Removal of Dissolved Organic Carbon and Color from Dyeing Wastewater by Pre-ozonation and Subsequent Biological Treatment

The effects of pre-ozonation and subsequent biological treatment on the decrease in dissolved organic carbon (DOC) and color from dyeing wastewater were investigated. Moreover, the compositions of organic compounds in raw wastewater (RW) and the respective treated waters were estimated, and microscopic observations of the mixed liquor were conducted. The amount of ozone required to remove 1 mg of DOC and the DOC removal rate brought about by pre-ozonation ranged from 6.6 to 13.2 mgO₃/mgC and 12 to 15%, respectively. The total amount of DOC removed was increased by the combined use of pre-ozonation and subsequent biological treatment, and pre-ozonation did not necessarily lead to an increase in the amount of DOC removed by biological treatment. However, this combined method was effective in decreasing color and adsorbable organic halide formation potential (AOXFP). The rates of the dyestuff in RW and the respective treated waters were less than 10% of total DOC, and those of the other non-biodegradable compounds were much higher than those of the dyestuff. The morphological difference was observed in the predominant bacteria in RW with and without pre-ozonation.     

Preozonation of Chlorophenolic Wastewater for Subsequent Biological Treatment

Preozonation was investigated for its effects on the biodegradability of five chlorophenolic compounds in activated-sludge systems. The biodegradability was expressed in terms of the oxidation of each compound itself and of the total organic contents of the whole sample.

Results indicate that preozonation could either promote or retard the biodegradability, depending primarily on whether or not the sludge used in the subsequent biological system had been acclimated beforehand. For unacclimated sludge, preozonation was found to be helpful in promoting the biodegradability of all the compounds, especially the chlorophenols with a meta-position chlorine attachment. For acclimated sludge, a reverse effect generally, was observed.     

Application of Ozonation to Dyeing Wastewater Treatment—Case Study in Nishiwaki Treatment Plant

Three treatment methods, raw wastewater (RW)?→?coagulation?→?biological treatment (RCB), RW→?pre-ozonation?→?biological treatment (ROB) and RW?→?biological treatment?→?post-ozonation (RBO), were investigated to clarify their effectiveness in treating dyeing wastewater from a treatment plant. The decrease in dissolved organic carbon (DOC) was in the following order: RCB?≥?RBO?>?ROB. DOC removal of 200 mg/L by biological treatment of RW was clearly higher than that of 12 mg/L by ozonation. On the other hand, only DOC removal of 108 mg/L was observed by biological treatment in RW after ozonation. The decrease in biological oxygen demand (BOD₅) was in the following order: ROB?≥?RCB?>?RBO. Because of the enhancement of biodegradability brought about by ozonation, BOD₅ after ozonation in RBO was higher than that of RW after biological treatment. Color was effectively removed by ozonation for both RW and RW after biological treatment, and the decrease in color was in the following order: RBO?>?ROB?≥?RCB. Adsorbable organic halide formation potential (AOXFP) and toxicity unit (TU15, exposure time is 15 min) were more effectively decreased by biological treatment than by coagulation or ozonation, although the differences among RCB, ROB and RBO were very small.     

Oxone Enhanced Biological Activated Carbon in Denver,Colorado: A Pilot Plant Study

Five parallel ozone and activated carbon systems were compared for their effectiveness in treating unchlorinated effluent from the Denver Metropolitan Sewage Disposal District No. 1 wastewater facility. Data were gathered over four months of continuous operation. The objective of the study was to assess the potential for enhanced carbon column performance through the use of ozone.     

有机絮凝剂应用于印染废水的脱色研究

研究了二甲基二烯丙基氯化铵聚合物（PDMDAAC）和阳离子型聚季铵盐类有机高分子聚合物（BT-03）絮凝处理印染废水的效果,考察了药剂投量、pH值、搅拌时间、沉淀时间对处理效果的影响。研究结果表明：BT-03处理印染废水脱色效果和COD去除率好于PDMDAAC,两者受pH值影响较小。     

新型絮凝剂对印染废水净化的研究

用自制的新型复合絮凝剂处理印染厂印染废水 ,研究了废水的pH值、处理时间、搅拌强度、絮凝剂加入量等因素对处理效果的影响。在最佳工艺条件下 ,可使色度去除率达到 90 %以上 ,CODcr去除率达到 80 %以上 ,且工艺流程简单 ,容易操作 ,效果较好     

A New Approach to Determine the Practical Ozone Dose for Color Removal from Textile Wastewater

In this study, the effect of applied ozone dose and pH on color removal from textile wastewater was studied. A lab-scale ozonation system was used in the experiments. When the applied ozone dose increased, the color removal efficiency and the rate constants increased, whereas ozone utilization ratio decreased. On the other hand, increasing the pH increased color removal efficiency and ozone consumption but decreased specific ozone dose. By using the experimental results, a new model has been developed to determine the required ozone dose for the removal of color. By means of this method, it was possible to determine the required ozone dose for reducing the amount of color up to desired levels. Experimental results and the model predictions were in good agreement not only for textile wastewater but also for different industrial effluents. Some parameters affecting ozone utilization such as pH, could also be incorporated into the model.     

