Ozonation of oxytetracycline and toxicological assessment of its oxidation by-products

Antibiotic formulation effluents are well known for their difficult elimination by traditional bio-treatment methods and their important contribution to environmental pollution due to its fluctuating and recalcitrant nature. In the present study the effect of ozonation on the degradation of oxytetracycline (OTC) aqueous solution (100mgl(-1)) at different pH values (3, 7 and 11) was investigated. Ozone (11mgl(-1) corresponds the concentration of ozone in gas phase) was chosen considering its rapid reaction and decomposition rate. The concentration of oxytetracycline, chemical oxygen demand (COD), biochemical oxygen demand (BOD) and BOD5/COD ratio were the parameters to evaluate the efficiency of the ozonation process. In addition, the toxic potential of the OTC degradation was investigated by the bioluminescence test using the LUMIStox 300 instrument and results were expressed as the percentage inhibition of the luminescence of the marine bacteria Vibrio fischeri. The results demonstrate that ozonation as a partial step of a combined treatment concept is a potential technique for biodegradability enhancement of effluents from pharmaceutical industries containing high concentration of oxytetracycline provided that the appropriate ozonation period is selected. At pH 11 and after 60min of ozonation of oxytetracycline aqueous solutions (100 and 200mgl(-1)) the BOD5/COD ratios were 0.69 and 0.52, respectively. It was also shown that COD removal rates increase with increasing pH as a consequence of enhanced ozone decomposition rates at elevated pH values. The results of bioluminescence data indicate that first by-products after partial ozonation (5-30min) of OTC were more toxic than the parent compound.     

Decolorization and biodegradability of photocatalytic treated azo dyes and wool textile wastewater

The photodegradation and biodegradability have been investigated for four non-biodegradable commercial azo dyes, Reactive YellowKD-3G, Reactive Red 15, Reactive Red 24, Cationic Blue X-GRL, an indicator. Methyl Orange, and one industrial wool textile wastewater, using TiO2 suspensions irradiated with a medium pressure mercury lamp. The color removal of dyes solution and dyeing wastewater reached to above 90% within 20-30 min. of photocatalytic treatment. Biochemical oxygen demand (BOD) was found to increase, while chemical oxygen demand (COD), total organic carbon (TOC) decreased, so that the ratio of BOD5/COD of the wastewater increased from original zero up to 0.75. The result implies that photocatalytic oxidation enhanced the biodegradability of the dye-containing wastewater and therefore relationship between decolorization and biodegradability exists. When the color disappeared completely, the wastewater biodegraded normally and could be discharged for further treatment. The experimental results demonstrate that it is possible to combine photocatalysis with conventional biological treatment for the remedy of wastewater containing generally non-biodegradable azo dyes.     

Ozonation of an azo dye C.I. Remazol Black 5 and toxicological assessment of its oxidation products

The effect of ozonation (20.5 mgl(-1)) on the degradation processes of an azo dye, Remazol Black 5 (RB5; CI) was studied. Conventional parameters such as chemical oxygen demand (COD), total organic carbon (TOC), pH, conductivity, colour removal, biodegradability (BOD(5/28)), and toxic potential of the dye and its degradation products were monitored during the process. The results obtained indicated that ozonation is a highly effective way to remove the colour of a corresponding dye solution. However, a considerable organic load still remained as indicated by high COD and TOC residues. The COD, TOC reductions were about 40% and 25% for 6 h ozonation of 2 gl(-1) RB5 aqueous solution. During the ozonation process the rapid decrease of pH and the sharp increase of conductivity indicated the formation of acidic by-products and small fragments and ions which were identified by high performance ion chromatography. The BOD28 data revealed that first by-products after partial ozonation (10-150 min) of RB5 were more biodegradable than the parent compound and ozonation can enhance the biodegradability of azo dyes. During the first 150 min of total 360 min of oxidation, the formation of first by-products with high toxic potential took place as it could be confirmed by two acute toxicity-screening tests, the bioluminescence test (Vibrio fischerii) and the neutral red cytotoxicity assay (rat hepatoma cells). The significant enhancement of microbial biodegradability after long-term ozonation could also be seen as a decrease of toxic intermediates in correlation with the ozonation time as indicated in BOD28 biological degradation test results.     

