Advanced Oxidation Techniques Research Articles

Plasma-Catalytic Mineralization of Toluene Adsorbed on CeO2

In the context of coupling nonthermal plasmas with catalytic materials, CeO2 is used as adsorbent for toluene and combined with plasma for toluene oxidation. Two configurations are addressed for the regeneration of toluene saturated CeO2: (i) in plasma-catalysis (IPC); and (ii) post plasma-catalysis (PPC). As an advanced oxidation technique, the performances of toluene mineralization by the plasma-catalytic systems are evaluated and compared through the formation of CO2. First, the adsorption of 100 ppm of toluene onto CeO2 is characterized in detail. Total, reversible and irreversible adsorbed fractions are quantified. Specific attention is paid to the influence of relative humidity (RH): (i) on the adsorption of toluene on CeO2; and (ii) on the formation of ozone in IPC and PPC reactors. Then, the mineralization yield and the mineralization efficiency of adsorbed toluene are defined and investigated as a function of the specific input energy (SIE). Under these conditions, IPC and PPC reactors are compared. Interestingly, the highest mineralization yield and efficiency are achieved using the in-situ configuration operated with the lowest SIE, that is, lean conditions of ozone. Based on these results, the specific impact of RH on the IPC treatment of toluene adsorbed on CeO2 is addressed. Taking into account the impact of RH on toluene adsorption and ozone production, it is evidenced that the mineralization of toluene adsorbed on CeO2 is directly controlled by the amount of ozone produced by the discharge and decomposed on the surface of the coupling material. Results highlight the key role of ozone in the mineralization process and the possible detrimental effect of moisture.

Combining ozone with UV and H2O2 for the degradation of micropollutants from different origins: lab-scale analysis and optimization

ABSTRACT The degradation of micropollutants (MPs), including pesticides, herbicides, pharmaceuticals and endocrine disrupting compounds, by ozone-based advanced oxidation techniques (AOP) was investigated in this study. The effect of different factors, such as ozone concentration, hydrogen peroxide concentration and initial pH, on the removal rate was studied in detail. The combination of UV with ozone/ H2O2 increased the MPs degradation. For example, atrazine removal increased from 12.6% to 66.9%. Increasing the concentration of ozone and H2O2 can enhance the degradation efficiency of MPs, while excess H2O2 plays a role as a scavenger for •OH. In addition, the optimizing conditions of degradation of MPs by an ozone-based AOP were investigated in this study. The optimal dosages of ozone for atrazine (ATZ), alachlor (ALA), carbamazepine (CBZ), 17-α-ethinylestradiol (EE2) and pentachlorophenol (PCP), were in the range of 0.6–0.75, while for ATZ a much higher dosage (5.4 mg/l) is needed. The optimal dosages of H2O2 concentration were at 0.75, 0.2, 0.47, 0.75 and 0.63 mM, and pH were at 10, 10, 7, 10 and 10, and reaction time at 38.5, 33.5 43, 6 and 6 min, respectively. Ozone-based AOP and in particular combination of UV with ozone and H2O2 is efficient to degrade atrazine, alachlor, carbamazepine, 17-α-ethinylestradiol and pentachlorophenol, and is attractive for future application of real wastewater treatment.

Removing volatile organic compounds in cooking fume by nano-sized TiO2 photocatalytic reaction combined with ozone oxidation technique

