Bioremediation of chlorobenzene-contaminated ground water in an in situ reactor mediated by hydrogen peroxide

New in situ reactive barrier technologies were tested nearby a local aquifer in Bitterfeld, Saxonia-Anhalt, Germany, which is polluted mainly by chlorobenzene (CB), in concentrations up to 450 microM. A reactor filled with original aquifer sediment was designed for the microbiological remediation of the ground water by indigenous bacterial communities. Two remediation variants were examined: (a) the degradation of CB under anoxic conditions in the presence of nitrate; (b) the degradation of CB under mixed electron acceptor conditions (oxygen+nitrate) using hydrogen peroxide as the oxygen-releasing compound. Under anoxic conditions, no definite degradation of CB was observed. Adding hydrogen peroxide (2.94 mM) and nitrate (2 mM) led to the disappearance of CB (ca. 150 microM) in the lower part of the reactor, accompanied by a strong increase of the number of cultivable aerobic CB degrading bacteria in reactor water and sediment samples, indicating that CB was degraded mainly by productive bacterial metabolism. Several aerobic CB degrading bacteria, mostly belonging to the genera Pseudomonas and Rhodococcus, were isolated from reactor water and sediments. In laboratory experiments with reactor water, oxygen was rapidly released by hydrogen peroxide, whereas biotic-induced decomposition reactions of hydrogen peroxide were almost four times faster than abiotic-induced decomposition reactions. A clear chemical degradation of CB mediated by hydrogen peroxide was not observed. CB was also completely degraded in the reactor after reducing the hydrogen peroxide concentration to 880 microM. The CB degradation completely collapsed after reducing the hydrogen peroxide concentration to 440 microM. In the following, the hydrogen peroxide concentrations were increased again (to 880 microM, 2.94 mM, and 880 microM, respectively), but the oxygen demand for CB degradation was higher than observed before, indicating a shift in the bacterial population. During the whole experiment, nitrate was uniformly reduced during the flow path in the reactor.     

O3/H2O2法去除浮选药剂丁基黄药

采用O3/H2O2法去除水中丁基黄药,考察了H2O2/O3摩尔比、pH值、丁基黄药初始浓度、温度和自由基抑制剂对丁基黄药的去除效果的影响。结果表明,在相同O3投加量下,H2O2量越大,丁基黄药去除率越高。pH值为7～9,温度在293～303 K的范围内,O3/H2O2对丁基黄药都有很高的去除率。碳酸氢根和叔丁醇能在一定程度上降低丁基黄药的降解效率。研究还发现,在O3和H2O2投加量相同的条件下,H2O2多次投加对水中丁基黄药的处理效果明显优于一次性投加。GC/MS分析表明,O3/H2O2氧化丁基黄药氧化产物为羧酸类物质。     

O3/H2O2法去除浮选药剂丁基黄药

采用O3/H2O2法去除水中丁基黄药,考察了H2O2/O3摩尔比、pH值、丁基黄药初始浓度、温度和自由基抑制剂对丁基黄药的去除效果的影响。结果表明,在相同O3投加量下,H2O2量越大,丁基黄药去除率越高。pH值为7～9,温度在293～303 K的范围内,O3/H2O2对丁基黄药都有很高的去除率。碳酸氢根和叔丁醇能在一定程度上降低丁基黄药的降解效率。研究还发现,在O3和H2O2投加量相同的条件下,H2O2多次投加对水中丁基黄药的处理效果明显优于一次性投加。GC/MS分析表明,O3/H2O2氧化丁基黄药氧化产物为羧酸类物质。     

The importance of atmospheric ozone and hydrogen peroxide in oxidising sulphur dioxide in cloud and rainwater

