Ozone Application for the Improvement of UASB Reactor Effluent. II. Toxicity Evaluation

In order to improve the effluent from domestic sewage treatment through an anaerobic process in an upflow anaerobic sludge blanket reactor (UASB), CETESB - The Environmental Protection Agency for Sao Paulo State, and FILSAN - Equipamentos e Sistemas S/A, developed a joint program to study the effectiveness of ozonation of the effluent as a post-treatment process. As the effluents treated by this system could contain toxic chemicals, Daphnia similis toxicity tests were applied. Two ozonation conditions were evaluated: (1) contact time of 30 min, mean ozone application dosage of 15.9 mg/L; (2) contact time of 50 min, mean ozone application of 16.7 mg/L. Toxicity reduction occurred for all samples but one. The ozonation system eliminated the residual toxicity associated with the effluent treated by the UASB reactor.     

Effect of ozonation on chemical oxygen demand fractionation and color profile of textile wastewaters

Filtration and ultrafiltration with a size range of 2–1600 nm were used to evaluate the effect of ozonation on the particle size distribution‐based chemical oxygen demand (COD) and color profiles of textile wastewater before and after biological treatment. Ozonation induced a net effect of 9% COD reduction in the influent and 15% in the effluent. However, a more in‐depth evaluation based on particle size distribution and mass balance for the influent revealed different mechanisms of ozonation, which were interpreted as total oxidation in the soluble range, replenishment of soluble COD through solubilization of organics into simpler compounds and polymerization towards the upper size range (>220 nm). For the biological treatment effluent, the greatest effect of ozonation was in the lower particle size range (<8 nm). Ozone was very effective for color removal, giving 80–93% optical density reductions in the influent and 96–99% in the effluent, depending on the excitation wavelength selected. Ozonation of the influent removed practically all color fractions, except in the particulate range. In the effluent, the particulate fraction was removed by biological treatment and settling and consequently the remaining color were almost entirely removed by ozonation. Copyright © 2005 Society of Chemical Industry     

Investigation into Ozonation of Coal Coking Processing Wastewater for Cyanide,Thiocyanate and Organic Removal

A laboratory investigation was carried out to establish whether ozonation could be used to oxidize cyanides, thiocyanates and color in wastewater from a coal coking plant to supplement biological and activated carbon treatment (GAC). Ozonation was found to be capable of oxidizing cyanide and cyanate to sufficiently low levels at relatively high stoichiometric ratios as a result of competitive ozone consumption by organic substances in the wastewater. While good color removal was also achieved with ozonation, organic removal could not match GAC in overall organic removal. Ozonation was not found to be economical for the remaining nine years of a build, own, operate and transfer (BOOT) contract period. Ozonation would be competitive over longer operational periods and more environmentally friendly than presently used technology.     

生活污水对成熟厌氧氨氧化颗粒污泥的影响

部分短程硝化和厌氧氨氧化技术的研究主要集中在高氨氮废水方面，对低氨氮浓度生活污水的研究相对较少。使经过除碳和部分短程硝化后的实际生活污水进入厌氧氨氧化UASB反应器，探究生活污水对成熟厌氧氨氧化颗粒污泥的影响。结果表明，当厌氧氨氧化UASB反应器的进水由配水变为生活污水后，反应器出水中氨氮浓度可降到5 mg·L^-1以下，亚硝态氮浓度可降到1 mg·L^-1以下，但是硝态氮的生成量高于理论值，可能是溶解氧被带入UASB反应器使硝化作用增强。UASB反应器内厌氧氨氧化污泥颜色由红色变为红黑色，T-EPS含量减少，PN/PS由1.13增大到3.66，沉降性变好，反应器内污泥中厌氧氨氧化菌Candidatus Brocadia所占比例由17.7%减少为14.4%，系统内AOB和NOB菌的含量增加，如果能够降低进入UASB反应器的溶解氧，有可能会减少出水硝氮，达到较好总氮去除效果。     

Removal of Pesticides by a Combined Ozonation/Attached Biomass Process Sequence

Different combinations of ozonation and biological treatments were tested on an industrial effluent containing high pesticide concentrations. Ozonation was performed in 450 L columns at 1.5 h HRT each. Biological treatment was carried out in a submerged filter (BIOFOR). Ozone was effective in removing herbicides but dosages up to 1000 mg L^?1 were needed. The improved biodegradability of the organic compounds after pre-ozonation was demonstrated by Oxygen Uptake Rates (OUR) tests and by the efficiency of biological treatment towards COD, and pesticides. The Italian discharge limit of 50 ppb total pesticides was achieved by combining pre-ozonation, biological treatment, and post- ozonation.     

