脱硫石膏粒径分布与脱水性能实验研究

脱硫石膏粒径分布是影响脱硫石膏浆液脱水性能的重要因素之一,以干法、湿法筛分和研磨破碎获得不同粒径分布的脱硫石膏,在相同的过滤条件下,对不同粒径分布脱硫石膏浆液脱水性能进行了研究,实验结果表明,当脱硫石膏粒径d50大于50μm且（d90-d10）小于100μm,真空过滤最大真空度不低于0．098MPa,过滤时间不少于2．5min,滤饼厚度不超过20mm时,石膏滤饼含水率可以降低到12％以下（最低可达10％）;d50在17μm为脱硫石膏在相同的过滤条件下能够实现真空脱水干燥的转折点;d50和（d90-d10）共同影响石膏脱水性能,d50小于20μm时,仅表现为d50的影响。     

好氧颗粒污泥强化解体实验与机理研究

在120r／min的搅拌及pH=1的强酸条件下,进行好氧颗粒污泥的强化解体实验,研究颗粒污泥的总数、平均粒径和粒径分布的变化情况。在15h实验时间内,搅拌强化解体的颗粒平均粒径从1230μm降至320μm,颗粒总数从30个／mL增至193个／mL。强酸强化解体结果类似,但解体时间为110h。搅拌比强酸对颗粒解体的强化作用更明显。粒径分布结果显示,小颗粒所占比例明显增加。颗粒解体过程中粒径分布均符合对数正态分布,但颗粒粒径的期望值石,随解体时间明显减小。根据颗粒的解体机理,即4种解体类型：破碎、破裂、剥落和研磨,结合实验结果,将解体过程分为对数期、平缓期、二次对数期和稳定期。     

复合生物活性填料对活性污泥生物特性的影响

为了考察生物活性填料对活性污泥生物特性的影响,采用电子扫描显微镜、激光粒度仪和Miseq高通量测序技术,分别对SBR中污泥的形态、粒径和微生物群落分布进行了研究。结果表明,投加生物填料可以降低污泥的产率,促进污泥沉降,增强脱氮除磷效能;投加生物活性填料的SBR相比对照组SBR的污泥结构紧密,污泥颗粒分布均匀,且颗粒粒径大;内置填料和外置填料的活性污泥粒径在28.988~124.573μm的颗粒占据了大部分的比例,而对照组的活性污泥粒径在0.554~23.538μm的颗粒占据了大部分的比例;3个微生物群落主要分布在Sphingobacteriales、Xanthomonadales、Burkholderiales、Rhodocyclales、Flavobacteriales和Spirochaetales等6个目内;内置填料活性污泥微生物群落(17.12%)和外置填料活性污泥微生物群落(23.17%)中的黄色单胞菌目,要比对照组活性污泥微生物群落(5.51%)的比例高,说明通过复合生物活性填料的作用,能够改善活性污泥微生物群落的除磷能力,这与反应器实际运行效果和污泥粒径分析研究内容一致。     

柴油机尾气中微粒粒径分布特征的实验研究

柴油机尾气中的微粒粒径大小分布范围广泛,不同直径的微粒所占的比例以及对环境和人身健康造成的危害各不相同,因此对微粒粒径特征进行研究更具有实际意义。本研究分别采用滤膜称重法和光散射法对厦工XG951Ⅲ装载机配置的国Ⅲ柴油发动机怠速工况下的尾气进行测试,研究了微粒的质量浓度分布、数量浓度分布以及质量浓度与数量浓度分布的关系。研究结果表明,从微粒质量上看,可吸入微粒(PM10)占微粒总量(TSP)的74.0%,可入肺微粒(PM2.5)占可吸入微粒的48.1%;2.5μm以下粒径范围内的微粒质量浓度是2.5~10μm粒径范围内微粒质量浓度的将近3倍,是10~100μm粒径范围内微粒质量浓度的52倍;2.5~10μm粒径范围的微粒质量浓度是10~100μm粒径范围内微粒质量浓度的18倍。数量上,在不同的数量级上,微粒数量浓度随粒径变化差距很明显,尤其是1μm以下的微粒较多。另外,质量浓度的粒径分布滞后于数量浓度。因此PM2.5排放标准中应考虑以个数浓度代替质量浓度为标准。     

颗粒污泥粒径的工程测定方法

厌氧反应器污泥粒径分布的测试方法目前主要有激光粒度分析、照相、沉降法和筛分法.快速方便的实用方法是筛分法,但筛分时需用缓冲剂,考察了分别用缓冲液和自来水作为冲洗介质的筛分结果.结果表明,作为现场应用自来水替代缓冲液是可行的,能够准确反映出污泥颗粒粒径变化的趋势,同时给出了试验测定方法和原则,确定了最佳污泥取样量为20 mL.     

