Advanced oxidation of a pulp mill bleaching wastewater.

The degradation, by several advanced oxidation reactions, of a pulp mill ECF bleaching effluent, was studied. The initial biodegradability of the organic matter present in the effluent, estimated as the BOD5/COD, was low (0.3). When the effluent was submitted to ozonation and to five different advanced oxidation systems (O3/UV, O3/UV/ZnO, O3/UV/TiO2, O2/UV/ZnO, O2/UV/TiO2), the biodegradability increase significantly. After five minutes of reaction, the O3/UV system appears as the most efficient in to transform the organic matter to more biodegradable forms. A similar effect was observed when the effluent was submitted to an activated sludge treatment. The COD, TOC and toxicity reduction correlated well with the biodegradability enhancement after AOPs treatments.     

Comparison of various advanced oxidation processes and chemical treatment methods for COD and color removal from a polyester and acetate fiber dyeing effluent

In this paper, a comparison of various advanced oxidation processes (O3, O3/UV, H2O2/UV, O3/H2O2/UV, Fe2+/H2O2) and chemical treatment methods using Al2(SO4)3.18H2O, FeCl3 and FeSO4 for the chemical oxygen demand (COD) and color removal from a polyester and acetate fiber dyeing effluent is undertaken. Advanced oxidation processes (AOPs) showed a superior performance compared to conventional chemical treatment, which maximum achievable color and COD removal for the textile effluent used in this study was 50% and 60%, respectively. Although O3/H2O2/UV combination among other AOPs methods studied in this paper was found to give the best result (99% removal for COD and 96% removal for color), use of Fe2+/H2O2 seems to show a satisfactory COD and color removal performance and to be economically more viable choice for the acetate and polyester fiber dyeing effluent on the basis of 90% removal.     

真空紫外光臭氧降解偏二甲肼的研究

研究比较了臭氧氧化（O₃）、紫外臭氧（O₃/UV）和真空紫外臭氧（O₃/VUV）对推进剂——偏二甲肼的处理效果，O₃/VUV最为有效，反应速率常数分别比O₃/UV和O₃高39.8%和65.6%，中间产物——甲醛去除得更迅速，反应50 min即无法检出。初始pH 9时，O₃/VUV降解偏二甲肼的速率最快，达到0.4461 min^-1；反应速率常数随臭氧投加量的增加而线性增大；随偏二甲肼初始浓度从100 mg/L增加到2 000 mg/L，反应动力学由一级转为零级。碳酸盐浓度在0～2 mmol/L范围内对O₃/VUV降解偏二甲肼没有明显的抑制作用。偏二甲肼的无机氮产物以氨离子为主，无机氮只占总氮的40%～60%，说明仍有相当比例的氮以有机氮形式存在。     

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。     

O3、H2O2／O3及UV／O3在焦化废水深度处理中的应用

采用O3、H2O2／O3及UV／O3等高级氧化技术（AOPs）对某焦化公司的生化出水进行深度处理，考察了O3与废水的接触时间、溶液pH、反应温度等因素对废水COD去除率的影响，确定出O3氧化反应的最佳工艺参数为：接触时间40min，溶液pH8．5，反应温度25℃，此条件下废水COD及UV254的去除率最高可达47．14％和73．47％；H2O2／O3及UV／O3两种组合工艺对焦化废水COD及UV254的去除率均有一定程度的提高，但H2O2／O3系统的运行效果取决于H2O2的投加量。研究结论表明，单纯采用COD作为评价指标，并不能准确反映出O3系列AOPs对焦化废水中有机污染物的降解作用。     

Fenton's pre-treatment of mature landfill leachate

The aim of this study was to check the effectiveness of the Fenton's reagent (Fe2+ + H2O2 + H+) for the pre-treatment of a municipal landfill leachate with the objective of improving its overall biodegradability, evaluated in terms of BOD5/COD ratio, up to a value compatible with biological treatment. The leachate came from a municipal sanitary landfill located in southern Italy and the average values of its main parameters were: pH=8.2; COD=10,540 mgl(-1); BOD5=2,300 mgl(-1); TOC=3,900 mgl(-1); NH4-N=5210 mgl(-1); conductivity=45,350 microScm(-1); alkalinity=21,470 mgl(-1) CaCO3. The effect of initial pH value on the pre-treatment effectiveness was evaluated by titrating the amount of acidic by-products formed. The extent of leachate oxidation was monitored and controlled by both pH and redox potential measurements. The best operational conditions for achieving the desired goal (i.e., BOD5/COD> or =0.5) resulted: Fe2+=275 mgl(-1); H2O2=3,300 mgl(-1); initial pH=3; reaction time=2 h. At the end of the Fenton's pre-treatment, in order to permit a subsequent biological treatment, residual ferric ions were removed increasing the pH up to 8.5 by adding 3 gl(-1) of Ca(OH)2 and 3 mgl(-1) of a cationic polyelectrolyte, the latter as an aid to coagulation. This final step also resulted in a further modest removal of residual COD due to co-precipitation phenomena.     

