WATER POLLUTION (S SENGUPTA, SECTION EDITOR (original) (raw)
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Application of oxidation processes in the purification of wastewaters from phenolic compounds
Revue Roumaine de Chimie
Natural phenolic compounds are significant component of the human diet, as they are present in fruits and vegetables, and they have very important biological activity in the living organisms. Because of their structure, they are subject of numerous oxidation processes, such as autoxidation, but are easily to oxidize in presence of various oxidizing agents and enzymes. Many authors have been investigating phenolic oxidation processes, and have successfully identified their pathways and a significant number of intermediates and products generated by these processes. Also, particular attention has been made to the effects of these processes on food quality and other biological processes in living organisms. Phenols are persistent pollutants of water systems from various agricultural activities and industrial wastewater discharges. It is known that the presence of phenolic compounds in water supplies and industrial effluents directly affects natural processes in the environment due to their toxicity and natural ability to decompose. This property, to easily oxidize and, as a result of it, to mineralize, is practically useful for the treatment of the wastewaters, so it is of global concern to manage the best technology to remove phenols and other organic pollutants, assisted with the oxidation processes. In the aspect of treatment of wastewaters polluted with phenols, we reviewed oxidative processes such as autoxidation, enzyme-catalyzed oxidation, photo-oxidation, electrochemical oxidation and oxidation by Fenton's reagent and, based on the literature data, we presented advantages and disadvantages of these processes compared to each other.
Phenolic Compounds in Water: Sources, Reactivity, Toxicity and Treatment Methods
Phenolic Compounds - Natural Sources, Importance and Applications, 2017
Phenolic compounds exist in water bodies due to the discharge of polluted wastewater from industrial, agricultural and domestic activities into water bodies. They also occur as a result of natural phenomena. These compounds are known to be toxic and inflict both severe and long-lasting effects on both humans and animals. They act as carcinogens and cause damage to the red blood cells and the liver, even at low concentrations. Interaction of these compounds with microorganisms, inorganic and other organic compounds in water can produce substituted compounds or other moieties, which may be as toxic as the original phenolic compounds. This chapter dwells on the sources and reactivity of phenolic compounds in water, their toxic effects on humans, and methods of their removal from water. Specific emphasis is placed on the techniques of their removal from water with attention on both conventional and advanced methods. Among these methods are ozonation, adsorption, extraction, photocatalytic degradation, biological, electro-Fenton, adsorption and ion exchange and membrane-based separation.
Phenol wastewater remediation: Advanced oxidation processes coupled to a biological treatment
Water Science and Technology, 2007
Nowadays, there are increasingly stringent regulations requiring more and more treatment of industrial effluents to generate product waters which could be easily reused or disposed of to the environment without any harmful effects. Therefore, different advanced oxidation processes were investigated as suitable precursors for the biological treatment of industrial effluents containing phenol. Wet air oxidation and Fenton process were tested batch wise, while catalytic wet air oxidation and H 2 O 2promoted catalytic wet air oxidation processes were studied in a trickle bed reactor, the last two using over activated carbon as catalyst. Effluent characterisation was made by means of substrate conversion (using high liquid performance chromatography), chemical oxygen demand and total organic carbon. Biodegradation parameters (i.e. maximum oxygen uptake rate and oxygen consumption) were obtained from respirometric tests using activated sludge from an urban biological wastewater treatment plant (WWTP). The main goal was to find the proper conditions in terms of biodegradability enhancement, so that these phenolic effluents could be successfully treated in an urban biological WWTP. Results show promising research ways for the development of efficient coupled processes for the treatment of wastewater containing toxic or biologically non-degradable compounds.
Degradation of Phenol Containing Wastewater by Advance Catalysis System – A Review
Annual Research & Review in Biology, 2015
Phenols and their derivatives are broadly distributed as a characteristic pollutant due to its frequent presence in effluents of many industrial processes. Most of the phenolic compounds are toxic to living organisms as well as environment, even at low concentration. These phenol derivatives introduced into the environment, they may accumulate in soil and water. This signifies enormous environmental issues and if they enter into the food cycle through that polluted water, they can cause numerous health problems to humans. They show adverse effects on human being which are short term as well as long term effects. Enzymes are good biocatalysts. We discussed in this study about an enzymatic treatment on effluent containing phenols. Phenol degrading enzymes and their delivery systems in effluent shortly discussed. We focused only on the phenol degrading peroxidase enzyme. Numerous researchers extracted the peroxidase from various plants and their parts. Many researchers have reported that methods of biodegradation of phenols by peroxidase with additives to retain the specificity of peroxidase through their whole reaction. In conclusion, the plants having a great source of enzymes, such as horseradish roots, soybean seed hulls and turnip roots are having rich sources of enzymes. The enzymes are time saving and inexpensive catalyst.
Phenolic Wastewaters: Definition, Sources and Treatment Processes
InTech eBooks, 2017
This chapter aims the state of the art concerning the development of advanced oxidation processes (AOPs) for treatment of organic-aqueous effluent for the reuse of liquid water. It presents the major oxidative processes applied for industrial and domestic treatment, where the effluents are often contaminated by phenolic compounds. A special emphasis is given to a relatively new technique called direct contact thermal treatment (DiCTT) that has the advantages of conventional AOP without its inconveniences. The DiCTT process is characterized by the generation of hydroxyl radicals (•OH) by combustion of natural gas, its compact installation and easy operation, being able to be used in offshore oil-exploration platforms, where natural gas is available and the space is reduced. Also, in this chapter, original results on the treatment of the DiCTT technique are presented, which are considered unconventional, by evaluating the oxidation and the conversion of the total organic carbon (TOC) of phenolic compounds at low temperature and atmospheric pressure, with identification and quantification of the intermediate compounds, using high-performance liquid chromatography (HPLC), which may be more toxic than the original pollutants.