Chinese cooking fume is one of the sources of volatile organic compounds (VOCs) in the air. An innovative control technology combining photocatalytic degradation and ozone oxidation (UV/TiO2+O3) was developed to decompose VOCs in the cooking fume. Fiberglass filter (FGF) coated with TiO2 was prepared by an impregnation procedure. A continuous-flow reaction system was self-designed by combining photocatalysis with advanced ozone oxidation technique. By passing the simulated cooking fume through the FGF, the VOC decomposition efficiency in the cooking fume could be increased by about 10%. The decomposition efficiency of VOCs in the cooking fume increased and then decreased with the inlet VOC concentration. A maximum VOC decomposition efficiency of 64% was obtained at 100 ppm. Similar trend was observed for reaction temperature with the VOC decomposition efficiencies ranging from 64 to 68%. Moreover, inlet ozone concentration had a positive effect on the decomposition of VOCs in the cooking fume for inlet ozone≤1000 ppm and leveled off for inlet ozone>1000 ppm. 34% of VOC decomposition efficiency was achieved solely by ozone oxidation with or without near-UV irradiation. A maximum of 75% and 94% VOC decomposition efficiency could be achieved by O3+UV/TiO2 and UV/TiO2+O3 techniques, respectively. The maximum decomposition efficiencies of VOCs decreased to 79% for using UV/TiO2+O3 technique with adding water in the oil fume. Comparing the chromatographical species of VOCs in the oil fume before and after the decomposition of VOCs by using UV/TiO2+O3technique, we found that both TVOC and VOC species in the oil fume were effectively decomposed.

Applicability evaluation of advanced processes for elimination of neurophysiological activity of antidepressant fluoxetine

Presence of the antidepressant fluoxetine in different water bodies has raised significant concerns due to its detrimental effects on non-targeted organisms, especially on fish. When seeking for an appropriate technology able to remove fluoxetine residue from a complex water matrix, special attention needs to be paid to the elimination of the neurophysiological activity that eventually lies behind the noxious effects of the parent compound. Our aim was to probe the applicability of advanced oxidation techniques for this purpose using in situ generated free radical system based on OH-initiated peroxyl radical-mediated processes. By performing product analysis experiments along with quantum chemical calculations, the most probable reaction paths were analyzed including aromatic hydroxylation, defluorination, O-dealkylation and C-dealkylation. The candidates for neurophysiological activity were further investigated by molecular docking. The hydroxylated derivatives are well accommodated in the binding pocket of the corresponding protein, suggesting that these compounds may retain the activity of the parent compound. From a worst-case perspective, we suggest that prolonged treatment needs to be applied to further transform hydroxylated derivatives.

Novel water-purification hybrid processes involving in-situ regenerated activated carbon, membrane separation and advanced oxidation

The reported pilot-scale development of hybrid process alternatives, combines in-situ regenerated powdered activated carbon (PAC), H2O2-based advanced oxidation techniques and membrane ultrafiltration (UF). Commercial PAC and special iron-impregnated PAC (PAC-Fe) were used as adsorbents, whereas diclofenac (DCF), a commonly detected pharmaceutical in water-sources, was employed as representative micro-pollutant. For PAC regeneration, modest on-line H2O2 dosage was adopted, alone or in combination with UV-C irradiation. Large DCF uptake was measured for both PAC (154.5mg/g) and PAC-Fe (116.7mg/g), while the regeneration efficiencies achieved with the photo-assisted H2O2 processes were much greater (122.2% and 131.6% for H2O2+UVC and photo-Fenton, respectively) than those obtained with H2O2 alone (70% and 77.6% for H2O2 and Fenton, respectively). For PAC-Fe, enhanced recovery of adsorption capacity suggests occurrence of heterogeneous Fenton-like reactions on iron-oxide particle surfaces leading to generation of OH and other reactive species by H2O2-decomposition.The catalytic adsorbent (PAC-Fe) retained its stability and activity after three operating cycles, which would significantly reduce operating cost in practical applications. Considering the rather short regeneration-time of present tests (180min) and the nearly basic pH of feed solutions, the novel processes investigated herein, involving PAC regeneration in the same equipment employed for water purification, hold distinct advantages over conventional methods.

