Organic Compounds In Wastewater Research Articles

Visible and UV photocatalysis of aqueous perfluorooctanoic acid by TiO2 and peroxymonosulfate: Process kinetics and mechanistic insights.

The global occurrence and adverse environmental impacts of perfluorooctanoic acid (PFOA) have attracted wide attention. This study focused on the PFOA photodegradation by using photocatalyst TiO2 with peroxymonosulfate (PMS) activation. Aqueous PFOA (50mgL-1) at the pH 3 was treated by TiO2/PMS under 300W visible light (400-770nm) or 32W UV light (254nm and 185nm). The addition of PMS induced a significant degradation of PFOA under powerful visible light compared with sole TiO2. Under visible light, 0.25gL-1 TiO2 and 0.75gL-1 PMS in the solution with the initial pH 3 provided optimum condition which achieved 100% PFOA removal within 8h. Under UV light irradiation at 254nm and 185nm wavelength, TiO2/PMS presented excellent performance of almost 100% removal of PFOA within 1.5h, attributed to the high UV absorbance by the photocatalyst. The intermediates analysis showed that PFOA was degraded from a long carbon chain PFOA to shorter chain intermediates in a stepwise manner. Furthermore, scavenger experiments indicated that SO4•-radicals from PMS and photogenerated holes from TiO2 played an essential role in degrading PFOA. The presence of organic compounds in real wastewater reduced the degradation efficacy of PFOA by 18-35% in visible/TiO2/PMS system. In general, TiO2/PMS could be an ideal and effective photocatalysis system for the degradation of PFOA from wastewater using either visible or UV light source.

Ozonation of trace organic compounds in different municipal and industrial wastewaters: Kinetic-based prediction of removal efficiency and ozone dose requirements

For the wide application of ozonation in (industrial and municipal) wastewater treatment, prediction of trace organic compounds (TrOCs) removal and evaluation of energy requirements are essential for its design and operation. In this study, a kinetics approach, based on the correlation between the second order reaction rate constants of TrOCs with ozone and hydroxyl radicals (OH) and the ozone and OH exposure (i.e., ∫[O3]dt and ∫[OH]dt, which are defined as the time integral concentration of O3 and OH for a given reaction time), was validated to predict the elimination efficiency in not only municipal wastewaters but also industrial wastewaters. Two municipal wastewater treatment plant effluents from Belgium (HB-effluent) and China (QG-effluent) and two industrial wastewater treatment plant effluents respectively from a China printing and dyeing factory (PD-effluent) and a China lithium-ion battery factory (LZ-effluent) were used for this purpose. The OH scavenging rate from the major scavengers (namely alkalinity, effluent organic matter (EfOM) and NO2−) and the total OH scavenging rate of each effluent were calculated. The various water matrices and the OH scavenging rates resulted in a difference in the requirement for ozone dose and energy for the same level of TrOCs elimination. For example, for more than 90% atrazine (ATZ) abatement in HB-effluent (with a total OH scavenging rate of 1.9 × 105 s−1) the energy requirement was 12.3 × 10−2 kWh/m3, which was lower than 30.1 × 10−2 kWh/m3 for PD-effluent (with the highest total OH scavenging rate of 4.7 × 105 s−1). Even though the water characteristics of selected wastewater effluents are quite different, the results of measured and predicted TrOCs abatement efficiency demonstrate that the kinetics approach is applicability for the prediction of target TrOCs elimination by ozonation in both municipal and industrial wastewater treatment plant effluents.

Advanced Oxidation Technology for Refractory Organic Compounds in Wastewater

As a relatively important task in the current industrialization development, wastewater treatment has become increasingly demanding in the context of China’s current rapid industrialization. In order to improve the quality of industrial wastewater treatment, it is necessary to clarify the relevant treatment technologies according to the requirements of the treatment process. Meanwhile, scientific treatment methods should also be combined with the requirements in the wastewater treatment technology, especially for the treatment of refractory organic compounds in wastewater. In other words the quality of wastewater treatment can be improved only by scientific treatment of refractory substances in wastewater. Therefore, this paper analyzes the advanced oxidation technology for degrading refractory organic compounds in wastewater, with the aim to clarify the treatment of refractory organics in wastewater and thenimprove wastewater treatment quality.

