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4-chlorophenol (4-CP) is one of the most important phenolic compounds in various industries. Different technologies have been applied for 4-CP degradation in aquatic environment. Current study is focused on 4-CP degradation by the combination of UV and MnO 2 for peroxymonosulfate (PMS) activation to degrade 4-CP. MnO 2 nanoparticles were synthesized and characterized by X-ray powder diffraction, field emission scanning electron microscope, energy-dispersive X-ray spectroscopy and Brunauer–Emmett–Teller (BET). The effects of operational parameters were evaluated and their results indicated the highest performance in pH = 4.0, 1 mM PMS and 0.25 g/L MnO 2 . Complete degradation of 4-CP during 30 min was a representative of high performance of UV/MnO 2 /PMS. Kinetic study showed that the co-activation of PMS by MnO 2 and UV had a synergistic effect on 4-CP degradation. MnO 2 could keep its performance at least 4th cycle while Mn leaching was negligible. Bicarbonate and hydrogen phosphate ions suppressed the performance of the process in degradation of 4-CP whereas no change was observed in the presence of chloride ions. Quenching experiments showed that hydroxyl radical was dominant radical for 4-CP degradation. The results of toxicity and biodegradability tests indicated that treated sample by UV/MnO 2 /PMS process was relatively non-toxic and easy biodegradable. The function of UV/MnO 2 /PMS system for treatment of real industrial wastewaters (pharmaceutical and petrochemical wastewaters) was tested. Finally, it was concluded that hybrid activation of PMS can be a new perspective for PMS-based processes to treat industrial wastewater. [ABSTRACT FROM AUTHOR]

Utilization of hybrid treatment schemes involving advanced oxidation processes and hydrodynamic cavitation in the wastewater treatment forms the prime focus of the present work. The initial phase of the work includes analysis of recent literature relating to the performance of combined approach based on hydrodynamic cavitation (HC) for degradation of different pollutants followed by a detailed investigation into degradation of 2,4,6-trichlorophenol (2,4,6-TCP). The degradation of the priority pollutant, 2,4,6-TCP, using combination of HC based on slit-venturi used as the cavitating device, ozone and H 2 O 2 has been investigated. The effect of operating pressure (2–5 bar) and initial pH (3 −1 1) have been investigated for the degradation using only HC. The degradation using only ozone (100–400 mg/h) and only H 2 O 2 has also been studied. The efficacy of the combined operation of HC + O 3 at different ozone flow rates (100–400 mg/h) and the combined operation of HC + H 2 O 2 at different loadings of H 2 O 2 (2,4,6-TCP:H 2 O 2 as 1:1–1:7) have been subsequently investigated. The degradation efficacy has also been established for the combined treatment strategies of O 3 + H 2 O 2 and HC + O 3 +H 2 O 2 at the optimum conditions of temperature as 30 °C, inlet pressure of 4 bar and initial pH of 7. Extent of 2,4,6-TCP degradation, TOC and COD removal obtained for HC + O 3 process were 97.1%, 94.4% and 78.5% respectively whereas for O 3 + H 2 O 2 process, the values were 95.5%, 94.8% and 76.2% and for HC + O 3 + H 2 O 2 process the extent of reduction were 100%, 95.6% and 80.9% in the same order. The combined treatment approach as HC + O 3 + H 2 O 2 was established as the most efficient approach for complete removal of 2,4,6-TCP with near complete TOC removal. [ABSTRACT FROM AUTHOR]

The presence of chlorophenols (CP) in industrial wastewater is a major concern due to their microbial toxicity. The present study was performed to investigate the efficacy of advanced oxidation process (i.e., conventional and modified Fenton's process) for the degradation of 4-chlorophenol (4-CP) in an aqueous solution (concentration = 200 mg L−1) under varying reaction conditions. The decomposition of 4-CP was confirmed by chemical oxygen demand (COD) reduction, total organic carbon (TOC) reduction, detection of low molecular weight carboxylic acids (such as oxalic, acetic, formic and malonic) and Cl- concentration in the treated 4-CP aqueous solution. The maximum COD and TOC reductions were 74% and 42% after 30 min of Fenton reaction at an initial pH, Fe2+ concentration, and H2O2 to Fe2+ molar ratio of 3.0, 1.26 mM and 20, respectively which were found to increase to 79 and 55%, respectively when Cu2+ was also added with Fe2+ during modified Fenton process. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1734-1742, 2017 [ABSTRACT FROM AUTHOR]

The effectiveness of ozone and ozone-UV processes on effluents containing chlorophenol was evaluated. Experiments were performed using 3.06 mM of 2,5-dichlorophenol in distilled water and wastewater at pH 7 with ozone dose of 37 mg/L. An ozone dose of 1.2 g/h was effective in completely degrading 2,5-dichlorophenol and reducing the toxicity of its by-products. Overall, ozone-UV process was more effective in the oxidation of 2,5-DCP. Ozone-UV treatment of wastewater showed the highest mineralization (53%), dechlorination (100%), COD removal (75%), and biodegradability (BOD5/COD = 0.85). The organic/inorganic matters in wastewater seem to have a positive effect on the oxidation of 2,5-DCP and supports the use of ozone and ozone-UV processes for industrial effluent treatment. [ABSTRACT FROM AUTHOR]

The influence of the chemical oxygen demand (COD)/N ratio on the performance of a granular sequencing batch reactor (SBR) system degrading 4-chlorophenol (4CP) was evaluated. Two SBR were operated under the same conditions, but with two different COD/N ratios, 150 and 20. It was observed that successful granule formation was obtained when activated sludge was initially acclimated to 4CP without using a co-substrate, and then hydrodynamic pressure selection was used to generate granules. Removal efficiencies of 4CP were >99.7%, and the specific degradation rates were up to 87 mg 4CP/(mg volatile suspended solid) per hour. It was found that nitrogen limitation had no effect on the removal efficiencies of 4CP and on the specific degradation rates. However, the results indicated that under nitrogen-limited conditions, higher granule sizes and a denser biomass were promoted. [ABSTRACT FROM AUTHOR]

Highlights: [•] Full degradation of p-chlorophenol by B/Fe/Pd nanoparticles and Bacillus fusiformis. [•] p-CP was dechlorinated by B/Fe/Pd and the formation of the phenol. [•] Phenol was biodegraded by BF Bacillus fusiformis. [•] A integrated approach using both B–Fe/Pd nd sequential biodegradation. [Copyright &y& Elsevier]

One of the most studied process for the decomposition of phenolic compounds involves the use of different microbial species or consortia. The main drawback of biological methods is the possible inhibitory effect of high concentrations of phenolic compounds impacting on the microorganisms. To overcome these difficulty bacteria can be acclimated to higher concentrations of phenols and the use of supplemental carbon sources. In this work a Pseudomonas putida strain isolated from a waste treatment plant receiving phenolic waste was tested for 4-chlorophenol removal using 1% (w/v) glucose as a co-substrate. Total removal of 4-chlorophenol concentrations of 50, 150 and 200 mg l-1 were obtained in approximately 27, 53 and 93 h respectively. For a higher 4-chlorophenol concentration of 250 mg l-1, only 22% of degradation was obtained suggesting that at this high concentration, the 4-chlorophenol exerts an inhibitory effect on the bacteria [ABSTRACT FROM AUTHOR]