Application of Ozone Involving Advanced Oxidation Processes to Remove Some Pharmaceutical Compounds from Urban Wastewaters

Different UVA radiation and advanced oxidation systems, most of them involving ozone, have been applied to remove mixtures of three contaminants of pharmaceutical type: diclofenac (DCF), sulfamethoxazole (SMT) and caffeine (CFF), both in ultrapure and secondary treated wastewater. The influence of the water matrix has been studied in terms of individual compound concentration and TOC removal. Also, biodegradability of the treated wastewater before and after the advanced oxidation process, as BOD/COD ratio, the partial oxidation yield, the increment of average state of carbon oxidation and ozone consumption have been determined. For mgL^?1 to 100 μgL^?1 concentrations and regardless of the ozone process and water type, DCF and SMT are removed in less than 10 min mainly by direct reaction with ozone, especially in the case of DCF. CFF, on the contrary, is mainly removed through hydroxyl radicals. For lower concentration (≤100 μgL^?1), DCF still disappears by direct ozonation, CFF by hydroxyl radicals oxidation and SMT through both direct ozonation and hydroxyl radical oxidation. Once DCF and SMT have disappeared, TOC is removed by reacting with hydroxyl radicals, regardless of the water matrix. Photocatalytic ozonation allows the highest TOC degradation rate, partial oxidation yield, increment of average state of carbon oxidation and biodegradability together to the lowest ozone consumption per mg TOC eliminated.     

Effect of Catalytic Ozonation Coupling with Activated Carbon Adsorption on Organic Compounds Removal Treating RO Concentrate from Coal Gasification Wastewater

This paper reports a novel system of catalytic ozonation coupling with activated carbon adsorption for removing the organic compounds treating in the RO concentrate from coal gasification wastewater. The effect of ozone dosage, catalyst dosage, reaction time, influence pH, and temperature on organic compounds removal were examined for the processes. In the catalytic ozonation process, increasing solution pH, dosages ozone, and catalyst were statistically significant for improving the performance. In addition, the high salinity with chloride concentration of 15 g/L could reduce the catalyst specific surface area by 18%. Thus, high salinity showed negative influence on the catalytic effect in TOC removal. Regarding activated carbon adsorption process, modified activated carbon by NaOH revealed advantages in adsorbing organic compounds treating catalytic ozonation effluent. With the ozone dosage of 120 mg/L, catalyst dosage of 2.0 g/L, catalytic ozonation reaction time of 1 h, and modified activated carbon adsorption time of 1 h, the average TOC removal efficiencies were maintained at the stable level of 58% with the TOC concentration of 26 mg/L.     

Improvement of Biodegradability of Oil Field Drilling Wastewater Using Ozone

The possibility of improving the biodegradability of drilling wastewater using ozone was investigated following coagulation pretreatment. The biodegradability of wastewater was improved significantly following the start of ozonation, and the molecular weight of organic compounds decreased continuously with the progress of oxidation. It is interesting that minimum biochemical oxygen demand, total organic carbon (BOD/TOC) ratio (0.4 g/g) was observed when wastewater was treated with ozone continuously for 15 min. The combination of ozonation for 5 min (ozone consumption ratio of 2.6 g ozone/g TOC) followed by biological degradation produced a total TOC removal rate of 54.3%, which was comparable to direct ozonation for 30 min under the same conditions (TOC removal rate of 54.9%; ozone consumption ratio of 8.7 g ozone/g TOC). It is clear that biological treatment following short-term ozonation was very efficient in TOC removal. A process of successive coagulation-precipitation, ozone oxidation, and biodegradation seemed to be a good option for drilling wastewater treatment.     

Catalysts to improve the abatement of sulfamethoxazole and the resulting organic carbon in water during ozonation

Sulfamethoxazole (SMX), one pharmaceutical compound, has been treated in aqueous solutions with catalysts (copper and cobalt type perovskites and cobalt–alumina) and promoters (activated carbons). Hydrogen peroxide and saturated carboxylic acids were identified as intermediates. The effects of adsorption and pH have been investigated. Removal of the starting SMX accomplished with ozone alone is a fast process but catalytic or promoted ozonation is needed to significantly reduce the resulting organic carbon. SMX is, thus, mainly removed through direct ozone reaction while hydroxyl radical oxidation is the mechanism of removal the remaining TOC. The kinetics of the process has also been investigated. Perovskite catalytic ozonation resulted to be a chemical control process and apparent rate constants for homogeneous and heterogeneous ozonation were determined. For activated carbon ozonation, external diffusion of ozone to solid particles controlled the process rate.     

