Non-biodegradable Organic Compounds Research Articles

Degradation of residual dyes in actual textile wastewater using UV/H<sub>2</sub>O<sub>2</sub>: Evaluation of the impact of operating variables through multi-layer perceptron analysis

UV/H<sub>2</sub>O<sub>2</sub> is a commonly used advanced oxidation process for removing non-biodegradable organic compounds. However, additional efforts are needed to understand the relative significance of operational factors during the UV/H<sub>2</sub>O<sub>2</sub>. Here, we investigated the effect and specific contribution of crucial factors such as H<sub>2</sub>O<sub>2</sub> concentration, UV intensity, and reaction time on the color and total organic carbon (TOC) removal efficiency in textile wastewater using the one-factor-at-a-time method and multi-layer perceptron (MLP) analysis. The results showed that color removal was enhanced with high H<sub>2</sub>O<sub>2</sub> concentration, high UV intensity, and long reaction time. Overall, more than 99% removal of color was achieved by the UV/H<sub>2</sub>O<sub>2</sub>, utilizing the following parameters: H<sub>2</sub>O<sub>2</sub> concentration of 5 mM, UV intensity of 26.6 W/m<sup>2</sup>, and reaction time of 180 min. On the other hand, the removal of TOC was increased by high H<sub>2</sub>O<sub>2</sub> concentration and long reaction time, but not by high UV intensity. In the MLP analysis, the H<sub>2</sub>O<sub>2</sub> concentration was identified as the primary factor affecting both color and TOC removal, accounting for 43% and 50% reduction of the color and TOC, respectively. Overall, this study helps to understand the relative importance of the most critical operating factors in treating actual textile wastewater by the UV/H<sub>2</sub>O<sub>2</sub>.

Fenton Process - A Pretreatment option for Hospital Waste Water

The treatment of wastewater with non-biodegradable organic compounds can be done by advanced oxidation processes such as Fenton, Photo Fenton and Photo Oxidation. These processes use iron and hydrogen peroxide as reagents to produce reactive hydroxyl radicals that break down organic pollutants into harmless substances. The Fenton reaction is fast, cheap, non-toxic and easy to operate compared to other advanced oxidation processes. This study explores the use of Fenton reaction as a pre-treatment method for hospital wastewater. The main goal of this study is to assess the increase in biodegradability of pollutants in hospital wastewater by using the photo-Fenton process. The wastewater samples were taken from Korambayil Memorial Hospital, Malappuram, Kerala. The physical and chemical properties of the wastewater were examined. The process variables were optimized by conducting experiments with different doses. The efficiency of the process was evaluated under different operating conditions. The optimal conditions for applying the photo-Fenton process to hospital wastewater are presented for the design of the treatment process.

Changes in Organics and Nitrogen during Ozonation of Anaerobic Digester Effluent

The objective of this study is to investigate the consequence of ozone dosage rate on the qualitative change in organic compounds and nitrogen in anaerobic digester effluent during the ozone process. Therefore, ozonation improves the biodegradability of recalcitrant organic compounds, quickly oxidizes the unsaturated bond, and forms radicals that continue to deteriorate other organic matter. In this study, ozonation was performed in a microbubble column reactor; the use of microbubble ozone improves the status of chemical oxygen demand (COD) and changes of organic nitrogen to inorganic compounds. The ozone injection rates were 1.0, 3.2, and 6.2 mg/L/min. The samples obtained during the ozone treatments were monitored for CODMn, CODCr, TOC, NO2−-N, NO3−-N, NH4+-N, T-N, and Org-N. The ozone dose increased 1.0 to 6.2 mg/L and it increased the degradation ratio 40% and the total organic carbon 20% during 20 min of reaction time. During the ozonation, the CODCr and CODMn values were increased per unit of ozone consumption. The ozone treatment showed organic nitrogen mineralization and degradation of organic compounds with the contribution of the microbubble ozone oxidation process and is a good option for removing non-biodegradable organic compounds. The original application of the microbubble ozone process, with the degradation of organic compounds from a domestic wastewater treatment plant, was investigated.

