Ozonation of Humic Substances: Effects on Molecular Weight Distributions of Organic Carbon and Trihalomethane Formation Potential

Four different sources of humic substances were studied to determine the effects of ozonation on molecular weight-distributions, based on dissolved organic carbon (DOC) and trihalomethane formation potential (THMFP). Solutions of two soil-derived fulvic acids and a one soil-derived humic acid, as well as dissolved organic matter (DOM) associated with a natural water source were studied. Both gel permeation chromatography (GPC) and ultrafiltration (UF) were employed to define apparent molecular weight (AMW). Applied ozone doses ranged from 2.0 to 2.5 mg O₃/mg DOC. Overall samples of untreated and ozonated waters, as well as individual molecular weight fractions, were characterized according to DOC, UV absorbance, and THMFP. Ozonation resulted in a significant disappearance of higher AMW material with a corresponding increase in lower AMW material. Although little overall reduction in DOC concentration was observed, significant overall reductions in UV absorbance and THMFP levels were observed.     

Behavior Of Glyoxal During Granular Activated Carbon Treatment

Glyoxal, which was the strong mutagen formed by ozonation of humic substances, was treated with granular activated carbon (GAC) and the behavior of glyoxal was investigated. Glyoxal itself was adsorbed well on GAC at pH 5–7. But, glyoxal increased by GAC treatment of ozonated humic substances when the ozone dose was insufficient to decolorize the humic substances. The precursors of glyoxal may be among other ozonated products which may be changed to glyoxal on GAC.     

Bromate Ion Analysis By Ion Chromatography

Bromate ion occurs during ozonation of bromide-containing waters. The current WHO guideline for bromate ion is 25 μg/L. Bromate analysis in drinking waters can be performed by various techniques. However, given the commonly low concentrations of bromate ion found in drinking waters, the classical methods do not fit for bromate analysis in most cases.

A specific conductimetric method with anion suppression which enhances analyte detection by lowering the eluent conductivity is described in this paper for low bromate level analysis. Three eluents have been tested in order to have the best signal to noise ratio. Some other parameters likely to interfere in bromate ion detection (nitrate and sulfate in particular) are also investigated. Taking into account the results of three interlaboratory trials between six European laboratories, a 2 μg/L detection level for bromate can be established.     

臭氧消毒技术研究进展

主要综述了臭氧消毒技术的研究现状,包括消毒机理以及主要影响因素,如温度、pH、有机物、颗粒物和无机离子等对消毒效果的影响,并介绍了消毒联合工艺研究进展。总体而言,臭氧具有较强的杀菌能力,是有较好前景的消毒技术。     

基于嵌入式系统的智能超声波清洁器

以Philips的89LPC936单片机作为智能化软硬件平台,综合超声波清洗,臭氧消毒,负离子保健等手段进行面部美容的新方法.实际运用表明,该方法能深入一般方法难以涉及的皮肤深层.加快新陈代谢,用于面部美容,起到了很好的作用.     

Preozonation of Chlorophenolic Wastewater for Subsequent Biological Treatment

Preozonation was investigated for its effects on the biodegradability of five chlorophenolic compounds in activated-sludge systems. The biodegradability was expressed in terms of the oxidation of each compound itself and of the total organic contents of the whole sample.

Results indicate that preozonation could either promote or retard the biodegradability, depending primarily on whether or not the sludge used in the subsequent biological system had been acclimated beforehand. For unacclimated sludge, preozonation was found to be helpful in promoting the biodegradability of all the compounds, especially the chlorophenols with a meta-position chlorine attachment. For acclimated sludge, a reverse effect generally, was observed.     

Modelling Industrial Wastewater Ozonation In Bubble Contactors. 1. Rate Coefficient Determination

A study of the ozonation of distillery and tomato wastewaters was carried out in a small bubble contactor in order to obtain kinetic data for scaling-up. Thus, several parameters, such as chemical oxygen demand (COD), 254 nm absorbance (A₂₅₄) and organic carbon content (OC), were followed during ozonation at different experimental conditions.

For distillery wastewaters all parameters investigated have the highest decreases during the first minutes of ozonation, A₂₅₄ showing the highest disappearance rates. Thus, during the first fifteen minutes of ozonation an important decrease of the 254 nm absorbance (? 75%) was observed. At further reaction times values of all parameters studied decrease slowly, eventually reaching a plateau value. During approximately the first two hours of reaction, dissolved ozone was never found, which suggested that fast or moderate gas-liquid reactions took place in the wastewaters.     

A bootstrap goodness of fit test for the generalized Pareto distribution

This paper proposes a bootstrap goodness of fit test for the Generalized Pareto distribution (GPd) with shape parameter γ. The proposed test is an intersection–union test which tests separately the cases of γ≥0 and γ<0 and rejects if both cases are rejected. If the test does not reject, then it is known whether the shape parameter γ is either positive or negative. A Monte Carlo simulation experiment was conducted to assess the power of performance of the intersection–union test. The GPd hypothesis was tested on a data set containing Mexico City’s ozone levels. ¹     

Comparative Efficiency Of Three Systems (O3, O3/H2O2, and O3/TiO2) For The Oxidation Of Natural Organic Matter In Water

CATAZONE is a new process of heterogeneous catalytic ozonation in which water is ozonated in the presence of a solid catalyst composed of titanium dioxide. The efficiency of this O₃/TiO₂ system has been compared to the two well-known oxidant systems: ozone alone and ozone combined with hydrogen peroxide.

This comparison was undertaken on three models of natural organic compounds : an aquatic fulvic acid, a protein and a disaccharide. The first results showed the following order of relative efficiency: O₃/TiO₂ > O₃/H₂O₂ > O₃ as far as Total Organic Carbon (TOC) removal was concerned.     

Catalytic ozonation of natural organic matter on alumina

The paper aims to show the potential of catalytic ozonation in the presence of alumina for the removal of natural organic mater from drinking water. An investigation into the efficiency of catalytic ozonation, ozonation by-products formation and their biodegradability was the main goal of the paper. Characterisation of fresh and worn alumina was also conducted. The results clearly indicated the high activity of alumina over a long period of time, which is crucial in water treatment technology. The application of alumina to the ozonation system doubled the efficiency of NOM removal from water when compared to ozonation alone. Furthermore, catalytic ozonation resulted in lower by-products and biodegradable organic carbon formation.