废弃马铃薯渣改性制备瓦楞纸板粘合剂研究

研究了胶体磨湿法超微粉碎及高压蒸气处理对废弃污染物——马铃薯渣粒径分布及颗粒破坏程度的影响,调节胶体磨齿间隙为12μm处理30 min,并结合高压蒸气121℃处理20 min的条件下,通过显微镜观察和激光粒度分析证明马铃薯渣颗粒粒径明显减小且分布更加均匀,细胞壁和纤维素被破坏,体现出胶粘剂的性质。进而通过氧化变性处理改善其流动性,并添加一系列的助剂,制得了一种瓦楞纸板用粘合剂,其主要性能均接近于目前广泛使用的淀粉基瓦楞纸板粘合剂。     

新型一体化脱硫工艺反应器内流场的数值模拟研究

基于颗粒动力学理论,利用Fluent软件中的气体-颗粒两相流体模型,对新型一体化脱硫工艺(NID)反应器中不同工况下的三维流场进行数值模拟,并结合工厂实测数据及文献数据对模拟结果进行验证。结果表明,Fluent软件的模拟数据与工厂实测数据及文献数据相吻合,利用Fluent软件模拟了NID反应器内颗粒速度和浓度的分布,分析了反应器内流场的形成机制以及烟气进速和颗粒粒径对塔内压降的影响。由模拟结果可知,在烟气进速为18m/s、颗粒粒径为0.5~50.0μm时,颗粒浓度分布均匀,塔内回流区最小,压强变化稳定,最有利于提高实际工业运行的稳定性与安全性。     

宝鸡市冬季城郊水溶性离子浓度的昼夜变化及粒径分布特征

为研究宝鸡市冬季城郊水溶性离子浓度的昼夜变化及粒径分布特征,用分级采样器在宝鸡市城区和郊区同步采集2017年12月至2018年1月大气颗粒物,用离子色谱法分析9种离子的粒径分布。结果表明:(1)宝鸡市PM2.1(粒径≤2.1μm的细粒子)和PM2.1(粒径2.1μm的粗粒子)均呈郊区高于城区、夜间高于昼间的特征,PM2.1是颗粒物主要组成部分。二次离子(SO24-、NO3-和NH4+)是水溶性离子的主要成分,且主要存在于PM2.1中。城郊NO3-/SO24-(质量比)均大于1.6,表明宝鸡市移动污染源贡献大;(2)城郊PM2.1、PM2.1及6种主要离子均呈双模态分布,二次离子主峰分布于0.43～1.10μm粒径段,Ca2+、Na+、K+的主峰分布于4.70～5.80μm粒径段;(3)不同粒径段的硫氧化率(SOR)和氮氧化率(NOR)均呈双模态分布,主峰分布于0.43～1.10μm的细粒径段,说明在PM2.1中更易发生硫氧化反应和氮氧化反应。人为活动及车流量的昼夜时段性差异是造成城郊SOR和NOR差异的重要原因。     

废弃印刷电路板的破碎解离特性研究

废弃印刷电路板(WPCB)的破碎解离是WPCB进行后续资源化利用的前提条件,采用剪切式破碎机和万能高速破碎机分别对WPCB进行了粗破碎和细破碎,筛分后对不同粒径的粉碎产物进行粒径分布分析、显微镜观察和单体解离度研究。结果表明,WPCB经两次粗破碎后,大部分粗碎产物粒径≥1.2mm,占总产物质量的85%以上,经细破碎后,约有50%(质量分数)细碎产物粒径0.30mm。WPCB的细碎产物破碎至粒径0.90mm,可以认为金属和非金属基本分离;破碎至粒径0.60mm,可以认为金属和非金属完全解离。金属主要集中分布在粒径为0.30~1.20mm的细碎产物中。     

应用化学提取法评价大气颗粒物中重金属的生物有效性

以广州市楼顶降尘为研究对象,在分析其粒度分布和重金属总量的基础上,采用单一化学提取法(DWLP、TCLP)和多级化学提取法(SEP)研究了大气颗粒物中4种重金属元素的生物有效性.结果表明:样品中96%以上颗粒小于100 μm,其中10 μm和2.5 μm以下颗粒分别占33%和11%.大气颗粒物中重金属含量很高,Cu、Pb、Zn和Cd的平均含量分别为362.43、1 033.81、830.32和5.80 mg/kg,是广东省环境土壤背景值的17～64倍.单一提取法中,TCLP的提取效率明显高于DWLP,表明pH值是影响大气颗粒物中重金属释放的主要因素.SEP法结果显示,Zn和Cd的生物可利用态比例远高于Cu和Pb.经DWLP和TCLP法提取后,颗粒物中重金属的总含量有不同程度的降低,生物可利用态所占比例明显增加.通过综合分析,发现SEP比其他两种方法更适用于评价大气颗粒物中重金属的生物有效性.     

