Removal of endocrine-disrupting chemicals by ozonation in sewage treatment.

Treatment experiments by two laboratory scale semi-batch reactors and a demonstration scale process were both carried out to evaluate endocrine disrupting chemical removal characteristics by ozonation in sewage treatment. In the semi-batch mode experiments, secondary effluent and primary effluen of sewage treatment plants were ozonated respectively. Behaviour of brominated by-products was also evaluated. The results based on these studies indicated that estrogenicity in wastewater can be removed by ozonation effectively. The condition of ozonation until dissolved ozone concentration increased to 0.1 mg/L, which corresponded to 1 mgO3/mgC and 0.4 mgO3/mgC of ozone consumption per initial DOC for secondary effluent and primary effluent, respectively, is proposed as an appropriate operational condition for efficient removal of EDCs as well as UV254 and SUVA without production of brominated by-products.     

Potential of activated sludge ozonation.

The disposal of sewage sludge and the agricultural use of stabilised sludge are decreasing due to more stringent regulations in Europe. An increasing fraction of sewage sludge must therefore be dewatered, dried, incinerated and the ashes disposed of in landfills. These processes are cost-intensive and also lead to the loss of the valuable phosphate resources incorporated in the sludge ash. The implementation of processes that could reduce excess sludge production and recycle phosphate is therefore recommended. Partial ozonation of the return sludge of an activated sludge system significantly reduces excess sludge production, improves the settling properties of the sludge and reduces bulking and scumming. The solubilised COD will also improve denitrification if the treated sludge is recycled to the anoxic zone. However, ozonation partly kills nitrifiers and could therefore lead to a decrease of the effective solid retention time of the nitrifier, thus reducing the safety of the nitrification. This paper discusses the effect of ozonation on sludge reduction, the operating stability of nitrification, the improvement of denitrification and also presents an energy and cost evaluation.     

三卤甲烷在臭氧工艺中的形成与控制

研究了臭氧氧化对三卤甲烷生成潜能的去除规律,发现臭氧对氯仿生成潜能有较好的去除效果,但对溴仿生成潜能的去除能力很差.在高臭氧投加量下,臭氧会明显促进溴仿的生成.臭氧对总三卤甲烷生成潜能的去除效果是其对"氯代三卤甲烷生成潜能的去除"和对"溴代三卤甲烷生成潜能的促进"两方面综合作用的结果.     

Recalcitrant COD degradation by an integrated system of ozonation and membrane bioreactor.

In order to treat wastewater to a low residual COD-concentration such as 125 mg/L, classical biological treatment is not sufficient for many types of industry. This research focused on the integrated treatment of the wastewater of the paper industry, with a membrane bioreactor (MBR) and an oxidation step. The optimal configuration was examined. Screening tests with different types of oxidation showed that ozonation after biological treatment could reduce the COD with 40% with an ozone dose of 0.4-0.8g O3/g COD. BOD/COD ratio could be increased up to 0.19. Neither combination of ozone with UV and/or hydrogen peroxide nor the process H2O2/UV or (photo-)Fenton reagents gave any improvement in COD reduction or BOD increase, unless the doses were very high. Based on these results, an integrated system MBR-ozonation was designed, with recirculation of MBR effluent over ozonation. This test showed that reduction of COD up to 125 mg/L immediately behind the MBR required a lot of ozone. A technically feasible solution was to discharge the water after an extra ozonation step, which resulted in a high total ozone dosage. The alternative, the consecutive treatment activated sludge-ozonation-activated sludge, did not give a better COD-removal with the same ozone dose as the integrated concept. The economic evaluation proves that the integrated chemical and biological treatment is expensive for the paper industry if a low discharge limit of COD has to be complied with.     

Elimination of the musk fragrances galaxolide and tonalide from wastewater by ozonation and concomitant stripping.

Ozone reacts with the musk fragrances tonalide and galaxolide with rate constants of 8 M(-1)s(-1) and 140 M(-1)s(-1), respectively. In wastewater, ozone eliminates only the more reactive compound, galaxolide, in competition with its reaction with the wastewater matrix. As both compounds are also stripped in a bubble column, tonalide is also eliminated to some extent.     

Potential of ozonation for the degradation of antibiotics in wastewater.

