氧化物催化剂对非热等离子体催化降解甲苯的影响

考察了在干燥气氛下不同氧化物催化剂对非热等离子体催化降解甲苯的影响。从甲苯降解率、碳平衡、CO2选择性和O3去除4个方面,对比了氧化物催化剂的介电性能、表面供氧能力和比表面积与多孔结构对反应产生影响的强弱。结果表明,催化剂的介电性能有利于甲苯降解率、碳平衡和O3产量的提高,但对CO2选择性和O3去除的影响极小;一定能量密度下,催化剂比表面积与多孔结构对CO2选择性和O3去除所产生的影响要强于介电性能;催化剂表面供氧能力可明显促进反应的进行,其对反应所产生的影响要强于比表面积与多孔结构。     

稠油污水回用锅炉处理工艺的应用

新疆油田公司稠油污水处理普遍采用成熟的离子调整旋流反应水处理技术,污水处理后达到回用锅炉水质标准SY/T 0097-2000《稠油油田采出水用于蒸汽发生器给水处理设计规范》,供给油田专用高压注汽锅炉用水。采用相同技术建成的采油一厂稠油处理站污水回用锅炉处理工艺投用后,处理后污水回用锅炉,减少了含油污水的外排,充分利用了稠油污水的热能,取得了良好的经济和社会效益。     

充分利用环保倒逼机制促进产业结构调整升级

淄博市污染聚集,环境质量易受外来因素影响,产业结构不合理,污染物排放量大,排放强度高。但其充分发挥环保的倒逼作用,通过建立健全环保政策法规体系,严格执行高于省及国家标准的地方环保标准,大力发展高新技术和现代服务业,加快改造传统产业,极大地促进了产业结构升级和经济发展方式的转变。     

Anaerobic degradation of microcrystalline cellulose: kinetics and micro-scale structure evolution

The degradation kinetics and micro-scale structure change of microcrystalline cellulose during anaerobic biodegradation were investigated. A modified Logistic model was established to properly describe the kinetics, which showed good fitness and wide applicability for cellulose degradation. A maximum degradation rate of 0.14 g L⁻¹ h⁻¹ was achieved after cultivating for 51.5 h. This result was in good agreement with the scanning electron microscope and X-ray diffraction analysis. Channels of 400-500 nm size started to occur on the crystalline surface of cellulose at around the inflexion time. Accordingly, the crystallinity significantly decreased at this point, indicating a degradation of the crystalline structure zones by anaerobic bacteria. This study offers direct morphological evidence and quantitative analysis of the biodegradation process of cellulose, and is beneficial to a better understanding of the cellulose degradation mechanism.     

Electrogeneration of H(2) for Pd-catalytic hydrodechlorination of 2,4-dichlorophenol in groundwater

A novel electrolytic groundwater remediation process, which used the H₂ continuously generated at cathode to achieve in situ catalytic hydrodechlorination, was developed for the treatment of 2,4-dichlorophenol (2,4-DCP) in groundwater. Catalytic hydrodechlorination using Pd supported on bamboo charcoal and external H₂ showed that 2,4-DCP was completely dechlorinated to phenol within 30 min at pH ? 5.5. In a divided electrolytic system, the catalytic hydrodechlorination of 2,4-DCP in cathodic compartment by H₂ generated at the cathode under 20 and 50 mA reached 100% at 120 and 60 min, respectively. Two column experiments with influent pHs of 5.5 (unconditioned) and 2 were conducted to evaluate the feasibility of this process. The 2,4-DCP removal efficiencies were about 63% and nearly 100% at influent pHs of 5.5 and 2, respectively. Phenol was solely produced by 2,4-DCP hydrodechlorination, and was subsequently degraded at the anode. A low pH could enhance the hydrodechlorination, but was not necessarily required. This study provides the preliminary results of a novel effective electrolytic process for the remediation of groundwater contaminated by chlorinated aromatics.     

