Life cycle assessment of high concentration organic wastewater treatment by catalytic wet air oxidation

There have been many studies on life cycle assessment in sewage treatment,but there are scarce few studies on the treatment of industrial wastewater in combination with advanced oxidation technology,especially in catalytic wet air oxidation(CWAO).There are no cases of using actual industrialized data onto life cycle assessment.This paper uses Simapro 9.0 software to establish a life cycle assessment model for the treatment of high-concentration organic wastewater by CWAO,and comprehensively explains the impact on the environment from three aspects:the construction phase,the operation phase and the demolition phase.In addition,sensitivity analysis and uncertainty analysis were performed.The results showed that the key factors affecting the environment were marine ecotoxicity,mineral resource consumption and global warming,the operation stage had the greatest impact on the environment,which was related to high power consumption during operation and emissions from the treatment process.Sensitivity analysis showed that electricity consumption has the greatest impact on abiotic depletion and freshwater aquatic ecotoxicity,and it also proved that global warming is mainly caused by pollutant emissions during operation phase.Monte Carlo simulations found slightly higher uncertainty for abiotic depletion and toxicity-related impact categories.

Pretreatment of apramycin wastewater by catalytic wet air oxidation

The pretreatment technology of wet air oxidation(WAO) and coagulation and acidic hydrolysis for apramycin wastewater was investigated in this paper. The COD, apramycin, NH^+_4 concentration, and the ratio of BOD_5/COD were analyzed, and the color and odor of the effluent were observed. WAO of apramycin wastewater, without catalyst and with RuO_2/Al_2O_3 and RuO_2-CeO_2/Al_2O_3 catalysts, was carried out at degradation temperature of 200℃ and the total pressure of 4 MPa in a 1 L batch reactor. The result showed that the apramycin removals were respectively 50 2% and 55 0%, COD removals were 40 0% and 46 0%, and the ratio of BOD_5/COD was increased to 0 49 and 0 54 with RuO_2/Al_2O_3 and RuO_2-CeO_2/Al_2O_3 catalysts in catylytic wet air oxidation(CWAO) after the reaction of 150 min. With the pretreatment of coagulation and acidic hydrolysis, COD and apramycin removals were slight decreased, and the ratio of BOD_5/COD was increased to 0 45, and the effluents was not suitable to biological treatment. The color and odor of the wastewater were effectively controlled and the reaction time was obviously shortened with WAO. HO_2· may promote organic compounds oxidized in WAO of the apramycin wastewater. The addition of CeO_2 could promote the activity and stability of RuO_2/Al_2O_3 in WAO of apramycin wastewater.

Catalytic wet air oxidation for the treatment of emulsifying wastewater

The wet air oxidation(WAO) and catalytic WAO(CWAO) of the high strength emulsifying wastewater containing nonionic surfactants have been investigated in terms of COD and TOC removal. The WAO and homogeneous CWAO processes were carried out at the temperature from 433 K to 513 K, with initial oxygen pressure 1 2 MPa. It was found that homogeneous catalyst copper(Cu(NO_3)_2) had an fairly good catalytic activity for the WAO process, and the oxidation was catalyzed when the temperature was higher than 473 K. Moreover, several heterogeneous catalysts were proved to be effective for the WAO process. At the temperature 473 K, after 2 h reaction, WAO process could achieve about 75% COD removal and 66% TOC removal, while catalysts Cu/Al_2O_3 and Mn-Ce/Al_2O_3 elevated the COD removal up to 86%—89% and that of TOC up to 82%. However, complete elimination of COD and TOC was proved to be difficult even the best non-noble catalyst was used. Therefore, the effluent from WAO or CWAO process need to be further disposed. The bioassay proved that the effluent from WAO process was amenable to the biochemical method.