Ozone-Based Decomposition of Main Endocrine Disruption Chemicals in Sewage Effluent

In order to decompose endocrine disruption chemicals (EDCs) in sewage effluent, ozone based oxidation of nonylphenol (NP), bisphenol A (BPA) and 17β-estradiol (E2) was investigated. Experimental results showed that these EDCs were decomposed easily even in the presence of other organic substances of TOC 5 mg/L. The simulation using kinetic constants obtained from the experiments indicated that these EDCs in sewage effluent were removed to below the detection limit with an amount of ozone consumed less than 0.5 mg/L. Ozonation also reduced the estrogenic activity and the aquatic acute toxicity of these EDCs solution. From these results it was concluded that ozonation was very effective in decomposing these EDCs in sewage effluent.     

Impact of Ozonation on Decolorization and Mineralization of Azo Dyes: Biodegradability Enhancement,By-Products Formation,Required Energy and Cost

In the present study ozonation process was implemented to analyze the effect of ozonation time on the rate of chemical oxygen demand (COD) removal, mineralization and rate of decolorization of azo dyes. Three types of azo dyes i.e. Acid Red 14, Direct Red 28 and Reactive Black 5 were selected. Decolorization and mineralization of samples were conducted in batch scale. The COD and color removal efficiency were found to be increasing at a certain time of ozonation. The results with Acid Red 14, Congo Red and Reactive Black 5 dyes solutions lead to maximum COD reduction of 75%, 67% & 50% respectively. 93%, 92% and 94% color removal were achieved after 25 min of ozonation time of the same dyes which highlighted that ozonation process was found to be more efficient for reactive dye decolorization. Ozonation by-products analyzed by ion chromatography resulted that it partially mineralized with the formation of chloride, fluoride, sulphate, nitrate and oxalate ions. During ozonation process a rapid decrease in pH value indicated the acidic nature of by-products. The effect of buffered dye solutions on the ozonoation process highlighted that the decolorization efficiency decreases in comparison to unbuffered dye solutions. Ozonation led to enhancement of biodegradability ratio (BOD₅/COD) and increased electrical conductivity of the dye solutions. Optimum ozonation time required for degradation of dye solutions reflected the evaluation of energy consumption and cost of the treatment after ozonation.     

Ozone treatment of textile effluents and dyes: effect of applied ozone dose,pH and dye concentration

The ozonation of wastewater supplied from a treatment plant (Samples A and B) and dye‐bath effluent (Sample C) from a dyeing and finishing mill and acid dye solutions in a semi‐batch reactor has been examined to explore the impact of ozone dose, pH, and initial dye concentration. Results revealed that the apparent rate constants were raised with increases in applied ozone dose and pH, and decreases in initial dye concentration. While the color removal efficiencies of both wastewater Samples A and C for 15 min ozonation at high ozone dosage were 95 and 97%, respectively, these were 81 and 87%, respectively at low ozone dosage. The chemical oxygen demand (COD) and dissolved organic carbon (DOC) removal efficiencies at several ozone dose applications for a 15 min ozonation time were in the ranges of 15–46% and 10–20%, respectively for Sample A and 15–33% and 9–19% respectively for Sample C. Ozone consumption per unit color, COD and DOC removal at any time was found to be almost the same while the applied ozone dose was different. Ozonation could improve the BOD₅ (biological oxygen demand) COD ratio of Sample A by 1.6 times with 300 mg dm^?3 ozone consumption. Ozonation of acid dyes was a pseudo‐first order reaction with respect to dye. Increases in dye concentration increased specific ozone consumption. Specific ozone consumption for Acid Red 183 (AR‐183) dye solution with a concentration of 50 mg dm^?3 rose from 0.32 to 0.72 mg‐O₃ per mg dye decomposed as the dye concentration was increased to 500 mg dm^?3. © 2002 Society of Chemical Industry     

The Effect Of Preozonation,Ozone/Hydrogen Peroxide Treatment,And Nanofiltration On The Removal Of Organic Matter From Drinking Water

Pilot scale experiments were performed to evaluate the ability of ozonation, ozone/hydrogen peroxide treatment and nanofiltration to reduce levels of organic matter, mutagenicity, total adsorbable halogens, color and turbidity from purified and bank-filtered surface water rich with humic material.

Ozonation and ozone/hydrogen peroxide decreased the amount of organic material from drinking water by about 20 percent measured as TOC and COD_Mn. Color and turbidity level reductions were 49 and 11 percent, respectively. Ozonation reduced the AOX concentrations formed during postchlorination from 150 μgL^?1 to 75 μgL^?1. The addition of hydrogen peroxide further improved the removal to 37 and 26 μgL^?1 depending on the ratio of H₂O₂/O₃. The mutagenicity reduction followed the same pattern: without ozonation the chlorination-derived mutagenicity was 1,450 net revertant L^?1 after the ozonation 700 and after the H₂O₂/O₃ treatment from <100 to 400 net revertant L^?1 depending on the H₂O₂/O₃ ratio. Nanofiltration appeared to be the most effective way to remove organic material. The removal of TOC was 68%, COD_M 72%, color 90%, turbidity 68%, AOX 88%, and mutagenicity 85%.     

