UV/H2O2和UV/TiO2/H2O2去除水中微量硝基苯的比较研究

研究比较了UV/H2O2和UV/TiO2/H2O2对水中微量硝基苯的降解效果,并考察了水中常见HCO-3和腐殖酸对硝基苯降解的影响.结果表明,薄膜状TiO2的存在对UV/H2O2降解硝基苯有显著的促进作用,在最佳H2O2投加量2.1 mg/L时,UV/TiO2/H2O2的反应速率常数比UV/H2O2高32.8%;2 min内UV/TiO2/H2O2对硝基苯的去除率达到80%以上.HCO-3和腐殖酸对硝基苯降解有很强的抑制作用,HCO-3和腐殖酸浓度分别为2 mmol/L和3.2 mg/L时,UV/TiO2/H2O2对硝基苯的反应速率常数分别下降84.6%和92.2%.     

Classification of the degradability of 30 pharmaceuticals in water with ozone, UV and H2O2.

Experiments were conducted to assess the degradability of 30 PPCPs, selected on the basis of consumption and environmental relevance, by O3 process, UV process and AOPs consisting of UV/ H2O2, O3/UV and O3/H2O2. A batch reactor with volume of 22L of water including the PPCPs was used. For UV process, combination of UV and H2O2 or O3 that can generate OH radicals was capable of degrading the PPCPs faster than UV radiation alone. On the other hand, O3 process and O3-based/UV-based AOPs could remove a variety of the PPCPs effectively, while some PPCPs such as 2-QCA, DEET and cyclophosphamide showed a relatively low degradability compared with the other PPCPs. However, further evaluation on formation of intermediate products resulting from the degradation of the parent PPCPs will be needed because DOC concentration was not decreased with lowered concentrations of the PPCPs.     

O3、O3/H2O体系处理染料废水酸性嫩黄G的试验研究

以配制的酸性嫩黄G染料废水为研究对象,考察O3、O3/H2O2体系对去除染料废水中的COD.和色度,提高可生化性的效果,分析pH值、初始污染物浓度、H2O2投加量等各种因素对O3氧化染料废水的影响.试验结果表明:臭氧氧化对COD.去除率达55.1%,对色度的去除率接近100%,B/C由原水的0.08上升到03;臭氧化酸...     

H2O2/UV enhanced degradation of pesticides in wastewater.

Photodegradation of organic pesticides in industrial wastewater was examined in a UV/H2O2/air system. An experimentally determined optimal amount of hydrogen peroxide (0.008% v/v) indicates that hydrogen peroxide concentration controlled the efficiency of photodegradation. Pre-treatment operations such as sedimentation, filtration and coagulation were used to obtain better efficiency of pesticide removal and to cut down on irradiation time. Finally, scale-up experiments in the air-sparged hydrocyclone (ASH) reactor were carried out. After 5 min irradiation of 100 dm3 industrial wastewater almost all pesticides were destroyed. Thus the ASH reactor proved to be an effective contactor for carrying out photochemical reactions.     

UV/H2O2联用工艺去除水中微量有机污染物的中试研究

为了考察UV/H2O2工艺对微量有机物的去除效果,在砂滤池出水后接UV/H2O2高级氧化中试设备,并投加了特征污染物(阿特拉津、臭味物质2-MIB与Geosmine)。结果表明,UV/H2O2工艺对Geosmine去除效果最好,去除率能达到90%以上,对MIB和阿特拉津的去除效果比较接近,去除率均在50%以上,对UV254的去除率为20%～38%。在UV/H2O2工艺中无溴酸盐生成。     

Modelling the kinetics of UV/H2O2 oxidation of dichloroacetic acid.

The intrinsic reaction kinetics of the decomposition of dichloroacetic acid (DCA) using UV/H2O2 was studied. A complete mathematical model, including the effect of the absorbed radiation intensities and H2O2 concentration was developed. The results of the kinetic measurements were analysed using a complete mathematical model of the experimental device that was used for the laboratory operation (a differential reactor inside a recycle). In this way it was expected to obtain intrinsic kinetic parameters. Experimental data agree well with theoretical predictions esmploying just two kinetic parameters derived from the proposed reaction mechanism.     

