimum COD concentration of 94 mg/L using UV-TiO2photocatalysis. In absence of photocatalyst (TiO2), there was no COD reduction from the bio treated effluent. Similarly, there was insignificant reduction in COD from the raw CWW using photocatalysis without biological treatment. Considerable COD reduction (78.5%) was observed only in the wastewater subjected to integrated biological system. The overall COD removal efficiency of the combined treatment system was found to be 96.2%, which resulted in an effluent COD concentration less than 94 mg/L.
The investigations of the ultrasonic decomposition of NH3‐N and organic compounds (i.e., CODCr) in coke plant wastewater are presented in this work. The process parameters were controlled with respect to the presence (or absence) of air atmosphere, initial pH value, initial concentration, and ultrasonic power density in the process of ultrasonic decomposition. It is noted that the ultrasonic removal efficiencies for both the NH3‐N and the CODCr were increased in the presence of the air atmosphere and significantly affected by the initial pH value. The removal efficiencies increased with increasing the ultrasonic power density while they decreased with increasing the initial concentration. The effects of n‐butyl alcohol as an effective OH radical scavenger on the removal efficiencies indicates that the ultrasonic decomposition of the NH3‐N was carried out mainly via the mechanism of thermal decomposition in cavitation bubbles or in the interfacial region, whereas the ultrasonic decomposition of the CODCr mainly resulted from the reactions with OH radicals in the bulk solution. The GC/MS analysis indicates that most of the organic compounds in the wastewater were effectively destroyed by ultrasound.
The aim of this study was to determine the most efficient method of coke wastewater treatment. This research examined two processes - advanced oxidation with Fenton and photo-Fenton reaction. It was observed that the use of ultraviolet radiation with Fenton process had a better result in removal of impurities.