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•Application of hydrodynamic and acoustic cavitation to oxidation of organic pollutants.•Design of cavitation devices for effluent treatment.•Comparison of efficiency of oxidation of ...organic pollutants in the cavitation processes.
Hydrodynamic and acoustic cavitation combined with advanced oxidation processes (AOPs), including, among others, the Fenton process, is a promising alternative to the technologies of wastewater treatment technologies in use today. The present review discusses processes based on cavitation combined with AOPs and evaluates their effectiveness in oxidation of organic contaminants. Complete degradation of, among others, p-nitrotoluene, p-aminophenol, 1,4-dioxane, alachlor, chloroform, trichloroethylene, sodium pentachlorophenate and carbon tetrachloride was achieved by using hydrodynamic cavitation or acoustic cavitation alone. Cavitation is also an effective method of disinfection of water. Complete oxidation of hardly degradable organic contaminants, including pharmaceuticals, organic dyes, insecticides, phenol and its derivatives was observed when using hybrid processes: hydrodynamic or acoustic cavitation combined with the Fenton process, ozonation, hydrogen peroxide, UV irradiation, catalysts and persulfates. The review also discusses the cavitational reactors used in the wastewater treatment and the effect of process parameters (including pH, temperature, concentration and kind of contaminants) on the effectiveness of oxidation. The oxidation effectiveness for individual treatment methods is compared and their advantages and limitations discussed. The analysis of economics of the treatment processes performed to evaluate the possibility of scaling up reveals that the only economical processes should be based on hydrodynamic cavitation (mainly due to low cost of reactors and low consumption of electrical energy compared with ultrasonic reactors).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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•The MNZ removal efficiency in UV/PDS was superior to that in UV/H2O2 and UV/chlorine.•Impacts of various water matrix constituents were investigated in three UV-AOPs.•The ...concentrations and contributions of radicals in MNZ removal were evaluated in three UV-AOPs.•HO was conducive to attack MNZ via HAT and RAF, while SO4− and Cl oxidation favored RAF.•UV/PDS consumed less electrical energy than UV/H2O2 and UV/chlorine in various water matrixes.
Metronidazole (MNZ) is widely employed as an antibiotic, but it is recalcitrant in the water environment. The residual of MNZ has sparked significant concern because to its detrimental impacts on environmental safety and human health. In this study, the elimination of metronidazole (MNZ) was comparatively examined by UV/hydrogen peroxide (UV/H2O2), UV/peroxydisulfate (UV/PDS), and UV/chlorine processes. The best degradation rate constant was demonstrated by the UV/PDS (2.4 × 10−3 s−1), followed by UV/H2O2 AOP (1.0 × 10−3 s−1) and UV/chlorine AOP (3.7 × 10−4 s−1). The hydroxyl radicals (HO) played significant roles in UV-AOPs eliminating MNZ by 87.7 %, 30.2 %, and 43.0 % in UV/H2O2, UV/PDS, and UV/chlorine treatments, respectively. Additionally, the sulfate radical (SO4−) and chlorine radical (Cl) were essential for the elimination of MNZ, contributing 63.0 % and 36.2 %, respectively, in UV/PDS and UV/chlorine. The first-order rate constants (kobs) increase linearly with the increasing oxidant dosage in various UV-AOPs. The higher degradation efficiency of MNZ was observed in acid conditions due to the transition of oxygen active species. The presence of chloride (Cl−), bicarbonate (HCO3–), nitrate (NO3–), and humid acid (HA) remarkably inhabited the degradation of MNZ in UV/H2O2 and UV/PDS, whereas NO3– showed a promotion effect in UV/chlorine. In diverse water matrixes, UV/PDS usually consumed less electrical energy than UV/H2O2 and UV/chlorine. Combining density functional theory calculations and transformation products identification, it was revealed that HO was conducive to attack the nitrogenous heterocycle of MNZ via hydrogen atom transfer (HAT) and radical adduct formation (RAF) pathways, whereas SO4− and Cl oxidation favored RAF route. Some chlorine- and hydroxylation-intermediates, notably those produced in UV/chlorine AOP, displayed higher toxicity than the parent compounds. Overall, the findings unequivocally prove that UV-AOPs are effective, economical, and practical for the remediation of antibiotics-contaminated water.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Agro-industrial wastewater management becomes a major task while environmental regulations are becoming stricter worldwide. Agro-industrial wastewaters are known by high content of organic pollutants ...that cause an adverse effect on the water bodies. Industries are looking for efficient, easy-to-use and affordable treatment processes. Sulfate radical based advanced oxidation processes (S-AOPs) are arising as suitable alternatives for agro-industrial effluents treatment. In this review, the major findings regarding the application of this technology for real agro-industrial wastewater depuration are discussed. Moreover, these technologies are compared as an alternative to Fenton's process, which is a widely studied advanced oxidation process and with high efficiency in the treatment of agro-industrial effluents. The studies already carried out are promising, but there is still a great lack of studies in this area and using this technique.