Solid Phase Catalytic Ozonation Process for the Destruction of a Model Pollutant

Pure metal oxides, mixed metal oxides, and platinum metals were evaluated as ozonation catalysts. Batch reactor experiments were performed using deionized water at pH 7 and semi-continuous ozonation experiments were performed using a natural water. p-Chlorobenzoic acid (pCBA), a non-adsorbing model micropollutant that does not react directly with molecular ozone, was included in both solution matrixes. Titanium dioxide, cobalt oxide, nickel oxide, copper oxide, and a mixed metal oxide comprised of copper, zinc, and aluminum did not accelerate the removal pCBA in deionized water. However, cobalt oxide and the mixed metal oxide catalyst were effective at accelerating the removal of pCBA in a natural water matrix. The mixed metal oxide catalyst may have the most potential as an ozonation catalyst because it also was very stable (i.e., low solubility). A ruthenium / alumina catalyst also increased the removal of pCBA, but this metal may follow a different reaction mechanism than the metal oxide catalysts.     

负载型稀土臭氧氧化催化剂在水处理中的应用进展

非均相催化臭氧氧化技术是一种高效的水污染控制技术。负载型稀土臭氧氧化催化剂因稀土元素独特的电子构型,展现出优异的催化性能,不仅具有良好的稳定性和较长的使用寿命,还可有效解决催化剂流失及出水金属离子超标问题,被认为是最有前景的非均相臭氧氧化催化剂。本文着重从负载型稀土臭氧氧化催化剂的制备、催化反应机理以及单稀土、稀土-过渡金属、双稀土-过渡金属氧化物负载型臭氧氧化催化剂在近几年的污水处理领域中的应用进展进行概述与总结。多稀土复合型非均相臭氧氧化催化剂的开发,以及对催化氧化过程的作用机理的深入研究,是未来非均相催化臭氧氧化技术在水处理中的重点研究方向。     

硅铁合金催化臭氧氧化水中布洛芬

近几年,在各地的饮用水中不断检测到微量布洛芬,其环境毒性引起了广泛关注。选用工业硅铁作为催化剂,催化臭氧氧化去除水中的布洛芬,并通过单因素试验,确定了反应体系的最佳条件。结果表明,在硅铁的作用下,催化臭氧氧化可以明显提高布洛芬的去除率。在硅铁投加量为1 g/L、水溶液初始pH值为8、臭氧浓度9.0 mg/L、布洛芬初始浓度为10 mg/L时,经过80 min,水样总有机碳(TOC)的去除率可达75.5%,较单独臭氧氧化提高了38.0%。将碳酸氢钠作为自由基抑制剂加入反应体系,可明显降低TOC的去除率,间接证明了催化臭氧氧化布洛芬的反应遵循自由基机理。     

Degradation and Transformation of Organic Compounds in Songhua River Water by Catalytic Ozonation in the Presence of TiO2/Zeolite

This paper presents experimental results of the catalytic ozonation of Songhua River water in the presence of nano-TiO₂ supported on Zeolite. The removal efficiency of TOC and UV₂₅₄, the variation of AOC and molecular weight distribution of organics was studied. Results showed that TOC and UV₂₅₄ removal efficiency by ozone was improved in the presence of TiO₂/Zeolite, and increased by 20% and 25%, respectively. The part of organic compounds less than 1000 Da increased in ozonation, but decreased in catalytic ozonation. The AOC of water increased in catalytic ozonation, and the increase of AOC was particularly obvious when ozone dose increased from 28.8 mg·L^?1 to 46.6 mg·L^?1. The degradation and transformation of organic compounds was analyzed by means of GC-MS. The total number of organic compounds was reduced from 50 in the untreated water to 36 and 20, respectively, in ozonation and catalytic ozonation. The removal efficiency of the total organic compounds peak area in ozonation and catalytic ozonation were 23.5% and 62.5%, respectively. Most of the hydrocarbons could be removed easily in ozonation and catalytic ozonation. The organic compounds having hydroxyl, carboxyl or carbonyl groups were hard to be removed in ozonation, but could be removed efficiently in the presence of TiO₂/Zeolite.     