Study of the Solubility, Supersolubility, and Metastable Zone Width of Ternary System (NaCl + Na2SO4 + H2O) Containing Organic Impurity at 333.15 K

Typically, the industrial evaporation process is operated at a high evaporation rate in a nonequilibrium stable or dynamic state within a temperature range of 323 to 393 K. During this process, both the solubility and the crystallization of salt are affected by organic impurities in the system. In this work, glutaraldehyde, one of the main organic compounds in wastewater produced from the coal chemical, was selected as a representative organic impurity, and the chemical oxygen demand (COD) of glutaraldehyde solution was used to simulate the COD of highly saline coal chemical wastewater. The stable and metastable solid–liquid equilibria of the (Na2SO4–NaCl–H2O) system containing the organic impurity at 333.15 K were studied. The results showed that the solubility and supersolubility of Na2SO4 increased with the increase of COD. However, the solubility and supersolubility of NaCl had begun to increase when the COD value is around 450 mg L–1. When the COD value reached to 3290 mg L–1 (the content of actual w...

Optimization of electro-Fenton process for the removal of non-biodegradable organic compounds in instant coffee production wastewater using composite Fe3O4–Mn3O4 nanoparticle catalyst

Wastewater from instant coffee production has high organic content. The non-biodegradable compounds of the organic portion, such as caffeine, trigonelline, and diterpene, are difficult to be removed by conventional processes. Electro-Fenton (EF) with particulate catalyst has been found to be a promising method to treat such compounds. Comparing with homogenous Fenton process, EF uses fewer chemicals and generated less sludge. The catalysts can be easily recovered by magnets if they have magnetic properties. In this study, 30–60 nm composite Fe3O4–Mn3O4 nanoparticles were prepared and used as EF catalyst for the treatment of non-biodegradable organic matters in biologically pre-treated wastewater from instant coffee production. These particles were found to contain Fe3O4, γ-Fe2O3, and Mn3O4, which were effective metal sources for Fenton reactions. The correlations between three important operating parameters (i.e., pH, catalyst concentration, and current density) and the treatment efficiency of the non-biodegradable compounds were elucidated by response surface method (Box–Behnken design) via Modde software. An optimal condition was found at a pH of 3.8, a Fe3O4–Mn3O4 concentration of 0.5 g/L, and a current density of 19.6 mA/cm2. After 60 min of treatment at this condition, the highest removal efficiencies of chemical oxygen demand (COD), color, and total organic carbon in the wastewater were 88%, 98%, and 93%, respectively. With this degree of treatment, the COD and color in treated wastewater met the highest treatment level of Vietnam National Technical Regulation on Industrial Wastewater (QCVN 40:2011, column A, 75 mgO2/L for COD, and 50 Pt–Co for color).

Zinc doped FeS2/MWCNTs nanocomposites for photo-degradation application: preparation and structural

The present work, Pure and zinc doped Iron sulfide (FeS2)/multi-walled carbon nanotubes (MWCNTs) were synthesized via the solvothermal process. The structural, morphological, and textural properties of the as-synthesized nanocomposite were characterized by powder x-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), UV–vis absorption and photoluminescence spectroscopy, and Brunauer–Emmett–Teller (BET). This study aimed at exploring the effectiveness of Zn-FeS2/MWCNTs nanocomposites in the degradation of methylene blue dye under UV-light. The crystallite size of FeS2 was estimated as 25.1 nm. The specific surface area of FeS2 QDs, FeS2/MWCNTs, Zn-FeS2/MWCNTs (1:1) are 47.245, 234.591 and 282.211 m2 g−1, respectively. The photo-activity towards the decomposition of methylene blue with high removal was found within 40 min in acidic medium (pH = 3.5). The novel Zinc doped FeS2/MWCNTs nanocomposites has an excellent potential photo-degradation of organic compound in wastewater.

