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1.
Removal of Congo red from textile wastewater by ozonation   总被引：7，自引：6，他引：1  
Congo red, which has a complex molecular structure with various diazo aromatic groups, is widely used in textile industry as an anionic dye. The purpose of this study was to investigate the degradation of Congo red in laboratory solution which had the chemical properties of the rinse waters of textile manufacturing dye-houses and the samples with Congo red alone wastewater by ozonation and to optimize the reaction parameters such as pH and time which influence the efficiencies of total organic carbon, total kjeldahl nitrogen and chemical oxygen demand removal. Ozonation of Congo red dye were carried out in a semi-batch reactor with constant ozone flow rate and concentration of 23 mL/sec and 13.6 mg/L, respectively. Decolorization was complete within a few minutes of ozonation possibly due to the cleavage of chromophore groups. It was observed that its structural destruction occurs predominantly at higher pHs. The reduction of chemical oxygen demand and destruction of the dye was more than 60 % and 42 %, respectively. Total kjeldahl nitrogen removal was accompanied by slight changes in nitrogen oxides. It can be deduced from the experimental results that: (a) the mineralization is very weak; (b) the reaction follows the indirect mechanism; i.e., the interaction of hydroxyl radicals with the dye and (c) the nitrification is rather predominant. Biological oxygen demand is declined in simulated alkalic and neutral samples respectively. At 13.6 mg O3/L, the biological oxygen demand levels were significantly enhanced. This might be attributable to the enhancement of its biodegradation at alkaline pHs.  相似文献   

2.
In recent years, concerns about the occurrence and fate of active pharmaceutical ingredients, solvents, intermediates and raw materials that could be present in pharmaceutical industry effluents have gained increasing attention. Conventional treatment methods, such as activated sludge, are not sufficient enough to remove active pharmaceutical ingredients completely. As a result, complementary treatment methods like coagulation and flocculation are often used and play a critical role in industrial and municipal wastewater treatment. The primary goal of these methods is to destabilize and remove colloidal particles along with other organic/inorganic contaminants. Recently empirical works have considered ozone as the most promising oxidant for the removal of micro-pollutants. The current study examined the effectiveness of coagulation/flocculation process using ferric chloride, polyaluminum chloride, and aluminum sulfate as a reasonable approach to tackle the issue of treating pharmaceutical wastewater. In addition, the results were compared with the process using only ferric chloride that was the coagulant of an actual treatment plant. Then, improvement of the process performance was investigated using ozone as an oxidant. In conclusion, it was found out that polyaluminum chloride presented better performance among two other coagulants and also adding 200 mg/L of polyaluminum chloride can lead to 97–98 % turbidity removal efficiency. Moreover, polyaluminum chloride was capable of reducing most of the environmental parameters such as chemical oxygen demand and total dissolved solid with the removal efficiency of 70 and 68 %, respectively. Additionally, ozonation improved the coagulation process, especially iron ion removal, and dramatically decreased the concentration from 5.68 to 0.19 mg/L.  相似文献   

3.
Exhausted Reactive dye bath samples of Turquoise Blue, Olive Green and Navy Blue shades were collected from cotton knit wear dyeing units in Tirupur. Ozonation was conducted in a column reactor system fed with ozone at the rate of 0.16 g/min to assess its efficiency in reducing the color, chemical oxygen demand and total organic carbon. Complete decolorization of the effluent was achieved in 10 min contact time and ozone consumption of 153 mg/ L for Turquoise Blue, 128 for Olive Green and 143 for Navy Blue shades effluents respectively. The corresponding COD removal was 43%, 44% and 43% for the three shades while TOC removal efficiency was 45%, 45% and 40% respectively. The results from the reusability studies indicate that the dyeing quality was not affected by the reuse of decolorized dye bath for two successive cycles. It is concluded that ozonation is efficient in decolorization of exhausted dye bath effluents containing conventional reactive dyes. However, the corresponding removal of COD from the textile effluent was not significant.  相似文献   