Study of the Efficiency of Proxone Method as Advanced Oxidation Process to Remove 4-Chlorophenol from Aqueous Solution

Introduction: 4-chlorophenol is one of the common contaminants in wastewater resulted from chemical and petrochemical industries. This matter is resistant to biodegradation due to presence of chlorine and benzene ring in its structure. Various methods have been used to remove this contaminant from environment but the advanced oxidation techniques are more capable. In this study, proxone method (hydrogen peroxide plus ozone) was investigated to remove, 4-chlorophenol. Materials & methods: This study is experimental and some parameters including pH, 4-chlorophenol initial concentrations, contact time, and the concentrations of oxidant (H2O2) during proxone process were investigated to remove 4-chlorophenol. All tests were conducted on actual solution (effluent of coal cleaning plant). Microsoft Office Excel 2013 software and SPSS 15 were used for data analysis. Findings: The maximum removal efficiency of 4-chlorophenol at optimum condition (including pH=9, contact time=30 minutes, ozone concentration=0.09 g/hr, the initial concentration of 4-chlorophenol=100 ppm, the optimum concentration of H2O2=0.001 molar) were achieved 96.8% and 92.65% for synthetic and actual solution, respectively. Discussion & conclusions: Advanced oxidation, according to Peroxone method is a suitable way to remove 4-chlorophenol and is able to remove this material from actual wastewater with efficiency of 92.65%. So, this method can be used for water purification and contaminated wastewater with this pollutant.

Sono-photo-Fenton oxidation of bisphenol-A over a LaFeO3 perovskite catalyst

In this study, oxidation of bisphenol-A (IUPAC name – 2,2-(4,4-dihydroxyphenyl, BPA), which is an endocrine disrupting phenolic compound used in the polycarbonate plastic and epoxy resin industry, was investigated using sono-photo-Fenton process under visible light irradiation in the presence of an iron containing perovskite catalyst, LaFeO3. The catalyst prepared by sol–gel method, calcined at 500°C showed a catalytic activity in BPA oxidation using sono-photo-Fenton process with a degradation degree and a chemical oxygen demand (COD) reduction of 21.8% and 11.2%, respectively. Degradation of BPA was studied by using individual and combined advanced oxidation techniques including sonication, heterogeneous Fenton reaction and photo oxidation over this catalyst to understand the effect of each process on degradation of BPA. It was seen, the role of sonication was very important in hybrid sono-photo-Fenton process due to the pyrolysis and sonoluminescence effects caused by ultrasonic irradiation. The prepared LaFeO3 perovskite catalyst was a good sonocatalyst rather than a photocatalyst. Sonication was not only the effective process to degrade BPA but also it was the cost effective process in terms of energy consumption. The studies show that the energy consumption is lower in the sono-Fenton process than those in the photo-Fenton and sono-photo- Fenton processes.

WITHDRAWN: Removal of microcystins in water by ultrasound coupled advanced oxidation techniques

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Pharmaceuticals, benzene, toluene and chlorobenzene removal from contaminated groundwater by combined UV/H2O2 photo-oxidation and aeration

This study was performed to test the feasibility of several decontamination methods for remediating heavily contaminated groundwater in a real contaminated locality in the Czech Republic, where a pharmaceuticals plant has been in operation for more than 80 years. The site is polluted mainly by recalcitrant psychopharmaceuticals and monoaromatic hydrocarbons, such as benzene, toluene and chlorobenzene. For this purpose, an advanced oxidation technique employing UV radiation with hydrogen peroxide dosing was employed, in combination with simple aeration pretreatment. The results showed that UV/H2O2 was an efficient and necessary step for degradation of the pharmaceuticals; however, the monoaromatics were already removed during the aeration step. Characterization of the removal mechanisms participating in the aeration revealed that volatilization, co-precipitation and biodegradation contributed to the process. These findings were supported by bacterial metabolite analyses, phospholipid fatty acid analysis, qPCR of representatives of the degradative genes and detailed characterization of the formed precipitate using Mössbauer spectroscopy and scanning electron microscopy. Further tests were carried out in a continuous arrangement directly connected to the wells already present in the locality. The results documented the feasibility of combination of the photo-reactor employing UV/H2O2 together with aeration pretreatment for 4 months, where the overall decontamination efficiency ranged from 72% to 99% of the pharmaceuticals. We recorded even better results for the monoaromatics decontamination except for one month, when we encountered some technical problems with the aeration pump. This demonstrated the necessity of using the aeration step.