Treatment of desizing wastewater from the textile industry by wet air oxidation

This paper describes the application of wet air oxidation to the treatment of desizing wastewater from two textile companies. A two\|liter high temperature, high pressure autoclave reactor was used in the study. The range of operating temperatures examined was between 150 and 290℃, and the partial pressure of oxygen ranged from 0.375 to 2.25 MPa. Variations in pH, COD Cr and TOD content were monitored during each experiment and used to assess the extent of conversion of the process. The effects of temperature, pressure and reaction time were explored extensively. More than 90% COD Cr reduction and 80% TOC removal have been obtained. The results have also been demonstrated that WAO is a suitable pre\|treatment methods due to improvement of the BOD\-5/COD\-\{Cr\} ratio of desizing wastewater. The reaction kinetics of wet air oxidation of desizing wastewater has been proved to be two steps, a fast reaction followed by a slow reaction stage.

Catalytic wet air oxidation of phenol over RuO_2/γ-Al_2O_3 catalyst

A kind of CWAO catalyst, RuO_2/γ-Al_2O_3, was prepared by dipping Al_2O_3into the aqueous solution of RuCl_3·3H_2O. XRD, SEM and TEM were used to determine the catalyticstructure. Influences of the calcination temperature, the initial pH of the feed solution anddegradation temperature on the activity of the RuO_2/γ-Al_2O_3 catalyst were investigated and thereaction mechanism was preliminarily studied. Results showed that uniform dispersion of RuO_2crystallites was observed on the surface of the catalyst. The activity of the catalyst was higher atcalcination temperature of 300℃ for 3 h and the particle reunion occurred and some large RuO_2crystallites were abundant at high calcination temperature of 500℃ The activity of the catalyst wasbetter in the acid solution than in the alkaline solution. Increasing degradation temperature andusing the catalyst could shorten the induction periods so that the phenol and COD removal wereincreased. For RuO_2/γ-Al_2O_3 catalyst, the phenol and COD removal were respectively 98% and 80%in a temperature of 150℃, pH of 5.6 and pressure of 3 MPa after a 2 h reaction. This indicated thatRu/γ-Al_2O_3 catalyst had good activity.

Kinetics of Wet Air Oxidation of Wastewater from Natural Fiber Web Desizing

This work described the application of wet air oxidation (WAO) to the treatment of desizing wastewater from natural fiber processing. A two-liter autoclave batch reactor was used for the experiments. The range of operating temperature examined was between 150 and 290℃, and partial pressure of oxygen ranged from 0.375 to 2.25 MPa standardized at 25℃. Variations in Chemical Oxygen Demand(COD) and Total Organic Carbon(TOC) were monitored during each experiment and used to assess the performance of the process. Experimental results showed that WAO can be an efficient method for the treatment of desizing wastewater. Furthermore, Catalytic Wet Air Oxidation (CWAO) was applied to reduce the reaction temperature and pressure in WAO process. A higher COD removal ratio was achieved under more mild reaction condition with the aid of CWAO. A mathematical model was also proposed to simulate the WAO process of desizing wastewater, in which three distinct kinetics steps were considered to describe the degradation of starch. The model simulations were in well agreement with the experimental data.

Use of catalytic wet air oxidation (CWAO) for pretreatment of high-salinity high-organic wastewater

Catalytic wet air oxidation(CWAO)coupled desalination technology provides a possibility for the effective and economic degradation of high salinity and high organic wastewater.Chloride widely occurs in natural and wastewaters,and its high content jeopardizes the efficacy of Advanced oxidation process(AOPs).Thus,a novel chlorine ion resistant catalyst Bsite Ru doped LaFe_(1-x)Ru_(x)O_(3-)δin CWAO treatment of chlorine ion wastewater was examined.Especially,LaFe_(0.85)Ru_(0.15)O_(3-δ)was 45.5% better than that of the 6%RuO_(2)@TiO_(2)(commercial carrier)on total organic carbon(TOC)removal.Also,doped catalysts LaFe_(1-x)Ru_(x)O_(3-)δshowed better activity than supported catalysts RuO_(2)@LaFeO_(3) and RuO_(2)@TiO_(2) with the same Ru content.Moreover,LaFe_(0.85)Ru_(0.15)O_(3-)δhas novel chlorine ion resistance no matter the concentration of Cl^(−) and no Ru dissolves after the reaction.X-ray diffraction(XRD)refinement,X-ray photoelectron spectroscopy(XPS),transmission electron microscope(TEM),and X-ray absorption fine structure(XAFS)measurements verified the structure of LaFe_(0.85)Ru_(0.15)O_(3-)δ.Kinetic data and density functional theory(DFT)proved that Fe is the site of acetic acid oxidation and adsorption of chloride ions.The existence of Fe in LaFe_(0.85)Ru_(0.15)O_(3-)δcould adsorb chlorine ion(catalytic activity inhibitor),which can protect the Ru site and other active oxygen species to exert catalytic activity.This work is essential for the development of chloride-resistant catalyst in CWAO.