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•Can SRbAOP be an alternative to the Fenton process for wastewater treatment?•SRbAOP are arising as suitable alternatives for agro-industrial effluents treatment.•SRbAOP have similar efficiency to Fenton’s for POME and OMW effluents depuration.•By-products toxicity must be accounted when developing new oxidation technologies.•Pilot-studies are required to understand and optimize SRbAOP technologies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•A new UV/H2O2 reactor was designed using impinging jet atomization.•Impinging jet atomization was applied to form thin liquid sheets and achieve highly efficient mixing.•Re number ...and impingement angle could be used for conceptual design of large scale reactors.•Complete removal of 50 mg L−1 methyl orange dye solution was obtained within 120 min.
The concept of augmenting UV/H2O2 reactor with impinging jet atomization to achieve highly efficient mixing and thin fluid sheet formation capability was investigated. The collision of two jets forming a free-standing thin liquid sheet allowed the establishment of an effective UV/ H2O2 advanced oxidation setting. The response surface methodology (RSM) was applied to model and optimize the photochemical degradation process, which provides three level designs for RSM fitting. Three variables namely, Re (15000–31000), impingement angle (60–120 degree) and H2O2 dosage (1000−3000 mg L-1) were applied in BBD to model and optimize the effects of three key operational parameters. The optimum methyl orange (MO) removal percentage (after 90 min) and the apparent first order rate constant were 93.6% and 2.438 min-1, respectively. The influences of initial dye concentration, UV radiation power, and jet diameter were also investigated as the other main operating parameters. ANOVA analysis indicated that the Re number has the highest impact of the three considered parameters and additional experiments showed that the jet diameter does not have any significant effect on MO degradation. A pseudo-first-order kinetic model was applied for the prediction of contaminant degradation and rate coefficients. The good agreements between the model predictions and experimental results indicate that the proposed model could successfully describe the effectiveness of the augmented UV/H2O2 reactor due to the maximum degradation of the model contaminant.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Two things are needed for any technology to be suitable for use in the industry, viz. 1. Technical feasibility and 2. Economical feasibility. The use of ultrasound for waste water treatment has been ...shown to be technically feasible by numerous reports in the literature over the years. But there are hardly any exhaustive reports which address the issue of economical feasibility of the use of ultrasound for waste water treatment on industrial scale.
Hence an attempt was made to estimate the cost for the waste water treatment using ultrasound. The costs have been calculated for 1000
L/min capacity treatment plant. The costs were calculated based upon the rate constants for pollutant degradation. The pollutants considered were phenol, trichloroethylene (TCE) and reactive azo dyes. Time required for ninety percent degradation of pollutant was taken as the residence time. The amount of energy required to achieve the target degradation was calculated from the energy density (watt/ml) used in the treatability study. The cost of treatment was calculated by considering capital cost and operating cost involved for the waste water treatment. Quotations were invited from vendors to ascertain the capital cost of equipments involved and operating costs were calculated based on annual energy usage. The cost was expressed in dollars per 1000
gallons of waste water treated. These treatment costs were compared with other established Advanced Oxidation Process (AOP) technologies. The cost of waste water treatment for phenol was in the range of $89 per 1000
gallons for UV/US/O
3 to $15,536 per 1000
gallons for US alone. These costs for TCE were in the range of $25 per 1000
gallons to $91 for US
+
UV treatment and US alone, respectively. The cost of waste water treatment for reactive azo dyes was in the range of $65 per 1000
gallon for US
+
UV
+
H
2O
2 to $14,203 per 1000
gallon for US alone.
This study should help in quantifying the economics of waste water treatment using ultrasound on industrial scale. We strongly believe that this study will immensely help the researchers working in the area of applications of ultrasound for waste water treatment in terms of where the technology stands today as compared to other available commercial AOP technologies. This will also help them think for different ways to improve the efficiency of using ultrasound or search for other ways of generating cavitation which may be more efficient and help reduce the cost of treatment in future.
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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.
