Yelena Veressinina

Ozonation, Ozone/UV and UV/H2O2 Degradation of Chlorophenols

Abstract The performance of the O3, O3/UV and UV/H2O2 processes for degradation of six chlorophenols (4-chlorophenol, 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol) were studied in laboratory reactors. Comparative study showed that chlorophenols can be degraded successfully by all of the methods studied, whilst traditional ozonation at high pH was determined to be the most effective method to treat chlorophenols. Even though the molar absorptivity of chlorophenols is known to be relatively high in the UV-region, the combination of UV-radiation with ozone did not accelerate the degradation of chlorophenols further. The toxicity of degradation products formed during ozonation of chlorophenols has been compared with the toxicity of pure chlorophenols utilizing Daphnia magna 24 hours test. Ozonation of chlorophenols yielded less toxic or even nontoxic products for Daphnia magna compared with parent compounds.

Fenton Process for Landfill Leachate Treatment: Evaluation of Biodegradability and Toxicity

The single Fenton or the Fenton process implemented in combined scheme as a posttreatment after the ferric chloride coagulation was applied for leachate collected from a real waste disposal site. Depending on the ratios of H2 O2 /chemical oxygen demand, H2 O2 / Fe2+ , and pH, the Fenton oxidation or both the Fenton oxidation and the Fenton coagulation were involved in chemical oxygen demand reduction. The implementation of ferric chloride coagulation as a pretreatment stage or acidification of raw leachate did not result in the improvement of chemical oxygen demand reduction efficacy of the following Fenton process comparing with that obtained by the direct Fenton treatment of raw leachate. The direct Fenton treatment with a higher (3/1) H2 O2 /chemical oxygen demand ratio applied to raw leachate without pH preadjustment ( H2 O2 / Fe2+ =10/1 ) , produced more oxidized organic compounds (measured as dissolved organic carbon/chemical oxygen demand ratio), more biodegradable by-products (measured as a 7-day ...

Catalytic Ozonation of m-Dinitrobenzene

The efficiency of catalytic ozonation with homogeneous (containing dissolved ions of Fe2+, Mn2+, Cu2+, Ni2+, Co2+, V5+, Cr3+, Mo6+) and heterogeneous (MnO2, Ni2O3, Fe2O3, CuO, Al2O3, CoO, V2O5, Cr2O3, MoO3, TiO2) catalysts and non-accompanied ozonation was compared for degradation of m-dinitrobenzene (m-DNB). Several transition metals in homogeneous and heterogeneous form improved significantly the ozone performance for degradation of m-DNB. This improvement was found to be due to supplementary formation of reactive species (hydroxyl radicals) and better ozone utilization. The effects observed were found to be strongly dependent on the treatment conditions.

Combination of Ozonation and the Fenton Processes for Landfill Leachate Treatment: Evaluation of Treatment Efficiency

Single processes such as ozonation, ozone/hydrogen peroxide, Fenton and several combined treatment schemes were applied for leachate collected from a waste disposal site. The implementation of combined Fenton and ozonation processes resulted in the highest chemical oxygen demand removal (77% from initial value) among all the treatment methods applied, while biodegradability improvement was observed during the Fenton pre-treatment only. Some decrease of chemical oxygen demand was obtained during the single ozonation or combined schemes including ozone resulting in slight if any biodegradability improvement. The addition of hydrogen peroxide to ozonation did not enhance chemical oxygen demand, dissolved organic carbon or biochemical oxygen demand removal compared to ozone alone. Ferric chloride coagulation used as a pre-treatment stage did not improve subsequent chemical oxygen demand removal by ozonation or the Fenton processes. Taking into account the effective chemical oxygen demand, dissolved organic carbon removal and biodegradability improvement the single Fenton process seems to be a preferable treatment method for the leachate treatment. Some reduction in toxicity to Daphnia magna was observed after the application of the studied treatment methods.

Fenton treatment efficacy for the purification of different kinds of wastewater

The Fenton chemistry comprises both the classical Fenton reagent and its modification, so-called Fenton-like techniques, which have received great attention as a promising technology for wastewater treatment. In the present study real wastewater from different sources (leachate from oil shale semicoke landfill, pharmaceutical effluents from medical ointment production, municipal landfill leachate and wastewater originated from food-processing) were treated by means of Fenton/Fenton-like systems. The effectiveness of wastewater treatment was assessed by COD removal. Additionally, biodegradability improvement (BOD7/COD) and acute toxicity reduction of investigated wastewater samples were observed. The application of the Fenton chemistry to wastewater samples with different origin resulted generally in 70% or higher COD removal. Thus, the Fenton could be effectively applied both as a single treatment method and pre-treatment step to improve subsequent biodegradability of wastewater effluents.

Degradation of aqueous nitrophenols by ozone combined with UV-radiation and hydrogen peroxide

Abstract The degradation of nitrophenols with ozone and ozone combined with hydrogen peroxide and/or UV-radiation was studied. These combinations accelerated the degradation of nitrophenols and decreased the ozone specific consumption mostly at low pH values. O3/UV/H2O2 combination was the most effective for the degradation of nitrophenols. According to the Daphnia magna acute toxicity test, the treatment led to complete detoxification of nitrophenols. A high degree of nitrogen mineralization was achieved.

Cost Effectiveness of Ozonation and AOPs for Aromatic Compound Removal from Water: A Preliminary Study

The capital and operating costs for several aromatic compounds (phenanthrene, 2,4-dimethylphenol, 2,4,6-trichlorophenol, nitrobenzene) removal from polluted groundwater using ozonation and advanced oxidation have been estimated on the basis of the laboratory experiments in semibatch conditions. The pollutants initial concentration was in the range of 0.01–1.0 mM. In the calculations the polluted groundwater flow rate was taken 40 m3/h with the initial pH = 7.0. It is shown that polluted groundwater purification from the aromatic pollutants with the initial concentration in the range of 0.01–1.0 mM using ozonation and advanced oxidation is economically feasible.

Application of Ozonation, UV Photolysis, Fenton Treatment and other Related Processes for Degradation of Ibuprofen and Sulfamethoxazole in Different Aqueous Matrices

Abstract Two pharmaceuticals ibuprofen (IBP) and sulfamethoxazole (SMX) were treated with ozone and advanced oxidation processes (AOPs): UV photolysis, O3/H2O2, O3/UV, O3/H2O2/UV, H2O2/UV, the Fenton and photo- Fenton process. The efficacy of AOPs for degradation of pharmaceuticals as well as the impact of the matrix (pure water, urea and wastewater) on drugs’ decay was evaluated. The experimental study has been carried out using concentration of the pharmaceuticals in the level of 100 mg/L. IBP was more resistant to all types of treatment than SMX. Ozonation was effective for removal of SMX and IBP when carried out under alkaline conditions. The ultimate elimination of SMX could be achieved with UV photolysis, whereas more rapid removal of IBP was attained with H2O2/UV. The complete SMX removal and more than 90% IBP degradation by the ordinary Fenton treatment were reached with oxidant overdosing only. Additional UV-radiation improved substantially the performance of the Fenton oxidation for elimination of both pharmaceuticals. The elimination rates determined in the pure water cannot be directly used to predict the oxidation of SMX and IBP in the wastewater.