Photochemical degradation and mineralization of 4-chlorophenol

INTENTION, GOAL, SCOPE, BACKGROUND: Since the intermediate products of some compounds can be more toxic and/or refractory than the original compund itself, the development of innovative oxidation technologies which are capable of transforming such compounds into harmless end products, is gaining more importance every day. Advanced oxidation processes are one of these technologies. However, it is necessary to optimize the reaction conditions for these technologies in order to be cost-effective. OBJECTIVE: The main objectives of this study were to see if complete mineralization of 4-chlorophenol with AOPs was possible using low pressure mercury vapour lamps, to make a comparison of different AOPs, to observe the effect of the existence of other ions on degradation efficiency and to optimize reaction conditions. METHODS: In this study, photochemical advanced oxidation processes (AOPs) utilizing the combinations of UV, UV/H2O2 and UV/H2O2/Fe2+ (photo-Fenton process) were investigated in labscale experiments for the degradation and mineralization of 4-chlorophenol. Evaluations were based on the reduction of 4-chlorophenol and total organic carbon. The major parameters investigated were the initial 4-chlorophenol concentration, pH, hydrogen peroxide and iron doses and the effect of the presence of radical scavengers. RESULTS AND DISCUSSION: It was observed that the 4-chlorophenol degradation efficiency decreased with increasing concentration and was independent of the initial solution pH in the UV process. 4-chlorophenol oxidation efficiency for an initial concentration of 100 mgl(-1) was around 89% after 300 min of irradiation in the UV process and no mineralization was achieved. The efficiency increased to > 99% with the UV/H2O2 process in 60 min of irradiation, although mineralization efficiency was still around 75% after 300 min of reaction time. Although the H2O2/4-CP molar ratio was kept constant, increasing initial 4-chlorophenol concentration decreased the treatment efficiency. It was observed that basic pHs were favourable in the UV/H2O2 process. The results showed that the photo-Fenton process was the most effective treatment process under acidic conditions. Complete disappearance of 100 mgl(-1) of 4-chlorophenol was achieved in 2.5 min and almost complete mineralization (96%) was also possible after only 45 min of irradiation. The efficiency was negatively affected from H2O2 in the UV/H2O2 process and Fe2+ in the photo-Fenton process over a certain concentration. The highest negative effect was observed with solutions containing PO4 triple ions. Required reaction times for complete disappearance of 100 mgl(-1) 4-chlorophenol increased from 2.5 min for an ion-free solution to 30 min for solutions containing 100 mgl(-1) PO4 triple ion and from 45 min to more than 240 min for complete mineralization. The photodegradation of 4-chlorophenol was found to follow the first-order law. CONCLUSION: The results of this study showed that UV irradiation alone can degrade 4-CP, although at very slow rates, but cannot mineralize the compound. The addition of hydrogen peroxide to the system, the so-called UV/H2O2 process, significantly enhances the 4-CP degradation rate, but still requires relatively long reaction periods for complete mineralization. The photo-Fenton process, the combination of homogeneous systems of UV/H2O2/Fe2+ compounds, produces the highest photochemical elimination rate of 4-CP and complete mineralization is possible to achieve in quite shorter reaction periods when compared with the UV/H2O2 process. RECOMMENDATIONS AND OUTLOOK: It is more cost effective to use these processes for only purposes such as toxicity reduction, enhancement of biodegradability, decolorization and micropollutant removal. However the most important point is the optimization of the reaction conditions for the process of concern. In such a case, AOPs can be used in combination with a biological treatment systems as a pre- or post treatment unit providing the cheapest treatment option. The AOP applied, for instance, can be used for toxicity reduction and the biological unit for chemical oxygen demand (COD) removal.     