Treatment of aquaculture wastewater contaminated with metronidazole by advanced oxidation techniques

This work analyses the treatment of ornamental aquaculture wastewater contaminated with the antibiotic metronidazole (MTZ) using a reactor with supported TiO2. Preliminary photolysis and hydrolysis studies revealed inefficient elimination of this pollutant under the study conditions.The activity of various photocatalysts in suspension in the elimination of 40 mg·L−1 of MTZ was studied, as well as the degradation performance in different aqueous matrices using UV-A radiation. Process efficiency was strongly and negatively affected by the presence of ions in solution, with a 20% decrease in mineralization. The highest reaction rates was observed with the Evonik-P90 (0.0625min−1) versus Hombikat (0.0078min−1).A number of configurations were evaluated to optimise the performance of the reactor with immobilized catalyst in MTZ degradation. Different types of illumination (UV-A and UV-C) were tested as well as the positions of both lamp and catalyst inside the reactor. Various configurations were able to completely eliminate 10 mg·L−1 of MTZ. A greater efficiency was observed in general in the degradation processes with the catalyst immobilized on the outer tube with the internal UV-C lamp (kE.UVC; 0.042min−1), compared UV-A lamp (kE.UVA; 0.022min−1). The best configuration was catalyst immobilized on the outer with the internal UV-C lamp and hydrogen peroxide (k E.UVC*; 0.055min−1).The deposited catalyst was also successfully subjected to continuous re-runs using the optimised configuration with no catalyst deactivation observed. Despite a decrease in photocatalytic activity of 24% after the sixth re-run, 100% MTZ elimination was still achieved. The degradation pathway of metronidazole using TiO2 photocatalysis has also been proposed and detoxification of the samples after the photocatalytic treatment was evaluated using V. fischeri bacteria test.

Decolorization of brilliant green dye using immersed lamp sonophotocatalytic reactor

The textile and dye industries require an enormous amount of water for processing and produce a large volume of wastewater. Generated wastewater had potential hazards and a threat to the aquatic biota. The present work investigates the decolorization of brilliant green dye using a combination of two advanced oxidation techniques viz sonocatalysis and photocatalysis (immersed lamp) known as sonophotocatalysis (3 L capacity). The efficiency of decolorization is further improved in the presence of various additives viz. copper oxide, zinc oxide, and sodium chloride. The maximum decolorization of brilliant green (BG) (94.8% in 120 min) obtained in the presence of zinc oxide. The total organic carbon of the treated samples was measured to monitor complete mineralization of BG. The sonophotocatalytic process (in the presence of zinc oxide) shows maximum mineralization. Synergic combination of two oxidation processes increased the production of oxidizing radicals. Continuous cleaning of catalyst surface (due to sonolysis effect) improves the activity of the catalyst for photolysis operation. The present work is highly useful for the development of a sonophotocatalytic process.

Novel approaches based on ultrasound for treatment of wastewater containing potassium ferrocyanide

Industrial wastewaters containing biorefractory compounds like cyanide offer significant environmental problems attributed to the fact that the conventional methods have limited effectiveness and hence developing efficient treatment approaches is an important requirement. The present work investigates the use of novel treatment approach of ultrasound (US) combined with advanced oxidation techniques for the degradation of potassium ferrocyanide (KFC) for the first time. An ultrasonic bath equipped with longitudinal horn (1kW rated power and 25kHz frequency) has been used. The effect of initial pH (2–9) on the progress of degradation has been investigated initially and subsequently using the optimized pH, effect of addition of hydrogen peroxide (ratio of KFC:H2O2 varied over the range of 1:0.5–1:5) and TiO2 in the presence of H2O2 (1:1 ratio by weight of TiO2) as process intensifying approach has been studied. Combination of ultrasonic irradiation with ozone (O3) (100–400mg/h) and ultraviolet irradiation (UV) has also been investigated. Use of combination of US with H2O2, H2O2+TiO2 and ozone resulted in extent of KFC degradation as 54.2%, 74.82% and 82.41% respectively. Combination of US with both UV and ozone was established to be the best approach yielding 92.47% degradation. The study also focused on establishing kinetic rate constants for all the treatment approaches which revealed that all the approaches followed first order kinetic mechanism with higher rate constants for the combination approaches. Overall, it has been conclusively established that ultrasound based combined treatment schemes are very effective for the treatment of KFC containing wastewaters.