Catalytic Ozonation of Sulfosalicylic Acid

The investigation of heterogeneous catalytic ozonation of sulfosalicylic acid (SSal) in aqueous solution is reported in this paper. It was found that catalytic ozonation in the presence of V-O supported on silica gel had a more positive effect on the removal rate (62% in 30 min) of total organic carbon (TOC) than that of ozonation alone (20% in 30 min), and the catalyst supported on TiO₂ had similar results. The experimental results also showed that the ozone dosage should be sufficient for achieving the catalytic effect. Efficient removal of TOC in catalytic ozonation was probably attributed to producing more powerful oxidants than molecular ozone.     

Ozone-activated Carbon Mineralization of 17-α-Ethynylestradiol Aqueous Solutions

Ozone and activated carbon (AC) have been used on the removal of 17α-ethynylestradiol (ETOL), a pharmaceutical compound, and its oxidation by-products. Although single ozonation is not able to totally remove the by-products formed from the degradation of the parent compound (about 65% of TOC removal at pH 7 after 2-hour reaction), the ozone/AC system led not only to higher TOC removal at the same conditions (about 90% in the case of P110 Hydraffin AC) but also to lower ozone consumption. In addition, samples treated with the catalytic process presented ecotoxicity values lower than those resulting from the application of single ozonation.     

Memory effect-enhanced catalytic ozonation of aqueous phenol and oxalic acid over supported Cu catalysts derived from hydrotalcite

Mg/Al supported metal (Fe, Co, Ni and Cu) oxide catalysts were prepared by co-precipitation of hydrotalcite-like clay materials as precursors, calcined, and used for the ozonation reaction of phenol and oxalic acid. The reaction was carried out using the catalyst and aqueous solution of phenol or oxalic acid in an O₃/O₂ mixed gas-flow at 20 °C. In the ozonation of phenol, the combination of ozone and supported metal oxide catalysts was effective for the removal of total organic carbon (TOC). Also in the ozonation of oxalic acid as the main TOC component, Cu/Mg/Al catalysts showed the highest activity, followed by Ni/Mg/Al catalyst, while both Fe/Mg/Al and Co/Mg/Al catalysts were not active. Leaching of Cu and Ni, probably due to the chelation of metals by oxalic acid, was significantly observed at the beginning of the reaction. However the metal leaching disappeared at the end of the reaction possibly due to the entire consumption of oxalic acid during the reaction. The best result of oxalic acid mineralization was observed over Cu/Mg/Al catalyst calcined at 600 °C, on which least leaching of the metal was detected. Moreover, a “memory effect” of hydrotalcite accelerated the mineralization of oxalic acid over the Cu/Mg/Al catalyst; oxalate anions were captured and decomposed in the reconstituted hydrotalcite interlayer space on the surface of the Cu/Mg/Al catalyst, resulting in a remarkable enhancement in the catalytic activity of the ozonation.     

Impact of ozonation on subsequent treatment of azo dye solutions

BACKGROUND: Aqueous solutions of four azo‐dyes, Acid Red 14 (AR14), Congo Red (CR), Reactive Black 5 (RB5), and Reactive Violet 5 (RV5) were treated with ozone, and the impact of ozonation on their subsequent treatability by aerobic biodegradation processes was investigated. RESULTS: In all cases, ozonation at the highest ozone doses investigated could remove more than 96% of the original dye, and the corresponding residual colour of the azo dye solutions declined to less than 20 on the Pt‐Co scale. Ozonation also resulted in reduction of chemical oxygen demand (COD), total organic carbon (TOC) the COD/TOC ratio and pH, while in all cases electrical conductivity of the dye solutions increased. Activity of the microbial colonies present in domestic wastewater was not inhibited when un‐ozonized solutions of these dyes were mixed in a 1:1 volumetric ratio with domestic wastewater, although the dyes themselves were not degraded. Also, no significant inhibition of microbial activity was observed in 1:1 mixtures of ozonized dye solutions and domestic wastewater, especially when the initial dye concentration was low and the applied ozone dose was high. In almost all cases, progressively enhanced BOD exertion was observed in mixtures containing dye solutions ozonized with progressively higher doses. This indicated that some ozonation by‐products of the above dyes could be degraded by microorganisms present in domestic wastewater. CONCLUSIONS: It was concluded that the above dye solutions, after ozonation for partial or complete colour removal, could be mixed with domestic wastewater for subsequent treatment by aerobic biological processes, with no adverse impact on the activity of the microbial colonies present in domestic wastewater. Copyright © 2007 Society of Chemical Industry     