Metal-based catalysts for persulfate and peroxymonosulfate activation in heterogeneous ways: A review

A growing number of emerging organic contaminants associated with the potential risks for ecosystem and human health are frequently detected in environment. Sulfate radical-based advanced oxidation processes have attracted increasing attention during the past decades, owing to their high reactivity and oxidation capability of a wide range of toxic and non-biodegradable organic compounds. Metal-based materials have been proven to be effective heterogeneous catalysts for activating persulfate to degrade many refractory organic pollutants. This article reviews the up-to-date research progresses on various heterogeneous metal-based catalysts for persulfate (PS) and peroxymonosulfate (PMS) activation, including single metal and mixed metal catalysts. The activation mechanisms of these catalysts and their fundamental behaviors in PS/PMS activation are emphatically elucidated, in which contaminants can be eliminated through radical and/or non-radical reaction pathways. In addition, an in-depth discussion about metal composite namely metal spinel, metallic glasses and other metal hybrids in PS or PMS systems for organic degradation and possible environmental applications are presented. Finally, the perspectives on the metal-based PS/PMS activation method and their remediation potential for recalcitrant compounds in practical application are also proposed.

Development of a novel polyvinylidene fluoride membrane integrated with palm oil fuel ash for stabilized landfill leachate treatment

Stabilized landfill leachate is a complex wastewater containing high concentration of non-biodegradable organic compounds and Ammoniacal nitrogen. Thus, an advanced treatment such as membrane technology is required to treat leachate effectively. In this study, membrane filtration process was employed to treat stabilized leachate. A new type of membrane was fabricated by incorporating palm oil fuel ash (POFA) into hydrophobic polyvinylidene fluoride (PVDF) polymer to produce flat sheet membrane via phase inversion technique. Response Surface Methodology (RSM) was applied to optimize the membrane fabrication. The filtration process was carried out using cross-flow ring (CFR) test. The best removal efficiencies of COD, colour and NH3–N was found using a membrane with the following composition: 13.9 wt% PVDF and 1.2 wt% POFA. To improve the permeability and anti-fouling ability, the best performing membrane was further modified using polyvinyl alcohol (PVA). The performance and characterization of unmodified and modified membranes were systematically analyzed. The results showed that filtration properties of modified membrane were efficiently developed by 0.5 wt% of PVA. Pure water flux value was enhanced from 40.16 to 81.08L/m2.h and transmembrane pressure was reduced from 0.60 to 0.55 bar as a result of the surface and pore size improvements. Moreover, the modified membranes significantly enhanced the removal of COD (57.06%), colour (58.27%) and NH3–N (55.44%) due to the newly developed microstructure. This study offers the best way to develop PVDF- POFA membrane improved by PVA for stabilized landfill leachate treatment. The produced PVDF membrane was also economical compared to the commercially available PVDF membrane.

USING IRON-CONTAINING METAL OXIDE AS CATALYST FOR HETEROGENEOUS FENTON PROCESS IN TEXTILE INDUSTRY WASTEWATER

The unconscious use of surface and ground waters and the rapid pollution of water, which is the main source of life for all living creatures as a result of drought due to global warming, pose a serious problem. The rapidly increasing world population and the need for clean water have brought up a global water crisis. The textile industry is one of the largest producers of wastewater in the world. Textile industry wastewater contains high amounts of non-biodegradable organic compounds, high concentrations of dyestuffs, salt, detergent and soap. Therefore, it is of great importance to remove organic pollutants in this wastewater. Since traditional methods are insufficient to remove organic compounds in wastewater, advanced treatment methods are required. Advanced oxidation processes (AOPs) are one of the alternative treatment methods preferred in recent years. In this study, color removal from textile industry wastewater was researched by the heterogeneous Fenton process, which is an advanced oxidation process. The parameters such as catalyst dosage, pH, hydrogen peroxide concentration, temperature, reaction time and mixing speed that effect heterogeneous Fenton processes were investigated. Under optimum experimental conditions, the color removal efficiency was achieved as 87%.

Photocatalytic Degradation of Organic Pollutants: The Case of Conductive Polymer Supported Titanium Dioxide (TiO<sub>2</sub>) Nanoparticles: A Review

In recent years development of different type of industries are enlarged and these industries are connected with the discarding of organic pollutants which are harmful to aquatic system and the human health. The presence of those organic pollutants in the aquatic system can result in pollution of wastewater which affects the ecosystem. Therefore, the removals of pollutants have become an ecological concern and they are vital for the environmental sustainability. Many practices have been widely applied in the treatment of organic effluent such as biological treatment, reverse osmosis, ozonation, filtration, adsorption on solid phases, incineration, and coagulation. However, each of the methodologies has its own advantages and limitations. The recent research demonstrates that advanced oxidation processes (AOPs) based on photocatalysts are valuable and this method benefits complete mineralization of organic molecules into nontoxic CO2 and H2O at the atmospheric conditions by generating active species such as hydroxyl radicals (•OH) which can remove even non-biodegradable organic compounds from wastewater. These review papers give an overview of the enhanced photocatalytic activities of titanium dioxide (TiO2) based photocatalyst. An effort has also been made to give an overview of expedient photocatalytic activity of these supported nanoparticles for their potential application in environmental remediation. In this review article also, various methods used to enhance the photocatalytic characteristics of TiO2 including doping, coupling and other supporting are discussed. It is observed that the degradation of dyes depends on several parameters like pH, catalyst load, dye concentration, reaction temperature and scavengers on the degradation of dyes.

