废旧农膜再利用的发展

将废旧农膜通过高效绿色的方法进行处理,可得到可利用的原材料。废旧农膜的处理主要过程为分拣、清洁、再加热、造粒、成型或化工处理。造粒料可用于其他高分子材料的生产,经化工方法处理可得到油、汽等。废旧农膜回收处理方式基于其自身线性或支链结构表现出的热塑性,可达到回收重复成型利用的效果。     

Physico-chemical treatment of strong municipal wastewater

Direct chemical flocculation-clarification of strong new wastewater followed by adsorption on activated carbon has been investigated. The fate of specific organic components (low organic acids, carbohydrates, proteins, fats as well as BOD and COD) in the chemical treatment process was also studied. Excellent removals of phosphates, fats and suspended solids and a clear effluent were obtained in the chemical treatment. The clear ‘primary chemical’ effluent is, however, of high soluble organic content, the largest fraction being the soluble (low) organic acids and carbohydrates. Adsorption of the chemically treated wastewater on activated carbon gave a 60 per cent removal and a final effluent of a relatively high organic content including BOD. The high concentration of remaining organics is ascribed to poor adsorbability of the low organic acids anions on activated carbon.The significance of the findings for process considerations is discussed.     

Comparative assessment of genotoxicity of mineral water packed in polyethylene terephthalate (PET) and glass bottles

The potential migration of genotoxic compounds into mineral water stored in polyethylene terephthalate (PET) bottles was evaluated by an integrated chemical/biological approach using short-term toxicity/genotoxicity tests and chemical analysis. Six commercial brands of still and carbonated mineral water bottled in PET and in glass were stored at 40 °C for 10 days in a stove according to the standard EEC total migration test (82/711/EEC), or at room temperature in the dark. After treatment, the samples were analysed using gas-chromatography/mass spectrometry (GC/MS) to detect volatile and non-volatile compounds, the Microtox^® test to evaluate potential toxicity of the samples, and three mutagenicity tests - Tradescantia and Allium cepa micronucleus tests and the Comet assay on human leukocytes - to detect their genotoxic activity.GC/MS analysis did not detect phthalates or acetaldehyde in the water samples. The Microtox^® test found no toxic effects. Mutagenicity tests detected genotoxic properties of some samples in both PET and glass bottles. Statistical analyses showed a positive association between mineral content and mutagenicity (micronuclei in A. cepa and DNA damage in human leukocytes). No clear effect of treatment and PET bottle was found. These results suggest the absence of toxic compounds migrating from PET regardless of time and conditions of storage. In conclusion, bottle material and stove treatment were not associated with the genotoxic properties of the water; the genotoxic effects detected in bottled water may be related to the characteristics of the water (minerals and CO₂ content).     

DCS系统在化学水处理程控中的应用

以仪征化纤热电生产中心化学水处理程控系统DCS改造为例,探讨了DCS—HOLLiASMACSSM系统在电厂化学水处理程控系统中的应用,取得了良好的应用效果,可为其他电厂水处理程控改造提供参考。     

Occurrence and removal of selected organic micropollutants at mechanical, chemical and advanced wastewater treatment plants in Norway

In Norway the combined hydraulic capacity of all domestic wastewater treatment plants is relatively equally distributed between three major treatment plant types; mechanical, chemical, and combined chemical and biological. The Western coast from Lindesnes in the south to the Russian boarder in the North is dominated by mechanical treatment plants, constituting approximately 68% of the treatment capacity in that area. In the present study we report concentrations and removal efficiencies of polycyclic aromatic hydrocarbons (PAHs), nonylphenols, phthalates, polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) found in five Norwegian wastewater treatment plants (WWTPs) applying different levels of treatment. Concentrations of organic micropollutants in the influents to the WWTPs were generally in the low range of what have been reported by others for domestic wastewater in Europe and North-America. More than 90% removal could be obtained for nonylphenols, PBDEs, and the more hydrophobic 4-6 ring PAHs by chemical precipitation, however, biological treatment appeared to be necessary for efficient removal of the less lipophilic 2 and 3 ring PAHs, the medium- to short-chained nonylphenol ethoxylates and diethyl phthalate. SigmaPCB(7) was removed by more than 90% by combined biological/chemical treatment, while removal efficiency by chemical treatment was not possible to estimate due to low inlet concentrations. Low or insignificant removals of PAHs, phthalates and nonylphenols with their ethoxylates were observed at the mechanical WWTP, which was in accordance with the minuscule removal of TOC.     

