模拟医疗废物在管式电阻炉上的热解特性研究

在管式电阻炉上对由聚丙烯、面巾纸、纱布、医用脱脂棉、一次性口罩、医用乳胶手套等按一定比例组成的模拟医疗废物在氮气气氛进行了热解研究。重点探讨了10K／min，20K／min，30K／min和40K／min等不同升温速率对热解产物分布、产气特性和热解过程的影响。结果表明，随着温度升高，模拟废物的热解产生气体的主要成分逐渐由CO2和CO转变为C3H6、CH4、C2H6、C2H4和C3H8。同时，热解处理对模拟废物的减量化效果比较明显，固体残留率仅为5．61％～7．02％。而且，加热速率对模拟医疗废物热解过程的影响较大。     

城市污泥两段式催化热解制合成气研究

为了把城市污泥中温热解产生的挥发性产物转化为可直接利用的洁净可燃性气体或重要的化工原料合成气,采用两段式热解装置对城市污泥进行了催化热解实验研究,讨论了不同催化剂对城市污泥热解挥发性产物的催化裂解能力,结果表明:城市污泥在热解终温500℃,热解液产率最大,超过500℃,热解液产率减少,热解气增多,固相产率基本不变;城市污泥热解液的裂解温度需在900℃以上,产生的气体组分主要为H2、CO、CH4等小分子非冷凝性气体;Ni/分子筛复合催化剂对热解液转化为合成气的作用效果较好,合成气体(H2+CO)体积含量占气体总量的85%以上.     

医疗废物典型组分的热重分析及新的动力学模型

为研究医疗废物的热解失重规律和反应动力学机制，对其热失重过程进行了模拟．利用差热热重分析仪，在氮气气氛下对医疗废物的14种典型组分进行了热解实验，建立了“整体两步四反应模型”．结果显示，样品失水后，在160℃-290℃之间开始热解，次序依次为药物类、塑料类、蛋白质类、生物质类、合成纤维类和橡胶类；经过一步或两步失重，在800℃时热解基本完成．所建立的“整体两步四反应模型”能很好地描述样品的热解行为，最大相对误差为1．68％，并可以对医疗废物的热解产物进行预测．     

一种医疗废物的安全处置设备-FSL系列热解焚烧炉

鉴于中小城市及县乡级医院不具备单独处理医疗废物的条件,本文从实际工作出发,介绍了FSL型热解焚烧炉对医疗废物无害化处置的工作原理,对其焚烧医疗废物产生的主要废气污染物进行了测试.测试结果表明FSL型热解焚烧炉废气污染物排放达到国家现行环保排放标准要求.     

垃圾填埋场渗滤液有机物成分分析及蒸发处理研究

采用GC-MS对某垃圾填埋场渗滤液中的有机物成分进行检测分析。结果表明:渗滤液中至少含有50种有机污染物,相对含量最高的有机污染物是尼古丁和3-甲酚。研究真空度、蒸发温度和pH值对渗滤液蒸发过程中冷凝液的COD、TOC和氨氮浓度的影响,并对冷凝液进行有机物成分检测,结果表明:蒸发速率和冷凝液COD值均随蒸发温度和真空度的增加呈增加趋势,蒸发温度和真空度对冷凝液TOC值影响不大,随蒸发温度升高冷凝液中氨氮含量整体呈下降趋势;在蒸发温度60～120℃范围内,冷凝液的有机物成分以烷烃类有机物和尼古丁为主;烷烃类有机物的析出仅与蒸发温度有关,苯酚类有机物的析出与真空度和蒸发温度均有关;在酸性条件下蒸发冷凝液的COD值和TOC值均远大于在中性和碱性条件下的数值,但氨氮含量相反;酸性条件下冷凝液有机物成分主要为有机酸和烷烃类有机物。     

基于添加热解炭的干垃圾高效洁净热解研究

干垃圾经过源头分离后,可通过热解实现资源利用和能源回收。为了获得清洁的热解过程,有必要减少焦油的产生。该研究采用了典型的热解添加剂,即CaO、MgO和Fe₂O₃,在800℃,15℃/min的升温速率,40 min的保温时间等条件下进行热解,以制备热解炭,制备的热解炭返回到热解系统中与干垃圾进行热解。研究发现,加入添加剂获得的副产品热解炭,Ca-C、Fe-C、Mg-C作为新的添加剂重新加入热解系统中,Fe-C热解炭可以成为最佳选择,其用量范围为10%～30%。在20%/80%(Fe-C/干垃圾)的情况下,它可以减少约4.52个百分点的焦油,H₂和CO含量分别上升了4.67和2.85个百分点,SO₂和NO_x的去除率分别为85.56%和83.60%,热解炭和铁的结合能促进焦油的分解。将Fe-C作为热解炭添加剂进行干垃圾热解,可能是一种有效的废物处理途径。     

医疗废物无害化处置工艺设计

采取AB型热解两次焚烧(3T控制)和烟气净化处理新技术进行医疗废物无害化处置工艺设计,运行结果表明:该工艺技术能有效地处理医疗废物,具有无二次污染和社会、经济、环境效益好等优点,值得在实践中进一步推广应用。     

医疗废物热解焚烧过程中NOX的控制

论述了医疗废物热解焚烧过程中产生的NOX类型，介绍了医疗废物热解焚烧系统控制NOX排放的技术措施。     

医疗废物典型组分在回转窑内的热解-气化研究

在小型回转窑上对模拟医疗废物的4种典型组分进行了批量热解-气化试验.实验结果表明,热解-气化反应物料的转化率较高（80%～100%）,基本上随热解-气化终温（FPT）的升高而升高.热解-气化反应中物料的热裂解反应在30min以内基本结束.FPT的升高,有利于挥发分的析出、减少残渣量和处置时间.从试验结果来看,第一段初级处理中采用约700℃的回转窑反应温度比较适合实现医疗垃圾的完全热解和气化.     

生活垃圾与木薯茎共热解制油试验研究

选取木薯茎作为与生活垃圾共热解的试验物料,采用热重分析(TG-DTG)、动力学分析、红外分析(FTIR)等方法,研究不同比例木薯茎对生活垃圾热解产物的影响、最佳添加量及协同作用。结果表明:热解主要分为脱水、热解和炭化3个阶段,生活垃圾与木薯茎混合共热解的温度区间主要在200~550℃;生活垃圾、木薯茎及20%木薯茎与生活垃圾混合的热解活化能分别为50.72、37.72及43.36 k J/mol,添加一定量的木薯茎可以降低生活垃圾热解的表观活化能,并对生活垃圾的热解具有一定的促进作用;木薯茎最佳添加量为20%,热解液的产率提高了6.24%;与生活垃圾单独热解相比,添加20%木薯茎的共热解油中羧酸、醇、酚的含量有所减少,有利于脱氧、脱酸,提高热解油的热值,增加热解液的有机物种类与数量。     

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.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

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

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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.