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     

Application of Ozone in Stripping of Cotton Fabric Dyed with Reactive Dyes

ABSTRACT

This paper discusses the color stripping of cotton fabric dyed with four reactive dyes using ozone. An ozone color stripping process has been optimized in terms of pH, ozone dose, treatment time and dye concentration. Color stripping efficiency of the process is evaluated in light of the color properties including Lightness (L*), Lightness Difference (?L*), and Color Difference (?E*) in addition to strength properties, i.e., copper number and degree of polymerization as well as compared with a control method (conventional reductive color stripping method). The results demonstrate maximum color stripping at an ozone dose of 10 g/h, exposure time of 45 min, and pH maintained at 5. The Stripping Efficiency, however, decreases with increasing dye concentration from 0.5% to 4%, which implies that decolorization of dyed fabric with higher initial dye concentration requires higher ozone dose and/or longer exposure time. The strength of the ozone-stripped fabric sample is almost similar to that of control. The chemical oxygen demand of effluent generated by ozone stripping process is 97% lower than the effluent produced by the conventional stripping method. The Ozone Stripping Process hence proves to be environment-friendly as it consumes less water, energy, and chemicals.     

Decolourisation of leather dye by ozonation

Sewage and industrial effluent treatment plants are installed with primary and secondary biological treatment units to reduce the discharge of pollution load into the environment. These treatment plants normally reduce the organic load in terms of BOD but not the pollution load in terms of inorganic salts (total dissolved solids—TDS) and colour in the effluent. To eliminate the contamination of ground and surface water bodies and to conserve water sources, the regulatory authorities have taken very stringent regulations to implement zero liquid discharge (ZLD) for industrial effluents, i.e., water recovery from wastewater and reuse. It is difficult to recover water from secondary treated wastewater directly, as it does not meet the reverse osmosis feed requirements. In order to achieve the feed requirements, different tertiary treatment methods are being tried. In this study, removal of colour due to residual dyes has been attempted using ozone. The main purpose of this study is to decolourise the dye used in leather processing. Also, the effect of pH and dye concentration on dye decolourisation has been investigated. From the study it has been observed that maximum decolourisation efficiency up to 97% could be achieved for the pH values (4,7, 9 and 11) and dye concentrations (30, 65, 180 and 360 mg/L) studied.     

O3—BAC工艺炭滤池pH变化关键因素探究

针对南方湿热地区深度处理O3-生物活性炭(BAC)工艺炭滤池出水pH大幅降低问题,研究了主接触池O3投加量、炭滤池内的酸性气体CO2、炭滤池进水水质等因素对炭滤池出水pH的影响。结果表明,当主接触池O3投加量增加至5 mg·L-1时,炭滤池内pH无变化;炭滤池产生CO2对炭滤池pH的影响可忽略不计;但当炭滤池进水pH从6.10～9.10改变时,炭滤池出水pH维持在6.80～7.00。炭滤池是个酸碱缓冲系统,其关键作用的是活性炭自身。活性炭表面化学性质研究发现,活性炭表面含氧官能团具有两性性质,能中和水中的H+或OH-。且活性炭表面含氧官能团的数量随着其使用时间的延长而逐渐减少,从而使活性炭pH下降,致使炭滤池在长期使用过程中出现pH下降的现象。     

臭氧-活性炭工艺深度处理煤制气废水试验研究

以煤制气废水为研究对象,考察臭氧接触时间和臭氧通量对色度和UV254去除效果的影响,研究了臭氧-活性炭工艺在煤制气废水深度处理中的应用效果及影响因素。结果表明,与臭氧直接氧化相比,臭氧催化氧化对色度和UV254的去除效果显著提高,最佳臭氧接触时间为2 h,最佳臭氧通量为5 L/min,在此试验条件下连续运行该工艺深度处理煤化工废水,进水SS浓度和pH值对处理效果有较大影响,CODCr和色度去除率分别为89.95%和86.50%,出水CODCr的质量浓度小于30 mg/L,色度为30度,远优于GB 8978—1996《污水综合排放标准》中一级标准的要求,达到废水回用相关标准的要求。     

The use of ozone to decolorize residual direct paper dyes in kraft paper machine whitewater