Removal of several pesticides in a falling water film DBD reactor with activated carbon textile: Energy efficiency

Bio-recalcitrant micropollutants are often insufficiently removed by modern wastewater treatment plants to meet the future demands worldwide. Therefore, several advanced oxidation techniques, including cold plasma technology, are being investigated as effective complementary water treatment methods. In order to permit industrial implementation, energy demand of these techniques needs to be minimized. To this end, we have developed an electrical discharge reactor where water treatment by dielectric barrier discharge (DBD) is combined with adsorption on activated carbon textile and additional ozonation. The reactor consists of a DBD plasma chamber, including the adsorptive textile, and an ozonation chamber, where the DBD generated plasma gas is bubbled. In the present paper, this reactor is further characterized and optimized in terms of its energy efficiency for removal of the five pesticides α-HCH, pentachlorobenzene, alachlor, diuron and isoproturon, with initial concentrations ranging between 22 and 430 μg/L. Energy efficiency of the reactor is found to increase significantly when initial micropollutant concentration is decreased, when duty cycle is decreased and when oxygen is used as feed gas as compared to air and argon. Overall reactor performance is improved as well by making it work in single-pass operation, where water is flowing through the system only once. The results are explained with insights found in literature and practical implications are discussed. For the used operational conditions and settings, α-HCH is the most persistent pesticide in the reactor, with a minimal achieved electrical energy per order of 8 kWh/m3, while a most efficient removal of 3 kWh/m3 or lower was reached for the four other pesticides.

Degradation of Vancomycin Hydrochloride by Electrooxidation

Many pharmaceuticals are considered recalcitrant pollutants and represent a problem for human and animal health due to continuous contribution in the aquatic environment and the bacteria resistance development to antibiotics. Vancomycin is one of the most antibiotics administered in medicine, nevertheless, there is not much knowledge about the presence, fate and the effects of Vancomycin in the environment. The advanced oxidation techniques (AOTs) are shown as alternatives for the treatment of water and wastewater in order to degrade pollutants and contaminants. Therefore, this work is aimed to evaluate the Vancomycin degradation in an aqueous medium using electrooxidation (EO) technique and to optimize the reaction conditions. The experiments were conducted in a homemade electrochemical cell in acrylic with a working volume of 500 cm3; DSA electrodes – Dimensionally Stable Anodes (70TiO2-30RuO2) were used (effective area of work - 41.25 cm2); NaCl P.A. was used as supporting electrolyte; 130 mg L-1 of Vancomycin was used in aqueous solution. The optimization was done using central composite design (CCD) totaling 18 experiments. The evaluated factors were: interelectrodes distance (ID), applied current and supporting electrolyte concentration. All experiments were conducted for 20 minutes with sampling at 0, 1, 2, 3, 4, 5, 10 and 20 minutes. Vancomycin concentrations were determined by High Performance Liquid Cromatography with Diode-Array Detection (HPLC-DAD) (Mobile phase: phosphate buffer 0.05 mol L-1, pH 4.7: MeOH: ACN [80:15:5, v/v], Injection volume: 40 L; C18 with flow rate of 1.0 mL min-1, λ: 210 nm. The results show that the electrooxidation is effective in Vancomycin degradation, showing as an alternative to degradation of this drug. The method used obtained 100% of degradation in 2 minutes of treatment in optimum conditions: 400 mA, 3 cm interelectrodes distance and 1,100 mg L-1 NaCl.