The process by which sulphur dioxide is oxidised in atmospheric droplets has been studied in laboratory experiments designed to collect a large amount of chemical data pertinent to the atmospheric situation. Thus the oxidation of sodium sulphite solutions by oxygen, ozone and hydrogen peroxide has been studied at different pH's and temperatures. In all cases the reaction is first order with respect to sulphite ion but the order with respect to oxidant differs. For oxygen the order is zero whereas the order for ozone and hydrogen peroxide is one. Varying the hydrogen ion concentration has little effect on the oxygen reaction rate between pH 6 and 9; the ozone reaction rate is inversely proportional to the square root of the hydrogen ion concentration and the hydrogen peroxide rate is almost directly proportional to the hydrogen ion concentration. These last two observations are very important since in the case of ozone it indicates that the reaction proceeds via a free radical mechanism involving hydroxyl radicals and in the case of hydrogen peroxide it is the only oxidation process of sodium sulphite so far investigated that shows a positive response to the presence of hydrogen ions.The experimental data was used to calculate the rate of sulphate formation in water droplets under atmospheric conditions for each of the three oxidants. If it is assumed that the ozone and hydrogen peroxide gas phase concentrations are initially 50 parts in 10⁹ and 1 part in 10⁹ by volume respectively, then the rates of sulphate formation are equal in cloud water at pH 5.8. Above this pH the ozone reaction is faster and below it the hydrogen peroxide reaction is faster due to the positive catalysis by hydrogen ions; the oxygen rate is unimportant by comparison at all pH's below 7. The rate of hydrogen peroxide reaction is such that substantial amounts of sulphate can still be formed rapidly in water droplets at pH values from 3 to 5, and thus this process will be very important in creating acidity in rainwater.     

Treatment of two insecticides in an electrochemical Fenton system

Abstract

The ability of an electrochemical Fenton system to degrade the organophosphorous insecticides malathion and methyl parathion was studied. A combination of hydrogen peroxide and electrochemically‐generated iron was found to be successful in degrading the two insecticides, and optimization of the system was pursued. Augmentation with near UV light at an intensity of 1.67xl0¹⁷ quanta/sec and centered at a wavelength of 370 nm improved the degradation of malathion at low iron concentrations but did not affect other treatments. Adding the hydrogen peroxide slowly over the course of treatment rather than all at once at the beginning of each treatment did, however, greatly improve the system. Removal efficiencies of 98.0% or greater were achieved for both pesticides.     

Modified Fenton reaction for trichlorophenol dechlorination by enzymatically generated H2O2 and gluconic acid chelate

Glucose oxidase is a well-known enzyme that catalyzes the oxidation of β-d-glucose to produce gluconic acid and hydrogen peroxide. Fenton reaction is a powerful oxidation technology used for the oxidation of groundwater pollutants. For the application of Fenton reaction in groundwater remediation, successful operation of Fenton reaction near neutral pH, and on-site generation of both H₂O₂ and chelate will be beneficial. The focus of this experimental study was to couple the glucose oxidation reaction with chelate-based Fenton reaction. The idea was to use the hydrogen peroxide and chelate gluconic acid generated during glucose oxidation for the dechlorination of 2,4,6-trichlorophenol (TCP) by Fenton reaction. The oxidation of glucose was achieved using the enzyme in free and immobilized forms. The rate of production of hydrogen peroxide was determined for each system, and was used to estimate the time required for complete consumption of glucose during the process, thus avoiding any traces of glucose in the Fenton reaction. In the case of free enzyme reaction, separation of the enzyme was achieved using an ultrafiltration membrane before initiating the Fenton reaction. The oxidation of TCP by Fenton reaction was performed at varying ratios of gluconic acid/Fe, and its effect on the decomposition of TCP and H₂O₂ was studied. TCP degradation was studied both in terms of parent compound degradation and free chloride generation.     

Spatial and seasonal variations of the contamination within water body of the Grand Canal, China

To delineate the character of contaminations in the Grand Canal, China, a three-year study (2004-2006) was conducted to investigate variations the water quality in the canal. Results showed that the variation of water quality within the Grand Canal was of there is remarkable spatial and seasonal heterogeneity regarding water quality within the Canal. Values of contaminants in dry-season were obviously higher than those in wet-season. Sites influenced strongly by industry and urbanization showed higher contents of nutrients and lower levels of dissolved oxygen in water body; moreover these sites were severely polluted by dissolved metals with the contents of cadmium, chromium and copper exceeding the Criteria Maximum Concentration (CMC), US EPA. Multivariate statistical analysis suggested nutrient and dissolved metals pollution was the dominant environmental problems within the Canal. Anthropogenic influences played a dominant role in the character of contaminations in the Grand Canal.     

碳纳米管电极原位产生过氧化氢及其对亚甲基蓝脱色效果

将碳纳米管固定化制成多孔疏水性导电薄膜构建电化学阴极还原体系，实现过氧化氢在阴极的原位产生。电极特性研究表明，电极在较宽的电压范围内均具有较好的活性。考察了阴极电位、电极成分、氧气流量和电解质浓度对过氧化氢原位产生的影响，在优化条件下经过120min后过氧化氢达到66．17mg／L，并探讨过氧化氢原位产生的机理。在此基础上考察原位过氧化氢氧化工艺下对亚甲基蓝的脱色效果，并分析其脱色机理。     

碳纳米管电极原位产生过氧化氢及其对亚甲基蓝脱色效果简

将碳纳米管固定化制成多孔疏水性导电薄膜构建电化学阴极还原体系，实现过氧化氢在阴极的原位产生。电极特性研究表明，电极在较宽的电压范围内均具有较好的活性。考察了阴极电位、电极成分、氧气流量和电解质浓度对过氧化氢原位产生的影响，在优化条件下经过120 min后过氧化氢达到66.17 mg/L，并探讨过氧化氢原位产生的机理。在此基础上考察原位过氧化氢氧化工艺下对亚甲基蓝的脱色效果，并分析其脱色机理。     

类Fenton反应对偶氮染料橙黄II的脱色研究

以橙黄II染料溶液为研究对象,通过正交实验确定了Fe-NTA/H2O2构成的类Fenton反应中各影响因子的最佳操作条件为:[H2O2]=20 mmol/L,[Fe-NTA]=2.5 mmol/L,pH=3。同时考察了反应时间、溶液pH值、H2O2浓度、Fe-NTA浓度对脱色效率的影响。实验表明脱色反应在30 m in内基本完成,类Fenton试剂能在较宽的pH范围内保持较好的脱色效果,而且在pH=6时,类Fenton试剂比传统Fenton试剂的脱色效率提高约75%。增加双氧水浓度可以提高橙黄II溶液脱色率,但超过20 mmol/L后效果提高不明显。在0.5~2.5 mmol/L的范围内,Fe-NTA浓度对脱色效果的影响不显著。     

水体中酮硝基麝香的臭氧氧化降解研究

采用臭氧氧化水体中的酮硝基麝香,考察pH、H2O2等因素对降解程度的影响,结果表明提高初始pH能加快酮硝基麝香的氧化降解,当pH为12时,反应时间1 h,酮硝基麝香几乎完全去除,浓度为2 mol/L和5 mol/L的H2O2存在有利于O3分解生成·OH自由基,使得酮硝基麝香的氧化降解速率加快,当H2O2浓度超过5 mol/L,H2O2会成为·OH的清除剂,降低·OH利用率;无论O3单独作用和O3/H2O2协同作用,酮硝基麝香降解符合准一级动力学规律;酮硝基麝香氧化降解产物包括甲酸、二乙酸和硝酸根等,其中硝基从苯环上脱落降低了硝基麝香对环境的风险.     

Atrazine removal by ozonation processes in surface waters

Atrazine (6-chloro-N-ethyl-N'-isopropyl-1,3,5-triazinedyl-2,4-diamine) was treated with ozone alone and in combination with hydrogen peroxide or UV radiation in three surface waters. Experiments were carried out in two bubble reactors operated continuously. Variables investigated were the ozone partial pressure, temperature, pH, mass flow ratio of oxidants fed: hydrogen peroxide and ozone and the type of oxidation including UV radiation alone. Residence time for the aqueous phase was kept at 10 min. Concentrations of some intermediates, including deethylatrazine, deisopropylatrazine and deethyldeisopropylatrazine, were also followed. The nature of water, specifically the alkalinity and pH were found to be important variables that affected atrazine (ATZ) removal. Surface waters with low alkalinity and high pH allowed the highest removal of ATZ to be reached. There was an optimum hydrogen peroxide to ozone mass flow ratio that resulted in the highest ATZ removal in each surface water treated. This optimum was above the theoretical stoichiometry of the process. Therefore, to reach the maximum removal of ATZ in a O3/H2O2 process, more hydrogen peroxide was needed in the surface waters treated than in ultrapure water under similar experimental conditions. In some cases, UV radiation alone resulted in the removal of ATZ higher than ozonation alone. This was likely due to the alkalinity of the surface water. Ozonation and UV radiation processes yield different amounts of hydrogen peroxide. Combined ozonations (O3/H2O2 and O3/UV) lead to ATZ removals higher than single ozonation or UV radiation but the formation of intermediates was higher.     