Ti（Ⅳ）催化臭氧／过氧化氢预处理酸性难降解废水

在Ti（Ⅳ）和过氧化氢存在条件下，考察了臭氧化酸性苯乙酮溶液、硝基苯溶液和垃圾渗滤液（浙江衢州某垃圾填埋场）的预处理效能。结果表明，在pH2．86条件下，单独臭氧化处理对苯乙酮、硝基苯和垃圾渗滤液的COD去除率分别为10．1％、44％和28．6％。BOD，／COD值分别从原来的0．039、0．060和0．085提高到了0．130、0．158和0．174，仍属生化难降解废水。当体系加入Ti（Ⅳ）后，臭氧化苯乙酮和硝基苯的COD去除率分别达到了75．5％和65％，BOD；／COD则提高到了0．679和0．314，可生化性提升明显。对于垃圾渗滤液，只有当体系加入Ti（Ⅳ）和H22后，臭氧化COD的去除率达到66．6％，BOD、／COD提高至0．425。上述结果对酸性难降解废水的处理实际意义非常突出。     

臭氧氧化预处理难降解农药废水的研究

采用臭氧氧化技术预处理脲类农药生产废水，调节废水pH至弱碱，在此基础上考察废水臭氧氧化预处理的影响因素，得出最佳预处理条件：COD为200 mg/L，初始pH为11.3，臭氧投加量为14.2 mg/L。连续预处理180 min后，可生化性从0.12提高到0.58，说明该项技术可大大提高脲类农药废水的可生化性。     

Ozonation of hydrolyzed azo dye reactive yellow 84 (CI).

The combination of chemical and biological water treatment processes is a promising technique to reduce recalcitrant wastewater loads. The key to the efficiency of such a system is a better understanding of the mechanisms involved during the degradation processes. Ozonation has been applied to many fields in water and wastewater treatment. Especially for textile mill effluents ozonation can achieve high color removal, enhance biodegradability, destroy phenols and reduce the chemical oxygen demand (COD). However, little is known about the reaction intermediates and products formed during ozonation. This work deals with the degradation of hydrolyzed Reactive Yellow 84 (Color Index), a widely used azo dye in textile finishing processes with two monochlorotriazine anchor groups. Ozonation of the hydrolyzed dye in ultra pure water was performed in a laboratory scale cylindric batch reactor. Decolorization, determined by measuring the light absorbance at the maximum wavelength in the visible range (400 nm), was almost complete after 60 and 90 min with an ozone concentration of 18.5 and 9.1 mg/l, respectively. The TOC/TOC0 ratio after ozonation was about 30%, the COD was diminished to 50% of the initial value. The BOD5/COD ratio increased from 0.01 to about 0.8. Oxidation and cleavage of the azo group yield nitrate. Cleavage of the sulfonic acid groups of aromatic rings caused increases in the amount of sulfate. Formic acid and oxalic acid were identified as main oxidation products by high performance ion chromatography (HPIC). The concentrations of these major products were monitored at defined time intervals during ozonation.     

Slurry-phase ozonation for remediation of sediments contaminated by polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are a group of toxic, persistent, bioaccumulating organic compounds containing two or more fused aromatic rings. They are listed by the U.S. Environmental Protection Agency as priority pollutants because of their carcinogenicity and toxicity. Employing ozonation as a remediation technique, this work investigated the treatability of a sediment sample from a freshwater boat slip subjected to coal tar contamination over a long period. The contaminated sediment sample contained high levels of PAHs in the forms of naphthalene, phenanthrene, pyrene, and benzo[a]pyrene, among other byproducts present in the humic and solid phases of the sediment. The objectives of this work were to examine (1) the degradation of PAHs in the contaminated sediment as treated by ozonation in the slurry form, (2) the effects of ozonation upon the soil matrix and the biodegradability of the resultant PAH intermediates, and (3) the feasibility of a combined technique using O3 as a pretreatment followed by biological degradation. The sediment was made into 3% w/w soil slurries and ozonated in a 1.7-L semi-batch, well-stirred reactor equipped with pH control and a cold trap for the gaseous effluent. Samples were collected after different ozonation durations and tested for biochemical oxygen demand (BOD), chemical oxygen demand (COD), UV absorbance, and toxicity, along with quantitative and qualitative determinations of the parent and daughter intermediates using gas chromatography/flame ionization detection (GC/FID), GC/mass spectrometry (MS), and ion chromatography (IC) techniques. The GC/MS technique identified 16 compounds associated with the humic and solid phases of the sediment. Intermediates identified at different ozonation times suggested that the degradation of PAHs was initiated by an O3 attack resulting in ring cleavage, followed by the intermediates' oxidation reactions with O3 and the concomitant OH radical toward their mineralization. Results suggested that ozonation for 2 hr removed 50-100% of various PAHs in the solid and liquid phases (as well as the aqueous and gaseous media resulting from the treatment process) of the sediment sample and that organic and inorganic constituents of the sediment were also altered by ozonation. Measurements and comparisons of BOD, COD, UV absorbance, and toxicity of the samples further suggested that ozonation improved the bioavailability and biodegradability of the contaminants, despite the increased toxicity of the treatment effluent. An integrated chemical-biological system appeared to be feasible for treating recalcitrant compounds.     