Evaluating filterability of different types of sludge by statistical analysis: The role of key organic compounds in extracellular polymeric substances

An investigation was conducted for 20 different types of sludge in order to identify the key organic compounds in extracellular polymeric substances (EPS) that are important in assessing variations of sludge filterability. The different types of sludge varied in initial total solids (TS) content, organic composition and pre-treatment methods. For instance, some of the sludges were pre-treated by acid, ultrasonic, thermal, alkaline, or advanced oxidation technique. The Pearson's correlation results showed significant correlations between sludge filterability and zeta potential, pH, dissolved organic carbon, protein and polysaccharide in soluble EPS (SB EPS), loosely bound EPS (LB EPS) and tightly bound EPS (TB EPS). The principal component analysis (PCA) method was used to further explore correlations between variables and similarities among EPS fractions of different types of sludge. Two principal components were extracted: principal component 1 accounted for 59.24% of total EPS variations, while principal component 2 accounted for 25.46% of total EPS variations. Dissolved organic carbon, protein and polysaccharide in LB EPS showed higher eigenvector projection values than the corresponding compounds in SB EPS and TB EPS in principal component 1. Further characterization of fractionized key organic compounds in LB EPS was conducted with size-exclusion chromatography-organic carbon detection-organic nitrogen detection (LC-OCD-OND). A numerical multiple linear regression model was established to describe relationship between organic compounds in LB EPS and sludge filterability.

Ultra-thin silicon oxide layers on crystalline silicon wafers: Comparison of advanced oxidation techniques with respect to chemically abrupt SiO2/Si interfaces with low defect densities

Six advanced oxidation techniques were analyzed, evaluated and compared with respect to the preparation of high-quality ultra-thin oxide layers on crystalline silicon. The resulting electronic and chemical SiO2/Si interface properties were determined by a combined x-ray photoemission (XPS) and surface photovoltage (SPV) investigation. Depending on the oxidation technique, chemically abrupt SiO2/Si interfaces with low densities of interface states were fabricated on c-Si either at low temperatures, at short times, or in wet-chemical environment, resulting in each case in excellent interface passivation. Moreover, the beneficial effect of a subsequent forming gas annealing (FGA) step for the passivation of the SiO2/Si interface of ultra-thin oxide layers has been proven. Chemically abrupt SiO2/Si interfaces have been shown to generate less interface defect states.

An Integrated Simulation-based Process Control and Operation Planning (IS-PCOP) System for Marine Oily Wastewater Management

The chronic discharge of oily wastewater, mainly including bilge water, offshore produced water and ballast water, has been referred to as a major contributor to marine oil pollution. Although gravity-based treatment techniques have been widely used to separate oil from wastewater, many dissolved toxic organics, particularly Polycyclic Aromatic Hydrocarbons (PAHs), are not likely to be effectively removed and may cause severe environmental problems. Further treatment has therefore become necessary for the shipping and offshore oil and gas industries, particularly in the harsh environments (e.g., the Arctic Ocean) where ecosystems are extremely vulnerable. Among many chemical and biological treatment techniques, ultraviolet (UV) irradiation and advanced oxidation techniques have been recently regarded as promising solutions to the removal of PAHs. Such advanced treatment systems, as compared to the traditional ones, are usually lack of in-depth understanding of reaction mechanisms and kinetics, process control requirements, and long-term planning strategies. More particularly, the integration of process control and operation planning has been proven in the literature to greatly reduce process cost and improve system performance. However, such integration is usually complicated by many factors such as the multi-scale nature of decisions, the lack of knowledge of process dynamics and control, and uncertainty. These deficiencies can drastically hinder the widespread application of these advanced treatment systems in the shipping and offshore industries. In response to these knowledge and technique gaps, this research proposes an integrated process control and operation planning system to aid marine oily wastewater management based on experimental study, process modeling, process control, operation planning and their coupling.

Heavy metals removal from aqueous environments by electrocoagulation process- a systematic review.