4.
为研究双金属催化剂去除有机污染物的效果,采用自制Fe/Ag催化剂对模拟苯酚废水进行了臭氧催化氧化处理。通过扫描电子显微镜(SEM)、比表面积分析仪(BET)和X射线衍射(XRD)对催化剂进行表征,并考察了催化剂类型、催化剂投加量和溶液初始pH值对降解效果的影响规律。结果表明:与Fe相比,Fe/Ag比表面积减少了22.8%,在Fe/Ag/O3与含苯酚废水的反应体系中,反应遵循臭氧直接作用和活性自由基(·OH、·O2、H2O2)共同作用的机理;Fe/Ag在反应过程中体现出良好的协同作用;300 mg/L的苯酚模拟废水在pH=6.3、Fe/Ag投加量为1.00 g的最优反应条件下经60 min反应,苯酚与化学需氧量(COD)去除率比单独臭氧氧化分别提高了18.4%和29.4%。  相似文献   

5.
The objective of this study was to propose a method for efficient degradation of tetracycline as a water contaminant. UV-C rays, ozonation, and iron chelates were used for removal of tetracycline from water. Aqueous solution of tetracycline (5 × 10?5 M) was exposed to UV-C rays (in two doses—6 and 12 W), ozonation (at 6–12 mg ozone), or iron chelates: iron(III) sodium ethylenediaminetetraacetate, iron(III) trisglycinate, and iron(III) citrate. For each of iron compounds, three doses were studied: 2.5 × 10?5 M, 5 × 10?5 M, 10 × 10?5 M. The experiments have shown that aqueous solution of tetracycline (5 × 10?5 M) is immediately degraded as a result of ozonation with 12 mg ozone. Absorbance of tetracycline decreased from A = 0.78 to A = 0.35 after 20-min ozone treatment of sample. The fluorescence spectra revealed the presence of two ozone-induced TC degradation products with fluorescence maxima at 523 and 531 nm appearing immediately after the ozonation treatment. On the other hand, iron(III) sodium ethylenediaminetetraacetate and iron(III) trisglycinate gave rise to a single TC degradation product with a fluorescence maximum at 531 nm, observed after 10 days of the experiment. On application of iron(III) trisglycinate, at any studied concentration, tetracycline becomes degraded faster—in 4 days. Iron(III) citrate degraded 90 % of tetracycline, when used at the level 10 × 10?5 M. The biggest changes in tetracycline concentration were obtained as a result of ozonation and iron(III) citrate treatments.  相似文献   

6.
《Applied Geochemistry》2002,17(8):1165-1170
The objectives of this study were to determine the feasibility of ozonation in unsaturated porous media, and consequently to observe its features and to identify possible limiting factors. Diesel fuel was chosen to represent a complex organic contaminant that is widespread in the environment. In this experiment, the effects of several ozonation features were investigated. Sand was spiked with commercially available diesel fuel (17.024 g diesel/kg dry sand), and packed into a column. Ozone was supplied into the column in a downward direction. When the sand was treated for 7 h at 20 mg ozone/l of air, 40% of the diesel was removed. As the ozone concentration increased from 5 to 20 mg ozone/l, the removal efficiency increased. The removal rate varied significantly depending on the ozone concentration and the treatment duration. At higher ozone concentration, significant quantities of ozone were consumed by the intermediates produced by the ozonation process, and therefore, the removal efficiency and the apparent removal rate of diesel became lowered. The low removal efficiency of diesel results from the high concentrations of normal alkanes. Total hydrocarbon concentration (THC) in the effluent gas was measured using a total hydrocarbon analyzer. The THC decreased with the period of exposure and increasing ozone concentration. Ozonation decreased the gas-extractable fraction and accordingly, the THC decreased. Water-extractable fractions formed by the action of ozone were further oxidized by ozone. Due to the reduction of WEOC (water-extractable organic C) caused by ozone treatment, the potential spread of contamination can be reduced.  相似文献   