Increasing concern in recent years over the occurrence and fate of low-level concentrations of pharmaceuticals in the aquatic environment stimulates research on alternative treatment methods. This paper presents a study of the degradation of sulphamethoxazole, an antibiotic used on humans and animals in order to treat various bacterial infections, by ozonation. After 4.5 min of treatment, the concentration of sulphamethoxazole was below the HPLC detection limit of 0.6 mgL(-1), indicating degradation efficiency higher than 99.24%. This value is comparable and in some cases higher than published data on the degradation in drinking water. Kinetic analysis of the data indicated an overall first-order reaction with a rate constant of 1.0594 min(-1) at 20 degrees C. The reaction order differs with the second-order reaction observed by other researchers. This change of reaction order could be explained by the different treatment conditions used. Preliminary analysis using the FT-IR technique was also performed in order to obtain information on the structure of the degradation products. Further analysis using a GC-MS is needed in order to elucidate the structure of the degradation products. Finally, based on the experiments performed, ozonation seems to be a promising technique for the degradation of antibiotics, even in wastewater.     

Effect of ozonation on sludge reduction in a SBR plant.

This paper provides new insights on the application of the ozonation process for the reduction of activated sludge production in a Sequencing Batch Reactor. The study was performed on two identical lab-scale SBRs plant, fed with domestic sewage: a fraction (1/3 of the working volume) of the activated sludge from one reactor (Exp SBR) was periodically subjected to ozonation for 30 minutes at 0.05 g O(3)/gSS and then recirculated before the beginning of the cycle; the other reactor was used as control and therefore managed at the same sludge retention time but without the application of ozonation. The effects of the recirculation of the ozonated sludge to the Exp SBR were evaluated in terms of biological nitrogen and carbon removal efficiencies, Mixed Liquor Volatile and Suspended Solids (MLSS and MLVSS, respectively) concentrations, effluent quality and sludge settleability. Besides, characterization of the ozonated sludge was carried out for different oxidant dosages (0.05, 0.07 and 0.37 g O(3)/gSS) and durations of the ozonation process (10, 20 and 30 minutes). The results show that at 0.05 g O(3)/gSS and 30 minutes contact time MLVSS as well as MLVSS/MLSS ratio do not change appreciably. Ozone dosage must be increased much further to obtain a relevant effect.     

A kinetic study of enhancing effect by phenolic compounds on the hydroxyl radical generation during ozonation.

Ozone decomposition in aqueous solution proceeds through a radical type chain mechanism. These reactions involve the very reactive and catalytic intermediates O2- radical, OH radical, HO2 radical, OH-, H2O2, etc. OH radical is proposed as an important factor in the ozonation of water among them. In the present study, the enhancing effects of several phenolic compounds; phenol, 2-, 3-, 4-monochloro, 2,4-dichloro, 2,4,6-trichlorophenol on OH radical generation were mathematically evaluated using the electron spin resonance (ESR)/spin-trapping technique. OH radical was trapped with a 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a stable adduct, DMPO-OH. The initial velocities of DMPO-OH generation in ozonated water containing phenolic compounds were quantitatively measured using a combined system of ESR spectroscopy with stopped-flow apparatus, which was controlled by homemade software. The initial velocities of DMPO-OH generation increased as a function of the ozone concentration. The relation among ozone concentration, amount of phenolic compounds and the initial velocity (v0) of DMPO-OH generation was mathematically analyzed and the following equation was obtained, v0 (10(-6) M/s) = (A' x [PhOHs (10(-9) M)] + 0.0005) exp (60 x [ozone (10(-9) M)]). The equation fitted very well with the experimental results, and the correlation coefficient was larger than 0.98.     

臭氧催化氧化改善水质安全性指标中试与生产性研究

从水的生物稳定性、遗传毒性、颗粒物去除、臭氧氧化副产物以及催化剂的稳定性等方面研究了臭氧催化氧化-生物活性炭技术在净水处理过程中的安全性问题.结果表明,催化剂具有优良的物理化学稳定性,能够催化臭氧氧化进一步控制AOC及其前质,减小了活性炭的污染物负荷;与生物活性炭联用可以明显减小有害有机物穿透水处理工艺的能力,进一步消减了水的遗传毒性;联用工艺可以显著地去除水中与致病原生动物相关性极大的2～10 μm颗粒物,进一步提高了饮用水的卫生安全性;催化剂对剩余臭氧的消减抑制了BrO-3生成.     

Full-scale application of anaerobic digestion process with partial ozonation of digested sludge.