Environmentally acceptable effect of hydrogen peroxide on cave "lamp-flora", calcite speleothems and limestones

Mosses, algae, and cyanobacteria (lamp-flora) colonize illuminated areas in show caves. This biota is commonly removed by a sodium hypochlorite solution. Because chlorine and other deleterious compounds are released into a cave environment during lamp-flora cleansing, hydrogen peroxide was tested as an alternative agent. In a multidisciplinary study conducted in the Kateinská Cave (Moravian Karst, Czech Republic), 12 algae- and cyanobacteria taxons and 19 moss taxons were detected. The threshold hydrogen peroxide concentration for the destruction of this lamp-flora was found to be 15 vol.%. Based on laboratory experiments in stirred batch reactors, the dissolution rates of limestones and calcite speleothems in water were determined as 3.77 x 10-3 and 1.81 x 10-3 mol m-2 h-1, respectively. In the 15% peroxide solution, the limestone and speleothem dissolution rates were one order of magnitude higher, 2.00 x 10-2 and 2.21 x 10-2 mol m-2 h-1, respectively. So, the peroxide solution was recognised to attack carbonates somewhat more aggressively than karst water. In order to prevent the potential corrosion of limestone and speleothems, the reaching of preliminary peroxide saturation with respect to calcite is recommended, for example, by adding of few limestone fragments into the solution at least 10 h prior to its application.     

Kinetics of simazine advanced oxidation in water

Comparison of the effects and kinetics of UV photolysis and four advanced oxidation systems (ozone, ozone/hydrogen peroxide, ozone/UV radiation and UV radiation/hydrogen peroxide) for the removal of simazine from water has been investigated. At the conditions applied, the order of reactivity was ozone < ozone/hydrogen peroxide < UV radiation < ozone/UV radiation and UV radiation/hydrogen peroxide. Rate constants of the reactions between ozone and simazine and hydroxyl radical and simazine were found to be 8.7 M-1s-1 and 2.1 x 10(9) M-1s-1, respectively. Also, a quantum yield of 0.06 mol.photon-1 was found for simazine at 254 nm UV radiation. The high value of the quantum yield corroborated the importance of the direct photolysis process. Percentage contributions of direct reaction with ozone, reaction with hydroxyl radicals and direct photolysis were also quantified.     

Atrazine removal by ozonation processes in surface waters

Abstract

Atrazine (6‐chloro‐N‐ethyl‐N'‐isopropyl‐1,3,5‐triazinedyl‐2,4‐diamine) was treated with ozone alone and in combination with hydrogen peroxide or UV radiation in three surface waters. Experiments were carried out in two bubble reactors operated continously. Variables investigated were the ozone partial pressure, temperature, pH, mass flow ratio of oxidants fed: hydrogen peroxide and ozone and the type of oxidation including UV radiation alone. Residence time for the aqueous phase was kept at 10 min. Concentrations of some intermediates, including deethylatrazine, deisopropylatrazine and deethyldeisopropylatrazine, were also followed. The nature of water, specifically the alkalinity and pH were found to be important variables that affected atrazine (ATZ) removal. Surface waters with low alkalinity and high pH allowed the highest removal of ATZ to be reached. There was an optimum hydrogen peroxide to ozone mass flow ratio that resulted in the highest ATZ removal in each surface water treated. This optimum was above the theoretical stoichiometry of the process. Therefore, to reach the maximum removal of ATZ in a O₃/H₂O₂ process, more hydrogen peroxide was needed in the surface waters treated than in ultrapure water under similar experimental conditions. In some cases, UV radiation alone resulted in the removal of ATZ higher than ozonation alone. This was likely due to the alkalinity of the surface water. Ozonation and UV radiation processes yield different amounts of hydrogen peroxide. Combined ozonations (O₃/H₂O₂ and O₃/UV) lead to ATZ removals higher than single ozonation or UV radiation but the formation of intermediates was higher.     

Simazine removal from water in a continuous bubble column by O3 and O3/H2O2.