Production of colored kraft papers results in strongly colored paper machine spent Whitewaters (ww). The residual dyes prevent efficient recycle of the ww and necessitate periodic system cleanings. Many of the dyes are not adsorbed or degraded by biological effluent treatment and therefore discolor receiving waters. Ozone was tested as a bleaching agent for 15 direct paper dyes added at typical residual levels to kraft mill ww. These dyes included azo, polyazo, stilbene, benzothiazole and phthalocyanine direct dyes commonly used in Canadian dyed paper production. Ozone charges of 15 ‐100 mg/L rapidly bleached most of the dyes, although a few of the yellow stilbene and azo dyes were quite resistant. The efficiency of ozone‐mediated residual dye bleaching was altered substantially by the pH, the ww concentration, and the target dye's chemical structure. Preozonation of residual dye‐containing ww greatly decreased the color conferred to bleached kraft pulp fibers added to the ww. Thus, ozonation should permit much more ww recycle (less effluent) when changing colors on the paper machine. Depending on the availability of oxygen or ozone in a mill, and local ozone economics, ozone may be the most efficient, cost‐effective way to improve ww quality, increase ww recycle and minimize effluent color problems and environmental impact.     

预处理对染料生产模拟废水可生化性的影响

本试验采用臭氧氧化法、Fenton法和微电解法对染料模拟废水进行预处理,用经过驯化的微生物和瓦勃呼吸仪检测染料的可生化性,分析预处理对染料可生化性的影响,并通过紫外-可见吸收光谱分析染料结构变化与可生化性的关系。实验结果表明：实验染料结构中的偶氮基和苯环对染料的可生化性有显著的影响;三种预处理方法均可不同程度地破坏染料的结构,提高染料的可生化性;臭氧预处理时,溶液pH、处理时间对预处理结果有显著影响。     

Adsorption de colorants ioniques sur des fibres de laine carbonisees

The study of the adsorption of an acid dye (AB-80) and of a basic dye (BR-22) has been carried out on charred woollen fibres, with a view to using that industrial waste material in the treatment of liquid effluents. The authors have first studied the dye diffusion; the diffusion of AB-80 appeared much slower than that of BR-22, due to the steric cumbersomeness of the AB-80 molecule. As a result, the temperature effect on the diffusion, owing to its influence on the dye aggregation, was clearly more pronounced for AB-80 than for BR-22; that fact was confirmed by the determination of adsorption isotherms at different temperatures. Under favourable conditions, the curves indicated satisfactory adsorption values; as they were cither of type H (AB-80) or L (Br-22), they also indicated the efficiency of the aforesaid fibres in the treatment of slightly-concentrated effluents. The above finding has been verified by a column treatment of an AB-80 solution; it then showed the very strong influence of the contact time as well as a wall effect on the effluent purification. In the study conclusion, the results obtained in the treatment of an industrial effluent in a stirred reactor are presented.     

UV/O_3高级氧化工艺深度处理垃圾渗滤液的研究

采用UV/O_3高级氧化组合工艺对垃圾渗滤液二级出水进行深度处理。研究反应时间、p H和臭氧进气流量等因素对处理效果的影响。结果表明,最佳工艺条件是p H=9、臭氧进气流量80 L/h、紫外光功率为10 W、反应时间120 min。在最佳工艺条件下,UV/O_3高级氧化组合工艺对垃圾渗滤液二级出水COD、氨氮、色度的去除率分别为80.61%、64.47%、91.70%,相比单独臭氧处理时,去除率分别提高了19.31%、17.77%、6.10%。     

Effectiveness of ozonation and catalytic ozonation (iron oxide) in the degradation of sunset yellow dye

Azo dyes present in industrial effluents represent a hurdle that regular treatments cannot overcome. In this study, the application of ozone and a catalytic (iron oxide) ozone treatment were proposed as a means of degrading aqueous sunset yellow dye. In order to understand the factors involved, a rotatable central composite design was applied using the variables time, initial dye concentration (C₀), pH, ozone inlet concentration (O₃), and mass of catalyst, which varied in each case. All variables were significant in colour removal. Extremes in pH, lower C₀, and higher ozone concentrations are conditions that favour dye degradation. A complete colour loss occurred for certain combinations of these parameters. The application of iron oxide as a catalyst did not present a satisfactory improvement in the reaction rate. Chemical oxygen demand and total organic carbon showed minimum values of 80% and 78%, respectively, for the worst experimental conditions (pH 7.0, C₀ of 45 mg · L⁻¹, and 5 g O₃ · m⁻³), while their values were 88% and 83% for the best conditions applied. There was no immobilization of Artemia salina nauplii, even for the experimental run where the maximum concentration of dye of the set was used (45 mg dye · L⁻¹). Ozonation is a promising alternative in the degradation of aqueous sunset yellow dye, being favoured in acidic or basic media, which is especially important since food effluents usually present low pH and show low toxicity. The mathematical model proposed can be useful in the design of wastewater treatment processes.     

