Ozonation And AOP Parameter Estimation From Countercurrent Film Absorber Data

Degradation of phenolic compounds in Kohtla-Järve oil shale ash dump wastewater (North-East Estonia) by O₃, O₃/UV, O₃/H₂O₂, O₃/H₂O₂/UV, O₃/TiO₂ and O₃/TiO₂/UV treatment in a countercurrent film absorber was studied experimentally. The mathematical model and the simulation algorithm of the processes were developed. The random search optimizer was applied to evaluate the values of reaction rate constant, mass transfer enhancement factor, stoichiometric coefficient and volatilization coefficient for organics into the process models. The evaluated coefficients for individual phenolic compounds, total content of phenolic compounds and COD for different oxidation systems are presented and discussed. “Operation” of the simulated film absorber (based on the evaluated coefficients) and the experimental column are compared.     

Azo Dye Ozonation Film Theory Utilization for Kinetic Studies

The ozonation kinetics of three azo dyes (Direct Yellow 27, Direct Blue 1 and Acid Black 52) in aqueous solution has been studied. Two types of reactors have been used, an agitated tank for studying the influence of variables and the stoichiometry, and an agitated cell for kinetic measurements. Both the film theory and the modes of ozone action on organic matter have been considered for obtaining the kinetic rate constants. A model of ozone absorption in the fast pseudo–m–th ozone order kinetic regime with two parallel reactions fits satisfactorily the experimental results. From it, the kinetic constants of both reactions have been evaluated.     

Ozonation Of Leachates From Aged Domestic Landfills

Ozonation was evaluated as a treatment process for domestic landfill leachates. Bench-scale batch and continuous flow experiments depicted that the process is effective in color removal but considerably less effective in TOC and ammonia removal. The high buffer capacity of the leachate maintained relatively constant pH through the process. Biodegradability of the leachate as measured by BOD/COD also improved.     

Identification Of Products Resulting From Ozonation Of Organtic Compounds In Water

Determination of ozonation by–products using five organic compounds and secondary effluents was carried out. Formaldehyde, acetaldehyde, propionaldehyde, furfural, methlyglyoxal, glyoxylic acid, and pyruvic acid were detected by gas chromatography of their 2,4–dinitrophenyl–hydrazones. Acetic acid, formic acid, and propionic acid were also detected. One–sixth to one–fifth of the total COD was accounted for by the TOD summations of formaldehyde, methylglyoxal, pyruvic acid and acetic acid produced by the ozonation of secondary effluents.     

Ozonation Of Wastewater Resulting From The Production Of Organochlorine Plaguicides Derived From DDT And Trichlorobenzene

In this work, a first step has been made in the characterization of the organic pollutants found in the residual water from the production of dicofol and tetradifon pesticides, derived from DDT and trichlorobenzene, respectively. The behavior of the effluent also was studied using degradation techniques - treatment with ozone and ozone combined with hydrogen peroxide - and the results compared by means of the pH, conductivity, TOC, COD, TOX, ecotoxicity, GC/ECD and GC/MS analysis of the samples after the treatment.     

Kinetics Of Competitive Ozonation Of Some Phenolic Compounds Present In Wastewater From Food Processing Industries

Ozonation of four phenolic compounds found in wastewater effluents from food manufacturing processes: Gallic (G-Ac) and p-hydroxybenzoic (pHB-Ac) acids, (+)-catechin ((+)-Cat) and tyrosol (Ty), has been carried out in ultrapure water. The results showed that the direct reaction between ozone and the organic compound seems to be the exclusive way of phenolic compounds elimination. A kinetic study of these reactions was completed by using a high concentration of phenolic substances (up to 3 g L^?1 total phenolic content) to simulate typical amounts of these compounds found in real wastewater. By means of a competitive method, rate constants of the direct reaction with ozone were determined at different pH. The following reactivity was found depending on pH: pHB-Ac < Ty < G-Ac < (+)-Cat in acidic conditions, pHB-Ac < Ty < G-Ac < (+)-Cat in neutral conditions and pHB-Ac < Ty for basic conditions. Finally, validation of the calculated rate constants was completed by checking the kinetic regime in which competitive reactions were developed.     

Efficiency Of Ozonation As A Unit Process In The Treatment Of Secondary Effluents From the Pulp And Paper Industry

Experiments were run in a batch reactor on samples of wastewater from pulping processes and paper making after biological treatment (secondary effluent). The samples then were treated in the following technological systems: ozonation alone, ozonation with alum or lime coagulation as a prior step, and ozonation with chlorination as a prior step. Of these, the coagulation-ozonation system was found to be the most effective, yielding high removal efficiencies.     

Kinetic Analysis On The Effects Of Dissolved Inorganic And Organic Substances In Raw Water On The Ozonation Of Geosmin And 2–MIB

The kinetics of geosmin and 2–MIB decomposition by ozonation in the presence of dissolved inorganic and organic substances were studied. As a first approximation, the decomposition rate of geosmin and 2–MIB were analyzed as a first–order reaction with respect to their concentration. The first–order rate constants decreased significantly with increase in the concentration of carbonate ion, free chlorine, alcohols and volatile fatty acids. Small amounts of humic acids or fulvic acids, however, enhanced the rate of decomposition. It was also demonstrated that the decomposition rates in natural waters were influenced mainly by the concentrations of carbonate and humic substances.     