Critical analysis of factors affecting the sensitivity of zooplankton and the reproducibility of toxicity test results

This paper concerns the variables that affect the sensitivity of test zooplankton and the reproducibility of results obtained from repeated toxicity tests. Among the variables considered are: (a) the nutrition of the test zooplankton, their health and diet; (b) culturing techniques, in particular, the effect of the ambient medium on demographic variables and testing results; (c) physical and chemical characteristics of the test compound; (d) purity of the test compound, and finally (e) the variation in results obtained with nominal and measured concentrations of the test compound.

Critical factors addressed include the effects of inadequate cobalamine or selenium concentrations in the diet, adversely affecting fertility, which may result in misleading interpretation of short-term toxicity test results involving Ceriodaphnia or chronic studies using Daphnia. Other factors considered are, for example, the problems of poor health, as measured by fertility or by the reproducibility of static acute toxicity test results, and their effect on zooplankton sensitivity to toxicants. The observation that diets of several algae result in greater tolerance of zooplankton to toxicants than do diets based on synthetic food are discussed. It is also noted that organisms reared in clean, frequently replenished and renewed habitats and fed axenic cultures of algae, are healthier than animals maintained in static environments. The observation that the results of interlaboratory comparisons of zooplankton response to toxicants are more uniform and exhibit smaller standard deviations when the test animals are sustained on algal foods rather than on synthetic diets is emphasized. Variability due to test compound characteristics include the observation that test compounds of variable purity often are responsible for poor test results reproducibility, and that the reproducibility of the toxic response is often variable due to physical and chemical characteristics of the test chemical. Finally, poor interlaboratory comparisons may result when nominal concentrations are the only ones considered. Data are selected from the published literature to illustrate the above discussion.     

A Daphnia magna feeding bioassay as a cost effective and ecological relevant sublethal toxicity test for Environmental Risk Assessment of toxic effluents

Environmental Risk Assessment of chemical products and effluents within EC countries require the use of cost effective standardized toxicity tests that in most cases are restricted to acute responses to high doses. Thus, subtle ecological effects are underestimated. Here we propose a short-term one day Daphnia magna feeding inhibition test as a cost effective and ecological relevant sublethal bioassay. The sensitivity and reliability of the proposed bioassay was tested in the laboratory against standardized bacteria, algae growth, D. magna and fish acute toxicity test by using 16 chemical mixture x water type combinations that included four different water types fortified with four complex chemical mixtures. Water types included ASTM hard water and three selected effluents diluted 1/10 in water to mimic worse field situations that many overexploited arid river ecosystems suffer during summer months when effluents are discharged into them with little dilution. The results obtained denoted a greater sensitivity of the proposed feeding bioassay in 51 out of 65 tests performed with an average sensitivity 50 fold greater than that of the standardized tests. The greater differences were obtained for mixtures that included narcotic chemicals and the lowest differences for those containing pesticides. Furthermore, feeding responses to the studied contaminant mixtures behaved differently to increasing TOC content than those based on bioluminescent bacteria and algae. Increasing TOC coming from sewage treated effluents decrease toxicity to the latter bioassays but increased those of D. magna feeding bioassays. These results empathize the need to include additional bioassays to monitor more accurately and realistically the toxicity of effluents or surface waters dominated by effluent discharges, a quite common situation in America and Mediterranean arid regions.     

黄土地区强夯法和桩基联合应用与研究

基于甘肃省某石油化工项目地基处理工程的大量试验实测数据,对强夯后地基再应用桩基的处理方法进行了讨论,得出了一系列对黄土地区地基处理工程极具参考价值的结论。     

Comparison of several microbiological toxicity screening tests

Four short-term microbiological toxicity screening tests were compared using the following test chemicals: 3,5 dichlorophenol, cetyl trimethyl ammonium chloride, sodium lauryl sulfate, phenol, copper(II) sulfate, mercury(II) chloride and zinc(II) sulfate. These seven chemicals represent a wide range of toxicity. The methods examined were Beckman's Microtox system, the Spirillum volutans motility test, inhibition of respiratory activity of activated sludge, and inhibition of activated sludge TTC-dehydrogenase activity.The results obtained indicate that each method has its own toxicity sensitivity pattern, and among the substances tested, only mercury(II) chloride and phenol were ranked equally by the four methods as the most and the least toxic chemical, respectively. In a tentative ranking of the methods, according to sensitivity, the Microtox test came out as the most sensitive test, followed by the Spirillum test, which in turn appeared more sensitive than the two sludge tests. This ranking has meaning only in a statistical sense, however, and the variable nature of the results support the philosophy that for assessing toxicity more thoroughly, a battery of several tests is required.     