Fe203-CeO2-Bi203/y-AI203 catalyst in the catalytic wet air oxidation （CWAO） of cationic red GTL under mild reaction conditions

The Fe203-CeO2-Bi203/-A1203 catalyst, a novel environmental-friendly material, was used to investigate the catalytic wet air oxidation （CWAO） of cationic red GTL under mild operating conditions in a batch reactor. The catalyst was prepared by wet impregnation, and characterized by special surface area （BET measurement）, X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS）. The Fe203-CeO2-]]i203/qt-A1203 catalyst exhibited good catalytic activity and stability in the CWAO under atmosphere pressure. The effect of the reaction conditions （catalyst loading, degradation temperature, solution concentration and initial solution pH value） was studied. The result showed that the decolorization efficiency of cationic red GTL was improved with increasing the initial solution pH value and the degradation temperature. The apparent activation energy for the reaction was 79 kJ. mo1-1. Hydroperoxy radicals （HO2.） and superoxide radicals （O2-） appeared as the main reactive species upon the CWAO of cationic red GTL.

Catalytic wet air oxidation of phenol, nitrobenzene and aniline over the multi-walled carbon nanotubes （MWCNTs） as catalysts

Wet air oxidation （WAO） is one of effective technologies to eliminate hazardous, toxic and highly concentrated organic compounds in the wastewater. In the paper, multi-walled carbon nanotubes （MWCNTs）, functionalized by 03, were used as catalysts in the absence of any metals to investigate the catalytic activity in the catalytic wet air oxidation （CWAO） of phenol, nitrobenzene （NB） and aniline at the mild operating conditions （reaction temperature of 155℃ and total pressure of 2.5 MPa） in a batch reactor. The MWCNTs were characterized with scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, gas adsorption measurements （BET）, fourier transform infrared spectroscopy （FT-IR）, and X-ray photoelectron spectroscopy （XPS）. The functionalized MWCNTs showed good catalytic performance. In the CWAO of phenol over the functionalized MWCNTs, total phenol removal was obtained after 90 rain run, and the reaction apparent activation energy was ca. 40kJ · mol^-1. The NB was not removed in the CWAO of single NB, while ca. 97% NB removal was obtained and 40% NB removal was attributed to the catalytic activity after 180 min run in the presence of phenol. Ca. 49% aniline conversion was achieved after 120 min run in the CWAO of aniline.

印染废水CWAO法处理中均相催化剂的研制

为了制备用于催化湿式氧化法处理高浓度印染废水的催化剂,实验中以COD达2 000 mg.L-1的亚甲蓝水溶液作降解对象,用均相催化湿式氧化法进行处理,催化剂性能以COD去除率和脱色率进行评价.在对19种可溶盐进行普选的基础上,对双组分催化剂进行复配.结果表明:铜盐和铁盐的催化活性居于前列,而硫酸铜和硫酸亚铁复配的Cu1Fe1催化剂在活性和成本上显示了优越性,同等条件下对水样的COD去除率比不加催化剂时提高约50%.对Cu1Fe1的作用机理分析表明,自由基反应以及Fe(Ⅲ)聚合物的混凝同时发挥了作用.