印染废水处理厂扩建工程设计实践与探讨

简评了印染废水的最新处理技术,在南方某市印染废水厂一期工程面临问题及优化方案的分析基础上,进行了二期扩建工程的设计,工艺为强化生物吸附+厌氧水解酸化+好氧生化处理,出水指标采用《纺织染整工业水污染物排放标准》GB4287-92一级标准。同时还对部分出水进行了回用处理的设计。     

Ozone and Activated Carbon for Tertiary Wastewater Treatment

Preozonation of biologically or physically–chemically treated wastewater effluents, followed by passage through granular activated carbon (GAC) for tertiary wastewater treatment was studied at the Duck Creek Wastewater Treatment in Garland, Texas. Whereas the average period of operation for the GAC before exhaustion without ozone pretreatment was 70 days, pretreatment with ozone or with oxygen alone extended GAC operation to at least 480 days, withoutexhaus–tion. Effluent streams consistently metapplicable discharge standards during this period of time, without the necessity of regenerating the GAC.     

黄原胶废水有机物的降解与色度去除的研究

黄原胶是一种微生物胞外多糖。黄原胶生产废水直接排放,会对环境造成很大的污染,世界上对黄原胶生产废水的研究很少。本课题所研究的是黄原胶废水好氧处理的影响因素及色度去除,实验中研究了恒温条件下好氧处理黄原胶废水在不同影响因素的条件下COD的降解效率和pH对黄原胶废水色度的去除的影响。     

Ozonation of C.I. Reactive Yellow 3 and Further Decrease in Dissolved Organic Carbon Concentration by Post-Biodegradation

Using C.I. Reactive Yellow 3 as the target compound, the effect of the combined use of ozonation and post-biodegradation on the decrease in dissolved organic carbon (DOC) concentration was investigated, and the synergistic effect (the difference in the amounts of DOC removed by the biological process between solutions with and without ozonation) was estimated. A decrease in DOC concentration was observed during ozonation and ΔO₃/ΔDOC was decreased from 16.0 to 5.2 with increasing ozonation time. Moreover, an enhancement of biodegradability was shown. A further decrease in DOC concentration was observed during the biodegradation after ozonation. The total amount of DOC removed by the combined method was increased from 73.6 mg at 30 min to 159.9 mg at 4 h. The synergistic effect was in the range of 22.7 to 39.2 mg. BOD₅ was a better indicator of the synergistic effect than BOD₅/DOC.     

Biological Nitrogen Removal Using the Supernatant of Ozonized Sludge as Extra Carbon Source

A sludge ozonation process with lab-scale anaerobic/oxic (A/O) system was used to investigate the utilization of the ozonized sludge (OS) supernatant as extra carbon source for denitrification. The optimal ozone dose for the sludge ozonation was 0.2 gO₃/gSS. The concentrations of SCOD, BOD, NH₃-N and TN in the supernatant increased respectively at this ozone dose. In the meantime, the sludge was significantly reduced. The OS supernatant had negative effect on nitrification because of low pH and alkalinity. After alkalinity adjustment, the A/O with the OS supernatant as the extra carbon source achieved a nitrogen removal rate of 78%, which was very close to the control experiment using glucose (79%).     

Dyes Color Removal by Ozone and Hydrogen Peroxide: Some Aspects and Problems

Application of oxidation processes with the use of strong oxidizing agents, ozone and hydrogen peroxide, is limited because of high costs and some problems with parameters of discoloration reactions. This paper presents findings concerning the use of ozone itself and hydrogen peroxide in combination with Fe²⁺ catalyst for discoloration of dye solutions of concentration 100 mg/L and wastewaters from production of dyestuffs Reactive Orange 20, Reactive Blue 13, Direct Blue 74, and Acid Violet 1. Both agents discolored both the dye solutions and wastewaters successfully. The paper presents a discussion about some aspects and problems occurring in the use of those oxidative agents for discoloration processes in laboratories. There is also a presentation of the effects that such parameters as consumption of oxidants and the doses applied, pH and temperature, had on the time required for discoloration reactions.     