UV/H2O2 degradation of endocrine-disrupting chemicals in water evaluated via toxicity assays.

Due to rising concern regarding the presence of endocrine-disrupting chemicals (EDCs) in surface water and groundwater throughout the United States, Asia and Europe, treatment of these chemicals in drinking water and wastewater to protect human health and the environment is an area of great interest. Many conventional treatment schemes are relatively ineffective in removing EDCs from water and wastewater. This is concerning because these chemicals are biologically active at very low concentrations and effects of mixtures are relatively unknown. 17-alpha-oestradiol (E2) and 17-beta-ethinyl-oestradiol (EE2), suspected EDCs, were degraded significantly by the UV/H2O2 AOP. The UV/H2O2 processes using either low or medium pressure lamps were degraded EDCs by between 80 and 99.3% at a 15 ppm H2O2 concentration and a UV dose of 1,000 mJ/cm2. Significantly greater removal was noted when the removal was based on total oestrogenic activity using a yeast oestrogen screen (YES) assay. These data indicated that a dose of less than 200 mJ/cm2 completely removed oestrogenic activity in lab water. Values for natural waters were slightly higher. A steady state model was developed to determine EDC destruction efficiency in waters of differing quality. The model effectively predicted destruction in water, where concentrations of all scavenging species were known. Based on these results it was concluded than complete destruction of oestrogenic activity was possible under practical advanced oxidation conditions for a variety of water qualities.     

Degradation of the endocrine disruptor carbofuran by UV, O3 and O3/UV.

The photodegradation of a carbamate insecticide, Carbofuran (CBF), which has been recognised as a potential endocrine disrupting chemical, was studied via different wastewater treatment processes. This study has shown the efficiency of advanced oxidation process, AOP (UV/O3) than those of the direct UV photolysis and ozonation process, by completely removing 0.2 mM CBF and achieving 24% mineralisation within 30min. The initial decay of CBF by UV/O3 accelerated from 0.05 to 0.16 min(-1) as the initial pH increasing from 3.0 to 11.3. The pH-dependency of CBF has also been shown in both ozonation and UV/O3 process. A linear relationship could be found for the latter process in all pH, while for the former process, two stages of reactions (steady and accelerating) were found in the acidic and alkaline pH condition, respectively.     

Potential of UV/H2O2 oxidation for enhancing the biodegradability of municipal reverse osmosis concentrates

UVC/H2O2 and VUV/H2O2 oxidation processes were evaluated for the degradation of organic pollutants in reverse osmosis concentrate (ROC) produced from a municipal secondary effluent. It was found that the oxidation by UVC/H2O2 and VUV/H2O2 processes could be described as a pseudo first-order reaction. For UVC increased oxidation occurred with increasing H2O2 dosage up to 2 mM above which improvement in oxidation performance decreased. At the same H2O2 dosage, VUV irradiation gave better overall oxidation performance. Compared with UVC/6 mM H2O2, VUV/2 mM H2O2 gave a greater rate of reduction of chemical oxygen demand, but a lower rate for reduction of dissolved organic carbon, suggesting that oxidation of organics by the two methods followed different pathways. The change of absorbance at 254 nm and fluorescence excitation emission matrix spectra of irradiated samples indicated that the large and complex compounds were fragmented rapidly by the *OH, resulting in rapid decolourisation. The biodegradability of the organics in the ROC was increased from 11% to 35% after 1 h treatment by UVC/3 mM H2O2, whereas a greater increase (41%) was obtained with VUV/2 mM H2O2. This increase in biodegradability indicates the potential for employing a subsequent biological treatment process.     