OZONE TREATMENT OF METHYLENE BLUE IN AQUEOUS SOLUTIONS

The kinetics of ozonation of the sulfur dye Methylene Blue in aqueous solution is studied. The experiments have been carried out in a bubble column, using a single nozzle as gas sparger. The influence of the operating variables (initial concentration of Methylene Blue, ozone partial pressure, temperature and pH) on the oxidation process is established. A stoichiometric ratio of 3 moles of ozone consumed per mol of dye reacted is deduced. A reaction scheme based on the direct ozone attack to the dye is suggested, and it agrees with the found stoichiometry. The overall reaction orders and rate constants as a function of pH and temperature are determined following the film theory which is applied to the experimental data. The process develops in the fast pseudo mth order kinetic regime of absorption.     

臭氧氧化法强化处理纤维素乙醇废水研究

为提高纤维素乙醇废水厌氧出水的可生化性,采用臭氧氧化法对其进行强化处理,考察了反应时间、臭氧投加量、初始p H及反应温度对纤维素乙醇废水可生化性、COD和氨氮去除效果的影响。结果表明,在初始pH为8~10,臭氧投加量为5 g/h,反应时间为80 min,反应温度为30℃的最优条件下,出水COD为1 450 mg/L左右,COD去除率稳定在35%左右;出水氨氮为220 mg/L左右,氨氮去除率稳定在40%以上,出水BOD_5/COD由0.1提高到0.3左右,废水的可生化性得到较大程度的提高。     

Heterogeneous Catalytic Ozonation of Aqueous Reactive Dye

The aqueous solution of a model reactive dye, C.I. Reactive Blue 5, was ozonated in the presence of a heterogeneous catalyst, CuS. It was found that CuS was very effective for catalyzing the decolorization so that both treatment time and ozone consumption were significantly reduced. For 1 g/L of the reactive dye, the stoichiometric ratios of ozone to dye in catalyzed and noncatalyzed ozonations were 2.7 and 10.6 (moles of ozone consumed)/(moles of dye oxidized), respectively, and the optimum catalyst load was 0.4 g/L. Although the noncatalytic ozonation was pseudo-first-order and the apparent pseudo-first-order rate constant declined with initial dye concentration logarithmically, in contrast, the experimental results showed that the catalytic ozonation was pseudo-second-order and the apparent pseudo-second-order rate constant decreased with initial dye concentration semilogarithmically. It was observed that the efficacy of ozone decolorization was higher at low pH and a scavenger test revealed that the amount of free radicals were negligible during ozonation. The experimental data further indicated that increase in temperature would increase the rate of the catalytic ozonation, however, the increment in the rate was not significant beyond 20°C.     

臭氧催化氧化处理制膜污水厂二级生化出水

某制膜企业污水处理厂二级生化出水的可生化性极低,难以达标排放。以其为原水,采用连续流动固定床反应器进行多相催化臭氧氧化试验,分别考察了吸附及催化性能、臭氧投加量、进气臭氧浓度、水力停留时间、床层高度对二级生化出水处理效果的影响。结果表明,采用多相催化臭氧氧化具有明显的处理效果,在臭氧质量浓度为30 g/m3、水力停留时间2 h、催化床层高度1 m的条件下,出水COD_(Cr)500 mg/L,可以达到北京市排入城镇污水处理厂标准要求。试验发现采用中间及底部分段进气时,可有效提高臭氧催化氧化效果。     

Experimental and mathematical evaluation of trichloroethylene removal from saturated soil using acetic acid with saturated ozone

The present study is an experimental and numerical analysis of trichloroethylene (TCE) removal from soil by ozone oxidation combined with acetic acid flushing. A one-dimensional advective–dispersive flow model is proposed to mathematically describe the TCE dissolution and oxidation from the porous medium using acetic acid and ozone, respectively. The model could reasonably well predict the experimental data in the effluent for dissolution, oxidation, and total removal of TCE. Sensitivity analyses evaluated the effects of different parameters, such as ozone and acetic acid concentration, flow rate, and initial TCE concentration, on the dissolution and oxidation processes. Remediation time was reduced by more than 29% by applying acetic acid solutions saturated with ozone. Increasing the ozone concentration was the best method for reducing remediation time, followed by increasing acetic acid concentration and increasing flow rate.     