基于催化臭氧氧化去除煤化工废水中污染物——苯系物

苯、甲苯、乙苯和二甲苯(BTEX)是煤化工废水中典型的难降解有机污染物,通常情况下BTEX较难通过传统的化学氧化技术去除。笔者自主制备了多孔臭氧催化剂,并对催化剂进行表征分析;考察了催化臭氧化降解BTEX的最佳反应条件,并对不同反应体系中自由基的激发情况进行比对;在此基础上探究催化臭氧化对BTEX的去除机理,为BTEX在实际处理过程中的技术应用提供理论基础。XRD分析结果表明,多孔臭氧催化剂含有氧化铝、氧化硅等,且含有沸石结构的化合物。XPS分析结果表明,所合成的催化剂含Si、O、Cu、Fe、Mn、Al等元素。SEM结果表明,催化剂由许多不规则的细小块状粉末构成,且表面非常蓬松,堆叠成多级结构,使催化剂呈多孔性。比表面积分析表明,催化剂的比表面积为20.8 m^2/g,孔隙直径主要集中在3.8 nm。使用该催化剂对BTEX进行催化臭氧化试验,结果表明,反应温度为30℃、溶液pH=8、臭氧投加量为3.5 mg/L、催化剂投加量为5 g/L时,BTEX的降解效果最佳。在该反应体系中有机物去除率为99.1%,其中苯、甲苯、乙苯、二甲苯的去除率分别为95.6%、98.2%、100%、100%。ESR分析结果表明,催化臭氧化反应体系中羟基自由基和超氧自由基的激发强度明显高于臭氧氧化反应体系,这是因为本文制备的催化剂含有Al、Fe、Mn、Cu氧化物,使催化反应过程中负载的金属氧化物价态间相互变化,转移的电子可促进臭氧分子分解,从而产生更多的自由基。催化臭氧化技术是以羟基自由基为主导,超氧自由基、催化剂吸附为辅助,协同实现煤化工废水中典型有机污染物BTEX的高效去除。     

臭氧氧化法深度处理造纸废水试验研究

首先采用复合混凝剂对造纸废水二级出水进行了预处理,再用臭氧进行氧化处理.研究了在不同臭氧量、pH条件下,臭氧氧化法对造纸废水中COD和色度的去除效果,及不同臭氧产生速率和反应时间对COD与色度的去除效果,分析了臭氧氧化污染物的机理.结果表明,臭氧氧化效果随臭氧量、反应时间的增加而增强,但增强幅度越来越小;臭氧投加速率为13.98 mg/min、停留时间为30 min时,COD和色度去除率分别可达62-3%和99.5%,去除效果明显.     

Influence parameters in the ozonation of phenol wastewater treatment using bubble column reactor under continuous circulation

The ozonation of phenol wastewater treatment system has been investigated with effective mass transfer between gas and liquid phase in a bubble column reactor. The designed bubble column reactor was investigated for increasing the rate of mass transfer of ozone, the rate of oxidation of phenol in the solution, the solubility and decomposition rate of ozone in the distilled water were also studied at different flow rates. The decomposition rate constants were calculated based on pseudo first order kinetics. The oxidation of phenol was investigated in order to provide the overall reaction rate constant for the reaction between ozone and phenol at 25 °C. The influence of the operating parameters like initial phenol concentration, ozone flow rate and pH for the destruction of phenol by ozonation were studied. The pseudo first order rate constant was depending on the initial concentration of phenol solution. A comparison of TOC removal percentage between bubble column reactor and bubble diffuser using ozonation were reported.     

Catalytic ozonation of dimethyl phthalate with RuO2/Al2O3 catalysts prepared by microwave irradiation

Ruthenium catalysts supported on alumina were synthesized by microwave irradiation and used to catalyze ozonation of dimethyl phthalate in water. The catalysts enhanced greatly the TOC (total organic carbon) removal. The contribution of catalysis and adsorption to the overall TOC removal were 33% and 50%, respectively. 300 W was the optimal irradiation power for catalyst preparation. Moisture content had little effect on the catalytic activity. Compared to conventional irradiation, microwave irradiation benefited the catalytic activity because it provided a homogeneous dispersion of metal on the support. It is a promising thermal treatment method for developing the catalysts used in catalytic ozonation.     