Treatment of wastewater from a cotton dyeing process with UV/H2O2 using a photoreactor covered with reflective material

Wastewater containing several dyes, including sulfur black from the dyeing process in a textile mill, was treated using a UV/H2O2 process. The wastewater was characterized by a low BOD/COD ratio, intense color and high acute toxicity to the algae species Pseudokirchneriella subcaptata. The influence of the pH and H2O2 concentration on the treatment process was evaluated by a full factorial design 22 with three replicates of the central experiment. The removal of aromatic compounds and color was improved by an increase in the H2O2 concentration and a decrease in pH. The best results were obtained at pH 5.0 and 6 g L(-1). With these conditions and 120 min of UV irradiation, the removal of the color, aromatic compounds and COD were 74.1, 55.1 and 44.8%, respectively. Under the same conditions, but using a photoreactor covered with aluminum foil, the removal of the color, aromatic compounds and COD were 92.0, 77.6 and 59.4%, respectively. Moreover, the use of aluminum foil reduced the cost of the treatment by 40.8%. These results suggest the potential application of reflective materials as a photoreactor accessory to reduce electric energy consumption during the UV/H2O2 process.     

Advanced treatment of benzothiazole contaminated waters: comparison of O3, AC, and O3/AC processes.

Benzothiazole (BT) is a toxic and poorly biodegradable contaminant, usually found in wastewater from rubber related applications. This compound could be effectively eliminated using advanced treatment processes. This paper compares experimental results on detoxification systems based on ozone oxidation, activated carbon adsorption, and simultaneous adsorption-oxidation using ozone in the presence of activated carbon. The effect of pH (2-11), and the presence of radical scavengers (tert-butyl alcohol and sodium carbonate) on process rates and removal efficiencies are assessed at laboratory scale. The experimental system consisted of a 1 L differential circular flow reactor and an ozone generator rated at 5 g O3/h. Results show that ozone oxidation combined with activated carbon adsorption increases the overall BT oxidation rate with respect to the ozonation process and activated carbon adsorption. In the presence of free radical scavenger, only a 44% reduction in BT removal rate is observed in the simultaneous treatment, as compared with 72% when ozonation treatment is used, suggesting that BT oxidation reactions mainly take place on the activated carbon surface.     

Treatability of cefazolin antibiotic formulation effluent with O3 and O3/H2O2 processes.

The effect of applying ozonation and perozonation to antibiotic cefazolin-Na formulation effluents were investigated in this study. Twenty minutes of ozonation at a rate of 1,500 mg/L-h was observed to remove COD by 38%, whereas a COD removal efficiency of 40% was achieved via H2O2 enhanced ozonation (same conditions + 31.25 mM H2O2). Both of the pretreatment alternatives were monitored to elevate the BOD5/COD ratio from 0.01 to 0.08. The initially inert COD was reduced by 38% using ozonation and by 60% employing H2O2 enhanced ozonation. In terms of the lowest achievable effluent COD levels after bio-treatment, ozonation was observed to yield a residual COD of 205 mgL(-1), while a residual COD of 135 mgL(-1) was involved for perozonation. According to the results of acute toxicity on Phaedactylum tricornutum, ozonated and perozonated samples exhibited more toxicity than the untreated effluent after 4 days. The activated sludge inhibition test demonstrated that both of the pretreatment alternatives efficiently eliminated the inhibition of investigated formulation effluent.     

Use of on-line UV/Vis-spectrometry in the measurement of dissolved ozone and AOC concentrations in drinking water treatment.

The concentrations of dissolved ozone and assimilable organic carbon (AOC) are important performance parameters in drinking water production. For the measurement of ozone, a spectral algorithm was developed that allows quantification in situ using a UV/Vis spectrometer probe. Furthermore, a strong correlation between the change in the absorption spectrum after individual treatment steps and the formation or removal of AOC in that treatment step was observed. This allowed the development of a spectral algorithm that predicts AOC formation during ozonation and subsequent removal in further treatment steps. This method has been verified at one pilot plant of the Amsterdam drinking water supply.     

A/O2-MBR组合工艺处理冷轧含油废水

采用A/O2-MBR组合处理冷轧含油废水,并应用固定化微生物技术克服了常规膜处理中"油封"对膜表面造成的污染,获得了一个长效、稳定的膜通量和高效的处理成果,出水CODCr＜70mg/L,出水水质可达《污水综合排放标准》(GB 8978-1996)一级标准.     