Application of Individual and Simultaneous Ozonation and Adsorption Processes in Batch and Fixed-Bed Reactors for Phenol Removal

Ozonation, adsorption onto activated carbon and catalytic ozonation in batch and in a fixed-bed reactor for the removal/degradation of phenol and COD were investigated. In the case of batch ozonation the oxidation capacity was greater than 6.9 g of phenol/g O₃, while the continuous ozonation system degraded 40% of the phenol and reduced the COD by 27.9%. The adsorption process provided over 99% removal for phenol and COD; however, it treated only 5 L compared with 17 L for the combined process, which also increased the total area and pore volume of the activated carbon, due to the formation of pores and a widening of micropores.     

Ozonation of Pyrolytic Aqueous Phase: Changes in the Content of Phenolic Compounds and Color

Ozonation on the phenols present in pyrolytic aqueous phases attained from biomass thermochemical conversion was evaluated. During ozonation, the dark color of original samples was found to decrease as a function of ozonation time. The oxidation kinetics of phenols was quantified by a method based on the color changes of samples. The oxidation profiles showed different behaviors and in some cases the phenols presented a positive correlation with the relative R color parameter, except eugenol, syringol, and vanillin which were markedly different. Finally, the color changes observed seem to be associated with the changes in the overall content of phenols and with the change in the molecular weight of the heavy fractions that include lignin oligomers.     

Pilot Testing Of Trace Metals Removal With Ozone At Snowbird Ski Resort

A pilot study at the Snowbird Ski Resort in Utah evaluated feasibility of ozonation replacing chlorine and sulfur dioxide for oxidation of iron and manganese in groundwater. Ozonation also was tested for the removal of lead and cadmium, occurring at concentrations exceeding drinking water Maximum Contaminant Levels. An ozone dose of 2 mg/L, contacted with the water for 1 minute prior to filtration, was selected as optimum for iron and manganese removal from 0.4 mg/L and 40 μg/L, respectively, to below detection limits. Lead, copper, and arsenic also were removed to below detection limits. The removal of cadmium and zinc improved when ozone was contacted for 10 minutes. With metals removal through ozonation and filtration, taste and odor enhancement also were reported.     

Ozonation Dynamics and Its Implication for Off-Gas Ozone Control in Treating Pulp Mill Wastewaters

Ozonation of biologically pretreated pulp mill wastewaters was studied using both bench and pilot scale fine bubble contactors to determine the oxidation efficiencies, mass transfer coefficients (k_La) and enhancement factors (E) due to the occurrence of chemical reactions. A sensitivity analysis based on the measured process parameters was then used to reveal the interrelated effects of key factors on off-gas ozone concentrations. It was shown that the removal efficiencies of color and AOX were simply related to the amount of utilized ozone, regardless of variation of other operating conditions. Furthermore, the rate of absorption fell within the fast or instantaneous kinetics regimes due to the occurrence of rapid chemical reactions. The Ek_La values were found to vary substantially during the course of ozonation, indicating that the enhancement factors were not only affected not only by operating conditions but also by wastewater characteristics. To effectively control the off-gas ozone emission, measures should be taken to minimize the backmixing, use a counter-current flow arrangement and provide adequate contact time.     

Ozonation and Precipitation for Treatment of Bleachery Effluents from Pulp Mills

Results from precipitation of an oxygen/peroxide-bleachery effluent from pulp mills with and without preozonation are presented. Reductions in DOC levels by about 60% were achieved at the pH optimum of 5.5 at an AI/D0C ratio of 0.25 g/g. Increasing alum dosages did not improve the elimination. Ozonation at pH 2 reduced COD, DOC, UV and color levels, while under alkaline conditions an increase of color could be obtained. This effect, based on a polymerization of organics, could be improved at low ozone dosages, by reducing the ozone dosage rate, elevating the pH up to 11 and diluting the wastewater. However, the shift towards high and low molecular weight fractions indicated competing degradation reactions, which counteract a suggested improvement of precipitation by preozonation.     

