Using FeGAC/H2O2 process for landfill leachate treatment

Due to the growing concern of highly contaminated landfill leachate problems in Taiwan, an innovative advanced catalytic oxidation (FeGAC/H(2)O(2)) process was developed and employed in this research to treat the landfill leachate from central Taiwan. Experimental results indicated that the FeGAC/H(2)O(2) process could effectively remove organic compounds from landfill leachate. The presence of iron oxide coated granular activated carbon (FeGAC) greatly improved the oxidative ability of H(2)O(2) for the removal of humic acids, fulvic acids and non-humic substance from leachate. For instance, at pH 6, the removal efficiencies of FeGAC/H(2)O(2) and H(2)O(2) processes were 70% and 8%, respectively. FeGAC/H(2)O(2) combined both advantages of FeGAC and H(2)O(2) where FeGAC had good organics adsorption ability and could effectively catalyse the hydrogen peroxide oxidation reaction for organics removal.     

铝铁复合淀粉絮凝-微波/H2O2氧化协同处理垃圾渗滤液

针对垃圾渗滤液成分复杂、污染物浓度高、可生化性差等特点,采用铝铁复合淀粉(CAFS)絮凝-微波/H2O2联用技术对垃圾渗滤液进行处理,考察了初始pH、絮凝剂投加量、微波辐射反应时间和H2O2投加量等因素对处理水质的影响。结果表明,絮凝最佳反应条件为pH 6.0,投加量13 mL/L;微波/H2O2氧化的最佳反应条件为pH 3.0,30% H2O2 25 mL/L,温度70℃,反应时间5 min。在上述最佳条件下,单独CAFS絮凝、单独微波/H2O2和CAFS絮凝-微波/H2O2联用对垃圾渗滤液COD的去除率分别为32.3%、42.4%和85.7%,CAFS絮凝与微波/H2O2联用,可利用CAFS残余的Fe2+与H2O2构成Fenton氧化体系,实现絮凝与微波催化氧化工艺的耦合,两者起到很好的协同作用。     

Organic-coated nanoparticulate zero valent iron for remediation of chemical oxygen demand (COD) and dissolved metals from tropical landfill leachate

The use of nanoparticulate zero valent iron (NZVI) in the treatment of inorganic contaminants in landfill leachate and polluted plumes has been the subject of many studies, especially in temperate, developed countries. However, NZVI’s potential for reduction of chemical oxygen demand (COD) and treatment of metal ion mixtures has not been explored in detail. We investigated the efficiency of NZVI synthesized in the presence of starch, mercaptoacetic, mercaptosuccinic, or mercaptopropenoic acid for the reduction of COD, nutrients, and metal ions from landfill leachate in tropical Sri Lanka. Synthesized NZVI were characterized with X-ray diffraction (XRD), transmission electron microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), thermal gravimetric analysis, Fourier transform infrared spectroscopy (FTIR) and Brunauer–Emmett–Teller. Of the samples tested, Starch-NZVI (S-NZVI) and mercaptoacetic-NZVI (MA-NZVI) performed well for treatment both COD and metal mixture. The removal percentages for COD, nitrate-nitrogen, and phosphate from S-NZVI were 50, 88, and 99 %, respectively. Heavy metal removal was higher in S-NZVI (>95 %) than others. MA-NZVI, its oxidation products, and functional groups of its coating showed the maximum removal amounts for both Cu (56.27 mg g^?1) and Zn (28.38 mg g^?1). All mercapto-NZVI showed well-stabilized nature under FTIR and XRD investigations. Therefore, we suggest mercapto acids as better agents to enhance the air stability for NZVI since chemically bonded thiol and carbonyl groups actively participation for stabilization process.     

日光/H2O2/草酸铁体系对垃圾渗滤液深度处理的试验研究

以草酸铁络合物／H2O2作光氧化剂,利用日光对垃圾渗滤生化出水进行了光氧化降解试验。结果表明,在溶液的初始体系pH=3．0,H2O2投加量为460mg／L,Fe^3＋质量浓度为20mg／L条件下,反应60min后,CODCr去除率可达80％以上;溶液初始体系的pH、H2O2和Fe^3＋的投加量及废水的水质对光解过程有显著影响,而且在太阳光照射下,CODCr去除率比紫外光照射下高。研究表明,在一定试验条件下,用日光／H2O2／草酸铁体系对城市垃圾渗滤液处理效果较好,可作为垃圾渗滤液的深度处理。     