Electrochemical Treatment of Simulated Textile Effluent

Electrooxidation of simulated Acid Blue 113 dye effluent has been carried out using a RuO₂/Ti electrode. The influence of the initial concentration of dye, supporting electrolyte, current densities and pH on COD reduction has been critically studied. Electrochemical analysis such as Instantaneous Current Efficiency (ICE) and Electrochemical Oxygen Demand (EOD) were used.     

臭氧氧化处理氰化废水的实验研究

采用臭氧氧化法处理金矿含氰废水,对臭氧投加量、pH值,催化剂等对除氰效果的影响进行了实验研究,研究结果表明,臭氧能够有效地去除金矿废水中的氰化物,臭氧投加量、pH值、Cu^2 对处理效果有一定影响。     

臭氧氧化活性染料及其降解产物毒性研究

在印染废水中,染料成分复杂、高浓度、高色度、难生物降解物质多,用常规的生物处理方法难以有效治理。高级氧化技术(AdvancedOxidationProcesses,简称AOPs)作为一种有效的废水处理手段,引起了越来越多的关注。以活性染料活性艳红KE-3B为对象,模拟印染废水的实际情况对染料进行臭氧氧化研究,探讨了该过程的动力学影响因素。研究发现在pH=10时,脱色速度快;随着臭氧投加量的增加,色度去除率也相应增加;Na2CO3作为自由基清除剂在一定程度上抑制了臭氧氧化,而NaCl对臭氧氧化的影响则较小;对比了组合工艺UV/O3/H2O2应用于活性染料的处理效果,发现UV/O3反应体系中加入少量的H2O2能够使脱色率增加。利用海洋性发光菌VibrioFischeri对臭氧氧化后的溶液进行了生物毒性监测与评价,结果显示,在氧化过程中溶液毒性明显升高;随氧化程度的进一步加深,毒性又趋于下降。     

荧光增白剂生产废水的处理

采用"曝气铁炭微电解-水解酸化-好氧生物处理-臭氧氧化"工艺对荧光增白剂生产废水进行了处理.研究了曝气铁炭微电解的铁炭质量比,反应时间和废水pH对处理效果的影响,以及水解酸化、好氧生物处理、臭氧氧化各处理阶段的处理效果,并对最终出水水质进行了分析.结果表明,采用"曝气铁炭微电解-水解酸化-好氧生物处理-臭氧氧化"工艺处理荧光增白剂生产废水,当进水COD为5 620 mg·L~(-1)左右时,出水TOC降至68.45mg·L~(-1),SS质量浓度降至25.9mg·L~(-1),浊度降至2.4NTU,色度降至0.     

Treatment of a textile effluent: application of a combination method involving adsorption and nanofiltration

A combination of adsorption and nanofiltration (NF) was adopted for the treatment of a textile dyehouse effluent containing a mixture of two reactive dyes. The effluent stream was first treated in a batch adsorption process with sawdust as an adsorbent to reduce the dye concentration of the effluent by about 83% for Dye 1 and 93% for Dye 2. The effluent from the adsorption unit was passed through an NF unit for the removal of the remaining small amount of dyes and to recover the associated chemicals (mainly salt) in the effluent stream. The dyes remaining after this step were less than 1 ppm. The percentage removal of COD was greater than 99%, and the salt recovery was on the order of 90%. Equilibrium studies were carried out with synthetic solutions of the dyes (both single component as well as two-component systems) at room temperature. The adsorption rates were studied in detail using varying amounts of the adsorbent. NF of the effluent was performed in a cross-flow system using a 400 molecular weight cut-off membrane. A detailed study was carried out to observe the effect of the process parameters, namely applied pressure and bulk velocity on the process outputs such as dye rejection, COD removal, permeate flux and salt recovery. Finally, direct NF of the effluent (with the original high concentration) was undertaken, and the performance of the process was compared with the combination method. The permeate flux for the proposed combined method was found to be about twice that for the direct NF method. The dye rejection improved significantly compared to adsorption.