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Sludge derived carbon (SC) has been widely used in advanced oxidation processes as an effective and economic catalyst. In this study, we applied surface modified SC for the first time ...to catalyze the heterogeneous photo-Fenton process with ciprofloxacin, a highly concerned emerging contaminant, as a model substance. H2SO4 was used to acidify the SCs under varying acid dosages, temperatures, and reaction time lengths. The surface acidity of SCs was quantitatively characterized with NH3-TPD. A strong correlation between the surface acidity and the catalytic activity was clearly demonstrated. The highest catalytic activity was obtained with SC whose acidity was 0.149 mmol·g−1 after being modified with 6 mol·L−1 H2SO4 at −20 ℃ for 24 h. In addition, XRD, XRF, BET, XPS, and HRTEM were also used to characterize the obtained SC. ·OH radicals were found to be the main reactive species by EPR. Ten transformation products were identified by GC–MS, based on which three possible reaction pathways were proposed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Objectives:In this study, through the results of the high-concentration 2-MIB (2-Methyl Isoborneol) treatment by two different types of advanced treatment plants (Post Peroxone+GAC, UV/H2O2+GAC F/A) ...which intake raw water from the same water intake facility, the 2-MIB removal characteristics by oxidation process of each WTPs (Water Treatment Plants) were compared and analyzed, and optimal operation methods were derived.Methods:The 2-MIB removal rate was compared and analyzed according to each AOP (Advanced Oxidation Process) operating conditions (Post Peroxone+GAC of the G WTP and UV/H2O2+GAC F/A of the I WTP). The optimal equations of chemical injection were derived through the correlation between the operating conditions of the AOP for each WTPs and 2-MIB removal rate. By analyzing the operating characteristics of each WTPs, the cost and unit price for optimal operation were calculated according to the 2-MIB concentration of raw water and water production. Optimal operating conditions were derived through the performance of oxidation facilities and chemical injection equations of each WTPs, and economical operating plans were reviewed through linked operation of 2 WTPs.Results and Discussion:The 2-MIB removal rates for each WTPs were 70~100% for the G WTP and 50~96% for the I WTP. The operating conditions affecting the 2-MIB removal were O3 injection×contact time, H2O2/O3 for Post Peroxone of the G WTP, and UV dose×H2O2 injection for UV/H2O2 of the I WTP. As a result of comparing the operating cost(electric power cost + chemical cost) of each WTPs, I WTP was 6.6~24.3 KRW/m3 higher than G WTP. It is considered to be because the H2O2 injection was 11~43 times for UV/H2O2 than Post Peroxone. Optimal operating conditions could be derived through the performance evaluation of each oxidation facilities and chemical injection equations of each WTPs. The G WTP and the I WTP are equipped with pipe line for linked operation in the water supply pipes, so the water production for each WTPs can be distributed. In the case of the same water production, it was confirmed that the unit price can be reduced when the water production ratio of the G WTP is increased. Because the decrease in cost of the I WTP is higher than the increase in cost of the G WTP.Conclusions:It was confirmed that both Post Peroxone+GAC of G WTP and UV/H2O2+GAC F/A of I WTP were effective in 2-MIB treatment. As for the operating cost, it was analyzed that UV/H2O2 had higher unit pice than Post Peroxone because of the large amount of H2O2 injection. Considering the 2-MIB removal rate and operating cost of each WTPs, it was possible to derive the optimal operating conditions for each WTPs and a linked operation plan.
In this study, UV based treatments were implemented at pilot scale to assess their ability to remove hormones from treated wastewater, especially with the view to equip small and medium size ...Wastewater Treatment Plants (WTPs). To this end, the degradation of a mixture of estrogenic hormones (Estrone (E1), β-Estradiol (E2), and 17α-Ethinyl Estradiol (EE2)) in waters by UV photolysis and UV/H2O2 process was investigated in real conditions. A particular attention was paid at designing a well validated laboratory scale pilot in order to optimise oxidant concentrations and UV fluence. A Low pressure lamp (254 nm) was used in a flow through commercial reactor. The effects of water matrices (drinking water and treated wastewater) and H2O2 concentrations (10, 40, and 90 mg/L) on the pilot efficiency were first determined. Only E1 could be partially degraded by UV photolysis whereas hormones were all well removed by UV/H2O2 process in both matrices. The second part of the study focused on a chemical and biological assessment of UV photolysis and UV/H2O2 process (30 and 50 mg/L). Degradation rate constants of hormones as well as changes in estrogenic activity (YES bioassay) and toxicity (Vibrio fischeri) were followed at the same time. UV photolysis could not remove neither estrogens nor estrogenic activity at relevant UV fluence in waters. However 80% of initial estrogenic compounds and estrogenic activity could be removed from treated wastewater by combining UV fluence of 423 and 520 mJ/cm(2) with 50 and 30 mg/L of H2O2, respectively. No high estrogenic or toxic by-products were detected by the two bioassays following UV photolysis or UV/H2O2 process. Operating costs were estimated for a full scale pilot. H2O2 was the major cost. By combining the appropriate concentration of H2O2 and UV fluence, it could be possible to design a cost effective treatment for treating estrogens in small and medium size WTPs
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