Study of the treatment of leachate after biodigestion using Electro-fenton method

Leachate contains many non-biodegradable organic compounds and nutrients with high concentrations, especially from urban waste landfills with long operating times (> 10 years), which affects the human health and environmental quality. Electro-Fenton is one of the advanced oxidation processes (AOPs) that has been recently studied for the treatment of many persistent organic compounds in water. In this study, post-biological leachate (continuous flow biological tank) was treated using Electro-Fenton method with heterogeneous catalysts as Iron (II) Sulfide and Iron Oxide on two electrodes Ti/IrO2-Ta2O5 and Ti/RuO2. The effect of different pH conditions on the pollutant removal efficiency in landfill leachate was studied. The results show that Ti/IrO2-Ta2O5 electrode and Iron (II) Sulfide catalyst obtain better leachate treatment performance than the others under the same experimental conditions. The heterogeneous Electro-Fenton process was capable of removing 71% of chemical oxygen demand (COD), 88% of total organic carbon (TOC), 89% of total nitrogen (TN), 93% of ammonium nitrogen N-NH4 + and 99% color at Ti/IrO2-Ta2O5 electrode and Iron (II) Sulfide catalyst at a pH 3, current density 333 mA/cm2 after 90 minutes of electrolysis. The results showed that the Electro-Fenton method capable effective treatment of pollutants in the post-biological leachate in the future.

Characteristics of textile waste water of Bhilwara (Rajasthan) and its photocatalytic bleaching with SnO2 catalyst

During the last decade, Bhilwara has developed into a leading place in the textile industry in India. The water used in textile industry is almost entirely discharged as waste. The effluents are very complex, containing salt, surfactants, ionic metals and their metal complexes, toxic organic chemicals, biocides, and toxic anions, which are harmful to both flora and fauna existing on our planet. Degradation of these non-biodegradable organic compounds is not possible by conventional treatment processes. The analysis of waste water with different quality parameters and photocatalytic bleaching was examined by using UV light in photochemical reactor with SnO2 catalyst.

Immediate one-step lime precipitation and atmospheric carbonation as pre-treatment for low biodegradable and high nitrogen wastewaters: A case study of explosives industry

The treatment of some industrial wastewaters is complex, since they usually contain complex non-biodegradable organic compounds or toxic compounds which are not easily treatable. These compounds are not removed by biological treatment in wastewater treatment plants and they may affect the removal of ammonium, nitrate, organic nitrogen by these treatment systems. Therefore, this research proposes a new and innovative low-cost and easy-to-apply pre-treatment to treat low biodegradable and high nitrogen wastewaters, using explosive wastewaters as case study. The pre-treatment is composed by immediate one-step lime precipitation (IOSLM) and atmospheric CO2 carbonation (AC) processes. The novelty of the proposed pre-treatment is based firstly on the use of one reactant (hydrated lime) at high concentrations, added in one step, that produces immediately an abundant and insoluble precipitate able to sweep the organic matter and other contaminants from wastewater in a short time and ensure conditions (pH and Ca2+) for the AC process. Secondly, the AC process uses the sludge produced in IOSLM to keep pH high for longer, allowing ammonia removal while simultaneously the pH is reduced by spontaneous reactions with atmospheric CO2. IOSLM results showed 92.1 %, 98.2 % and 100 % of organic matter, oils and fats, and organic nitrogen removals, respectively, for the optimal hydrated lime dose (7.76 g L−1). In AC process 61 % of ammonium nitrogen was removed and pH reduced to 8.1 in 10 days.

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).