污水出水有机物对臭氧氧化舒必利的影响

臭氧氧化可以有效去除诸如药物及个人护理品(PPCPs)等新兴有机污染物, 但去除效果受污水出水水质波动的影响。本研究选择了腐殖酸(HA)、牛血清蛋白(BSA)和海藻酸钠(AGS)3种典型有机物作为模型污水出水有机物(EfOM), 从降解速率和矿化程度两方面出发, 考察了EfOM对臭氧氧化去除一种常用抗精神病药物残留舒必利(SP)的影响。结果表明, 臭氧氧化能有效降低水溶液中SP的浓度, 在各反应条件下, 反应8min后去除率均可达85%以上。然而, 在研究条件下, 臭氧氧化对SP的矿化效果不佳, 反应25min后的TOC去除率小于10%。加入HA和BSA后, SP的臭氧氧化反应受到抑制, 随着HA和BSA浓度的增加, 臭氧氧化SP的反应速率逐渐降低, 反应溶液的矿化程度有所提高;而浓度为0~3.0mg/(L TOC)的AGS对臭氧氧化SP的影响较小。     

Removal of Bisphenol A and its Reaction-Intermediates from Aqueous Solution by Ozonation

In this study, the oxidation of Bisphenol A (BPA) and its reaction-intermediates in aqueous solution by ozonation was investigated. The results of the study indicated that ozonation is effective in oxidizing BPA. Catechol, resorcinol, acetone, formaldehyde and organic acids, acetic, formic, maleic, and oxalic acid, are identified as reaction-intermediates. Ozonation of 51 μM (770 μM C) of BPA resulted in peak concentrations of 16.3, 8.7, 6.8, and 2.0 μM C of catechol, resorcinol, acetone, and formaldehyde, respectively. These concentrations correspond to 2.1, 1.1, 0.9, and 0.3% of the initial concentration of BPA in terms of total organic carbon for catechol, resorcinol, acetone, and formaldehyde, respectively. It was observed that BPA's reaction-intermediates were resistant to ozonation compared to the parent compound and complete mineralization of BPA may need extended ozonation.     

OZONATION TREATMENT OF 2-NITROPHENOLIC WASTEWATER USING A NEW GAS-INDUCING REACTOR

Ozonation is a potential chemical process for the treatment of nitrophenolic wastewater. However, due to the low solubility and utilization rate of ozone, a conventional gas-inducing reactor for ozonation treatment has limited app-lication for treating phenolic wastewater. In this study, 2-nitrophenol wastewater ozonation was conducted in a new gas-inducing reactor that has been investigated in our laboratory over the past few years. The ozonation conducted in this reactor can be operated with a higher ozone utilization rate and lower power consumption than a conventional gas-liquid reactor. The ozone utilization rate increases with increasing pH value and can be maintained at over 95%. Kinetic studies show that a pseudo first-order reaction model derived from a two-film theory can describe the ozonation of 2-nitrophenol. Kinetic study of 2-nitrophenol ozonation shows that there are two stages in 2-nitrophenol ozonation. The observed rate constant in the second stage of 2-nitrophenol ozonation is higher than the first stage. A change in the 2-nitrophenol concentration is responsible for the change in the observed rate constant. Below pH 7, the oxidation rate of 2-nitrophenol increases with increasing pH and increasing ozone inlet concentration. This new gas-inducing reactor can improve the ozone utilization rate. The ozonation of 2-nitrophenol can be effectively conducted in this reactor.     

Reactions Involved in Phenolics Degradation from Sugarcane Juice Treated by Ozone

Ozone as an alternative process for the clarification of sugarcane juice has been studied because it presents as an advantage the mineralization of organic compounds that cause color in the crystal sugar. No residues harmful to humans were found after ozonation in contrast to the sulphitation process traditionally used. In this work, the degradation by ozonation of flavonoids and phenolic acids were studied using two compounds: rutin and caffeic acid. Ozonation was efficient and was monitored by liquid chromatography, UV scanning and direct infusion electrospray ionization mass spectrometry. From the collected data, degradation mechanisms and potential mineralization of rutin and caffeic acid after ozonation were proposed.     

Use of Ozone in Night Soil Treatment Process

Ozonation is used for the tertiary treatment, particularly for removal of colour, of the effluent from a night soil treatment plant in Japan. The practical system for effectively controlling the ozone treatment was investigated. The optimum ozonation was accomplished by monitoring the colour. This treatment plant worked in response to a sudden variation in the quality of raw water, i. e., nitrite ion concentration, COD, etc, and the quality of the ozonated water was kept at the levels of COD of 20 ~ 30 mg/2, and colour of 30 units. The water treated by this ozonation plant was found to be free from coliform bocilli, and to exhibit neither so strong acute toxicity to fishes nor mutagenicity.     

臭氧氧化法再生活性炭的研究

研究了利用臭氧氧化法再生吸附了对硝基苯酚的活性炭。实验结果表明，臭氧氧化法对活性炭有着较好的再生能力，但活性炭的吸附饱和程度对其再生效率有着重要的影响。当活性炭的吸附量比较小时，臭氧氧化法对其有着很好的再生效率；而当其吸附饱和程度较高时，臭氧对其的吸附能力几乎无法再生。臭氧对活性炭的再生效率与活性炭的干燥与否无关。臭氧氧化再生活性炭有一个较佳的处理时间，在本实验条件下只需10min即可，延长处理时间不会提高活性炭的吸附能力。