Chloroaromatic pollutants in mussels incubated in two finnish watercourses polluted by industry

Concentrations of different chlorinated compounds were measured in mussels incubated in two polluted watercourses, a river (the River Kymijoki) and a lake (Lake Vanaja) for four weeks in summer 1995. The sum concentrations of polychlorinated phenols (PCP) and biphenyls (PCB) were both about 1 μg/g lipid weight (lw) in Lake Vanaja mussels, while in the River Kymijoki mussels PCPs were non-detectable and PCBs were measured 120 ng/g lIw. The concentrations of toxic polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners ranged between <17 and 370 pg/g Iw in Lake Vanaja mussels and between <38 and 11,000 pg/g lw in the River Kymijoki mussels. Polychlorinated diphenyl ethers (PCDE) were detected in the mussels incubated in the River Kymijoki (0.4–1.1 ng/g Iw), but not in those incubated in Lake Vanaja. Polychlorinated phenoxyanisoles (PCPA) were measured 33 ng/g lw and polychlorinated phenoxyphenols (PCPP) 300 ng/g lw in the mussels incubated in the River Kymijoki. PCPAs were also detected in reference samples, which were sediment and pike from the River Kymijoki and Baltic salmon, seal and white-tailed sea eagle.     

Book review

The Pesticide Manual ‐ A World Compendium, 8th Edition, C.R. Worthing, Editor and S.B. Walker, Assistant Editor, British Crop Protection Council, BCPC Publications Sales, Bear Farm, Binfield, Bracknell, Berkshire RG12 5QE, England. 1987, 1100 pp., UK £50; Overseas £56. ISBN 0–948404–01–9.     

Patterns of volatile metabolites and nonvolatile trichothecenes produced by isolates of <Emphasis Type="Italic">Stachybotrys,Fusarium, Trichoderma,Trichothecium</Emphasis> and <Emphasis Type="Italic">Memnoniella</Emphasis>

We reported previously that trichodiene, a volatile trichothecene derivative, was produced by a Stachybotrys isolate, also known to produce highly cytotoxic, non-volatile, macrocyclic trichothecenes (satrotoxins). We investigated the relationship between the production of trichodiene and various non-volatile trichothecenes for several molds. Volatile metabolites were concentrated by adsorption on Tenax TA and analyzed by GC/MS, while non-volatile metabolites were separated by HPLC, derivatized and analyzed by GC/MS. Stachybotrys chartarum isolates producing macrocyclic trichothecenes secreted significantly larger amounts of trichodiene and other sesquiterpenes than isolates which only produced simple trichothecenes. The amounts of secreted trichodiene were relatively small in all cases. With the exception of Memnoniella, which excreted small amounts of sesquiterpenes, the other isolates produced varying amounts of sesquiterpenes, including trichodiene, as well as simple tricothecenes, no detectable trichodiene, but large amounts of griseofulvin derivatives. In Stachybotrys there is apparently a correlation between trichodiene and macrocyclic trichothecene production. In the remaining isolates, there was no simple relationship between trichodiene and non-volatile trichothecene synthesis. Trichodiene is produced in larger amounts by Stachybotrys isolates, which also produce satratoxins, but it will be difficult to utilize this metabolite to detect toxic isolates in buildings due to the relatively small amounts excreted.     

Observations on the influence of water and soil pH on the persistence of insecticides

Abstract

The pH‐disappearance rate profiles were determined at ca. 25°C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water‐ethanol (99: 1 v/v). Half‐lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (>1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1–2 days for trichlorfon and oxamyl to >1 year for fensulfothion and cyper‐methrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.     

The chemical stability of formulations of some hydrolyzable insecticides in aqueous mixtures with hydrolysis catalysts

Abstract

The active ingredients in commercial formulations of malathion, oxamyl, carbaryl, diazinon, and chlorpyrifos diluted to “spray tank”; concentrations with buffered distilled or natural water of pH 4–9 were stable for at least 24 hr. Formulations of trichlorfon were not stable at pH 7 or above but disappearance rates were slower than for the pure chemical in homogeneous solution. Cupric ion was observed to be an effective catalyst for the hydrolysis of a variety of pure organophosphorus insecticides but did not catalyze hydrolysis of the active ingredients of the formulations examined. Increasing the dilution of the formulation increased the susceptibility of malathion, oxamyl, and carbaryl to hydrolysis.     

