摘要:

A finite element analysis (FEA) computer program was used to model the hydraulic characteristics and to predict the corresponding residence time distribution (RTD) curves for four full-scale ozone contactors with hydraulic capacities ranging from 14.5 to 394 m3/min (5.5 to 150 mgd). On average, model predictions for contactor efficiency (T10/HDT) were within 7.9% of actual test values. The Metropolitan Water District of Southern California (Metropolitan) is using the finite element program as a design tool to optimize the hydraulics of future ozone contactors. For one template model, results from several optimization runs are presented which confirm that T10/HDT increases with increasing depth-to-length (D/L) ratio and which indicate that by adding two features, vanes or wall foils, the T10/HDT is improved from 0.63 to 0.68 or to 0.66, respectively. Results from the template model also indicate that the T10/HDT is unchanged with the addition of a single configuration of comer fillets.

ISSN:0191-9512    

DOI:10.1080/01919512.1995.10555771

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Anglian Water (AW) operates ozone facilities as a treatment stage at all its surface water sources. The main ozone treatment stage takes place after filtration in multi-compartment concrete ozone contactors. These have two stages of ozone gas injection via ceramic bubble diffusers and two decay stages.

ISSN:0191-9512    

DOI:10.1080/01919512.1995.10555772

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Azobenzenes and azoxybenzenes are two of the products identified from the aqueous reaction of anilines with ozone. Aniline concentration and functional groups on the benzene ring of aniline affected the amount of azobenzenes and azoxybenzenes formed; (1) decreasing the aniline concentration significantly increased azobenzene formation, and (2) electron-withdrawing groups increased the formation of its related azobenzene and azoxybenzene, whereas electron-donating groups had the opposite effect.

ISSN:0191-9512    

DOI:10.1080/01919512.1995.10555773

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Aqueous solutions of 4-chlorophenol, 2,4-dichlorophenol, methoxybenzene, 1-naphthol, and naphthalene at a concentration of 0.5-1 × 10−4M reacted with two equivalents of ozone at pH 7.25-10.65 to form various oxidation products. When the reactions were conducted in the presence of nitrite ion (0.5-1.0 × 10−4M), a nitration reaction occurred with three of the five aromatic compounds (4-chlorophenol, 2,4-dichlorophenol, and 1-naphthol). Aromatic compounds that undergo nitration under the conditions of the experiments have a higher reaction rate than that for the reaction of ozone and nitrite ion.

ISSN:0191-9512    

DOI:10.1080/01919512.1995.10555774

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Industrial phosphoric acid at 42-45% P2O5and containing organic matter (OM) in the range of 220 mg/L to 300 mg/L is treated by combined ozonation and activated carbon. Ozonation alone removes the initial dark color of the acid and eliminates the organic content. Adsorption on activated carbon alone can reduce OM levels by 80% for more than 25 g/kg P2O5. We find that a preozonation noticeably enhances activated carbon efficiency and reduces its specific consumption. Isoconversion curves are plotted in specific ozone and activated carbon ratio space.

ISSN:0191-9512    

DOI:10.1080/01919512.1995.10555775

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The batch ozonation of some fractions of aqueous humic substances (humic, fulvic and hydrophilic acids) extracted from natural waters is studied. The reaction leads to oxidation byproducts such as low molecular aldehydes and ketoacids. Formation conditions and origin of some of them (glyoxylic, pyruvic and ketomalonic acids) regarding the extracted fraction of natural organic matter is established.

ISSN:0191-9512    

DOI:10.1080/01919512.1995.10555776

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This article deals with the efficiency of an ozonation step in drinking water treatment plants remove pesticides. These tests are carried out with a laboratory technique, the “OZOTEST” method, which simulates operating conditions on site and allows a complete oxidation assessment.

ISSN:0191-9512    

DOI:10.1080/01919512.1995.10555777

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In the Netherlands many water supply companies are upgrading their surface water treatment plants in order to guarantee the water supply and water quality in the coming years. The Water Supply Company North West Brabant (WNWB) has plans to upgrade their treatment plant at Zevenbergen. In the retrofit plant chlorination will be abandoned and probably ozonation will be the major barrier against microorganisms. Pesticide concentrations will be decreased by three barriers: storage, ozonation and activated carbon filtration.

ISSN:0191-9512    

DOI:10.1080/01919512.1995.10555778

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The objective of our study was to compare the reactivity of coniferyl alcohol and ferulic acid with ozone at acidic pH in terms of ozone demand and byproducts formation. Both structures exert an ozone demand of about two moles of ozone per mole of initial compound. Similar ozonation byproducts were identified using gas chromatography/mass spectrometry analysis. Using a low ozone dose (below the ozone demand), byproducts were principally aromatic structures, with vanillin, 3,4-dihydroxy-5-meth-oxybenzaldehyde and vanillic acid as the main compounds. Applying a higher ozone dose (above the ozone demand), furan structures were produced. A reaction mechanism is suggested to explain the formation of such structures. A quantitative study showed that coniferyl alcohol was a stronger precursor of vanillin and vanillic acid than ferulic acid.

ISSN:0191-9512    

DOI:10.1080/01919512.1995.10555779

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0191-9512    

DOI:10.1080/01919512.1995.10555780

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor