Effect Of Pre-ozonation Research Articles

Effects and mechanisms involved in preoxidation and particle separation processes

Particle separation in water treatment can be enhanced by preoxidation with different chemicals. Effects were reported for preoxidation by ozone, chloride, chlorine dioxide, permanganate and chloramines. The observations depend on the raw water source, season, oxidant dosage and the applied particle separation processes. Most research interest has found preozonation for particle removal and the underlying mechanisms. The literature of the last decades include several mechanisms thought to be responsible for the observed effects. A significant role is played by the natural organic matter (NOM) in view of its efficiency in stabilizing dispersed particles by adsorption and by its reactions with the coagulants. Preozonation effects in algae-laden waters are important but require further studies.

Effects of Pre-Ozonation in Refractory Leachate Treatment by the Biological Activated Carbon Fluidized Bed Process

The removal efficiency of refractory landfill leachate organics by the biological activated carbon fluidized bed (BACFB) process was compared with and without pre-ozonation. Furthermore, the effects of ozonation upon the characteristics of the refractory leachate such as UV absorbance, dissolved organic carbon (DOC), BOD5, adsorbability, molecular size distribution and the content of humic substances were evaluated. The effectiveness of pre-ozonation in treating a refractory landfill leachate through the BACFB process was confirmed. The steady-state DOC removal was enhanced from 42% to 57% at a hydraulic retention time of 24 h. This improvement was due mainly to the pre-ozonation-enhanced biodegradability of the high-molecular-weight organics that could not be removed by the BACFB process alone. Ozonation of the leachate resulted in an exponential decrease in UV absorbance and a linear decrease in DOC with increasing the contact time. High-molecular-weight leachate organics degraded through ozonation to organic compounds having intermediate and low molecular weights. Humic substances accounted for 37% of the leachate DOC, and 60% of the humic substances were removed within 30 min of the contact time. Ozonation caused a significant decrease in adsorbability on activated carbon of the leachate and produced a substantial amount of non-adsorbable organics. The BACFB treatment of the pre-ozonated leachate enhanced its adsorbability and removed the non-adsorbable fraction.

Effects and mechanisms involved in preoxidation and particle separation processes

Particle separation in water treatment can be enhanced by preoxidation with different chemicals. Effects were reported for preoxidation by ozone, chloride, chlorine dioxide, permanganate and chloramines. The observations depend on the raw water source, season, oxidant dosage and the applied particle separation processes. Most research interest has found preozonation for particle removal and the underlying mechanisms. The literature of the last decades include several mechanisms thought to be responsible for the observed effects. A significant role is played by the natural organic matter (NOM) in view of its efficiency in stabilizing dispersed particles by adsorption and by its reactions with the coagulants. Preozonation effects in algae-laden waters are important but require further studies.

Competitive removal of dissolved organic carbon by adsorption and biodegradation on biological activated carbon

Improvement of biodegradability of dissolved organic carbon (DOC) by ozonation does not always induce improvement of DOC removal and extension of activated carbon service time, because most of biodegradable DOC increased by ozonation is adsorbable on activated carbon. The objective of this study is to clarify the fate of the biodegradable DOC increased by preozonation on biological activated carbon (BAC) and to evaluate effects of preozonation on BAC performance for the removal of DOC and extension of activated carbon service time. DOC breakthrough curve for BAC process obviously shifted to the right by combination with ozonation, indicating that preozonation extended BAC service time. Higher removal of DOC was noted in the ozone-BAC process than the BAC process after saturation with DOC. Ozonation increased biodegradable DOC by 2.89 mg·l−1 (31%). Although the increased biodegradable DOC had possibilities to be removed both by adsorption and biodegradation, most of it was removed by biodegradation on BAC which resulted in longer BAC service time. Biodegradation of the increased biodegradable DOC was responsible for the higher removal of DOC after saturation with DOC in the ozone-BAC process.

Impact of chemical oxidation on biological treatment of a primary municipal wastewater. 2. Effects of ozonation on kinetics of biological oxidation

Activated sludge biological oxidation of municipal wastewaters has been applied under different experimental conditions to observe the effect of preozonation on COD and process kinetics. In all cases, previous application of ozone allows significant improvement of COD level reduction during subsequent biological oxidation. Biomass concentration also exerts a positive influence on COD level reduction. Thus, 54 and 82% COD level reductions are achieved after biological oxidation without and with 30 minutes of preozonation. During the ozonation period, increase of pH from 2 to 9 leads to 15 to 24% COD level reductions, but biological oxidation should be followed at neutral pH since extreme conditions (pH 2 and 9) reduce considerably the biomass concentration and hence the yield of biodegradation. At the conditions investigated herein, there is an optimum ozone dose, 150 mg per liter of wastewater treated, that leads to the maximum COD level reduction in the combined process (chemical plus biological oxidation). Both single biological oxidation and combined with preozonation follows a Monod kinetic model assuming COD as the substrate of biomass. From kinetic results it is confirmed that a combination of chemical and biological oxidation leads to the highest maximum specific rates of COD consumption.

Competitive removal of dissolved organic carbon by adsorption and biodegradation on biological activated carbon

Improvement of biodegradability of dissolved organic carbon (DOC) by ozonation does not always induce improvement of DOC removal and extension of activated carbon service time, because most of biodegradable DOC increased by ozonation is adsorbable on activated carbon. The objective of this study is to clarify the fate of the biodegradable DOC increased by preozonation on biological activated carbon (BAC) and to evaluate effects of preozonation on BAC performance for the removal of DOC and extension of activated carbon service time. DOC breakthrough curve for BAC process obviously shifted to the right by combination with ozonation, indicating that preozonation extended BAC service time. Higher removal of DOC was noted in the ozone-BAC process than the BAC process after saturation with DOC. Ozonation increased biodegradable DOC by 2.89 mg-l−1 (31%). Although the increased biodegradable DOC had possibilities to be removed both by adsorption and biodegradation, most of it was removed by biodegradation on BAC which resulted in longer BAC service time. Biodegradation of increased biodegradable DOC was responsible for the higher removal of DOC after saturation with DOC in the ozone-BAC process.

Removal of non-specific dissolved organic matter from upland potable water supplies—II. Ozonation and adsorption

Ozone has traditionally been used in the U.K. for the removal of organic colour from upland raw waters concomitantly converting the composite organic compounds to lower molecular weight, more biodegradable organic acids. However, ozonation has substantially no effect on the dissolved organic compound concentrations and, although the organic removal efficiencies of GAC filtration processes are generally improved due to enhanced biological removals, ozonation typically results in a deterioration of the organics adsorption. Consequently, this paper investigates the effect of preozonation on the organics adsorption efficiencies of activated carbon, activated alumina, activated bauxite and bone char adsorbents.

Flocculation Effects of Ozone

Abstract There are numerous reports on coagulation/flocculation effects of preozonation, which cannot be interpreted by one single mechanism. About 7 basic processes are presently discussed. This paper presents results from drinking and wastewater treatment, indicating that preozonation effects can be explained with algae flocculation, with the destabilization of particles, and with polymerization of the dissolved organics. In view of the complexity of the systems, it is anticipated that several processes can be responsible, leading to an optimum ozone dosage.

The Performance and Microbiology of Ozone‐Enhanced Biological Filtration

Pilot‐scale studies were conducted to determine the effects of preozonation and water column biofilm support media on slow sand filtration. The performance of the enhanced slow sand filters was compared with that of the full‐scale treatment facility at Andover, Mass., which uses preozonation and granular activated carbon to enhance its conventional processes. Preozonation and biofilm support were observed to have a positive influence on filter performance, transformation of natural organic matter, microbiology, and removal of biodegradable dissolved organic carbon (BDOC). The pilot filter with the media of a larger effective size, an ozone dose of 2 mg per mg of nonpurgeable dissolved organic carbon (NPDOC), and biofilm support produced removals of turbidity, NPDOC, UV absorbance, and trihalomethane formation potential comparable to the full‐scale facility. And the enhanced pilot filter produced a lower finished‐water BDOC value than the full‐scale plant. Thus, enhanced slow sand filters hold promise for utilities that must comply with the Surface Water Treatment Rule and future disinfection by‐product rules.

Effect of Pre-Ozonation on Organics Removal by In-Line Direct Filtration

A pilot-scale study of the effects of pre-ozonation on the performance of in-line direct filtration was carried out. Performance measures included filtered water turbidity, unit filter run volumes, and organics in filtered waters: DOC, UV254, AOC and DBPs. Continuous operation of four dual media GAC/sand filters with and without pre-ozonation and chlorinated backwash and a dual media anthracite/sand filter were compared to full-scale performance. Pre-ozonation frequently results in longer filter runs, causes a twofold increase in raw water AOC and has little effect on raw water DOC. GAC/sand filters consistently reduced the AOC in the ozone train to levels below that of the full-scale plant and also provided 25 % lower DOC levels as compared to anthracite/sand filters. The effect of ozone and filtration on chlorinated DBPs followed overall DOC removal while DBPs created by ozonation followed AOC removal trends.

Effect of Pre-Ozonation on Removal of Organic Matter during Water Treatment Plant Operations

Pre-ozonation altered removal of organic matter during bench or full-scale water treatment through two main effects. First, pre-ozonation directly removed organic matter by mineralization, volatilization and/or stripping reactions, improving removal in comparison to unozonated systems. On the other hand, pre-ozonation decreased the surface charge of floc formed after coagulation with hydrolyzable metal salts, hindering adsorptive removal of the anionic organic molecules by floc surfaces and/or inducing stabilized floc formation; changes that decrease removal in comparison to unozonated systems. The relative importance of the two effects determined whether pre-ozonation enhanced or hindered removal of organic matter. In most water treatment plants pre-ozonation is predicted to have an adverse effect on physical removal of organic matter at ozone doses above about 0.7 mg O3/mg TOC, while enhanced removal may occur if relatively high concentrations of volatile organic matter are present. In ancillary results, pre-ozonation hindered turbidity removal and increased the concentration of coagulant metal residuals in finished drinking water at low coagulant doses.

Effect of Preozonation on Coagulant–NOM Interactions

Preozonation of water sources containing natural organic matter (NOM) may alter coagulant requirements, the total organic carbon (TOC) removed by coagulation, and the concentration of aluminum and iron in the finished drinking water. In this work, these phenomena were investigated and interpreted as resulting from (1) changes in the zeta potential of precipitates (floes) that form in the presence of ozonated NOM; (2) slight losses of TOC by oxidation and volatilization of NOM molecules; and (3) changes in the quantity of TOC removed by precipitation and sorption.

Elimination des precurseurs de composes organohalogenes et du carbone organique dissous biodegradable par coagulation de contact influence d'une préozonation

Abstract The effect of preozonation has been studied on a pilot plant on the Biver Seine near Paris. A new treatment of contact coagulation ‐ coagulation on filter with iron chloride has been tested. Two parameters were specially analysed: biodegradable organic carbon and organohalogenated precursors. Preozonation favours removal of these parameters.

Effect of Preozonation on Mutagenic Activity Generated by Chlorination of Humic Acid Dissolved in Water

Aqueous solution containing ahumic acid was treated by ozonation, which was followed by chlorination with HCIO. The TOC level in preozonated samples was varied by changing ozone dosage. When 50% of the TOC was removed, the THMFP and TOX were destructed to ca. 1/30 and 1/20 of the respective initial values. The effect of preozonation on the mutagenic activity of nonvolatile organic chlorides generated by the chlorination was evaluated by the Ames test after the solute was separated on the basis of affinity for hydrophobic XAD-2 adsorbent and fractionation with various solvents. The overall mutagenic activity, defined as the number of revertants per unit volume of the solution considered, was expressed by the product of the following factors: concentration of nonvolatile matter in solution, mass fraction of hydrophobic component in the nonvolatiles, and number of revertants per mg of dosed hydrophobic component. The contribution of each factor was evaluated experimentally. Preozonation was effective for the selective destruction of precursors of the hydrophobic component.

Effect of preozonation on reduction of mutagenic activity of chlorinated humic acids in water

Effect of preozonation on reduction of mutagenic activity of chlorinated humic acids in water

Effects of preozonation on the adsorbability and the biodegradability of aquatic humic substances and on the performance of granular activated carbon filters

Previous work carried out with test organic substances and under sterile and non-sterile conditions of filtration allowed us to show that the microbial degradation of biodegradable compounds increased the GAC adsorption capacities for non-biodegradable solutes (De Laat et al., 1985). This research extends the work to higher molecular weight compounds (isolated aquatic humic and fulvic acids, PHA and PFA) and evaluates the effects of a preozonation treatment on the performances of GAC filters. In the first part of this study, the effect of ozonation on some physical and chemical properties (carboxyl content, adsorbability on GAC, u.v.-absorbance) and on the biodegradability of humic substances were investigated. In the second part, GAC column filtrations were operated under sterile and non-sterile conditions in order to show the influence of preozonation treatment on the performance of GAC columns and to determine the parts due to adsorption and to biodegradation in DOC removal.

Effect of preozonation on the organic halide formation potential of an aquatic fulvic acid

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of preozonation on the organic halide formation potential of an aquatic fulvic acidJean Philippe Croue, Fernando J. Beltran, Bernard Legube, and Marcel DoreCite this: Ind. Eng. Chem. Res. 1989, 28, 7, 1082–1089Publication Date (Print):July 1, 1989Publication History Published online1 May 2002Published inissue 1 July 1989https://doi.org/10.1021/ie00091a030RIGHTS & PERMISSIONSArticle Views73Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (959 KB) Get e-Alerts Get e-Alerts

Effects of Preozonation on Anaerobic Biodegradability of O‐Cresol

Ozone pretreatment studies of a refractory phenolic compound, o-cresol, were conducted to evaluate the effects of ozonation on the anaerobic biodegradability and toxicity of the reaction products. Two types of batch studies, the biochemical methane potential (BMP) and the anaerobic toxicity assay (ATA), were performed on samples with and without preozonation. The ozonation products were well fermentable to methane after about 50% reduction in chemical oxygen demand (COD) or 32% reduction in dissolved organic carbon (DOC) was achieved by ozonation regardless of the initial concentration of o-cresol. Salicylic acid, glyoxylic acid, oxalic acid, propionic acid, acetic acid, and formic acid were the oxidation products identified. The reaction products formed in the basic pH range were more biodegradable and less inhibitory than those formed in the acid pH range. Phenol degradation was more susceptible to inhibition caused by ozonation products than was acetate utilization.

Preozonation as an aid in the coagulation of humic substances—Optimum preozonation dose

Using a number of commercial and natural water humic substances, the positive effect of preozonation as an aid to coagulation-flocculation of these compounds was confirmed by a 13–30% decrease in alum consumption. Experiments were conducted at a pH of 5.5 and humic substance concentrations of 20 mg/l (total organic carbon concentrations of approx. 10 mg/l). Standard jar test procedures were used to evaluate alum dosage requirements and the primary water quality parameters monitored were turbidity, u.v., TOC and color. In addition to decreased alum consumption the existence of an optimum preozonation dose (OPD) was also confirmed. For ozone dosages beyond the OPD, the benefit is reduced, then eliminated and further ozonation becomes detrimental to the coagulation-flocculation removal process. The OPD was found to be a function of the initial colloidal charge density (CCD) of the humic substances. The strong correlation of initial CCD to the OPD identified the major mechanism for preozonation to be effective as a reduction in CCD due to mild ozonation. Preozonation did not show a positive effect on a system with very low molecular weight (noncolloidal) humic substances.

Effect of preozonation on organics coagulation removal from water

Abstract The objective of this research was to study the effect of preozonation on a subsequent coagulation process when treating polluted surface waters. The results show for raw water containing only phenol, ozonation gives rise to more polar compounds, which are capable of forming hydrogen bonding or complexing among themselves or with hydrolytic products of the coagulants, so the organics removal may be enhanced. However, for raw water containing only humic acid, the effect of preozonation is insignificant. Furthermore, for the organic and clay mineral coexistence system, the hydrolytic products of co‐agulants may react preferentially with the ozonated organics; and turbidity removal is retarded. So, the effect of preozonation on coagulation depends on several factors, such as the type of dissolved organics, the existence of suspended solids, and the type and dosage of coagulants used.