Heavy metals pollution has become a more serious environmental problem in the last several decades as a result releasing toxic materials into the environment. Various techniques such as physical, chemical, biological, advanced oxidation and electrochemical processes were used for the treatment of domestic, industrial and agricultural effluents. The commonly used conventional biological treatments processes are not only time consuming but also need large operational area. Accordingly, it seems that these methods are not cost-effective for effluent containing toxic elements. Advanced oxidation techniques result in high treatment cost and are generally used to obtain high purity grade water. The chemical coagulation technique is slow and generates large amount of sludge. Electrocoagulation is an electrochemical technique with many applications. This process has recently attracted attention as a potential technique for treating industrial wastewater due to its versatility and environmental compatibility. This process has been applied for the treatment of many kinds of wastewater such as landfill leachate, restaurant, carwash, slaughterhouse, textile, laundry, tannery, petroleum refinery wastewater and for removal of bacteria, arsenic, fluoride, pesticides and heavy metals from aqueous environments. The objective of the present manuscript is to review the potential of electrocoagulation process for the treatment of domestic, industrial and agricultural effluents, especially removal of heavy metals from aqueous environments. About 100 published studies (1977–2016) are reviewed in this paper. It is evident from the literature survey articles that electrocoagulation are the most frequently studied for the treatment of heavy metal wastewater.

Effectiveness of advanced oxidation processes for the removal of manganese and organic compounds in membrane concentrate

The effectiveness of batch UV, ozone, and UV/ozone induced oxidation processes in treatment of manganese and organics in reverse osmosis concentrate stream is evaluated. The most effective advanced oxidation techniques are identified and the optimum operating conditions are determined. Application of UV alone (wavelength of 254nm, light intensity of 4400μW/cm2, and lighted length of 2.13in.) was found to be ineffective for removal of organic compounds while it led to a gradual decrease in manganese concentration. Although UV-ozonation could remove manganese completely at initial ozone concentration of 15.2ppm, oxidation with ozone alone at initial concentration of 6.2ppm is found to be the most suitable condition for manganese removal. At low initial ozone concentration of 6.2ppm, the removal for manganese reached 97.2%. The only limitation of ozonation is that over-oxidation occurs when the initial ozone concentration exceeds 6.2ppm, and therefore the efficiency of the treatment decreases due to the production of soluble permanganate. It was also found that the highest oxidation efficiency for the organic carbon is 89% which occurs in UV-ozonation treatment at the initial ozone concentration of 15.2ppm.

Treatment of Leachate by Electrocoagulation Technique Using Iron And Hybrid Electrodes

The most techniques for treating leachate and wastewater are physical, chemical, biological, advanced oxidation and electrochemical techniques. Developed oxidation techniques lead to high treatment cost and mostly are used in purifying grade waters. Among these techniques, the chemical coagulation technique not only is a slow process, but also produces a large amount of sludge. Electrocoagulation has been used for treating industrial effluent and leachate as a potential technique because of its compatibility and adaptability with environment. In this technique, a direct current source between metal electrodes plunged in the effluent is used to dissolve the electrode plates into the effluent. The metal ions with appropriate pH can create various types of coagulated species and metal hydroxides that in turn cause to rolling up and destabilizing the elements, or catalyzing and absorbing the dissolved pollutants. Therefore, the purpose of the current study is to examine the potentials of electrocoagulation in treating the leachate and wastewater by treating the heavy metals and their colour and salinity. Furthermore, the present study aims to investigate the electrocoagulation, electrochemical technologies and their design and application in treating the leachate, water, and wastewater. This work mostly dealt with the electrocoagulation (EC), electrodeposition, electroflotation (EF), and electrooxidation. It was shown that Electrodeposition is efficient in treating the wastewater stream and removing heavy metals. In addition, electrocoagulation was used for treating wastewater and producing clean water as well. It was also found that using aluminum, iron or the hybrid Al/Fe electrodes are more applicable. Keyword: Electrocoagulation, Treatment, Leachate, Wastewater, Iron and Aluminum Electrode, Hydride electrode