The Reduction of COD Levels in Domestic Waste Water Using Combination of Activated Sludge Methode – Activated Carbon Continously

Domestic waste water produced from Pujasera Politeknik Negeri Bandung has a relatively high organic compound. It can cause environmental pollution, so waste water treatment is required to reduce the concentration of organic compounds. The purpose of this study is to determine the efficiency of processing organic compounds in domestic wastewater using active sludge in combination with Activated carbon. The acclimation process is carried out in batches, while the waste water feed is continuously fed by varying the retention time and activated carbon concentration. Variation of retention time of 12, 18, 24 hours and variation of activated carbon concentration 50, 100, 150 ppm. The parameters used in aerobic wastewater treatment are COD, pH, and MLSS measurements. Based on the results of data analysis showed that the percentage decrease of COD from 861 mg / L to 160 mg / L with a pH range of 6.5 to 7 and MLSS averaged 2951 mg / L. The optimum retention time 24 hours with efficiency of COD effluent reduction without activated carbon was 74.91%. With the same operating conditions, at 24 hours of retention time using a combination of activated sludge - activated carbon of 150 ppm, the efficiency of COD effluent reduction was 89.97%.

Trends in Synthetic Diamond for Electrochemical Applications

Trends in Synthetic Diamond for Electrochemical Applications

MoO3 and Ag co-synthesized TiO2 as a novel heterogeneous photocatalyst with enhanced visible-light-driven photocatalytic activity for methyl orange dye degradation

In this study, the nano-composite photocatalyst of TiO2 was synthesized with MoO3 and Ag using sol–gel method followed by heat treatment. The consequential three-components alliance nano-composite exhibited predominately anatase structural phase. Subsequently, other favorable modifications were encountered in terms of rough surface morphology, higher pore volume along with surface area, smaller particle size (4.21 nm) and narrow band gap energy (2.84 eV). The photocatalytic methyl orange (model azo-dye) degradation experiment showed that Ag-MoO3-TiO2 nano-composite have a superior photocatalytic activity of about 97% degradation under solar irradiation for 300 min in comparison to MoO3-TiO2’s 91% and TiO2’s 79%. The respective rate constants for TiO2, MoO3-TiO2 and Ag-MO3-TiO2 were calculated to be 0.0048 min−1, 0.0069 min−1 and 0.0114 min−1. Therefore, it can be stated that an efficient novel heterogeneous nano-composite photocatalyst was synthesized. This study indicates that Ag-MoO3-TiO2 nano-composite is very promising for the removal of dye compounds from textile wastewater and can be considered as one of the key strategies for sustainable management of bio-persistent organic compounds in wastewater by means of the impact on environment.

Removal of Organic Compounds Found in the Wastewater through Electrochemical Advanced Oxidation Processes: A Review

Existence of an organic compounds, especially aromatic compounds in wastewater is observed as an emerging environmental problem because of their harmful effects on living organisms even at low concentration. Conventional wastewater treatment processes are ineffectual for an elimination of refractory organic compounds. Nowadays, it’s a challenge to reduce negative impact of such hazardous compounds on environment. So, Advanced Oxidation Processes (AOPs) have received more attention over a year of decades towards removal of an aromatic compounds. Among AOPs, Electrochemical Advanced Oxidation Processes (EAOPs), especially “Anodic Oxidation” and “Electro-Fenton,” have revealed good potential for mitigation of pollution caused by the presence of aqueous organic compounds in wastewater. This review has introduced an innovative collection of current knowledge on Electro-Fenton and Anodic oxidation type of processes. Fundamentals of these processes, electrolysers used, reaction mechanisms, experimental parameters affecting these electro-chemical treatment technologies with various applications are discussed in detail. This report also discusses effectiveness of EAOPs for elimination of organic compounds in aqueous systems.

A pH Study for the Degradation of Acetaminophen with Iron Oxide Nanostructures

Nowadays, there is an increasing interest in the degradation of organic compounds in wastewater, since they are detrimental for the water quality. Different metal oxides have been studied as photocatalysts in the photoelectrocatalytic degradation of pharmaceutical products using UV light. Iron oxide nanostructures are a promising option in this field since their band gap (~ 2.1 eV, corresponding to ~590 nm) can absorb visible light, which in turn allows the degradation by using sunlight.Iron oxide nanostructures are known to be stable in alkaline solutions, but some organic compounds can vary their structure with pH. Then, a pH study is needed in order to stablish the optimum value to guarantee both the nanostructures and the organic molecule stability. In this work, acetaminophen (more known as paracetamol) is studied in different pH media (from pH 9 to pH 13) in order to evaluate the viability of iron oxide nanostructures as photocatalysts in the acetaminophen degradation process.Results showed that pH is a determinant parameter in the degradation process since the paracetamol UV-Vis spectrum varied with it. However, a pH compromise value is stablished in order to ensure the viability of the usage of iron oxide nanostructures in the acetaminophen degradation process.

An integrated process of chemical precipitation and sulfate reduction for treatment of flue gas desulphurization wastewater from coal-fired power plant

Flue gas desulphurization process in coal-fired power plants, produces wastewater with concentrated sulfate, chloride, metals and refractory organic compounds, which leads to serious pollution and corrosion problem during recycling. In this study, an integrated process of chemical precipitation and sulfate reduction for treatment of coal-fired power plant flue gas desulphurization wastewater was developed. Without additional of heavy metal trapping and strong oxidizing agents, chemical precipitation was performed as pre-treatment for removal of suspended solid (97%) in raw flue gas desulphurization wastewater. Comparison study on treatment of pre-treated flue gas desulphurization wastewater were performed in three parallelly operated sequencing batch reactors, by cultured sulfate reducing bacteria strain BY7, SR10 and SR3, respectively. This study demonstrated that strain BY7 and SR10 sulfate reducing bacteria were able to adapted to high-salinity flue gas desulphurization wastewater, with high efficiencies of sulfate reduction (86–94%), metals (70–100%) and refractory organic compounds removal (85–95%). The highest sulfate loading rate of 0.5 kg SO42−/m3·d was achieved in sequencing batch reactors with strain BY7 and SR10. Besides, a sustainable removal of chloride and fluoride were achieved (about 35% and 55%, respectively), which probably relate to co-precipitation or biosorption processes. Up to 14 out of 25 refractory organic compounds in flue gas desulphurization wastewater could be completely removed after integrated treatment process. As response to flue gas desulphurization wastewater stress, abundance of monounsaturated fatty acids were increased, and upregulated expression of genes related to salt detoxification were observed in SBR_BY7 and SBR_SR10. Therefore, this study provided a potential low-cost flue gas desulphurization wastewater recycling technology with simultaneously removal of sulfate, refractory organic compounds, heavy metal and salts.

Toxicity of Manganese Titanate on Rat Vital Organ Mitochondria.

The TiO2, which is a main material in the field of photocatalytic reactions, includes rutile and anatase phase. Titanium dioxide has possessed notice due to its promising applications in the environmental photocatalytic degradation of pollutants of organic compound in waste water and utilization of solar energy. The nanosized manganese titanate (pyrophanite) MnTiO3 was collected by oxidation of Mn(OH)2 with TiO2 powder in cetyltrimethylammonium bromide (CTAB) micelle solutions and the calcinations of the produced powders. Therefore, it was decided to determine the Mechanistic mitochondria toxicity of nanoparticles towards liver, kidney, heart, and brain via new and reliable methods. Our results showed that nanoparticles induced mitochondria dysfunction via an increase in ROS production and membrane potential collapse, correlated to cytochrome c release. Also, increased disturbance in oxidative phosphorylation was also shown by the decrease in ATP. Recent studies have suggested that nanoparticles leading to cytosolic release of lysosomal content, and ultimately apoptosis. This study suggests that mitochondrial oxidative stress and impairment of oxidative phosphorylation in vital organ Mitochondria may play a key role in manganese titanate toxicity.