Kinetic and Mechanistic Studies of the Ozonation of Alicyclic Amines

Studies about the ozonation of the polar and mobile alicyclic amines pyrrolidine, piperidine, morpholine and piperazine were carried out in model water at pH 7.0. According to a pseudo-first order rate law the reaction-rate constants were determined from the decrease of the amine concentration vs. the reaction time. The order of degradation of the alicyclic amines by ozone, resulting from the kinetic constants obtained, is piperazine > morpholine ? piperidine > pyrrolidine. The pH value of the water, the chemical structure of the amines and their pK_A values are recognized to be parameters influencing the reactionrates of the amines.     

Effect Of Ozonation On Some Physical and ChemicalProperties Of Aquatic Natural Organic Matter

Natural Organic Matter (N0M) was isolated and extracted from a moderately-colored surface water, then fractionated using hydrophobic and ion exchangeresins into eight groups. Each was subjected to batch ozonation, and the rateof loss of ozone was measured. Then, selected fractions were analyzed forchanges in functional group content, molecular size and hydrophobicity; somewere further fractionated by size prior to functional group analysis. Fulvicacids and humic acids were the most reactive. These groups also showed thegreatest change in carboxyl group content and hydrophobicity. The results arediscussed with respect to impacts on coagulation. Although hydrophilicneutrals were of low to moderate reactivity, they showed the greatest promisefor improved coagulation following preozonation.     

Removal Of Residual Organics From Drinking Water By Ozonation And Activated Carbon Filtration: A Pilot Plant Study

The effects of ozonation, granular (GAC) and biological activated carbon (BAC) in the removal of natural organic matter and precursors of disinfection byproducts from drinking water were studied on pilot scale. Ozonation was determined to be the best method to reduce concentrations of the precursors of AOX, chloroform and mutagenicity, whereas BAC removed organic matter the most effectively. Reductions in TA100 mutagenicity were an average 40%, 4%, 26% in ozonated, GAC and BAC filtered water, respectively. Average reductions of AOX levels were similar at 48%, 7% and 35%, respectively. The chloroform formation potential always increased after GAC filtration.     

pH Effect on Ozonation of Ampicillin: Kinetic Study and Toxicity Assessment

Ampicillin (AP) is a penicillin-type antibiotic and one of the most widely used bacteriostatic antibiotics in human and veterinary medicine. A kinetic study was performed under different pH conditions (5, 7.2, and 9) to determine the degradation efficiency of AP by ozonation. The second-order rate constants for the direct reaction of AP with ozone were measured to be 2.2 ?5.4×10⁵ M^?1s^?1 under the pH conditions tested. The rate constants were greater at higher pH. The potential toxicity of the AP intermediates formed after ozonation under the various pH conditions were examined using a bioluminescence assay on Vibrio fischeri species. The biodegradability of the AP degraded products was also determined by measuring the BOD₅/COD of the ozonated samples under the different pH conditions. A lower biodegradability and acute toxicity was observed at the lowest pH (pH 5). These results suggest that higher pH conditions are needed for the removal of AP by ozonation in order to mitigate the residual toxicity that can remain even after complete removal of the parent compound by ozonation.     

A Kinetic Investigation on the Ozonation of Glycerol and its Oxygenated Derivatives

The ozonation of glycerol and its main oxygenated derivatives is studied aiming at evaluating the possibility to convert them into valuable products. The direct ozonation of glycerol results into a mixture of its oxygenated derivatives. In some cases the use of ozone to convert them into valuable products proceeds with good selectivity. A kinetic study to estimate the kinetic constants of ozone attack to the main glycerol oxygenated intermediates is carried out. The data found are in keeping with the few values found in the literature for alcoholic groups by ozone.     

An Approximate Innovation Method For The Estimation Of Diffusion Processes From Discrete Data

Abstract. In this paper, an approximate innovation method is introduced for the estimation of diffusion processes, given a set of discrete and noisy observations of some of their components. The method is based on a recent extension of local linearization filters to the general case of continuous–discrete state–space models with multiplicative noise. This filtering method provides adequate approximations for the prediction and filter estimates that are required by the innovation method in the estimation of the unknown parameters and the unobserved component of the diffusion process. The performance of approximate innovation estimators is illustrated by means of numerical simulations.     