7.
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8.
Degradation of 4-chloro-2-nitro phenol by ozonation in aqueous solution was studied in a semi batch reactor under constant ozone dosage and variable pH conditions. The effectiveness of the process was estimated based on the degree of conversion of 4-chloro-2-nitro phenol. It was observed that ozonation is more effective at alkaline reaction of medium than other conditions. The degree of conversion achieved (at the first 5 minutes of the process)at pH 9 was 99.64% compared to 99.03% and 77.35% at pH 7 and 3, respectively. Another parameter used to quantify the 4-chloro-2-nitrophenol during ozonation was the pseudo first order rate constant k [min?1]. Results showed that the rate constant of the process was approximately much higher at the alkaline pH compared to acidic ones. A considerable improvement in chemical oxygen demand removal was observed at pH above 7. At pH 9, the reduction in chemical oxygen demand at the end of the process reached 56.9 %. The degree of organically bounded nitrogen conversion to nitrate was higher at pH 3. Of the total organic carbon reduction, 15.89 % was observed at pH 9. The 4-chloro-2-nitro phenol degradation intermediate products were analyzed by mass- spectrometry. The main intermediate product was chlorophenol.  相似文献   

9.
异波折板多段两相厌氧城市污水处理工艺试验研究   总被引：2，自引：0，他引：2  
提出了异波折板多段两相厌氧城市污水处理工艺。通过反应器内异波折板的结构设计、液相流速设计和系统内生物相的分段调控,在提高传质效率的同时,使不同种群微生物的生化活性得到明显改善,有机污染物去除效率显著提高。实验结果表明,当水力停留时间大于10 h时,COD的去除率可达90%以上,而且受温度影响很小。  相似文献   

10.
This paper reports the results of the treatment of a yarn dyeing effluent using an integrated biological–chemical oxidation process. In particular, the biological unit was based on a sequencing batch biofilter granular sludge reactor (SBBGR), while the chemical treatment consisted of an ozonation step. Biological treatment alone was first performed as a reference for comparison. While biological treatment did not produce an effluent for direct discharge, the integrated process assured good treatment results, with satisfactory removal of chemical oxygen demand (up to 89.8 %), total nitrogen (up to 88.2 %), surfactants (up to 90.7 %) and colour (up to 99 %), with an ozone dose of 110 mg of ozone per litre of wastewater. Biomass characterization by fluorescence in situ hybridization has revealed that filamentous bacteria represented about 20 % of biomass (coherently with high sludge volume index values); thanks to its special design, SBBGR guaranteed, however, stable treatment performances and low effluent suspended solids concentrations, while conventional activated sludge systems suffer from sludge bulking and even treatment failure in such a condition. Furthermore, biomass characterization has evidenced the presence of a shortcut nitrification–denitrification process.  相似文献   

11.
Produced water (PW) from natural gas field, characterized with high organic contents, has brought high environmental concerns world widely. Fenton and enhanced Fenton technologies were considered as the potential methods to degrade the organic contaminates in the PW, but with very limited data or reference. Here, we examined the optimum conditions of Fenton on organics and colour removal from natural gas PW after coagulation pre-treatment. Simultaneously, the optimal Fenton process integrated with ultraviolet (UV) and ultrasonic (US) irradiation were applied to enhance pollutants removal efficiencies. The optimal Fenton conditions were found at 60 min with molar ratios of 6:1 and 25:1 for H2O2/COD and H2O2/Fe2+, respectively and the initial pH of 3. Among these the three treatment processes, chemical oxygen demand (COD), total organic carbon, 5-day biological oxygen demand (BOD5), and colour removal efficiencies were highest during UV–Fenton (82, 73, 68, and 95%,) followed by US–Fenton (79, 70, 66, and 95%) and Fenton treatment (70, 58, 51, and 92%), respectively. High biodegradability (BOD5/COD) was also observed after UV–Fenton process (0.76) than the others (both 0.73). The current study showed a satisfactory carbon and colour removal efficiencies from PW using different Fenton processes; however, there still is a need for final polishing such as biological treatment or low cost constructed wetland before discharge. This study can be a good reference for engineering application PW treatment.  相似文献   