Aerobic transformations of organic matters in sewer wastewater,a case study of Milan,Italy

Today, we know that not only the sewers carry urban wastewater, but also act as chemical and biological reactors, in which both organic and inorganic substances undergo significant transformations. This article describes a study on the western part of the sewer system of the city of Milan. The hydraulic model of the sewer system was coupled with the chemical and dynamic biological model to assess the extent of the degradation of organic matter in the network. The hydraulic and biological models were calibrated with real data obtained at the entrance of the wastewater treatment plant (WWTP) ‘Milan South’ and assuming standard values of daily per capita loads of COD and BOD₅.     

An adsorption-photocatalysis hybrid process using multi-functional-nanoporous materials for wastewater reclamation

In this study, two of our recently developed laboratory scale wastewater treatment systems, fluidised-bed reactor (FBR) using formulated clay mixture absorbents (clay-FBR adsorption) and an annular slurry photoreactor (ASP) using TiO₂ impregnated kaolin catalysts (TiO₂-K-ASP) were integrated as an adsorption-photocatalysis hybrid process to treat municipal wastewater as alternative secondary and tertiary treatment for wastewater reclamation. Primary effluent from sewage and secondary effluent from a membrane bioreactor treatment process were used to assess chemical removal capabilities of the FBR and ASP systems, and the hybrid process. The formulated clays-FBR system demonstrated the prevailing removal efficiency toward PO₄³⁻, NO₃⁻ and suspended solids. The TiO₂-K-ASP showed superior degradation of dissolved organic content; while the presence of inorganic ions caused a detrimental effect on its performance. The integration of the adsorption and degradation system as a hybrid treatment process resulted in a synergetic enhancement for the chemical removal efficiency. Complete elimination of PO₄³⁻ content was obtained in the adsorption stage; while 30% and 65% NO₃⁻ removal were obtained from the hybrid treatment of the primary and secondary effluents, respectively. The corresponding COD reduction during the photodegradation was further investigated by the high-performance size exclusion chromatography technique, where it revealed the shift of apparent molecular weight of the dissolved organic contaminants toward the smaller region. This present study demonstrated that this adsorption-photocatalysis hybrid technology can be used as a feasible alternative treatment process for wastewater reclamation.     

Drinking Water Treatment Options for Eliminating Freshwater Algae

A massive mixed algal growth may have many adverse effects on the water quality and causes acute problems, especially in different treatment steps for the production of drinking water. The effectiveness of drinking water treatment options for eliminating the nuisance created by River Nile water algae was the main objective of this study. The algal removal rate increased when using oxidants combined with alum-potassium permanganate; this was the most effective treatment combination for algal removal. When natural flocculant seeds of Moringa oleifera were used, the algal removal rate increased by more than 18% than that obtained by a chemical coagulant.     

Treatment of pharmaceutical wastewater (herbal) by a coagulation/flocculation process

Pharmaceutical factory wastewater (herbal nature) poses pollution problem due to its high COD and BOD. Moreover the characteristics of the wastewater depicts wide variation due to variation in the type of medicines manufactured and raw material utilization. Addition of solvents and oils as per the requirement also add to the pollution load. Because of this problems the conventional treatment units which employ activated sludge process (ASP) and trickling filter for the pharmaceutical factory (herbal) effluent treatment usually malfunctions. It was thus proposed to subject the wastewater to physico‐chemical treatment, using different coagulants and coagulant aids. Commonly available coagulants like lime, alum, ferrous sulphate, ferric chloride, polyaluminium chloride (PAC) and also polyelectrolyte were studied.

Results indicated that this wastewater is amenable to physico‐chemical treatment, and can be applied both as a pretreatment technology or as a polishing treatment. Lime: Alum: Polyelectrolyte resulted in good and most economical removals of SS, COD and BOD of 69.75%, 82.51% and 86.72%, respectively, at a dose of 300 : 100 : 0.1 mg/l, respectively.

The paper discusses in detail the results obtained with other coagulants and their comparative efficiency.     

The use of thiosemicarbazyde in the pressure-driven processes of wastewater teatment

We have investigated the possibility of using thiosemicarbazyde as a complexation agent when conducting pressure-driven purification o solutions obtained at chemical treatment of the surface of metals. The concentration of Fe³⁺ and Cu²⁺ in the initial solutions is determined by the standard preliminary purification of wastewaters at the level 70 mg/dm³. It was found that the optimal concentration of the complexation agent constitutes 10 mg/dm³.     