INVESTIGATION OF ELECTROCOAGULATION AND ELECTROOXIDATION METHODS OF REAL TEXTILE WASTEWATER TREATMENT

Industrial wastewaters are becoming a bigger problem every day depending on the development of the industry and technology. The textile industry discharges a large amount of wastewater containing non-biodegradable organic compounds and inorganic chemicals to the environment after various steps of production processing. Electrochemical technologies such as electrochemical oxidation, electrochemical reduction, indirect electro-oxidation with strong oxidants and electrocoagulation have received considerable attention for treating dye wastewaters during last decade. In this study, it was investigated the treatability of wastewater from textile industry by electrochemical treatment methods. Effect of important operating parameters such as, electrode type and combination (Al-Al, Fe-Fe, Al-Fe, Fe-Al, Pt-Fe), pH, reaction time and potential were investigated on removal efficiency of color and chemical oxygen demand (COD). The study was performed by both electrocoagulation and electrooxidation method using real textile wastewater. The initial color, and COD concentrations of the wastewater were 395 Pt-Co and 1040 mg/L, respectively. At the end of the electrocoagulation experiments, concentrations of color and COD were decreased to 28 Pt-Co and 115 mg/L, respectively. Results showed that at pH 3 and 6 V potential, up to 93% color and 89% COD removal efficiencies were obtained in the reactor consisting of Fe-Fe electrodes. COD and color were removed at the rate of 88% and 92%, respectively in the study done with Al-Al couple at 10 V in natural pH (6.96). COD removal was achieved in the ratio of 93% at 6V as a result of the electrooxidation study with a couple of Pt-Fe electrodes. The study showed that the removal process was promising and it was reached to the discharge limit values for the color and COD with each electrode couple specified in the regulation.

Aqueous Benzene Oxidation in Low-Temperature Plasma of Pulsed Corona Discharge

AbstractWastewaters polluted with non-biodegradable volatile organic compounds (VOCs), such as aromatic substances, present a growing problem meeting no adequately affordable technological response. Low-temperature plasma generated in the gas-phase pulsed corona discharge (PCD) presents competitive advanced oxidation technology in abatement of various classes of pollutants, although the process parameters, the pulse repetition frequency and the liquid spray rate, require optimization. The experimental research into aqueous benzene oxidation with PCD was undertaken to establish the impact of the parameters to the energy efficiency. The oxidation reaction was found under the experimental conditions to mostly proceed in the gas phase showing little influence of the pulse repetition frequency and the gas-liquid contact surface. Oxidation of benzene and, presumably, other volatile pollutants in the volume of PCD reactor compartment presents an effective strategy of aqueous VOCs abatement.

Identification of residual non-biodegradable organic compounds in wastewater effluent after two-stage biochemical treatment

AbstractThe main non-biodegradable compounds (soluble microbial product – SMP) of wastewater from the Maotai aromatic factories, located in the Chishui river region, were analyzed by UV spectroscopy, and by solid-phase extraction followed by gas chromatography coupled to mass spectrometry, after a two-stage biochemical treatment. The UV-Vis spectra revealed that the wastewater contained two double-bonds in conjugated systems (conjugated diene or α, β- unsaturated ketone, etc.) and simple non-conjugated chromophores containing n electrons from carbonyl groups or the like. The residual organic non-biodegradable substances were identified using SPE-GC/MS analysis as complex polymers containing hydroxyl, carbonyl, and carboxyl functional groups with multiple connections to either benzene rings or heterocyclic rings. As these compounds are difficult to remove by conventional biochemical treatments, our findings provide a scientific basis for the design of efficient new strategies to remove SMP from wastewater.

Biodegradability Enhancement of Papermaking Wastewater by Electron Beam Irradiation

Papermaking wastewater is one of six industry polluted sources. It generally contains various pollutants which can cause many problems during biological treatment. The biodegradability of papermaking wastewater was enhanced by electron beam irradiation with an activated sludge process. The value of the BOD5/COD ratio increased at a 20kGy dose. The non-biodegradable organic compounds were converted into biodegradable compounds. High organic removal efficiencies and high microbial activities were achieved in activated sludge process. The application of an integrated system can be a powerful process which contains electron beam irradiation and a biological treatment to papermaking wastewater.

촉매성 산화물 전극을 이용한 페놀의 전기화학적 분해

Electrochemical degradation of phenol was evaluated at DSA (dimensionally stable anode), JP202 (Ru, 25%; Ir, 25%; other, 50%) electrode for being a treatment method in non-biodegradable organic compounds such as phenol. Experiments were conducted to examine the effects of applied current (1.0~4.0 A), electrolyte type (NaCl, KCl, <TEX>$Na_2SO_4$</TEX>, <TEX>$H_2SO_4$</TEX>) and concentration (0.5~3.0 g/L), initial phenol concentration (12.5~100.0 mg/L) on phenol degradation and <TEX>$UV_{254}$</TEX> absorbance as indirect indicator of by-product degraded phenol. It was found that phenol concentration decreased from around 50 mg/L to zero after 10 min of electrolysis with 2.5 g/L NaCl as supporting electrolyte at the current of 3.5 A. Although phenol could be completely electrochemical degraded by JP202 anode, the degradation of phenol COD was required oxidation time over 60 min due to the generation of by-products. <TEX>$UV_{254}$</TEX> absorbance can see the impact of as an indirect indicator of the creation and destruction of by-product. The initial removal rate of phenol is 5.63 times faster than the initial COD removal rate.