Simazine, [2-chloro, 4,6-bis(ethylamino)-1,3,5-s-triazine], a common herbicide found in surface and ground water has been ozonized in continuous flow mode. Typical operating variables in ozonation processes have been investigated. Thus, the ozone dose fed to the system exerted a positive effect, while the gas flow rate did not influence the efficiency of the process provided ozone mass flow rate was kept constant. Increasing the pH led to a higher extension of the free radical degradation of simazine and, therefore, to a higher efficiency of the process. Also, addition of free radical promoters, i.e. hydrogen peroxide, did result in a significant improvement of the simazine removal rate. A first approach to process economy showed the system ozone/hydrogen peroxide as the most advantageous in terms of electrical energy requirements.     

SIMAZINE REMOVAL FROM WATER IN A CONTINUOUS BUBBLE COLUMN BY O3 AND O3/H2O2

Simazine, [2-chloro, 4,6-bis(ethylamino)-1,3,5-s-triazine], a common herbicide found in surface and ground water has been ozonized in continuous flow mode. Typical operating variables in ozonation processes have been investigated. Thus, the ozone dose fed to the system exerted a positive effect, while the gas flow rate did not influence the efficiency of the process provided ozone mass flow rate was kept constant. Increasing the pH led to a higher extension of the free radical degradation of simazine and, therefore, to a higher efficiency of the process. Also, addition of free radical promoters, i.e. hydrogen peroxide, did result in a significant improvement of the simazine removal rate. A first approach to process economy showed the system ozone/hydrogen peroxide as the most advantageous in terms of electrical energy requirements.     

Hydrogen peroxide stabilization in one-dimensional flow columns

Rapid hydrogen peroxide decomposition is the primary limitation of catalyzed H(2)O(2) propagations in situ chemical oxidation (CHP ISCO) remediation of the subsurface. Two stabilizers of hydrogen peroxide, citrate and phytate, were investigated for their effectiveness in one-dimensional columns of iron oxide-coated and manganese oxide-coated sand. Hydrogen peroxide (5%) with and without 25 mM citrate or phytate was applied to the columns and samples were collected at 8 ports spaced 13 cm apart. Citrate was not an effective stabilizer for hydrogen peroxide in iron-coated sand; however, phytate was highly effective, increasing hydrogen peroxide residuals two orders of magnitude over unstabilized hydrogen peroxide. Both citrate and phytate were effective stabilizers for manganese-coated sand, increasing hydrogen peroxide residuals by four-fold over unstabilized hydrogen peroxide. Phytate and citrate did not degrade and were not retarded in the sand columns; furthermore, the addition of the stabilizers increased column flow rates relative to unstabilized columns. These results demonstrate that citrate and phytate are effective stabilizers of hydrogen peroxide under the dynamic conditions of one-dimensional columns, and suggest that citrate and phytate can be added to hydrogen peroxide before injection to the subsurface as an effective means for increasing the radius of influence of CHP ISCO.     

Treatment of oily port wastewater effluents using the ultraviolet/hydrogen peroxide photodecomposition system.

This paper presents the nonselective degradation of mechanically pretreated oily wastewater by hydrogen peroxide (H2O2) in the presence and absence of UV irradiation. The effect of chemical oxidation on wastewater biodegradability was also examined. The exclusive use of H2O2 photolyzed by daylight results in quite efficient degradation rates for the low peroxide concentrations used. Higher hydrogen peroxide concentrations inhibit degradation of organic contaminants in the wastewater. The degradation rates of all contaminants are relatively high with an advanced oxidation system (UV/H2O2), but degradation efficiencies are not distinguishably different when 20 or 45 minutes of UV irradiation is used. The excess of H2O2 used in the process can inhibit phenolic degradation and may lead to the formation of a new phenolic fraction. The biodegradability of port wastewater did not increase significantly following the application of the advanced oxidation process.     

微波辅助双氧水氧化降解水中磺胺二甲嘧啶

采用微波辐照技术辅助双氧水氧化降解水中磺胺二甲嘧啶（SM2）,研究了微波辅助双氧水氧化降解水中SM2的影响因素。结果表明,单纯使用微波辐照并不能显著降解SM2,而微波辐照可显著促进双氧水对SM2的氧化作用,提高SM2的降解率。在初始浓度为50 mg/L,微波功率为900 W,加入0.25 mL质量分数为30%的双氧水,pH值为4的条件下辐照6 min,SM2的降解率可达96.5%,COD去除率为72%。