O3氧化工艺处理黄连素制药废水研究

采用臭氧（O3）氧化法处理含高浓度黄连素和COD的制药废水，探讨了废水初始pH、O3投加量及初始黄连素浓度等因素对O3氧化过程的影响，确定了O3氧化技术处理黄连素制药废水的最佳操作条件。结果表明，O3能够有效分解废水中的黄连素，降低其COD浓度；黄连素浓度为700mg／L、COD为3500mg／L、pH为0．88的废水，进气O3浓度为14．05mg／（L·min），处理时间为180rain（即投加量为2529mg／L）时，黄连素和COD的降解率分别可达77．46％和41．28％，BOD，／COD比（B／C比）从0．06提高到0．34，增加了4．7倍；随着废水中初始黄连素浓度的升高，废水COD降解率逐渐降低。O3氧化法是一种有效的黄连素制药废水预处理技术，可以大大提高废水的可生化性。     

废铁屑处理难生物降解染料废水

研究了用废铁屑处理难生物降解的染料废水，考察了进pH值、曝气时间、固液比、铁屑粒度对废水处理效果的影响，并确定了适宜实验条件。实验证明，该法可以有效去除染料废水的色度和CODcr，在实验考察范围内，脱色率和CODcr去除率分别可达90％、61.7%。同时废水可生化性也得到了改善，BOD5／CODcr从19.6%上升到29.5%，提高了50％,有利于后续生化处理。该法以废治废，是一种很有实用价值的废水处理方法。     

Degradation of 2,4-dichlorophenol by combining photo-assisted Fenton reaction and biological treatment.

The photo-Fenton reaction effect on the biodegradability improvement of 100 mg/L solution of 2,4-dichlorophenol (DCP) has been investigated. Biochemical oxygen demand (BOD) at 5 and 21 days, BODn/ chemical oxygen demand (COD) and BODn/total organic carbon (TOC) ratios, average oxidation state, and inhibition on activated sludge were monitored. For 50 mg/L hydrogen peroxide and 10 mg/L iron(II) initial concentrations and 40 minutes of reaction time in the photo-Fenton process, the biodegradability of the pretreated solution, measured as BOD5/COD ratio, was improved from 0 for the original DCP solution up to 0.18 (BOD21/COD = 0.24). At that point, all DCP was eliminated from the solution. To study the effect of the pretreatment step, the biological oxidation of pretreated solutions was tested in two semicontinuous stirred tank reactors, one operated with activated sludge and one with biomass acclimated to phenol. Results showed that more than 80% TOC removal could be obtained by codigestion of the pretreated solution with municipal wastewater. Total organic carbon removals of approximately 60% were also obtained when the sole carbon source for the aerobic reactors was the pretreated solution. The hydraulic retention times used in the bioreactors were of the same order of magnitude as those used at domestic wastewater treatment plants (i.e., between 12 and 24 hours). Kinetic studies based on pseudo-first-order kinetics have also been carried out. Constants were found to be in range 0.67 to 1.7 L x g total volatiles suspended solids(-1) x h(-1).     