산소-플라즈마 방전을 이용한 수중의 페놀 제거

Decomposition of non-biodegradable contaminants such as phenol contained in water was investigated using a dielectric barrier discharge (DBD) plasma reactor in the aqueous solutions with continuous oxygen bubbling. Effects of various parameters on the removal of phenol in aqueous solution with high-voltage streamer discharge plasma are studied. In order to choose plasma gas, gas of three types (argon, air, oxygen) were investigated. After the selection of gas, effects of 1st voltage (80 ~ 220 V), oxygen flow rate (2 ~ 7 L/min), pH (3 ~ 11), and initial phenol concentration (12.5 ~ 100.0 mg/L) on phenol degradation and change of absorbance were investigated. Absorbance of can be used as an indirect indicator of phenol degradation and the generation and disappearance of the non-biodegradable organic compounds. Removal of phenol and COD were found to follow pseudo first-order kinetics. The removal rate constants for phenol and COD of phenol were and , respectively.

Bismuth-modified rectorite with high visible light photocatalytic activity

Herein, we reported an ultrasonic-assisted synthesis of bismuth-modified rectorite with high visible light-induced photocatalytic activity. The as-synthesized samples were characterized by XRD, FT-IR, FESEM, TEM, BET, and UV–vis DRS techniques. Two toxic and nonbiodegradable organic compounds, Rhodamine B (RhB) and 2,4-dichlorophenol (DCP), were chosen as the target pollutants to characterize the adsorption performance and photocatalytic activity. The results showed that the prepared samples possessed strong adsorbility and exhibited high efficient photocatalytic activity under visible light irradiation. The excellent photocatalytic activity of bismuth-modified rectorite was ascribed to the strong adsorption ability, the interconnected heterojunction of Bi2O3 and Bi5O7NO3, and the produced OH. Finally, the possible mechanism was presented.

순환식 유전체 장벽 플라즈마 반응기를 이용한 수중 페놀 처리

Objectives: The purpose of this study was evaluating the applicability of the circulation dielectric barrier plasma process (DBD) for efficiently treating non-biodegradable wastewater, such as phenol. Methods: The DBD plasma reactor system in this study consisted of a plasma reactor (discharge, ground electrode and quartz dielectric tube, external tube), high voltage source, air supply and reservoir. Effects of the operating parameters on the degradation of phenol and absorbance such as first voltage (60-180 V), oxygen supply rate (0.5-3 l/min), liquid circulation rate (1.5-7 l/min), pH (3.02-11.06) and initial phenol concentration (12.5-100 mg/l) were investigated. Results: Experimental results showed that optimum first voltage, oxygen supply rate, and liquid circulation rate on phenol degradation were 160 V, 1 l/min, and 4.5 l/min, respectively. The removal efficiency of phenol increased with the increase in the initial pH of the phenol solution. To obtain a removal efficiency of phenol and COD of phenol of over 97% (initial phenol concentration, 50.0 mg/l), 15 min and 180 minutes was needed, respectively. Conclusions: It was considered that the absorbance of for phenol degradation can be used as an indirect indicator of change in non-biodegradable organic compounds. Mineralization of the phenol solution may take a relatively longer time than that required for phenol degradation.

수처리용 유전체 장벽 방전 플라즈마 반응기 개발

Non-thermal plasma processing using a dielectric barrier discharge (DBD) has been investigated as an alternative method for the degradation of non-biodegradable organic compounds in wastewater. The active species such as OH radical, produced by the electrical discharge may play an important role in degrading organic compound in water. The degradation of N, N-Dimethyl-4-nitrosoaniline (RNO) was investigated as an indicator of the generation of OH radical. The DBD plasma reactor of this study consisted of a plasma reactor, recycling pump, power supply and reservoir. The effect of diameter of external reactor (15 ~ 40 mm), width of ground electrode (2.5 ~ 30 cm), shape (pipe, spring) and material (copper, stainless steel and titanium) of ground electrode, water circulation rate (3.1 ~ 54.8 cm/s), air flow rate (0.5 ~ 3.0 L/min) and ratio of packing material (0 ~ 100 %) were evaluated. The experimental results showed that shape and materials of ground were not influenced the RNO degradation. Optimum diameter of external reactor, water circulation rate and air flow rate for RNO degradation were 30 mm, 25.4 cm/s and 4 L/min, respectively. Ground electrode length to get the maximum RNO degradation was 30 cm, which was same as reactor length. Filling up of glass beads decreased the RNO degradation. Among the experimented parameters, air flow rate was most important parameters which are influenced the decomposition of RNO.