Homogeneous (Fe(III)) and heterogeneous (TiO2) photocatalytic systems for pollutant removal from the aquatic compartment: comparison and complementarity.

Kinetics of the oxidative photodegradation of monuron (3-(4-chlorophenyl)-1-1-dimethylurea) in both homogeneous solution of Fe(ClO4)3 and heterogeneous suspension of TiO2, were investigated and compared. In the homogeneous system (Fe(II)), the speciation of Fe(III) aquacomplexes was shown to play an essential role in the rate of photodegradation. For high concentrations of TiO2 (> 500 mg L(-1)), the photodegradation rate was similar to the reaction rate obtained with a freshly prepared solution of Fe(II) (3 x 10(-4) mol L(-1)). In the combined system (TiO2 + Fe(III)), a synergy effect accelerating the monuron photodegradation was observed. Actually, in the presence of Fe(III) (in concentration compatible with a safe environment), a similar reaction rate for monuron photodegradation was obtained with a TiO2 concentration lower by a factor of 20.     

Removal of ibuprofen from wastewater: comparing biodegradation in conventional, membrane bioreactor, and biological nutrient removal treatment systems.

Pharmaceuticals are continually being introduced into the influent of municipal wastewater treatment plants (WWTPs). Developing a better understanding of pharmaceutical removal mechanisms within the different treatment processes is vital in preventing downstream contamination of our water resources. In this study, ibuprofen, a popular over-the-counter pain reliever, was monitored by taking wastewater samples throughout the City of Guelph municipal WWTP. Greater than 95% of ibuprofen was found to be removed in the aeration tank, with aerobic biodegradation being the dominant mechanism. For comparison, first-order kinetics were used to quantify ibuprofen biodegradation in a conventional WWTP aeration tank and in a membrane bioreactor (MBR) pilot plant. The rate constants, k biol, for the conventional tank and the MBR were determined to be (-6.8+/-3.3) L/g SS*d and (-8.4+/-4.0) L/g SS*d, respectively. These two rate constants were found to be statistically similar. Preliminary study of a biological nutrient removal pilot system also suggests that ibuprofen can be anaerobically degraded.     

Development of procedures for rapid detection of E. coli O157:H7 from source and finished water samples.

Enterohaemorrhagic Escherichia coli (EHEC) O157:H7, the causative agent for haemolytic uraemic syndrome, has become a significant health concern, due to an increasing number of cases. The focus of this project was rapid (<8 h) detection of E. coli O157:H7 from source and finished waters samples, either directly or indirectly, by dovetailing the procedures with existing total coliform procedures. Evaluation of four immunological lateral diffusion assays determined a detection range between 1 x 10(4) and 1 x 10(6) CFU, with the Reveal E. coli O157:H7 Test System (Neogen) being the most sensitive for detecting E. coli O157:H7. Evaluation of the BAX System for molecular detection determined that as few as 10 CFU could be reproducibly detected. Coupling either of these detection procedures with organism propagation using Tryptic Soy Broth (TSB) enabled sufficient quantities of E. coli O157:H7, such that the Reveal and BAX detection methods could be used with the 8 h time frame. Examination of matrix effects on the overall procedure indicated little impact on method performance.     

Relevance of the sludge retention time (SRT) as design criteria for wastewater treatment plants for the removal of endocrine disruptors and pharmaceuticals from wastewater.

Wastewater treatment plants (WWTPs) represent a significant source for the input of micro pollutants as endocrine disruptors (EDs) or pharmaceutically active compounds (PhACs) into the aquatic environment. Treatment efficiency of WWTPs often is reported, taking into account only inflow and effluent concentrations without further specification of the WWTP investigated. In order to allow comparison and evaluation of the removal efficiency of different layouts and concepts in wastewater treatment, additional information like the sludge retention time (SRT) and sludge load (F/M ratio) are necessary. Presented results from different WWTPs show correlation of removal of EDs and PhACs to the SRT. Compared to WWTPs with high F/M ratio implementation of the nitrification process on WWTPs results in a significant increase of the removal efficiency for EDs and PhACs. This paper describes an approach to determine comparable removal rates for different activated sludge systems based on mass balance and SRT.