For improving sludge digestion and biogas recovery, a new anaerobic digestion process combined with ozonation was tested at a full-scale unit for 2 years and its performance was compared with a simultaneously operated conventional anaerobic digestion process. The new process requires two essential modifications, which includes ozonation for enhancing the biological degradability of sludge organics and concentrating of solids in the digester through a solid/liquid separation for extension of SRT. These modifications resulted in high VSS degradation efficiency of ca. 88%, as much as 1.3 times of methane production and more than 70% reduction in dewatered sludge cake production. Owing to accumulation of inorganic solids in the digested sludge, water content of the dewatered sludge cake also reduced from 80% to 68%. An energy analysis suggested that no supplemental fuel was necessary for the subsequent incineration of the cake from the new process scheme. The process is suitable to apply to a low-loaded anaerobic digestion tank, where power production is used.     

Removal of volatile organic compounds by heterogeneous ozonation on microporous synthetic alumina silicate

A hybrid process combining adsorption and ozonation was examined as an alternative treatment for odorous volatile organic compounds (VOCs). Methyl ethyl ketone (MEK) was chosen to study the influence of operating parameters. Two synthetic aluminosilicates (faujasite-Y and ZSM-5) were tested for adsorption and reactivity with ozone. The adsorption equilibrium measurement on both adsorbents showed that adsorption performance depends on temperature but is not sensitive to relative humidity, due to the hydrophobic properties of the materials. Adsorbed VOCs were oxidized at low temperature when ozonated flow was sent to the reactor. Regeneration of the fixed bed was achieved at the same time, releasing mainly CO(2) and H(2)O. Intermediates of oxidation, such as 2,3-butanedione and acetic acid, were identified, leading to incomplete mineralization. The influence of concentration and humidity are discussed. Four successive cycles were tested: after the first adsorption/ozonation cycle, the adsorption efficiency was not affected during subsequent cycles. These results show that the same sample of adsorbent can be used in the treatment process for a long time. Ozonation regeneration is a promising process for VOC removal.     

臭氧与活性炭深度处理微污染原水试验研究

采用"预臭氧氧化 常规处理 GAC/O3-BAC深度处理"工艺针对南方某市微污染原水进行中试研究.结果表明:预臭氧能明显提高浊度、有机物和THMFP的去除效果,在此条件下常规出水浊度平均值＜O.1 NTU,与无预处理相比,CODMn去除率提高17.52%,氯消毒后CHCl3浓度降低86.4%;O3-BAC工艺对有机物、CHCl3的去除效果和吸附寿命均优于GAC工艺,但生物膜的脱落会影响浊度的去除效果;随着炭床厚度增加,GAC滤池中,CODMn呈线性降低,而BAC滤池中,上部500～1 000 mm厚度内,CODMn快速降低并稳定在一定的水平上.     

Improving the biodegradability of grain distillery wastewater for use as UASB substrate by combinations of ozonation/enzymatic pre-treatments.

The effect of ozonation and enzyme combination pre-treatments on the composition of grain distillery wastewater (GDWW) was investigated. Exposure of UASB granules to these pre-treated GDWW was evaluated by determining the effect on granule activity, visual appearance and lipid content of the granules. Pre-treatments involving a pre-ozonation step were found to be more effective in reducing the lipid and COD content of GDWW. The higher the lipid and COD reduction achieved by the pre-treatments the higher the granule activity after 24 d exposure, the lower the lipid content in the granule and the less severe the formation of an encapsulating layer.     

Sustainable removal of iodinated X-ray contrast media (XRC) by ozonation in a complex wastewater matrix--urine as example.

Pharmaceutical and diagnostic substances like antibiotics, cytostatics and iodised X-ray contrast media (XRC) are well-known for not being metabolised and are excreted soon after application. As a result, these preparations are difficult to biodegrade and their adsorption behaviour is rather poor. Finally, the refractory properties of these substances are leading to an accumulation in the natural waterbody depending on the hydrological situation. The elimination of contrast media from urine and diluted urine solutions by ozonation was investigated using a bubble column reactor to remove and recover the formed elemental iodine from the solution by gas stripping and down stream absorption. The experiments showed that the destruction of XRCs from concentrated solutions like urine is feasible and a recycling of elemental iodine from the exhaust gas is technically and economically possible.     

催化臭氧氧化深度处理印染废水中试研究

针对江苏某化工园区印染废水高效沉淀池出水,利用以氧化铝为载体的臭氧催化剂进行催化臭氧氧化中试,考察臭氧催化氧化技术对印染废水污染物的处理效果,同时为污水处理厂提标改造项目提供理论指导.实验结果表明:当臭氧催化剂载体为氧化铝时,系统的调试运行时间不应少于40 h,应避免因催化剂的吸附作用对实验结果造成的干扰.固定一个臭氧...     

