超重力环境下活性氧簇氧化吸收一氧化氮的研究

为了减少工业排放氮氧化物(NOx)对大气造成的污染,需要去除难溶性的NO。活性氧簇(ROS)可以将NO氧化为水溶性NO_2,超重力机可以强化气液传质效果。结合二者的优势,文章提出了一种在超重力环境下利用ROS氧化去除NO的方法。研究了吸收液pH值、转速、温度、气液比、气体浓度、吸收液循环对NO脱除率的影响,并对吸收产物进行了测定。结果表明,在20℃,H_2O_2浓度为1 mol/L,H_2O_2溶液pH为13,超重力机转速为1 200 r/min时,NO的脱除效率最好。当NO体积浓度为500×10~(-6),气液比为100时,NO的脱除效率可达96%。NO最终变为NO_3~-存在于液相中,且该吸收液可以用于同步脱硫脱硝。     

旋转填充床去除模拟餐饮废气油滴的研究

研究旋转填充床(rotating packed bed,RPB)去除模拟餐饮废气中油滴的效果,RPB中气液两相并流通过旋转床,摸索RPB转速、吸收液流速、吸收液组分对油滴去除效果的影响,研究发现:气液并流式RPB的气体压降不高,且随着RPB转速提高其气体压降不断降低;RPB对模拟餐饮废气中粒径为0.7μm油滴的去除效率较高(接近80%),吸收液流速提高和RPB转速提高都有利于模拟餐饮废气中油滴的吸收;此外,吸收液中添加适量表面活性剂也可明显提高RPB的油烟吸收效果,其原因很可能在于表面活性剂提高了吸收液和油滴的相溶性。由于RPB具有操作灵活、压降小、去除效率较高等显著优点,有望在餐饮废气的治理方面获得广泛应用。     

超重力环境下芬顿溶液氧化吸收NO的研究

NO的排放严重影响大气环境,其溶解度低不易被液相吸收。芬顿法产生的羟基自由基氧化性极强但寿命很短,超重力机具有混合速率快、液体停留时间短的特点,该文创新性地结合二者优势,对NO气体进行液相氧化吸收。分别研究了芬顿溶液pH值、浓度、H_2O_2与Fe~(2+)浓度比值、超重力机转速以及NO与芬顿溶液体积流量比等条件对NO脱除效果的影响。超重力机双进液口处即时混合H_2O_2与Fe~(2+)溶液,在1 400 r/min转速下使用pH=2,H_2O_2浓度0.2 mol/L,H_2O_2与Fe~(2+)浓度比为4的芬顿溶液对NO的脱除效果最优。当H_2O_2与Fe~(2+)液流量均为15 L/h,500×10-6 NO气流量为200 L/h时,NO的脱除效率可以达到75%。     

Na2S2O8/NaClO2复合吸收液工业脱硝新方法

针对氮氧化物排放标准日益严格而现有脱硝技术不能满足要求的现状,提出了Na_2S_2O_8/NaClO_2复合吸收液脱硝的新方法。在小型鼓泡反应器中进行脱硝实验,讨论了Na_2S_2O_8和NaClO_2浓度、反应温度、溶液pH、NO浓度等因素对NO脱除效率的影响,在此基础上分析了复合吸收液的脱硝机理。通过比较复合吸收液与单一吸收液的脱硝效果和成本,探究其在脱硝方面的工业应用前景。实验结果表明:当吸收液初始pH为5,Na_2S_2O_8浓度为0.05 mol/L,NaClO_2浓度为0.0025 mol/L,反应温度为50℃时,NO脱硝率可达95%;复合吸收液ClO~-_2、ClO_2、S_2O~(2-)_8共同参与NO的脱硝反应,中间产物ClO_2担负了重要氧化吸收作用,显著地提高了脱硝效率;Na_2S_2O_8/NaClO_2复合吸收液比单一吸收液脱硝成本低、效率高,工业应用前景良好。     

亚氯酸钠溶液烟气脱硝与烟气余热回收的一体化试验

锅炉烟气中的NO_x是大气污染的重要原因之一.针对燃气锅炉NO_x超低排放的要求以及烟气中大量余热被浪费的现状,提出了烟气脱硝与余热回收一体化的新方法,通过搭建一体化试验台,分析在烟气余热回收的条件下,c[NaClO₂（亚氯酸钠）]、液气比、喷淋水温度等因素对脱硝效率以及烟气余热回收效率的影响.烟气脱硝与余热回收一体化的新方法主要体现在逆流式烟气喷淋塔中,可利用NaClO₂溶液对低φ（NO_x）的烟气脱硝并同时回收烟气余热.试验结果表明,c（NaClO₂）越高、pH越低、液气比越大,NaClO₂溶液脱硝率越高.当c（NaClO₂）为0.020 0 mol/L、喷淋水温度在30~80℃之间变化时,存在最优的喷淋水温度64℃,使脱硝率最高为36%.同时,液气比及喷淋水温度对余热回收效果影响显著,液气比越大、喷淋水温度越低,余热回收效果越好.试验结果还显示了当烟气温度为83℃、喷淋水温度为48℃、c（NaClO₂）为0.015 0~0.020 0 mol/L、液气比为13.8 L/m3时,烟气脱硝效率约为40%,同时回收了26.4 kW的烟气余热.研究显示,在逆流式烟气喷淋塔中,利用NaClO₂溶液进行烟气脱硝并同时回收烟气余热的一体化方法是可行的,可应用于工程实践.      