A comparative study of the removal of 3-indolebutyric acid using advanced oxidation processes

In this study, advanced oxidation technologies, namely Fenton Process (FP), Fenton-Like Process (FLP), ozonation (O3) and O3/H2O2 processes, were applied to synthetic wastewater containing 3-indolebutyric acid (IBA). The effectiveness of each process was investigated at different pH values, Fe(+2), Fe(+3), O3 and H2O2 concentrations with respect to the removal efficiencies for chemical oxygen demand (COD) and total organic carbon (TOC). The best removal efficiencies were seen at pH 3 and 2 mM Fe concentration in both FP and FLP, in which the optimum H2O2 concentrations were 6 mM for FP and 10 mM for FLP. Optimum process conditions were pH 12 for the O3 process, pH 9 for the O3/H2O2 process and 1:1 O3/H2O2 molar ratio. The highest COD removal efficiency was 86 percent, obtained in the O3/H2O2 process and the highest TOC removal efficiency was obtained at 77 percent in the FP.     

铁炭微电解深度处理焦化废水的研究

采用曝气铁炭微电解工艺对焦化废水进行了深度处理.结果表明,在活性炭、铁屑和NaCl投加量分别为10 g/L、30 g/L和200 mg/L的条件下反应240 min,出水COD去除率在30%～40%;酸性条件可以进一步提高COD去除率;微电解可以去除原生化出水中的难降解有机物,出水物质的分子量主要集中于2000 Da以下,以脂类和烃类化合物为主;出水的可生化性有了大幅度提高,BOD5/COD由0.08增加到0.53.实验结果表明,铁炭微电解是深度处理焦化废水的一种有效工艺.     

臭氧-曝气生物滤池处理酸性玫瑰红染料废水

在实验室配制含酸性玫瑰红染料的印染废水，采用臭氧氧化-曝气生物滤池工艺开展处理试验。试验运行结果表明，臭氧氧化处理能提高模拟废水的可生化性，BOD／COD值由原水的0．18上升到0．36。经组合工艺处理后出水COD〈40mg／L，色度40倍以下，SS约50mg／L，处理效果良好。     

臭氧/ 生物活性炭深度处理循环养殖废水

随着工厂化循环水养殖的不断发展,高浓度循环养殖废水对环境污染日益严重.为实现环境友好和资源节约,采用臭氧/生物活性炭对循环养殖废水进行深度处理中试研究.实验结果表明,臭氧化臭氧最佳投加量为4 mg/L,显著增强水体的可生化性,使TOC(总有机碳)/UV254(在波长为254 nm处的单位比色皿光程下的紫外吸光度)提高80%.臭氧/生物活性炭对循环养殖废水中的有机物和氨氮具有良好的去除效果.臭氧/生物活性炭对TOC、高锰酸盐指数和UV254的最终去除率比生物活性炭分别高11.9%、13.4%和6.5%.臭氧/生物活性炭和生物活性炭对氨氮的最终去除率分别为96.0%、90.7%.     

Combined chemical treatment of pharmaceutical effluents from medical ointment production

Three wastewater samples from a pharmaceutical plant formulating medical ointments were subjected to lab-scale treatment by a Fenton-like system in combination with lime coagulation. All samples were plant pre-treated by adsorption/flocculation/filtration processes with utilization of bentonite, but the quality of effluents did not comply with the regulations for wastewater discharged to local sewerage. The optimization of Fenton-like oxidation demonstrated the highest process efficacy at H(2)O(2)/COD weight ratio of 2:1, H(2)O(2)/Fe(2+) molar ratio of 10:1 and 2h of treatment time. The fast pH decrease to acidic values approximately 3 during first min of oxidation for all effluents suggested that pH adjustment was unnecessary. Combination of Fe(III) precipitation and lime coagulation proved feasible to improve considerably COD and residual iron concentration reduction in pharmaceutical effluents. Additionally, considerable BOD(7) reduction and BOD(7)/COD ratio improvement of pharmaceutical wastewater samples was achieved by combined treatment. The application of Fenton-like oxidation with subsequent iron (III)/lime coagulation did not only enhance the quality of pharmaceutical effluents with different chemical characteristics and help to meet the requirements for wastewater discharged to sewage, but also improve the biodegradability of pharmaceutical effluents.     