Treatment of landfill leachate by electrochemical oxidation and anaerobic process.

The removal performance of typical refractory organic compounds in landfill leachate was investigated during the electrochemical (EC) oxidation and anaerobic process combined treatment system in this paper. The results indicated that the treatment of landfill leachate by the combined system was highly effective. The toxicity of leachate was notably decreased after the electrochemical oxidation process and the biodegradability was improved. The concentration of the organic acid with low molecular weight in the leachate increased from 28% to 90% based on the biodegradability assays after the EC oxidation process. The anaerobic digestion could further remove the residual organic compounds. At a hydraulic retention time (HRT) of 16 hours and an organic loading rate (OLR) of 8 kg COD/m3 d, the concentration of COD, SS, ALK, VA, N-TKN, N-NH4+ and P-PO4(3)- [corrected] in UASB effluent were 532, 12, 6744, 400, 540, 455 and 11.6 mg/L, respectively, with approximately 90% removal efficiency of COD. The organic compounds in the landfill leachate revealed different degradation characteristics in the combined system. p-chloroaniline, bisphenol A, 6-methyl-2-phenyl-quinoline, dimethylnaphthaline and N'-(2-methyl-4-chlorophenyl)-N-cyclohexyformamidine, classified into the first group in this paper, were completely removed by the EC oxidation and did not reappear in the effluent of the UASB reactor. Phenylacetic acid, 3-methyl-indole and N-cyclohexyl-acetamide, called the second group, were completely removed, but reappeared in the UASB reactor. 4-methyl-phenol, 3,4-dihydroisoquinoline, 2(3H)-benzothiazolone, exo-2-hydroxycineole and benzothiazole, the third group, were degraded little in the EC oxidation process, but extensively removed by the anaerobic process. Benzoic acid, benzenepropanoic acid and 2-cyano-3,5-dimethyl-1-hydroxypyrrole, the fourth group, concentration obviously increased in the EC process, but was completely removed in the UASB reactor. The content of volatile fatty acids (VFAs) markedly increased from 0.68% in the leachate to 16.18% in the effluent from the electrochemical oxidation process (EC(effl)). In addition, the degradation rate of organic compounds from the landfill leachate was different in the EC oxidation and anaerobic process.     

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。     

Screening of physical-chemical methods for removal of organic material, nitrogen and toxicity from low strength landfill leachates

Physical-chemical methods have been suggested for the treatment of low strength municipal landfill leachates. Therefore, applicability of nanofiltration and air stripping were screened in laboratory-scale for the removal of organic matter, ammonia, and toxicity from low strength leachates (NH4-N 74-220 mg/l, chemical oxygen demand (COD) 190-920 mg O2/l, EC50 = 2-17% for Raphidocelis subcapitata). Ozonation was studied as well, but with the emphasis on enhancing biodegradability of leachates. Nanofiltration (25 degrees C) removed 52-66% of COD and 27-50% of ammonia, the latter indicating that ammonia may in part have been present as ammonium salt complexes. Biological pretreatment enhanced the overall COD removal. Air stripping (24 h at pH 11) resulted in 89% and 64% ammonia removal at 20 and 6 degrees C, respectively, the stripping rate remaining below 10 mg N/l h. COD removals of 4-21% were obtained in stripping. Ozonation (20 degrees C) increased the concentration of rapidly biodegradable COD (RBCOD), but the proportion of RBCOD of total COD was still below 20% indicating poor biological treatability. The effect of the different treatments on leachate toxicity was assessed with the Daphnia acute toxicity test (Daphnia magna) and algal growth inhibition test (Raphidcocelis subcapitata). None of the methods was effective in toxicity removal. By way of comparison, treatment in a full-scale biological plant decreased leachate toxicity to half of the initial value. Although leachate toxicity significantly correlated with COD and ammonia in untreated and treated leachate, in some stripping and ozonation experiments toxicity was increased in spite of COD and ammonia removals.     