Catalyzed ozonation process with GAC and metal doped-GAC for removing organic pollutants.

The purpose of this study was to investigate the catalytic role of granular activated carbon (GAC), and metal (Mn or Fe) doped-GAC, on the transformation of ozone into more reactive secondary radicals, such as hydroxyl radicals (*OH), for the treatment of wastewater. The GAC doped with Mn showed the highest catalytic performance in terms of ozone decomposition into OH radicals. Likewise, activated carbon alone accelerated the ozone decomposition, resulting in the formation of *OH radicals. In the presence of promoters, the ozone depletion rate was enhanced further by the Mn-GAC catalyst system, even under aqueous acidic pH conditions.     

臭氧氧化用于污水回用的试验研究

对臭氧氧化深度处理生活污水进行了长期试验,以评价臭氧氧化对生活污水深处理的效能。研究结果表明,当臭氧投加量16 mg/L、臭氧氧化时间15 min,臭氧氧化后出水COD、UV254、色度、浊度、NH3-N的平均值分别为51.0 mg/L、0.140 cm-1、27.4度、5.0 NTU和18.7 mg/L,臭氧氧化对上述5个水质指标的平均去除率分别为30.3%、22.0%、53.7%、32.1%、14.6%。单独依靠臭氧氧化技术很难将上述5个水质指标降低到较低水平,因此,需要将臭氧氧化作为预处理技术与其他工艺进行组合,利用组合工艺对再生水进行深度处理将有广阔的发展前景。     

臭氧生物活性炭技术的工艺设计与运行管理

针对臭氧生物活性炭工艺应用中的关键问题,首先对工艺设计中的活性炭滤料选择、活性炭滤层结构设计、活性炭滤池选择、臭氧系统选择、臭氧接触池优化设计和复合预氧化设计等内容进行了分析和总结.然后对运行中存在的微生物安全性、大型微生物控制、活性炭滤池初滤水管理及pH控制、预臭氧和主臭氧工艺的运行管理等问题进行了总结,并提出了相应的解决方案.最后,建议今后应重点注意微生物安全性、臭氧副产物控制和工艺运行控制标准等问题.     

臭氧氧化工艺溴酸盐控制中试研究

通过1m3/h的中试装置研究了臭氧氧化工艺处理引黄水库水时溴酸盐控制技术。结果表明,在臭氧投加量为1.5mg/L时,臭氧氧化后溴酸盐产生量为0.006mg/L,活性炭过滤出水溴酸盐为0.002mg/L;在相同臭氧投加量条件下,降低原水pH、投加高锰酸钾和过氧化氢后溴酸盐生成量分别减少了50%、33%和100%,活性炭后出水中均未检出溴酸盐,同时提高了有机物去除率。     

Development of a hybrid ozonation biofilm-membrane filatration process for the production of drinking water.

Drinking water sources in Norway are characterized by high concentrations of natural organic matter (NOM), low alkalinity and low turbidity. The removal of NOM is therefore a general requirement in producing potable water. Drinking water treatment plants are commonly designed with coagulation direct filtration or NF spiral wound membrane processes. This study has investigated the feasibility and potential of a hybrid process combining ozonation and biofiltration with a rotating disk membrane for treating drinking water with high NOM concentrations. Ozonation will oxidize the NOM content removing colour and form biodegradable organic compounds, which can be removed in biological filters. A constructed water was used in this study which is representative of ozonated NOM-containing water. A rotating membrane disk bioreactor downstream the ozonation process was used to carry out both the biodegradation as well as biomass separation in the same reactor. Maintenance of biodegradation of the organic matter while controlling biofouling of the membrane and acceptable water production rates was the focus in the study. Three operating modes were investigated. Removal of the biodegradable organics was consistent throughout the study indicating that sufficient biomass was maintained in the reactor for all operating conditions tested. Biofouling control was not achieved through shear-induced cleaning by periodically rotating the membrane disks at high speed. By adding a small amount of sponges in the membrane chamber the biofouling could be controlled by mechanical cleaning of the membrane surface during disk rotation. The overall results indicate that the system can favorably be used in an ozonation/biofiltration process by carrying out both biodegradation as well as biomass separation in the same reactor.