Pressurized CO2/zero valent iron system for nitrate removal

A fluidized zero valent iron (ZVI) reactor pressurized by CO(2) gas for controlling pH was employed for nitrate reduction. The proposed CO(2) pressurized system potentially has advantages of using less CO(2) gas and reaching equilibrium pH faster than CO(2)-bubbled system. However, due to weak acid nature of carbonic acid, system pH gradually increased with increasing oxidation of ZVI and reduction of nitrate. As pH increased with progress of reaction, nitrate removal rate decreased continuously. The results indicate that nitrate removal efficiency increases with increasing initial ZVI dosage but reaches plateau at ZVI doses of higher than 8.25gl(-1), and initial nitrate concentration up to 100mg l(-1) as N has minimal impact on the removal efficiency. Unlike the fluidized system with pH control by strong acid reported in our pervious study, near 100% of nitrogen recovery was observed in the current process, indicating that nitrate reduction by ZVI with different pH controlled mechanisms will have different reaction routes.     

零价铁强化城市污泥与垃圾焚烧厂渗滤液协同厌氧消化

针对城市污泥(初沉污泥、剩余污泥)和垃圾焚烧厂渗滤液2种市政废物的协同厌氧消化产气量不足的问题,采用投加零价铁的方式,探究零价铁对厌氧消化过程中产酸和产甲烷阶段的强化作用,并研究消化前后COD、VSS、氨氮以及上清液离子的变化。以初沉污泥与剩余污泥体积比4∶1、渗滤液添加量为15%的基质作为底物,投加不同浓度零价铁进行厌氧消化。结果表明：零价铁能有效提升协同厌氧消化系统中总挥发性脂肪酸产量、促进丙酸分解、进一步降解复杂有机物;当零价铁投入量为4 g·L⁻¹时,累计产甲烷量最高达189.65 mL·g⁻¹(以VSS计),相比对照组提升了30.1%,其产气速率符合一次函数和Scholl Canyon模型指数衰减规律;在25 g·L⁻¹和40 g·L⁻¹的高投加量零价铁条件下,产气高峰提前,但累计甲烷产量低于对照组;随着零价铁的投加量增加,COD降解率呈下降趋势,VSS降解率提升,氨氮变化不大;此外,消化液上清液中,正磷酸盐、硫酸根浓度明显减少,这与亚铁离子的混凝沉淀作用相关,同时也是削弱零价铁强化作用的原因之一。研究结果可为城市污泥和垃圾焚烧厂渗滤液协同厌氧消化提供参考。     

垃圾渗滤液与城市污水同时处理系统优化运行策略探讨

采用倒置A2/O工艺处理垃圾渗滤液与城市污水的混合污水.模型试验结果表明,水力停留时间是影响混合污水氮和有机物去除的控制因素;水温为23～30℃、泥龄为20 d时,最优运行参数为:水力停留时间9h、DO2 mg/L、外回流比80％、内回流比200％,此时COD、NH3-N和TN去除率分别为76.4％～78.2％、95....     

Ti/Ru/SnO2+Sb2O5电极的制备及其对垃圾渗滤液的电催化氧化

通过实验探究了不同Ru掺杂量对 Ti/Ru/SnO2+Sb2O5电极电化学性能及表面结构的影响。结果表明：Sb含量10%,溶胶涂覆6层,煅烧温度600 ℃,煅烧时间1 h条件下,Ru掺杂量为10%的涂层电极的加速寿命最长,为50 min;该条件下制备的电极涂层表面金属氧化物 SnO2的特征峰强度较大,峰形窄;涂层表面光滑,无裂缝。同时用Ti/Ru/SnO2+Sb2O5电极处理垃圾渗滤液MBR出水,Ru掺杂为10%的电极对废水COD去除率最高,为93.33%,电解出水芳香化程度大幅降低,对腐殖质和芳香族化合物的去除效果良好。研究对Ti/Ru/SnO2+Sb2O5电极在实际工业生产中的应用具有指导意义。     

Performance investigation of electrochemical assisted HClO/Fe2+ process for the treatment of landfill leachate

Environmental Science and Pollution Research - The feasibility of removal of chemical oxygen demand (COD) and ammonia nitrogen (NH4+–N) from landfill leachate by an electrochemical assisted...     

O3/H2O2高级氧化技术H2O2加入量的简易控制方法

对与臭氧有着不同反应活性的3类有机污染物,探讨并建立了O3/H2O2高级氧化技术H2O2较优投加量的简易控制方法.结果表明,水中存在溶解臭氧是H2O2与臭氧降解效率具有协同作用的必要条件,另外,H2O2的较优加入量直接依赖于目标有机污染物与臭氧的反应活性.对于不同的有机物及在常规的臭氧化水处理时间内,H2O2加入量控制在单独臭氧化处理时水中溶解臭氧的20～30倍(质量比)之间为宜.这种简易控制H2O2加入量的方法对推广O3/H2O2技术在实际废水处理中的应用具有重要的意义.     