12.
桂林漓江水体溶解无机碳迁移与水生光合碳固定研究   总被引：1，自引：0，他引：1  
章程  肖琼 《中国岩溶》2021,40(4):555-564
河流溶解无机碳含量昼夜变化主要受碳酸盐反向沉积、水生光合利用和脱气作用控制,被水生光合利用的溶解无机碳是岩溶碳汇的组成部分,脱气作用比例的大小是影响碳汇稳定性的决定因素。本文以漓江中游省里—冠岩之间15 km长河段为研究对象,开展昼夜高分辨率水化学自动化监测与高频取样,分析水生植物光合作用利用HCO3-1及相关钙沉降过程。结果表明,监测河段水生光合利用的无机碳转化通量为859 kgC?d-1,单位流程光合作用溶解无机碳转化量和钙沉降量分别为2.06 t?（d?km）-1和0.78 t?（d?km）-1。光合作用与钙沉降消耗DIC约占总转化量的70 %,以光合有机碳和CaCO3形式储存于河床,成为岩溶碳汇组成部分。无机碳转化量约占输入DIC总量的6.0 %（其中1.7%以CO2形式返回大气）,说明夏季低水位期间强烈的水生植物光合利用溶解无机碳,可有效遏制白天水气界面CO2脱气过程发生,低脱气比例证实漓江水体的溶解无机碳还是比较稳定的。   相似文献   

13.
Despite of the importance of the aquatic ecosystems as organic matter pools within the global carbon cycle, specific studies in river sediments are still insufficient. This study was carried out in an Atlantic basin where nine sites were selected in the lowest middle stretch of the River. The analyses include total organic carbon, C/N ratios, humus composition (humic, fulvic and humin), A2/A4 and A4/A6 ratios, biologically active organic matter (BAOM), water soluble organic matter (WSOC) and coloured water soluble organic carbon (CWSOC). The results suggested a predominance of allochthonous sources to the organic matter, highly influenced by the land uses together with the river hydrodynamics, namely urban and forest at sites 1, 2 and 9, and agricultural at sites 7 and 8. The 38% of the total organic matter was humic and fulvic acids. The biologically active organic matter, which may act as a proxy of microbial activity, showed a mean value of 0.9% of the total organic matter, showing the lowest values at sites with the highest organic matter total, soluble or coloured. This coloured organic matter represented an average of 3.60% of the total organic matter, and showed the highest visible light absorption at those sites more affected by human activities, close to centres of population (1, 2 and 9). This coloured fraction showed also a high degree of photostability. C/N ratios were less effective to discriminate between allochthonous or autochthonous sources, whereas A4/A6 ratios were effective to estimate variations of autochthonous sources, as it measures the variations of phytopigments of the river bed sediments.  相似文献   

14.
为了去除矿井水中多种污染物,建立了"采空区+常规处理+深度处理"的井上下联合处理工艺组合。结果表明:受煤矿顶板含水层水岩作用,矿井水中Cl-、SO42-和Fe离子出现了超标现象,有的甚至达到Ⅴ类地下水标准;溶解性有机质含量较低,以大分子和芳香族化合物为主。采空区主要利用其顶板岩石破碎充填物吸附过滤矿井水中悬浮物,对Fe离子和有机质也有一定的处理效果,Fe离子去除率约20%,TOC和UV254的平均去除率分别为67.45%和65.40%。常规处理工艺对F-的去除率为11.90%~35.21%,铁锰离子则完全被去除;由于前端好氧沉淀池,硝酸盐和有机质含量略有升高,其中增加的有机质主要为溶解性微生物代谢产物。深度处理工艺对常规离子、硝酸盐、氟离子、有机质等有较好的去除效果,去除率均在95%以上。总体上,在采空区和常规处理工艺去除悬浮物和部分污染物的基础上,再利用深度处理工艺完成绝大部分污染物的去除,是一套比较有效的矿井水处理工艺组合。   相似文献   