A new bioseed for determination of wastewater biodegradability: analysis of the experimental procedure

A new bioassay proposed in the patent P201300029 was applied to a pre-treated wastewater containing a mixture of commercial pesticides to simulate a recalcitrant industrial wastewater in order to determine its biodegradability. The test uses a mixture of standardized inoculum of the lyophilized bacteria Pseudomonas putida with the proper proportion of salts and minerals. The results highlight that biodegradation efficiency can be calculated using a gross parameter (chemical oxygen demand (COD)) which facilitates the biodegradability determination for routine water biodegradability analysis. The same trend was observed throughout the assay with the dehydrated and fresh inoculums, and only a difference of 5 % in biodegradation efficiency (E _f) was observed. The obtained results showed that the P. putida biodegradability assay can be used as a commercial test with a lyophilized inoculum in order to monitor the ready biodegradability of an organic pollutant or a WWTP influent. Moreover, a combination of the BOD₅/COD ratio and the P. putida biodegradability test is an attractive alternative in order to evaluate the biodegradability enhancement in water pre-treated with advanced oxidation processes (AOPs).     

凤眼莲去除垃圾渗滤液中的COD、NH3-N和TP

在静态水培实验条件下,对不同浓度垃圾渗滤液条件下凤眼莲的生长状况及其净化效果进行了研究。结果表明,在高浓度(COD 3 546.7 mg/L、NH3-N 527.5 mg/L、TP 8.02 mg/L)垃圾渗滤液条件下(HCL)凤眼莲全部被毒害致死,在中浓度(COD 1 233.3 mg/L、NH3-N 182.9 mg/L、TP 2.83 mg/L)垃圾渗滤液条件下(MCL)生长状况差,生物量减少为实验前的32.6%。在低浓度(COD 660.0 mg/L、NH3-N 99.7 mg/L、TP 1.59 mg/L)垃圾渗滤液条件下(LCL)能够正常生长,且对低浓度垃圾渗滤液有较好的净化效果。24 d后COD、NH3-N和TP的去除率分别为85.9%,99.8%和84.8%。COD与NH3-N均达到《生活垃圾填埋场污染控制标准(GB16889-2008)》排放标准,TP达到《地表水环境质量标准(GB 3838-2002)》Ⅳ类排放标准。     

紫外光助O3、H2O2氧化降解炼油废碱水的可行性实验

炼油高浓度有机废碱水是石化行业中很难降解的废水.本实验用光化学氧化技术对其进行了降解研究,比较了紫外光/空气、紫外光/O3、紫外光/空气/H2O2系统的处理效果.结果表明,光化学氧化技术降解此废水是可行的,紫外光可使废水中COD、油、酚的降解率明显提高.当废水中O3的投加量每小时为22 mg/L,或H2O2投加量为1%/L时,UV/O3法与UV/空气/H2O2法的降解效果相近.同时,通过控制O3浓度或H2O2的投加量等条件,可使废水中COD、油、酚和硫化物降解到地方污染物二级排放标准.     

Elucidation of the behavior of tannery wastewater under advanced oxidation conditions

Diverse advanced oxidation process (AOP) techniques applying UV, TiO2/UV, O3 and O3/UV were used to degrade pollutants contained in tannery wastewater. The total mineralization of these pollutants is desirable, but it is quite energy consuming and sometimes impossible. Therefore the objective was to achieve an enhancement of biodegradability, preferentially with a decrease in toxicity in parallel. This work demonstrates that the dominant pollutants were chemically degraded by oxidation, while changes in carbon content were only marginal. These results were obtained monitoring the total organic carbon content (TOC), chemical and biochemical oxygen demand (COD and BOD), and substance-specific pollutant content by application of gas chromatography/mass spectrometry (GC-MS) and liquid chromatography/mass spectrometry (LC-MS). Daphnia magna toxicity testing performed in parallel proved a decrease in toxicity after AOP treatment of the tannery wastewater.     

Degradation of 4-chlorophenol by microwave irradiation enhanced advanced oxidation processes

In this work the synergistic effects of several microwave assisted advanced oxidation processes (MW/AOPs) were studied for the degradation of 4-chlorophenol (4-CP). The efficiencies of the degradation of 4-CP in dilute aqueous solution for a variety of AOPs with or without MW irradiation were compared. The results showed that the synergistic effects between MW and H2O2, UV/H2O2, TiO2 photocatalytic oxidation (PCO) resulted in a high degradation efficiency for 4-CP. The potential of MW/AOPs for treatment of industrial wastewater is discussed.     