纳米δ-FeOOH催化臭氧氧化降解水中萘普生

以氯化亚铁和氢氧化钠为原料,采用双氧水快速氧化氢氧化亚铁的方式,成功制备了δ-FeOOH纳米材料。首次将其应用于催化臭氧氧化,并探究了催化剂投加量、臭氧浓度、萘普生(NPX)初始浓度对目标污染物降解效果的影响。采用X射线衍射仪(XRD)、透射电子显微镜(TEM)、低温N2吸附脱附等温线对催化剂的晶体结构、形貌等进行表征。结果表明,制备的材料纯度高,是厚度约为4 nm的六角片层结构。该材料的BET比表面积达191.73 m2/g,并具有介孔特征。试验制备的材料显著提升了催化臭氧氧化萘普生的能力,反应15 min后TOC的最高去除率为64.5%,与单独臭氧相比提高了38.4%。同时,通过·OH抑制试验,初步探究了可能的纳米δ-FeOOH催化臭氧氧化机理。     

Application of Regression Analysis for Ozone and Catalytic Ozonation of Organic Compounds from Landfill Leachate with Ceramic Raschig Rings and Natural Manganese Ore

Treatment of landfill leachate could be improved by adding ceramic raschig rings and manganese ore as catalysts for ozonation. Regression analysis were carried out to assess effects of parameters (pH, reaction time, the amount of H₂O₂, the surface area of ceramic raschig rings and the amount of manganese ore) on removing organic compounds from landfill leachate by ozone alone, peroxone, ozone/ceramic raschig rings, peroxone/ceramic raschig rings, ozone/manganese ore and peroxone/manganese ore. Results showed that parameters of reaction time, the amount of H₂O₂ and the amount of manganese ore were the high effects on removal of organic compounds from landfill leachate, following by pH paremeter. Ceramic raschig rings did not have significant effect on color, COD and TOC removal.     

染料中间体废水多相催化氧化中几种催化剂的筛选研究

对于高浓度染料中间体废水多相催化氧化处理工艺的催化剂进行了研制工作，选择了染料中间体废水中的吐氏酸废水为处理对象。结果表明，过渡金属氧化物中Ｎｉ２Ｏ３与ＭｎＯ２是具有较高催化活性的组分，Ｃｕ、Ｆｅ等金属的氧化物没有明显的催化活性，但与Ｎｉ，Ｍｎ等组分相混合，却能体现较高的催化活性，而且，添加少量的Ｋ２Ｏ具有明显的助催化作用。对ＣＯＤ为１５００ｍｇ／Ｌ左右的叶氏酸废水，在Ｏ３投加量达１ｇ／Ｌ时，ＣＯ     

Enhancement in mineralization of some natural refractory organic compounds by ozonation–aerobic biodegradation

Two schemes, the first involving ozonation followed by final aerobic biodegradation (phase I experiments), and the second involving initial aerobic biodegradation, followed by ozonation and subsequent final aerobic biodegradation (phase II experiments), were examined for enhanced mineralization of refractory model compounds, viz. gallic acid, tannin and lignin. In all cases, and irrespective of the applied scheme, chemical oxygen demand (COD), total organic carbon (TOC), COD/TOC ratio, and specific UV absorbance at 280 nm attributed to the model compounds decreased with application of increasing ozone dose. The residual organic matter remaining after ozonation exhibited enhanced aerobic biodegradability in all cases. Further, in all cases and irrespective of the applied scheme, the overall amount of COD and TOC removed through the combination of ozonation and biodegradation processes increased with increase in ozone dose for all three model compounds, and more than 90% COD removal could be achieved with an ozone dose of 3 mg ozone absorbed per mg initial TOC, as compared with approximately 40% COD removal when no ozone was applied. Treatment by the first scheme resulted in the fraction of starting COD removed through biodegradation decreasing with increase in ozone dose in all cases, while this fraction increased or remained constant during treatment using the second scheme. In the case of tannin and lignin, similar overall COD removal could be achieved at lower ozone doses using scheme II. Due to incorporation of the initial aerobic biodegradation step in scheme II, the ozone requirement for additional mineralization, ie mineralization over and above that achieved by aerobic biodegradation, was also lower than that in scheme I. Copyright © 2005 Society of Chemical Industry