Unstationary Film Model for the Determination of Absolute Gas-Liquid Kinetic Rate Constants: Ozonation of Acid Red 27, Acid Orange 7, and Acid Blue 129

A method for the determination of absolute kinetic rate constants is proposed using an unstationary film model. This methodology avoids the experimental determination of parameters like the enhancement factor or the Hatta number which are usually model-dependent. The mathematical model is general for gas-liquid systems with irreversible second order reactions. An optimization procedure based on artificial neural networks is used to estimate the initial guess of the parameters and the subsequent application of Gauss-Newton algorithm for the final nonlinear parameter estimation. The model is tested with the ozonation reaction of Acid Red 27, Acid Orange 7 and Acid Blue 129. The second-order kinetic rate constants for the direct reaction with O₃ are 1615 ± 93, 609 ± 83, and 49 ± 2 M^?1s^?1, respectively.     

The Evaluation Of Ozonation and Chlorination On Disinfection By-Product Formation for a High-Bromide Water

High-bromide raw water was ozonated or chlorinated with and without hydrogen peroxide to study the effect of the disinfectants on the disinfection by-product (DBP) formation. Less bromate was formed when ozonation was made at the ambient pH of 5.8 as compared to ozonation at pH 7, showing the effectiveness of pH reduction in controlling the bromate formation. When chlorine dose was 1 mg/L instead of 2.3 mg/L, the trihalomethane formation was 50 μg/L instead of >100 μg/L, and the proportional distribution of the trihalomethanes was similar. The use of ozone for this water could provide good results in respect of the DBP formation.     

电影和照相胶片高温加工过程的理论和实践概况(上)

本文是作者自 196 2年至 1997年间研究照相材料高温加工过程所发表部分文章 (黑白照相材料 )的综述。文章介绍并讨论了加工浴组分在照相材料涂层中的扩散行为和影响扩散的因素 ,过程动力学的特点 ,工艺过程特点 (含显定合一过程特点及机理、防止灰雾的措施和机理、影响影像粒性和清晰度的因素及机理 )和设备简况。     

电影和照相胶片高温加工过程的理论和实践概况(下)

本文是作者自 196 2年至 1997年间研究照相材料高温加工过程所发表部分文章 (黑白照相材料 )的综述。文章介绍并讨论了加工浴组分在照相材料涂层中的扩散行为和影响扩散的因素 ,过程动力学的特点 ,工艺过程特点 (含显定合一过程特点及机理、防止灰雾的措施和机理、影响影像粒性和清晰度的因素及机理 )和设备简况     

Comparison of Activated Carbon and Hydrophobic Zeolite Efficiencies in 2,4-Dichlorophenol Advanced Ozonation

This study aims at comparing the removal of 2,4-dichlorophenol (2,4-DCP) by 3 methods; adsorption using hydrophobic zeolite (faujasite) or activated carbon (S-23 and L-27), conventional ozonation and hybrid adsorption/ozonation treatment. On the one hand, the three materials correctly adsorb 2,4-DCP; however the adsorption kinetics using zeolite is very low. On the other hand, ozonation totally removes 2,4-DCP after 1 h experiment and the simultaneous combination of adsorbent and ozone does not change the 2,4-DCP degradation. But, though ozonation and hybrid process appear to be equivalent for 2,4-DCP removal, activated carbons are able to decompose ozone and to improve chemical oxygen demand (COD) removal, whereas the zeolite does not show this catalytic effect. Similar results were also observed in a former study with nitrobenzene. Adsorbent degradation is evaluated by Brunauer, Emmet and Teller (BET) and differential thermogravimetric (DTG) analysis, which evidence that Faujasite and S-23 activated carbon are resistant to ozone exposure whereas the pore volume and the surface area of L-27 activated carbon decrease during ozonation.     

Comparison between Ozonation and Photo-Fenton Processes for Pesticide Methomyl Removal in Advanced Greenhouses

So-called “Advanced Greenhouses” are a new approach to the concept of protected agriculture. Among other technological and structural improvements, these facilities give the possibility of recycling the irrigation surplus water, rich in lixiviates, salts, pesticides and its metabolites. After many cycles, the current is so concentrated on those substances that it becomes necessary for the presence of a membrane separation stage which brine, highly concentrated on those named pollutants, has to be treated before being sent to the public sewage system. Advanced Oxidation Processes, among other chemical treatments, can be considered an alternative to process this current effluent. In this work, concentrated aqueous solutions of methomyl as model pesticide (200 mg·L^?1) have been subjected to two of those processes: ozonation and photo-Fenton reaction. Analysis of the elimination of the pesticide itself and the grade of mineralization achieved have shown how, while the ozonation is the most effective process decomposing the pesticide (eliminating the total concentration in 60 minutes), the photo-Fenton reaction mineralizes successfully the 40% of the total organic load (the ozonation only can cope with 20%) but only decompose a 40% of the pesticide. Evolution of biodegradability and toxicity of the effluent along both processes was also analyzed. Intermediates generated both by ozonation and photo-Fenton did not increase the biodegradability of the treated effluents. Nevertheless, while acute toxicity just after 15 minutes of treatment with ozone is notably higher than for raw solution, and it is maintained till the end of the experiment (120 min), though, toxicity along photo-Fenton reaction has two growing and decreasing regions, always shows lower values than the provoked during ozonation. None of the two assayed processes has been proved to increase biocompatibility of highly concentrated methomyl solutions.