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In the present study, sequential anaerobic–aerobic treatment was used for the enhanced degradation of selected nitrophenols. Five identical reactors were used to assess the degradation of 2-nitrophenol and 2,4-dinitrophenol. Reactor 1 was used as control, and another four reactors were operated in anaerobic phase followed by sequential aerobic trea...
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... Fig. 5, for the sequential aerobic reactor, it can be seen that COD removal for 5 mg/l of 2-NP, it was 95%, for 2,4-DNP, it was 90%; for 10 mg/l of 2-NP, it was 85%, for 2,4-DNP, it was 80%; for 20 mg/l of 2-NP, it was 80%, for 2,4-DNP, it was 80%; and for 40 mg/l of 2-NP, it was 65% and for 2,4-DNP, it was 60%. And it can be seen that as the ...
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Introduction: Nitrophenol compounds are toxic compounds found in industrial wastewaters. 2,4-dinitrophenol is the most dangerous compound among phenolic compounds. The aim of this study was to evaluate the removal of 2,4-DNP from wastewater by microwaved dried sludge adsorbent.
Materials and Methods: The results of 2,4-DNP removal were discontinuou...
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... Nitrophenol is usually used as a raw material for the preparation of pesticides and dyes. [1][2][3][4] Due to its high toxicity and difficulty in degradation, nitrophenol has become a common organic pollutant in waste water. [5][6][7][8] Notably, 4-NP is an important kind of nitrophenol compound. ...
Ag(0) nanoparticles were immobilized on various pyridine salt, imidazole salt and quaternary ammonium functionalized polyacrylonitrile fibers (PANFs) to prepare Ag(0)-immobilized fiber catalysts. The catalytic activities of these immobilized catalysts for 4-nitrophenol (4-NP) reduction were detected. Among them, the quaternary ammonium fiber with butyl group immobilized Ag(0) nanoparticle catalyst PANQA-C4F-Ag(0) showed the best catalytic activity, and can effectively catalyze 4-nitrophenol (4-NP) reduction with a high conversation rate of 99.6%. Furthermore, PANQA-C4F-Ag(0) can be easily recovered, and it was reused 20 times with little decrease in catalytic activity and moderate Ag retention (53.5%). Notably, the cationic groups in the functionalized fibers can stabilize Ag(0) nanoparticles through electrostatic interactions and steric effects, and play an important role in phase transfer catalysis. Accordingly, possible mechanisms for the 4-NP reduction catalyzed by PANQA-C4F-Ag(0) were proposed.
The widely applied aromatic nitration in modern industry leads to toxic p-nitrophenol (PNP) in environment. Exploring its efficient degradation routes is of great interests. In this study, a novel four-step sequential modification procedure was developed to increase the specific surface area, functional group, hydrophilicity, and conductivity of carbon felt (CF). The implementation of the modified CF promoted reductive PNP biodegradation, attaining 95.2 ± 0.8% of removal efficiency with less accumulation of highly toxic organic intermediates (e.g., p-aminophenol), compared to carrier-free and CF-packed biosystems. The constructed anaerobic-aerobic process with modified CF in 219-d continuous operation achieved further removal of carbon and nitrogen containing intermediates and partial mineralization of PNP. The modified CF promoted the secretion of extracellular polymeric substances (EPS) and cytochrome c (Cyt c), which were essential components to facilitate direct interspecies electron transfer (DIET). Synergistic relationship was deduced that glucose was converted into volatile fatty acids by fermenters (e.g., Longilinea and Syntrophobacter), which donated electrons to the PNP degraders (e.g., Bacteroidetes_vadinHA17) through DIET channels (CF, Cyt c, EPS) to complete PNP removal. This study proposes a novel strategy using engineered conductive material to enhance the DIET process for efficient and sustainable PNP bioremediation.
Domestic sewage is responsible for approximately 80% of the water pollution. Industrial wastewater discharged from the sugar industry, pulp and paper industry, textile industry, electroplating systems, pesticides, etc., contributes to the water pollution. Microorganisms which cause diseases, popularly known as pathogens, are spreading disease directly among humans from the pollution. It has become a necessity to treat impure water so that it can be used for agricultural, domestic, and industrial purposes. Usually water treatment plants are comprised of the following steps: preliminary treatment, disinfection, sedimentation, coagulation, flocculation and filtration. Applications of membrane processes are removing natural organic material, pathogens, bacteria, and other small solid particles which can impart color, odor, and taste. The importance and characteristics of membrane processes such as reverse osmosis, ultrafiltration (UF), microfiltration (MF), and nanofiltration for are clearly evident. The process of decomposition of a substance into its constituent elements is termed the biodegradation process, another treatment for degrading waste pollutants. Microorganisms (bacteria and fungi) naturally carry out biodegradation. The latest progress being made is with the membrane bioreactor. This is a combination of a filtration and biological unit, also defined as perm selective (MF/UF) along with a biological process. The chapter concludes with future challenges for waste remediation with biological processes.