O3／H2O2高级氧化技术H2O2加入量的简易控制方法

对与臭氧有着不同反应活性的3类有机污染物，探讨并建立了O3／H2O2高级氧化技术H2O2较优投加量的简易控制方法。结果表明，水中存在溶解臭氧是H2O2与臭氧降解效率具有协同作用的必要条件，另外，H2O2的较优加入量直接依赖于目标有机污染物与臭氧的反应活性。对于不同的有机物及在常规的臭氧化水处理时间内，H2O2加入量控制在单独臭氧化处理时水中溶解臭氧的20-30倍（质量比）之间为宜。这种简易控制H2O2加入量的方法对推广O3／H2O2技术在实际废水处理中的应用具有重要的意义。     

铁炭微电解-MAP沉淀法联合预处理垃圾渗滤液

采用铁炭微电解-磷酸氨镁(MAP)沉淀法对垃圾渗滤液进行预处理,实验结果表明,铁炭比为5∶1,pH值为3,反应时间为3 h时,铁炭微电解的COD的去除率为47.5%;在投加药剂n(Mg2+)∶n(PO43-)∶n(NH4+)为1.4∶1∶1,pH值为9,反应时间为1 h的条件下,垃圾渗滤液氨氮去除率达到79.7%。     

Kinetics of oxidation of chlorobenzenes and phenyl-ureas by Fe(II)/H2O2 and Fe(III)/H2O2. Evidence of reduction and oxidation reactions of intermediates by Fe(II) or Fe(III)

The rates of degradation of 1,2,4-trichlorobenzene (TCB), 2,5-dichloronitrobenzene (DCNB), diuron and isoproturon by Fe(II)/H2O2 and Fe(III)/H2O2 have been investigated in dilute aqueous solution ([Organic compound]0 approximately 1 microM, at 25.0 +/- 0.2 degrees C and pH < or = 3). Using the relative rate method with atrazine as the reference compound, and the Fe(II)/H2O2 (with an excess of Fe(II)) and Fe(III)/H2O2 systems as sources of OH radicals, the rate constants for the reaction of OH* with TCB and DCNB were determined as (6.0 +/- 0.3)10(9) and (1.1 +/- 0.2)10(9) M(-1) s(-1). Relative rates of degradation of diuron and isoproturon by Fe(II)/H2O2 were about two times smaller in the absence of dissolved oxygen than in the presence of oxygen. These data indicate that radical intermediates are reduced back to the parent compound by Fe(II) in the absence of oxygen. Oxidation experiments with Fe(III)/H2O2 showed that the rate of decomposition of atrazine markedly increased in the presence of TCB and this increase has been attributed to a regeneration of Fe(II) by oxidation reactions of intermediates (radical species and dihydroxybenzenes) by Fe(III).     

微波诱导催化剂Fe2O3／沸石氧化处理印染废水

以自制改性沸石为催化剂,通过微波诱导氧化技术,对活性嫩黄模拟废水进行氧化处理。采用尿素均匀沉淀包裹法制备Fe2O3／沸石微波诱导催化剂。利用SEM、XRD、IR等分析手段分别对催化剂的表面形态、物相结构等特性进行表征。实验考察了催化剂用量、微波辐射时间、微波辐射功率对活性嫩黄废水的降解效果。结果表明：在催化剂用量3g／L、微波功率900W、辐射时间4min的条件下,对50mg／L活性嫩黄的处理率达到97％。     

A2/O生物接触氧化工艺处理屠宰加工废水

采用A2/O生物接触氧化工艺处理屠宰加工废水,在实现有机物高效去除的前提下,对缺氧反硝化HRT、好氧硝化HRT、混合液回流比、溶解氧和进水氨氮负荷等因素对脱氮效果的影响进行了研究。结果表明,在好氧HRT和缺氧HRT分别为18 h和8 h,混合液回流比为200%,好氧柱内的DO为2.5~3.5 mg/L时,系统对氨氮和TN的平均去除率分别达到94%和68%以上。在原水氨氮负荷不超过0.109 kg/(m3·d)的情况下,出水水质均达到了广东省《水污染排放限值》(DB44/26-2001)第二时间段一级标准。     

改进倒置A2/O工艺处理生活污水试验研究

对倒置A2/O工艺进行了缺氧池生物挂膜实验,结果表明,在化粪池出水COD有一定波动情况下,缺氧池COD去除率不仅较高且较稳定,有利于后续硝化反应的进行,提高系统的脱氮效果.同时研究了C/N在缺氧池中对脱氮效果的影响,C/N(质量比)     