凤眼莲去除垃圾渗滤液中的COD、NH_3-N和TP

在静态水培实验条件下,对不同浓度垃圾渗滤液条件下凤眼莲的生长状况及其净化效果进行了研究。结果表明,在高浓度（COD 3 546.7 mg/L、NH3-N 527.5 mg/L、TP 8.02 mg/L）垃圾渗滤液条件下（HCL）凤眼莲全部被毒害致死,在中浓度（COD 1 233.3 mg/L、NH3-N 182.9 mg/L、TP 2.83 mg/L）垃圾渗滤液条件下（MCL）生长状况差,生物量减少为实验前的32.6%。在低浓度（COD 660.0 mg/L、NH3-N 99.7 mg/L、TP 1.59 mg/L）垃圾渗滤液条件下（LCL）能够正常生长,且对低浓度垃圾渗滤液有较好的净化效果。24 d后COD、NH3-N和TP的去除率分别为85.9%,99.8%和84.8%。COD与NH3-N均达到《生活垃圾填埋场污染控制标准（GB16889-2008）》排放标准,TP达到《地表水环境质量标准（GB 3838-2002）》Ⅳ类排放标准。     

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。     

垃圾渗滤液生物处理出水的深度处理组合工艺

采用"混凝-电解氧化-完全混合式活性污泥法(CSTR)"组合工艺深度处理垃圾渗滤液生物处理出水。探索了工艺的组合及各种工艺操作条件对垃圾渗滤液深度处理效果的影响,并对其影响机理进行了初步探讨。结果表明,以PAC为混凝剂时,在pH和药剂(有效成分)投加量分别为6.0和600 mg/L条件下,渗滤液COD去除率达到50%,有效降低了难溶惰性COD含量,缩短了后续电化学处置时间。混凝工艺后,采用电化学工艺处理,在最优工艺条件下:pH为6.0、电流I为1.2 A(电流密度为18.18 mA/cm2)、Cl-投加量为1 000 mg/L、极板距离为2 cm,电解30 min渗滤液COD去除率达到36%,同时,难降解有毒物含量明显降低,渗滤液可生化性TbOD/COD由10%提升至最大值64%。最后采用CSTR处理渗滤液电解出水,系统出水COD、氨氮和色度分别为100~150 mg/L、7~13 mg/L和25倍,为反渗透(RO)工序提供了良好的水质条件。     

Novel imazethapyr detoxification applying advanced oxidation processes

Different degradation methods have been applied to assess the suitability of advanced oxidation process (AOPs) to promote mineralization of imazethapyr [(RS)-5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid], a widely used imidazolinone class herbicide, the persistence of which has been demonstrated in surface and ground waters destined to human uses. Independent of the oxidation process assessed, the decomposition of imazethapyr always followed a pseudo-first order kinetic. The direct UV-irradiation (UV) of the herbicide as well as its oxidation with ozone (O?), and hydrogen peroxide tied to UV-irradiation (H?O?/UV) were sufficiently slow to permit the identification of intermediate products, the formation pathway of which has been proposed. Ozonation joined to UV-irradiation (O?/UV), ozonation joined to titanium dioxide photo-catalysis (TiO?/UV+O?), sole photo-catalysis (TiO?/UV), and photo-catalysis reinforced with hydrogen peroxide-oxidation (TiO?/UV+H?O?) were characterized by a faster degradation and rapid formation of a lot of small molecules, which were quickly degraded to complete mineralization. The most effective oxidation methods were those using titanium dioxide photo-catalysis enhanced either by ozonation or hydrogen peroxide. Most of all, these last processes were useful to avoid the development of dangerous by-products.     

EGSB反应器处理城市生活垃圾沥滤液

采用膨胀颗粒污泥床(EGSB)反应器对城市生活垃圾焚烧厂产生的垃圾沥滤液进行处理。实验结果表明:中温条件下,当COD浓度为55 000 mg/L左右,有机容积负荷(OLR)为22.8 kg COD/(m3.d)时,EGSB对垃圾沥滤液具有较好的的处理效果,COD去除率可达94.2%。当进水COD为72 000 mg/L左右时,为保证反应器的稳定运行,OLR应降低至18.2 kg COD/(m3.d),此时COD去除率可以达到88%左右,出水COD平均为9 103 mg/L。垃圾沥滤液和EGSB处理出水均以小分子量有机物为主,其中<4 kDa的有机物分别占76.5%和74.4%。EGSB对整个分子量区间的溶解性有机物都有较好的处理效果,其中对大分子有机物的处理效率相对更高。