Preparation of rare-earth metal complex oxide catalysts for catalytic wet air oxidation

Catalytic wet air oxidation(CWAO)is one of the most promising technologies for pollution abatement.Developing catalysts with high activity and stability is crucial for the application of the CWAO process.The Mn/Ce com-plex oxide catalysts for CWAO of high concentration phenol-containing wastewater were prepared by coprecipitation.The catalyst preparation conditions were optimized by using an orthogonal layout method and single-factor experimental analysis.The Mn/Ce serial catalysts were characterized by Brunauer-Emmett-Teller(BET)analysis and the metal cation leaching was measured by inductively coupled plasma torch-atomic emission spectrometry(ICP-AES).The results show that the catalysts have high catalytic activities even at a low temperature(80°C)and low oxygen partial pressure(0.5 MPa)in a batch reactor.The metallic ion leaching is comparatively low(Mn<6.577 mg/L and Ce<0.6910 mg/L,respectively)in the CWAO process.The phenol,COD_(Cr),and TOC removal efficiencies in the solution exceed 98.5%using the optimal catalyst(named CSP).The new catalyst would have a promising application in CWAO treatment of high concentration organic wastewater.

钌催化剂在模拟印染废水CWAO法处理中的应用

采用催化湿式氧化法对甲基橙模拟印染废水进行处理;催化剂的制备采用等量浸渍方法,以Cu、Fe为催化剂活性组分,Ce、La为催化助剂,加入贵金属钌制备多组分复合催化剂。研究了钌催化剂的加入对出水pH、吸光度和脱色率的影响。结果表明:加入钌催化剂处理后,出水pH呈先降低后升高的趋势,出水吸光度明显减小,脱色率增加显著,可达到98.3%。

CWAO法处理噻螨酮生产废水的催化剂研究

以过渡金属氧化物CuO为主活性组分,通过加入第二活性组分MnO2和掺入电子助剂La2O3,研制出适用于催化湿式氧化(CWAO)法处理噻螨酮生产过程中产生的高浓度有机废水(CODCr 15 730mg/L)的复合催化剂。考察了浸渍液中各组分浓度、焙烧温度和焙烧时间等制备条件对催化剂的催化活性和稳定性的影响,确定了最佳制备条件。试验结果表明,该复合催化剂在处理此种有机废水时表现出较好的催化活性和稳定性。在230℃,氧气分压为2.5MPa和pH为7.3的条件下,催化湿式氧化该废水,在120min内,CODCr去除率达到96.1%,而在相同条件下未加催化剂的湿式氧化CODCr去除率只有50.3%。

催化湿式氧化处理含模板剂有机胺废水

采用催化湿式氧化法处理含有机胺高化学需氧量(COD)废水。考察了催化剂类型和反应温度对废水处理效果的影响。结果表明:以贵金属为催化剂时,COD降幅最高,达到96%;当反应温度为270℃时,能耗较低,尾气中氧气体积分数约为13.1%,COD降幅约为96%,处理效果较佳。采用贵金属催化剂,在温度为270℃、压力为7.6 MPa的最优条件下,催化湿式氧化设备连续运行140 h,产水COD的平均降幅在96%以上。同时进行设备材料腐蚀试验和加速氧化小型试验,通过调整反应原水的pH,解决了设备腐蚀问题。从处理效果和运行成本综合考虑,催化湿式氧化法处理含有机胺高COD废水具有一定竞争力。

制药废水处理用催化湿式氧化贵金属催化剂的研究进展

制药废水组成复杂、生物毒性大、可生化性差,通常需要组合多种水处理工艺进行净化。催化湿式氧化贵金属催化剂可以实现对制药废水中有机物无差别高效氧化,兼具处理设备体积小和耐盐的特性,成为下一代高浓度有机废水的首选深度净化用催化材料。论文综述了目前针对制药有机废水处理的主流手段并对催化湿式氧化技术的催化反应机理以及催化湿式氧化系统中适配的贵金属催化剂进行了着重介绍。分析比较了Pt、Ru为主要活性组分的催化剂在制药有机废水催化湿式氧化工艺中的优劣,总结了影响Pt、Ru催化剂催化活性的主要影响因素,为进一步优化催化湿式氧化工艺处理制药有机废水提供参考。