Molecules, 2022
Advanced oxidation processes (AOPs) have been introduced to deal with different types of water pollution. They cause effective chemical destruction of pollutants, yet leading to a mixture of transformation by-products, rather than complete mineralization. Therefore, the aim of our study was to understand complex degradation processes induced by different AOPs from chemical and ecotoxicological point of view. Phenol, 2,4-dichlorophenol, and pentachlorophenol were used as model pollutants since they are still common industrial chemicals and thus encountered in the aquatic environment. A comprehensive study of efficiency of several AOPs was undertaken by using instrumental analyses along with ecotoxicological assessment. Four approaches were compared: ozonation, photocatalytic oxidation with immobilized nitrogen-doped TiO2 thin films, the sequence of both, as well as electrooxidation on boron-doped diamond (BDD) and mixed metal oxide (MMO) anodes. The monitored parameters were: removal...
Rasayan Journal of Chemistry, 2023
Water pollution is one of the main causes of imbalance in the Earth's ecosystem. Plant effluents have different compositions and concentrations of pollutants, depending on the kind of production and the water supply and sewerage system. The main sources of phenol-containing wastewater are coking plants, coke oven gas plants, semi-coking plants, gas generating stations, wood heat treatment plants, and the synthesis of artificial liquid fuels. They can also be the result of the activities of metallurgical plants, oil refineries, enterprises for the recovery of rubber, and the production of film, phenolphthalein, salicylic acid, and salol. Phenolic waters are dangerous for fishery reservoirs, worsen the organoleptic properties of water, and disrupt the natural processes of water self-purification. Water contaminated with phenolic wastewater contributes to the deterioration of groundwater quality. Thus, high-quality water purification from phenol to reduce/maximum prevent the ingress of phenols into industrial and drinking water is an urgent problem. Methods for deep treatment of phenolic wastewater are regenerative and destructive. The technology for purifying phenolic wastewater using the processes of oxidation of phenolic compounds with atmospheric oxygen on heterogeneous catalysts is one of the most promising technologies. Nanodisperse catalysts used to treat wastewater containing aromatic hydrocarbons and, in particular, phenolic compounds, should provide a high rate of oxidation of phenolic pollutants, efficient oxidation of a wide range of compounds with various functional groups, low cost, and long service life without a noticeable loss of catalytic properties, as well as high mechanical strength and immunity to catalytic poisons. Catalysts based on various metals and metal oxides and carrier-based systems, oxide-based magnetic composites show good efficiency in the oxidation of phenol with oxygen.
Phenolic compounds are widely used in industries and other daily life for various purposes and enter in the industrial effluent and ultimately the final disposal of this effluent which contain phenol compounds are different water bodies which may get contaminated through the continuous disposal of the these effluents. Highly toxicity and carcinogenicity of these compounds can cause considerable effects on the aquatic ecosystem and human health. The main focus of this research is to study the efficiency of photocatalytic degradation of phenolic compounds in aquatic solution by using UV and combination of UV/TiO2; this is one of the Advanced Oxidation Processes (AOPs), which are techniques for the degradation of detrimental organic pollutants resistant to traditional treatment methods. In this experimental research the phenol concentration used was 30mg/L (constant) and contact time, pH and amount of TiO2 were considered in photocatalytic system as the basic variables affecting the removal efficiencies. Phenol concentrations before and after the treatment were determined spectrophotometerically at 500 nm. The removal efficiencies of phenol by only UV exposure is negligible, combination of UV and TiO2 can cause higher efficiencies of phenol removal. By UV exposure only 7, 6 & 4 % of phenol was degraded although the UV/TiO2degrades 17, 13 & 30 % of phenol in 2 hours at pH 3, 7 & 11 respectively. It was found that increasing the value of variables in the experiment can maximally remove the phenol therefore combined UV/TiO2 process may be applied as an effective process for the removal of phenol from aquatic clarification such as industrial wastewaters and polluted water resources.
IOSR Journal of Environmental Science, Toxicology and Food Technology
The rising population, increasing urbanization, rapid industrialization and spread of more water intensive life styles are making water resources scarce and polluted. waste waters of various industries such as textile, petroleum, refining, plastics etc. contain phenolic compounds. (1) Due to toxicity of these compounds to aquatic organisms and humans, it is necessary that phenolic compounds are removed from contaminated water before they are discharged into any natural stream of water. In this study, the removal of phenolic contaminants was undertaken biologically by using peroxidase enzyme. This enzyme was extracted from various natural sources like carrot, radish, broccoli, beetroot, soybean as well as some microorganisms like Pseudomonas aeruginosa NCIM 2200, Bacillus subtilis and Staphylococcus aureus NCIM 2079. Peroxidases catalyse the oxidation of phenols by hydrogen peroxide which results in the formation of water insoluble polymers which can be separated by coagulation, sedimentation etc. The prime objective of this work was to develop an eco-friendly, economical and effective biological method of removing phenolic pollutants from the waste water. The most effective peroxidase enzyme was white radish peroxidase which showed maximum enzyme activity. It exhibited above 90% phenol removal potential. This compound could be tested further by making certain formulations.