折流旋转床吹脱含氨废水实验研究

应用折流式旋转床吹脱高浓度含氨废水,研究了在不同的工艺条件下,各工艺参数,如气液比、旋转填料床转速、温度等对含氨废水氨去除率的影响.研究表明:折流旋转填料床具有压降小、高传质性能,用于处理含氨废水能有效地提高氨去除率;在温度为23℃、pH为11左右,液体流量为60L/h、气体流量为160m2/h、转鼓转速为800 r/min的条件下,用旋转填料床处理含氨5 000mg/L废水的单程吹脱率可达82%;单元传质高度为36mm.     

基于臭氧氧化的喷淋散射塔氨法脱硝的模拟研究

采用数值方法对基于臭氧氧化的喷淋散射塔氨法脱硝过程进行了模拟研究,考证了其内部气液两相流动、热质传递和脱硝过程,并用示范装置结果进行了验证。考察了不同O3/NO摩尔比对NO氧化率的影响,研究了不同液气比,O3/NO摩尔比,烟气流量和浸没深度对脱硝效果的影响。结果表明:液气比,O3/NO摩尔比,浸没深度增大有利于脱硝,烟气流量越大则脱硝率降低。     

NaClO_2碱性溶液脱硝的热力学计算与实验研究

液相氧化脱硝技术被认为是最有前景的脱硝技术之一。在自制的鼓泡反应器中,进行NaClO2/NaOH溶液脱硝实验。热力学计算表明,300~380K,脱硝反应是放热反应,反应的平衡系数均非常大,但随温度的升高而减小。选取吸收时间、NaClO2浓度、初始、反应温度、模拟烟气流量以及烟气中pHNO含量为过程参数,脱硝率作为响应量,分别进行了单因素实验。结果表明:脱硝率随NaClO2浓度、反应温度的增加而升高,随吸收时间、烟气流量或NO含量的增加而降低,在pH7~10范围内,体系获得较好的脱硝效果;NaClO2浓度,初始0.02mol/LpH,10温度70℃,烟气流量0.4L/min的条件下,处理NO含量0.02%~0.05%范围内的烟气,吸收20min内体系脱硝率几乎为100%。     

烟道气中氮氧化物的快速测定

测定烟道气中 NO_x 的方法是,用含0.03%H_2O_2和0.1N 氢氧化钠的碱性过氧化物溶液吸收气体。约100ppm NO_x 被 H_2O_2迅速氧化为 NO_2或 N_2O_5,而达到完全吸收与吸收液的接触时间则需要2分钟。200ppm 以上的高浓度 NO_x,用含空气或 O 的溶液并激烈振荡在30分钟内亦能吸收。余下的 H_2O_2严重影响有色溶液的吸收率。过量 H_2O_2可用锌粉(0.5g)全部使其分解。     

火电厂石灰石湿法烟气脱硫效率模型的研究

本文在对进口SO2浓度、烟气流量X2、液气比、吸收浆液pH、浆液浓度和烟气停留时间等6种主要火电厂石灰石湿法烟气脱硫影响因素进行综合分析并建立数学公式的基础上,结合火电厂运行数据建立烟气脱硫效率模型.基于该数学模型,以2组火电厂石灰石湿法烟气脱硫数据为实例进行了模型验证,表明该模型能够较准确的反映脱硫效率.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

ＲｅｍｏｖａｌｏｆｈｅａｖｙｍｅｔａｌｓｆｒｏｍｓｅｗａｇｅｓｌｕｄｇｅｂｙｌｏｗｃｏｓｔｉｎｇｃｈｅｍｉｃａｌｍｅｔｈｏｄａｎｄｒｅｃｙｃｌｉｎｇｉｎａｇｒｉｃｕｌｔｕｒｅＷｕＱｉｔａｎｇ，ＮｙｉｒａｎｄｅｇｅＰａｓｃａｓｉｅ，ＭｏＣｅｈｕｉＦ...     

Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Alterations of organ histopathology and metallolhionein mRNA expression in silver barb, Puntius gonionotus during subchronic cadmium exposure

Common silver barb,Puntius gonionotus,exposed to the nominal concentration of 0.06 mg/L Cd for 60 d,were assessed for histopathological alterations(gills,liver and kidney),metal accumulation,and metallothionein(MT)mRNA expression.Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae,vacuolization in hepatocytes,and prominent tubular and glomerular damage in the kidney.In addition,kidney accumulated the highest content of cadmium,more than gills and liver.Expression of MT mRNA was increased in both liver and kidney of treated fish.Hepatic MT levels remained high after fish were removed to Cd-free water.In contrast,MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water.The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.