APPLICATION OF POTASSIUM FERRATE(VI) FOR OXIDATION OF SELECTED POLLUTANTS IN AQUATIC ENVIRONMENT – SHORT REVIEW

Abstract The paper provides comprehensive information on the recent progress of the use of potassium ferrate(VI) (K2FeO4) for the removal of selected pollutants from water and wastewater. K2FeO4 provides great potential for diverse environmental applications without harm to the natural environment. Therefore K2FeO4 was used in removal of cyanides from gold ore purification processes, degradation of dyes and organic compounds in wastewater and algae removal in the water treatment process. The quoted research results indicate that K2FeO4 due to its strong oxidizing and coagulating properties, could be an alternative to the use of Advanced Oxidation Processes (AOPs) or be an additional option to conventional methods of water and wastewater treatment. As a result of using K2FeO4, the emerge intermediates of the impurities decomposition are nontoxic or show less toxicity than the initial substrates. The use of K2FeO4 is also associated with certain limitations of technical and technological nature, which requires further research in order to use its high efficiency in the degradation of various types of contamination on a technical scale.

Effective Photocatalytic Removal of Different Dye Stuffs Using ZnO/CuO-Incorporated onto Eggshell Templating

The coupling of ZnO-CuO-supported on eggshell (ZnO-CuO/ES) catalyst was successfully produced through a facile one-pot electrochemical process. The photocatalytic activity of ZnO-CuO/ES catalyst were measured with degradation of various dyes and other organic compound such methylene blue (MB), malachite green (MG), crystal violet (CV), Congo red (CR), and phenol. Above 90% of all dyes and 69% of phenol degraded have been demonstrated. The organic compound in simulated wastewater shows higher degradation by ZnO-CuO/ES catalyst which are 97% (nearly complete).

Application of Catalytic Wet Peroxide Oxidation for Industrial and Urban Wastewater Treatment: A Review

Catalytic wet peroxide oxidation (CWPO) is emerging as an advanced oxidation process (AOP) of significant promise, which is mainly due to its efficiency for the decomposition of recalcitrant organic compounds in industrial and urban wastewaters and relatively low operating costs. In current study, we have systemised and critically discussed the feasibility of CWPO for industrial and urban wastewater treatment. More specifically, types of catalysts the effect of pH, temperature, and hydrogen peroxide concentrations on the efficiency of CWPO were taken into consideration. The operating and maintenance costs of CWPO applied to wastewater treatment and toxicity assessment were also discussed. Knowledge gaps were identified and summarised. The main conclusions of this work are: (i) catalyst leaching and deactivation is one of the main problematic issues; (ii) majority of studies were performed in semi-batch and batch reactors, while continuous fixed bed reactors were not extensively studied for treatment of real wastewaters; (iii) toxicity of wastewaters treated by CWPO is of key importance for possible application, however it was not studied thoroughly; and, (iv) CWPO can be regarded as economically viable for wastewater treatment, especially when conducted at ambient temperature and natural pH of wastewater.

Catalytic Liquid-Phase Oxidation of Phenolic Compounds Using Ceria-Zirconia Based Catalysts.