15.
Concentrations of Ca, Cd, Cu, Fe, and Pb and binding capacities for Cd, Cu, and Pb were determined for water samples collected from 12 lakes in southwestern Maine using atomic absorption and ion-selective electrodes, respectively. Surface waters in this area are soft and characterized by low pH. Some lakes were highly colored with refractory organics, whereas others had very low organic carbon concentrations. Both Cu and Pb concentrations were positively correlated with organic carbon content. Copper and Pb binding capacities were significantly correlated with organic carbon content, whereas Cd binding capacity was positively correlated with pH, but not with organic carbon. Surface water binding capacity for Pb was greater than that for Cu or Cd. More than 99% of the Ca from all waters studied was removed onto cationic exchange resins. Less than 1% of the total Cu existed as cationic species in highly humic waters, whereas as much as 65% existed as cationic species in less huic waters. Conversely, more than 99% of the Cd present in humic waters existed as cationic species, whereas as little as 50% existed as cationic species in less humic, more alkaline waters. These correlative studies indicate that binding by organic carbon is important for both Cu and Pb in this area and must be considered in models of trace metal speciation. However, Cd binding in the same waters is not correlated with organic carbon, which does not need to be considered in speciation models for Cd.  相似文献   

16.
More effective techniques are required to mineralize the increasing number of recalcitrant organic contaminants at low concentrations in the water environment using advanced oxidation process. Though relatively new, photocatalytic ozonation (O3/UV/TiO2) is considered superior to ozonation (O3) and photocatalysis (UV/TiO2), due to synergistic effects and use of immobilized TiO2 photocatalysts is a milestone in advance oxidation process. This article aimed to elucidate 2, 4-dichlorophenoxyacetic acid (2, 4-D) mineralization characteristics in low aqueous solutions by O3/UV/TiO2 using the world’s first high-strength TiO2 fiber catalyst in laboratory experiments. 2, 4-D degradation and TOC removal in O3, UV/TiO2 and O3/UV/TiO2 followed pseudo-first order reaction kinetic. The removal rates for 2, 4-D and TOC in O3/UV/TiO2 were respectively about 1.5 and 2.4-fold larger than the summation of the corresponding values in O3 and UV/TiO2. The O3/UV/TiO2 process was characterized by short-lived few aromatic intermediates, faster degradations of aliphatic intermediates and dechlorination as a major step in 2, 4-D mineralization. The significantly enhanced 2, 4-D mineralization in the process was attributed to increased ozone decomposition and reduced electron-hole recombination on TiO2 surface resulting to a large number of OH generation. The O3/UV/TiO2 process with the TiO2 fiber catalyst was very promising with respect to the major challenges being faced in AOP involving TiO2, namely separation of powder catalyst in suspension and reduced efficiency of immobilized catalysts (e.g. TiO2 film/fiber).  相似文献   

17.
Dissolved organic carbon (DOC) dynamics in the Pawcatuck River estuary, a small temperate estuary in Rhode Island, United States, were examined through the use of field transect and in situ production studies. In late summer, when river discharge was minimal, phytoplankton blooms occurred in the upper reaches of the estuary and released large amounts of autochthonous DOC that accumulated in the middle reaches of the estuary. DOC production rates in August months, calculated both by mixing diagrams and in situ DOC incubations, ranged from 6.67 to 34.7 μmol C l−1 d−1 and were positively correlated with DCMU-enhanced fluorescence, an estimate of phytoplankton photosynthetic activity (r2=0.796, p<0.001). The percent extracellular release (PER) of DOC from phytoplankton, calculated from measured in situ DOC production and net phytoplankton production (NPP) rates, ranged from 5.8% to 40.6% and was negatively correlated with NPP (r2=0.80, p<0.01). Accumulated DOC was principally nonhumic in nature, and the humic DOC component behaved quite differently with either conservative mixing or significant removal at the head of the estuary. Humic removal at times amounted to approximately 50% of the humic material and 25% of the total incoming riverine DOC. These large humic losses were not observed in bulk DOC-salinity mixing diagrams but required distinct analyses of the humic and nonhumic components. DOC addition and removal processes co-occur in this system and observation of bulk DOC mixing diagrams may mask the true dynamic nature of the estuarine DOC pool. The net result of the DOC addition and removal processes is a seasonally variable transformation of a humic-rich incoming riverine DOC to a nonhumic enriched bulk DOC component that varies seasonally and with river discharge.  相似文献   