CuO/活性炭催化湿式氧化甲基橙废水的研究

基于以硝酸铜为活性组分的前驱物,采取浸渍焙烧法制备了CuO/活性炭催化剂,并以H_(2)O_(2)为氧化剂,对比了在常压条件下催化湿式氧化工艺中处理质量浓度500 mg·L^(-1)甲基橙模拟废水的效果,分别考察了不同CuO/活性炭催化剂加入量、质量分数30%的H_(2)O_(2)氧化剂用量、脱色反应时间、脱色反应温度对甲基橙废水脱色率的影响。结果表明:随着CuO/活性炭催化剂加入量、30%H_(2)O_(2)氧化剂用量、反应温度的不断增加,甲基橙废水的脱色率明显增大;而增加反应时间对甲基橙废水脱色率增加幅度较小。当CuO/活性炭催化剂加入量为0.1 g、质量分数30%H_(2)O_(2)氧化剂加入量为6 mL、催化反应时间为2 h、催化反应温度为35℃时,其对甲基橙废水的脱色率可达到82.44%。

碱渣高压湿式氧化(WAO)出水在污水场的综合利用

根据进入污水处理场的WAO出水的性质,在污水处理生化系统的承受能力范围内充分利用其碱性,以达到降低生化系统碱耗及污水处理前端因调节pH而产生的酸耗,节约能源、降低处理费用。

WAO法处理中进水浓度对废水浊度去除的影响

采用湿式空气氧化法,对高浓度难生化有机废水进行处理。试验研究在湿式空气氧化法处理有机废水中不同进水浓度对浊度去除率的影响,通过测定水样浊度、浊度去除率的变化,发现,WAO法对不同进水浓度废水的处理效果都是随着反应时间增加而增加,而进水浓度越小,WAO法处理有机废水的效果越好。结果表明,当进水浓度COD=1000 mg/L、反应时间为60 min时,废水浊度去除率可高达86.3%。当进水浓度太大,大于4 000 mg/L时,反应时间也要相应增加,但浊度去除率不高,处理效果也不明显。

医院含菌废水污染特征及处理技术研究

医院废水污染性强,对其有着更为严格的处理要求。为进一步提高医院废水的处理效果,进行医院含菌废水处理污染特征及处理技术研究。以某医院为例,从污染物组成成分、水质、色度以及含菌量4个方面分析医院含菌废水污染特征;将MBR膜-生物反应器与紫外催化湿式氧化技术组合在一起,用于医院含菌废水处理。结果表明:处理后三种废水中的各种污染物去除率均达到了80%以上。处理后三粪大肠菌群数急剧减少,最后下降到了500(个/L)以下。处理前三种医院废水色度均较高,不符合处理标准,经过处理后,色度逐步下降,最终均达到了标准。

室温催化湿式氧化处理甲醛废水的Pt/层状双金属氧化物催化剂

详细研究了层状双金属氧化物(LDO)制备方法对Pt/LDO催化剂进行催化湿式氧化(CWAO)处理甲醛废水性能的影响,并对制备的催化剂进行X射线衍射、透射电镜、N_(2)物理吸-脱附、H_(2)程序升温还原和X射线光电子能谱等表征.催化剂评价结果表明:在室温和低Pt负载量(质量分数0.25%)的条件下,与Pt/LDO(P)(共沉淀法制备的LDO)相比,Pt/LDO(H)(水热法制备的LDO)催化剂具有更为优异的CWAO处理甲醛废水的催化性能.在室温(30℃)下反应5 h,Pt/LDO(H)可将甲醛完全转化,且能将84.1%的甲醛完全氧化为CO_(2);而在相同条件下,Pt/LDO(P)只能转化63.8%的甲醛,且仅有57.9%的甲醛被完全氧化为CO_(2).Pt/LDO(H)催化剂还具有良好的稳定性,在连续测试的5次反应内,保持高的甲醛转化率(约100%)和总有机碳转化率(约83%).表征结果显示,Pt/LDO(H)催化剂具有高的Pt分散性、强的金属-载体电子相互作用、丰富的表面氧物种、强的氧化能力和良好的抗流失性能,这是其具有优良催化性能的主要原因.