Degradation of polychlorinated dibenzo-p-dioxins in aqueous solution by Fe(II)/H2O2/UV system

The photodegradation of polychlorinated dibenzo-p-dioxins (PCDDs), which include tetra- to octa-CDDs (TeCDD, PeCDD, HxCDD, HpCDD and OCDD), was carried out in the presence of Fe(II) and H2O2 mixed reagent. The degradation efficiency was strongly influenced by UV irradiation, and the initial concentrations of H2O2 and Fe(II). An initial TeCDD concentration of 10 ng l(-1) was completely degraded within 20 min under the optimum conditions. All PCDDs tested were successfully degraded by Fe(II)/H2O2/UV treatment and complete degradation of TeCDD, PeCDD and HxCDD was achieved within 120 min. PCDD photodegradation rates decreased with the number of chlorine atoms. The degradation process of TeCDD by this system seems to be initiated by an oxidative reaction (OH* radical attack) because less chlorinated DDs as intermediate products were not detected. From the Frontier electron density calculation, the first OH* radical attack positions on TeCDD were found to be four C atoms neighboring two O atoms. The decomposition of TeCDD gave 4,5-dichlorocatechol as an intermediate product. A TeCDD degradation scheme was proposed based on the identified intermediate and the values of Frontier electron density. Based on these results, Fe(II)/H2O2/UV system could be useful technology for the treatment of wastewater containing persistent pollutants such as dioxins and polychlorinated biphenyls.     

微波诱导Fe2O3/沸石负载型催化剂催化氧化焦化废水的研究

以天然沸石为载体,采用尿素均匀沉淀法制备了Fe2O3/沸石负载型催化剂(简称负载催化剂),研究其在微波辐射下对焦化废水的处理效果,探讨了负载催化剂投加量、微波辐射功率、微波辐射时间等因素对处理效果的影响,并考察了负载催化刑的重复使用性能.结果表明,天然沸石、于350℃焙烧得到的负载催化刑和于550℃焙烧得到的负载催化剂...     

响应面法优化UV／H2O2光氧化法处理高浓度LAS废水

采用响应面法对UV／H2O2光氧化法处理高浓度LAS废水的工艺参数进行了系统研究。根据Box—BehnkenDesign（BBD）设计原理,以初始pH与H2O2投加量、反应时间和温度为主要影响因素,设计4因素3水平共29个实验点的实验方案,并建立了二次响应面拟合模型。方差分析表明,初始pH与H2O2投加量、反应时间和温度以及初始pH和H2O2投加量、H2O2投加量和温度之间的交互作用,对实验结果具有显著性影响。实验得到的光氧化高浓度LAS废水最佳工艺条件,pH为4．0,H2O2投加量为40mmol／L,反应时间为90min,温度为25℃,在此条件下,LAS的平均去除率为98．1％。     

Effectiveness evaluation of glyphosate oxidation employing the H2O2/UVC process: Toxicity assays with Vibrio fischeri and Rhinella arenarum tadpoles

The H₂O₂/UVC process was applied to the photodegradation of a commercial formulation of glyphosate in water. Two organisms (Vibrio fischeri bacteria and Rhinella arenarum tadpoles) were used to investigate the toxicity of glyphosate in samples M_1, M₂, and M₃ following different photodegradation reaction times (120, 240 and 360 min, respectively) that had differing amounts of residual H₂O₂. Subsamples of M₁, M₂, and M₃ were then used to create samples M_1,E, M_2,E and M_3,E in which the H₂O₂ had been removed. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities were measured in tadpoles to determine possible sub-lethal effects. In V. fischeri, M_1,E, which was collected early in the photodegradation process, caused 52% inhibition, while M_3,E, which was collected at the end of the photodegradation process, caused only 17% inhibition. Survival of tadpoles was 100% in samples M₂, M₃, and in M_1,E, M_2,E and M_3,E. The lowest percentages of enzymatic inhibition were observed in samples without removal of H₂O₂: 13.96% (AChE) and 16% (BChE) for M₂, and 24.12% (AChE) and 13.83% (BChE) for M₃. These results show the efficiency of the H₂O₂/UVC process in reducing the toxicity of water or wastewater polluted by commercial formulations of glyphosate. According to the ecotoxicity assays, the conditions corresponding to M₂ (11 ± 1 mg a.e. L^?1 glyphosate and 11 ± 1 mg L^?1 H₂O₂) could be used as a final point for glyphosate treatment with the H₂O₂/UV process.