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.     

Combined Physicochemical Treatment of Textile and Mixed Industrial Wastewater

Wastewaters derived from a textile factory and an industrial park were subjected to treatment with ferric chloride coagulation; ozonation; ferric chloride pre-coagulation/Fenton-based process/lime post-coagulation; Fenton-based process/lime post-coagulation; and ferric chloride pre-coagulation/ozonation. Schemes with the Fenton-based process proved the most efficient for treatment of both wastewater samples. The characteristics of wastewater samples treated by a Fenton-based process at H₂O₂/COD weight ratio 0.5:1 complied with the discharge limits stated by regulations for wastewater directed to local sewerage. The Fenton-based process/lime post-coagulation scheme proved more efficient than ferric chloride pre-coagulation/Fenton-based process/lime post-coagulation system. The increase of H₂O₂/COD weight ratio to 2:1 resulted in 5 and 10% of residual COD and DOC, respectively. All studied processes and combined physicochemical treatment schemes, except single ozonation, resulted in toxicity reduction and biodegradability improvement in both wastewater samples. The operational costs of applied treatment schemes were calculated and indicated the Fenton-based process schemes as the most feasible and cost-effective.     

Treatment of Industrial Landfill Leachates By Chemical And Biological Methods: Ozonation,Ozonation + Hydrogen Peroxide,Hydrogen Peroxide And Biological Post-Treatment For Ozonated Water

The objective of this study was to determine a suitable treatment method for variable waters from a forest industry landfill site. The main target was to find out the impact of different chemical treatments on the composition and biodegradability of those waters. Earlier studies have shown that biological treatment alone is not a suitable treatment method for these waters. That is why ozonation, ozonation+hydrogen peroxide and hydrogen peroxide treatment were studied in a laboratory scale. The ozonated waters were also biologically post-treated.

All the methods studied were able to degrade a part of the organic compounds and convert them into a more biodegradable form. Also the BOD/COD -ratio increased significantly. The removal of organic compounds by ozonation was 30 - 50 %. Hydrogen peroxide addition did not improve the degradation. The combination of pre-ozonation and biological post-treatment gave a total TOC removal between 50 - 95 %.     

Rapid Removal of Tetracycline (TC) by Ozonation after Extraction TC from Water into Acetic Acid Solution Using Granular Activated Carbon

This study quantifies the rapid removal of tetracycline (TC) in acetic acid solution by ozonation after extraction from water into acetic acid solution using granular activated carbon (GAC). Systematic laboratory experiments show that GAC can be used as an adsorbent to transfer TC from water to acetic acid. Ozone gas has a high degree of stability and solubility in acetic acid, and therefore apparently enhances the removal rate of TC. TC removal efficiency is better in 10% acetic acid solution than that in water, 15% and 20% acetic acid solution. Removal rate of TC in the acetic acid solution decreases as the initial molar ratio of TC and O₃ increases. Inhibition effect of tertiary butyl alcohol (TBA) on TC removal is smaller in acetic acid than that in water. metal-TC complex was produced in the presence of Fe³⁺ and Co³⁺, which inhibited the degradation of TC by ozone in acetic acid. Removal of TC by ozone in the acetic acid solution might be affected by multiple factors, which should be considered in practical applications.     

Removal of Color and Organic Matter in Industrial Phosphoric Acid by Ozone: Effect on Activated Carbon Treatment

Industrial phosphoric acid at 42-45% P₂O₅ and containing organic matter (OM) in the range of 220 mg/L to 300 mg/L is treated by combined ozonation and activated carbon. Ozonation alone removes the initial dark color of the acid and eliminates the organic content. Adsorption on activated carbon alone can reduce OM levels by 80% for more than 25 g/kg P₂O₅. We find that a preozonation noticeably enhances activated carbon efficiency and reduces its specific consumption. Isoconversion curves are plotted in specific ozone and activated carbon ratio space.     

活性炭催化剂臭氧催化氧化处理废水的研究进展

介绍了近年来国内外活性炭催化剂臭氧催化氧化的研究结果,对活性炭及金属负载型活性炭催化剂的反应机理进行了总结。讨论了非均相臭氧催化氧化过程中活性炭的主要作用,活性炭催化剂的表面物化性质、pH值、温度在臭氧催化氧化过程中的影响规律。并提出活性炭催化剂的降解机理以及催化剂性质与有机污染物的化学结构之间的关系还需要进一步的研究。     

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.