Catalytic liquid-phase oxidation using a catalyst and oxygen gas (Catalytic wet air oxidation, CWAO) is one of the most promising technology to remove hazardous organic compounds in wastewater. Up to now, various heterogeneous catalysts have been reported for phenolic compounds decomposition. The CeO2-ZrO2 based catalysts have been recently studied, because CeO2-ZrO2 works as a promoter which supplies active oxygen species from inside the lattice to the active sites. Since it is difficult to dissolve oxygen gas into water, the use of the promoter is effective for realizing the high catalytic activity at moderate conditions. Also, CeO2-ZrO2 shows high resistance for the metal leaching during the catalytic reaction in the liquid-phase. This article reviews the studies of the catalytic liquid-phase oxidation of phenolic compounds using CeO2-ZrO2 based catalysts.

Combination of Ozonation and Adsorption Using Granular Activated Carbon (GAC) for Tofu Industry Wastewater Treatment

Tofu industry wastewater is one of the environmental pollutants that need more effective treatment. Ozonation and adsorption method is known to have the capability to oxidize organic compound in wastewater. Adsorption is done by using granular activated carbon (GAC) as an adsorbent to increase tofu wastewater degradation process by adsorbing organic materials and increasing production of hydroxyl radical as the main oxidizing agent. This research is carried out to evaluate the performance of ozonation, adsorption, and combination of both in processing tofu wastewater. To evaluate the significance of ozone dosage and amount of GAC used, these variations are varied which are 60, 111, and 155 mg/h of ozone dosage and 50, 75, and 100 g of the amount of GAC used. Parameters of the process are organic substances of tofu wastewater such as COD, TSS, and pH. The measurements are being done using a spectrophotometer, colorimeter, and pH meter. The outcome of this research is to provide an alternative method in the liquid waste treatment of the tofu industry and the processed wastewater to meet the environmental quality standards. The more ozone and the more quantity of GAC used, the higher the quantity of hydroxyl radicals formed. Addition of GAC in the ozonation process results in more than 100% increase in hydroxyl radical production. Combination of ozonation and adsorption is able to remove 377.12 mg/L of COD and 26 mg/L of TSS.

Degradation of Organic Compounds in Actual Wastewater by Electro-Fenton Process and Evaluation of Energy Consumption

We investigated the Fe-regeneration-based cathodic electro-Fenton process using commercial electrodes, to achieve reducing the initial Fe dose and consequent sludge accumulation. The obtained results provided insights into the cathodic electro-Fenton process using two-electrode electrochemical system. The grade 2 Ti mesh electrode could effectively regenerate Fe(II) at 1.2 V, whose potential was lower than those of the two other electrode systems reported in the literatures. In the actual wastewater treatment, compared with general-Fenton process, the reduction in the initial Fe injection was 33% and the sludge reduction was 38%. Furthermore, the removal efficiency using electro-Fenton was at least 5% higher than that of the general-Fenton process at the same initial dose. The low cell voltage (1.2 V) led to lower energy consumption (3.5 J mg−1) relative to those of other electro-Fenton systems, i.e., anodic electro-Fenton and peroxide generation. With its competitive degradation performances, low energy consumption, and reduced initial Fe injection, the present cathodic electro-Fenton process was shown to be a promising route of waste treatment.

Study on the composition of resistant organics in winery wastewater and their degradation technique

Winery wastewater contains a large number of resistant organic compounds, and the residual effluent COD is high after common biological treatment processes, which is hard to meet the increasingly rigorous wastewater discharge standard in China. Two techniques, Fenton oxidation and Fenton oxidation + SBR processes, were applied to treat winery wastewater in this study, and Gas Chromatography (GC) was used to analyze the resistant organic compounds in the effluent. The results indicated that resistant organic compounds in winery wastewater are mainly composed of long chain alkanoic acids, polyphenols, macromolecular esters and alcohols, and the combination treatment of Fenton + SBR process could eliminate COD effectively, and only 0.43% COD left in the effluent compared to the raw winery wastewater. Fenton pre-oxidation not only can oxidize the resistant organics directly, but also can improve the biodegradability of winery wastewater, and the effluent COD meets 60 mg/L standard. The combination of Fenton pre-oxidation and SBR aerobic treatment is the optimal process treating winery wastewater.