垃圾渗滤液生物处理出水臭氧氧化的研究

对垃圾渗滤液生物处理出水进行了臭氧氧化的研究。研究表明,随着氧化时间的延长,CODCr去除率增大;在碱性条件下进行臭氧氧化。pH越高,CODCr去除效率越高。采用BOD5／CODCr来表征垃圾渗滤液的生物降解性,研究了臭氧氧化前后垃圾渗滤液生物处理出水的生物降解性变化规律,表明臭氧氧化可以提高垃圾渗滤液生物处理出水的生物降解性,但提高的幅度不大。通过色谱-质谱法（GC—MC）对臭氧氧化前后垃圾渗滤液的成分进行分析,结果表明,臭氧氧化前后废水中的主要成分没有发生变化,仍然为难降解物质;臭氧氧化使废水中的部分物质发生了结构上的变化,减少、消失和生成的物质多为可降解物质。     

Characteristics of electrolysis, ozonation, and their combination process on treatment of municipal wastewater.

The characteristics of municipal wastewater treatment by electrolysis, ozonation, and combination processes of electrolysis and aeration using three gaseous species (nitrogen [N2], oxygen [O2], and ozone [O3]) were discussed in this research using ruthenium oxide (RuO2)-coated titanium anodes and stainless-steel (SUS304) cathodes. Electrolysis and electrolysis with nitrogen aeration were characterized by a rapid decrease in 5-day biochemical oxygen demand (BODs) and total nitrogen and a slow decrease in chemical oxygen demand (COD). In contrast, ozonation, electrolysis with oxygen aeration, and electrolysis with ozone aeration were characterized by transformation of persistent organic matter to biodegradable matter and preservation of total nitrogen. The best energy efficiency in removing BOD5 and total nitrogen was demonstrated by electrolysis, as a result of direct anodic oxidation and indirect oxidation with free chlorine produced from the chloride ion (Cl-) at the anodes. However, electrolysis with ozone aeration was found to be superior to the other processes, in terms of its energy efficiency in removing COD and its ability to remove COD completely, as a result of hydroxyl radical (*OH) production via cathodic reduction of ozone.     

臭氧氧化法处理反渗透浓缩垃圾渗滤液

采用臭氧氧化法处理经反渗透膜处理后的浓缩垃圾渗滤液，考察了反应时间、臭氧投量、pH和温度对COD，色度以及浓缩液中腐殖酸的去除影响，通过BOD₅/COD变化分析了臭氧氧化对浓缩液生化性的提高作用。结果表明：在pH 8.0，温度30℃，臭氧投量5 g/h，反应时间90 min的条件下，浓缩液的COD、色度以及浓缩液中腐殖酸的去除率分别达到67.6%、98.0%和86.1%， BOD₅/COD从0.008提升到0.26，生化性有很大提高。     

FOP-EGSB-MBR组合工艺处理2-萘酚生产废水

2-萘酚生产废水具有COD高、BOD/COD值低和生物毒件高的特点,采用FOP-EGSB-MBR组合工艺对其模拟废水进行处理工艺的研究.结果表明:废水经Fenton氧化处理后,可将出水BOD/COD值从0.01提高至0.67;再经过厌氧和好氧处理后,出水COD为100 mg/L以下;该组合上艺总的COD去除去可达99%,且运行性能稳定,效果可靠.     

Phosphorus recovery from fosfomycin pharmaceutical wastewater by wet air oxidation and phosphate crystallization

Fosfomycin pharmaceutical wastewater contains highly concentrated and refractory antibiotic organic phosphorus (OP) compounds. Wet air oxidation (WAO)-phosphate crystallization process was developed and applied to fosfomycin pharmaceutical wastewater pretreatment and phosphorus recovery. Firstly, WAO was used to transform concentrated and refractory OP substances into inorganic phosphate (IP). At 200 °C, 1.0 MPa and pH 11.2, 99% total OP (TOP) was transformed into IP and 58% COD was reduced. Subsequently, the WAO effluent was subjected to phosphate crystallization process for phosphorus recovery. At Ca/P molar ratio 2.0:1.0 or Mg/N/P molar ratio 1.1:1.0:1.0, 99.9% phosphate removal and recovery were obtained and the recovered products were proven to be hydroxyapatite and struvite, respectively. After WAO-phosphate crystallization, the BOD/COD ratio of the wastewater increased from 0 to more than 0.5, which was suitable for biological treatment. The WAO-phosphate crystallization process was proven to be an effective method for phosphorus recovery and for fosfomycin pharmaceutical wastewater pretreatment.