18.
Organic emerging micropollutants are persistent during the biological process used in treatment plants and have the tendency to accumulate in the sludge. Since a common method of final sludge disposal is the land application, there are potential risks associated with the presence of contaminants within the sludge. In this work, the removal efficiency of endocrine-disrupting chemicals, namely bisphenol A, nonylphenol and triclosan from sludge was investigated using ozonation and electrooxidation using boron-doped diamond electrodes. Both procedures were studied to determine the optimal conditions (pH, current density and ozone flow) for removing these chemicals in an hour. With the obtained conditions, a coupled system ozonation–electrooxidation was used with the goal to have better pollutant elimination. Results indicate that these compounds could be effectively removed by the coupled system; the diminutions were Bisphenol A 86%, nonylphenol 68% and triclosan 67%. Also improvements in the quality of aqueous phase were obtained, and for instance, the chemical oxygen demand, color and turbidity, were abated in 62, 61 and 66%, respectively. Moreover, an additional advantage of the coupled system is the absence of any secondary pollution.  相似文献   

19.
反硝化条件下河岸渗滤过程中苯胺的降解   总被引：2，自引：0，他引：2  
吴耀国  曾睿  惠林  尹德忠 《地球科学》2006,31(2):273-278
通过河岸渗滤作用(riverbankfiltration, RBF) 诱发河水的补给, 增大地下水的允许开采量可以满足更多居民生活饮用水需求.受人类活动的影响, 河流等地表水体遭受苯胺污染, 可能通过RBF进入地下水, 以致饮用该地下水存在健康风险.为研究反硝化条件下, 苯胺在RBF中的转化, 采集渭河河床沉积物及沿岸地下水含水层的含水介质, 装置土柱, 进行土柱动态模拟实验.经过153 d的实验研究发现, 利用苯胺对RBF中土著反硝化微生物进行驯化, 大约经过37d菌种完全适应.具有该菌种的RBF系统, 对苯胺具有巨大降解能力, 在NO3——N约为23.0 mg/L的条件下, RBF系统可使40、80甚至400 mg/L浓度的苯胺100%降解, 矿化率分别达97.99%、91.39%与75.30%.反硝化条件下, 苯胺在RBF中的降解仅有少部分经过脱氨作用, 绝大部分与腐殖质以共价键形式形成耦合物, 该耦合物更易为微生物降解, 且降解过程中不产生对研究环境微生物有毒的中间产物, 可实现反硝化条件下RBF中苯胺的连续降解.   相似文献   

20.
The ultimate goal of the protection and restoration of water ecosystem is intended to facilitate the healthiness of ecosystems in rivers and lakes, and the basic premise of river healthiness is to ensure the ecological water demand of rivers. Shenyang City is the economic and cultural center of Northeastern China, and most rivers in the territory of Shenyang City are plagued with the ecology and environment problems such as dry-up of river way, wetland shrinkage and groundwater overdraft. In protection and restoration of water ecosystem, Shenyang City should first study the ecological water demand of rivers. In this paper, we first defined the connotation, composition and calculation method of ecological water demand of rivers and selected eight major rivers in Shenyang City for ecological water demand study and calculation according to the characteristics of the rivers and water resources conditions in Shenyang City. We calculated the basic eco-environmental water demand and consumptive water demand for evaporation and seepage of river ways respectively and thus obtained the total eco-environmental water demand for eight rivers. In total eco-environmental water demand of rivers, consumptive water demand for evaporation and seepage of river ways accounts for 51% and the eco-environmental water demand of rivers accounts for 49%  相似文献   

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