Toxicological effect of MPA-CdSe QDs exposure on zebrafish embryo and larvae

Cadmium selenium (CdSe) quantum dots (QDs) are semiconductor nanocrystals that hold wide range of applications and substantial production volumes. Due to unique composition and nanoscale properties, their potential toxicity to aquatic organisms has increasingly gained a great amount of interest. However, the impact of CdSe QDs exposure on zebrafish embryo and larvae remains almost unknown. Therefore, the lab study was performed to determine the developmental and behavioral toxicities to zebrafish under continuous exposure to low level CdSe QDs (0.05-31.25 mg L⁻¹) coated with mercaptopropionic acid (MPA). The results showed MPA-CdSe exposure from embryo to larvae stage affected overall fitness. Our findings for the first time revealed that: (1) The 120 h LC₅₀ of MPA-CdSe for zebrafish was 1.98 mg L⁻¹; (2) embryos exposed to MPA-CdSe resulted in malformations incidence and lower hatch rate; (3) abnormal vascular of FLI-1 transgenic zebrafish larvae appeared after exposure to MPA-CdSe including vascular junction, bifurcation, crossing and particle appearance; (4) larvae behavior assessment showed during MPA-CdSe exposure a rapid transition from light-to-dark elicited a similar, brief burst and a higher basal swimming rate; (5) MPA-CdSe induced embryos cell apoptosis in the head and tail region. Results of the observations provide a basic understanding of MPA-CdSe toxicity to aquatic organisms and suggest the need for additional research to identify the toxicological mechanism.     

Ozonation as an advanced oxidant in treatment of bamboo industry wastewater

The present study employed ozonation process to treat the bamboo industry wastewater (BIWW). The impact of ozone dosage and initial organic concentration on color, COD and TOC removal rates were studied along with characterization of the major organics in raw and treated wastewater. The results suggested the ozone dosage of 3.15 g h⁻¹ (concentration 52.5 mg L⁻¹) was suitable for the treatment. After 25 min ozonation of 1 L raw wastewater, the color, COD and TOC removal efficiencies were 95%, 56% and 40%, respectively, with an influent COD concentration of 835 mg L⁻¹. The ratio of kg O₃ kg⁻¹ COD at 3.15 g h⁻¹ was 2.8 (<3), revealing that ozonation was a cost effective process for tertiary treatment of BIWW. Longer oxidization time was required to achieve similar results for raw wastewater with higher COD concentration. The chromatogram from gel permeation chromatography revealed that ozonation resulted in the breakdown of high molecular weight compounds into lower molecular weight components but could not completely mineralize the organic matter. The majority of these compounds were identified in both raw and ozonated samples via GC-MS analysis. In addition to ester derivatives as the main intermediates of ozonation, 1-chloroctadecane, methyl stearate, benzophenone and α-cyperone were identified as the by-products of ozonation.     

Effect of inoculation methods on the composting efficiency of municipal solid wastes

Four types of inoculation methods were studied during the composting of municipal solid wastes and dry grass (MSWG). The methods included a control group as well as initial-stage, two-stage, and multi-stage inoculations. Fulvic acids were extracted from the composting materials and characterized by spectroscopic techniques. The results showed that inoculation of microbes in MSWG enhanced the biodegradation of aliphatics, proteins, and polysaccharides. The inoculation also increased the molecular weight, humic- and fulvic-like compound content, as well as humification degree of the composting products. The inoculation of microbes in MSWG significantly improved composting process and efficiency. The improvement efficiency was in the order of initial-stage < two-stage < multi-stage inoculations. Inoculation of microbes based on composting organic matter composition and temperature enhanced composting efficiency.     

Phytoavailability and geospeciation of cadmium in contaminated soil remediated by Rhodobacter sphaeroides

A microorganism was isolated from oil field injection water and identified as Rhodobacter sphaeroides. It was used for the remediation of simulated cadmium-contaminated soil. The phytoavailability of Cd was investigated through wheat seedling method to determine the efficiency of remediation. It was found that after remediation, the accumulation of Cd in wheat roots and leaves decreased by 67% and 53%, respectively. The Cd speciation in soil was determined with Tessier extraction procedure. It was found that the total Cd content in soil did not change during the experiments, but the geo-speciation of Cd changed remarkably. Among the five fractions, the concentration of exchangeable phases decreased by 27-46% and that of the phases bound to Fe-Mn oxides increased by 22-44%. The decrease of Cd accumulation in wheat showed significant positive correlation with the decrease of exchangeable phases. It could be concluded that the remediation of R. sphaeroides was carried out through the conversion of Cd to more stable forms. The decrease of sulfate concentration in supernatant indicated that the R. sphaeroides consumed sulfate.