Strength and deformability of mineral wool slabs under short-term compressive,tensile and shear loads

The results obtained in the experimental study of mineral wool slabs under short-term compressive, tensile and shear loads, used for insulating flat roofs, cast-in-place floors, curtain and external basement walls, as well as for sound insulation of floors, are presented. To describe the experimental data of strength and deformability of mineral wool slabs, the regression equations of the linear form, provided with one-sided confidence intervals for predicting the resultant characteristic with probability Р = 0.90, are used. The interrelationship between strength and deformability characteristics of mineral wool slabs under tension and shear, and their strength and deformability under short-term compression are determined. Based on the experimental data, differences in deformability and strength characteristics of mineral wool slabs under shear load in mutually perpendicular planes (in the direction of slab forming and perpendicular to it) are demonstrated.     

基于红外光谱法的SBS沥青光氧老化机理

通过AH-70基质沥青及PG76-22改性沥青的短期热氧老化(RTFO)和模拟光氧老化试验,运用红外光谱分析法研究真实环境中太阳光中紫外光对沥青胶结料的影响。探讨了沥青胶结料在紫外光和氧的双重因素的作用下,化学组分中各官能团的变化规律;从化学结构方面阐述了沥青胶结料的老化机理。     

The effect of chemical and mineralogical composition of aggregates on tensile adhesion strength of tiles

The fundamental requirement of the tile adhesive mortar is its adherence and durability. The properties of adhesives are affected by the chemical and mineralogical composition of the aggregates. The aggregates are obtained from the leading 10 companies that sell adhesives. First, chemical compositions of aggregates are determined from chemical analysis by XRF. Then, exact mineral compositions of aggregates determined from the chemical compositions by using CIPW norms. Aggregate size and granulometry is determined by microscope analysis. Ten different groups of dry-mixed adhesive samples are prepared for testing from the 10 different aggregate mixtures that are obtained from producing companies. Dry, wet, hot and freezing–thawing adhesive strengths are determined according to European EN 1348 and EN 12004 standards. The mineral and chemical composition of aggregate type that gives the highest adhesive strength is determined. It is found that the highest pull-out adhesive strength was obtained on samples those aggregates have high content (80–95%) of SiO₂ and with small amount (0.5–3.4%) of CaCO₃.     

高黏SBS改性沥青的流变性能与化学特性

为研究SBS掺量、稳定剂含量和老化对高黏SBS改性沥青流变性能与化学特性的影响,针对SBS掺量和稳定剂含量不同的高黏SBS改性沥青,分别采用动态剪切流变仪(DSR)和凝胶渗透色谱(GPC)试验对老化(短期老化和长期老化)前后的改性沥青进行流变性能与化学特性分析.结果 表明:相位角主曲线可以很好地表征高黏SBS改性沥青在老化过程中的流变性能;高黏SBS改性沥青中由于广泛的交联作用,使得SBS中形成了大量共价键,因此即便是长期老化,仍有足够数目的共价键来维持SBS结构的完整性;相比无稳定剂的SBS改性沥青,稳定剂的添加大幅度改善了高黏SBS改性沥青的性能,但在已有稳定剂的基础上再增加稳定剂的含量对其性能的提升有限;SBS掺量高的改性沥青需要更长的搅拌时间,以保证SBS在沥青中发生充分溶胀;稳定剂含量高的改性沥青也需要更长的搅拌时间,使SBS分子之间发生交联作用.     

Indicators of matrix dependent variation in effective dose for chromium and nickel aerosol exposures

Inhaled particulates containing Cr and Ni are partially cleared or dissolved thus contributing to short-term internal exposures and partial retention in airways and airspaces. The retained fraction may continuously contribute to internal exposure after external exposure has ceased, through intra- and extracellular chemical processes which continuously liberate various metallic species; i.e. via an active deposit. Recent experiments with Ni and Cr compounds, and freshly produced welding fumes, which contain Ni and Cr, demonstrate a strong dependence of the distribution of these metals on oxidation state, solubility, bioavailability and toxicity as measured by in-vitro bioassay, depending on the collection, storage and analytical technique. It is suggested that exposure limits must consider the wide variation in short- and long-term delivered dose of toxic metals to target tissue with matrix, and that current protocols may be inadequate to protect workers in different industries involving exposures to widely different types of aerosols having only the same chemical element in common.     

高等教育规模与经济关系的研究述评

从高等教育规模与经济的正相关关系研究和非正相关关系研究两个方面，对20世纪90年代以来我国关于高等教育规模与经济的关系研究进行了概述。其中取得比较一致的结论有：正相关关系只存在于经济发展的一定阶段，高等教育规模与经济增长之间存在着长期均衡与短期动态的关系、单向因果的关系，高等教育规模的扩大对促进经济发展的影响并非都是正相关的；但在高等教育规模扩大对短期经济增长的作用的研究等方面还存有争议。最后从研究方法和研究内容两方面对现有研究进行分析，并提出进一步研究的必要性。