Organochlorine compounds in a three-step terrestrial food chain

The concentrations of 15 organochlorine chemicals (PCBs and pesticides) were studied in a Central European oak wood food chain system: Great tit (Parus major), caterpillars (Tortrix viridana, Operophtera brumata, Erannis defoliaria), and oak-leaves (Quercus robur). Juvenile tits receive organochlorines from the mother via egg transfer and, eventually to a greater extent, from the caterpillar food source during nestling period. The concentrations of PCB 153 (2,2′,4,4′,5,5′-hexachlorobiphenyl, the most abundant in this study) was found in leaf material at ca. 1 ng/g, in caterpillars 10 ng/g, and in bird eggs 170 ng/g on an average and on a dry mass basis.     

Radionuclides and trace elements in fish collected upstream and downstream of Los Alamos national laboratory and the doses to humans from the consumption of muscle and bone

Abstract

The purpose of this study was to determine radionuclide and trace element concentrations in bottom‐feeding fish (catfish, carp, and suckers) collected from the confluences of some of the major canyons that cross Los Alamos National Laboratory (LANL) lands with the Rio Grande (RG) and the potential radiological doses from the ingestion of these fish. Samples of muscle and bone (and viscera in some cases) were analyzed for ³H, ⁹⁰Sr, ¹³⁷Cs, ^totU, ²³⁸Pu, ^239,240Pu, and ²⁴¹Am and Ag, As, Ba, Be, Cr, Cd, Cu, Hg, Ni, Pb, Sb, Se, and Tl. Most radionuclides, with the exception of ⁹⁰Sr, in the muscle plus bone portions of fish collected from LANL canyons/RG were not significantly (p<0.05) higher from fish collected upstream (San Ildefonso/background) of LANL. Strontium‐90 in fish muscle plus bone tissue significantly (p<0.05) increases in concentration starting from Los Alamos Canyon, the most upstream confluence (fish contained 3.4E‐02 pCi g^‐1 [126E‐02 Bq kg^‐1]), to Frijoles Canyon, the most downstream confluence (fish contained 14E‐02 pCi g^‐1 [518E‐02 Bq kg^‐1]). The differences in ⁹⁰Sr concentrations in fish collected downstream and upstream (background) of LANL, however, were very small. Based on the average concentrations (±2SD) of radionuclides in fish tissue from the four LANL confluences, the committed effective dose equivalent from the ingestion of 46 lb (21 kg) (maximum ingestion rate per person per year) of fish muscle plus bone, after the subtraction of background, was 0.1 ± 0.1 mrem y^‐1 (1.0 ± 1.0 μSv y^‐1), and was far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem y^‐1 (1000 μSv y^‐1). Of the trace elements that were found above the limits of detection (Ba, Cu, and Hg) in fish muscle collected from the confluences of canyons that cross LANL and the RG, none were in significantly higher (p<0.05) concentrations than in muscle of fish collected from background locations.     

Radionuclides in pinon pine (Pinus edulis) nuts from los alamos national laboratory lands and the dose from consumption

Abstract

One of the dominant tree species growing within and around the eastern portion of Los Alamos National Laboratory (LANL), Los Alamos, NM, lands is the pinon pine (Pinus edulis). Pinon pine is used for firewood, fence posts, and building materials and is a source of nuts for food—the seeds are consumed by a wide variety of animals and are also gathered by people in the area and eaten raw or roasted. This study investigated the (1) concentration of ³H, ¹³⁷Cs, ⁹⁰Sr, ^totU, ²³⁸Pu, ^{239, 240}Pu, and²⁴¹ Am in soils (0‐ to 12‐in. [31 cm] depth underneath the tree), pinon pine shoots (PPS), and pinon pine nuts (PPN) collected from LANL lands and regional background (BG) locations, (2) committed effective dose equivalent (CEDE) from the ingestion of nuts, and (3) soil to PPS to PPN concentration ratios (CRs). Most radionuclides, with the exception of ³H in soils, were not significantly higher (p < 0.10) in soils, PPS, and PPN collected from LANL as compared to BG locations, and concentrations of most radionuclides in PPN from LANL have decreased over time. The maximum net CEDE (the CEDE plus two sigma minus BG) at the most conservative ingestion rate (10 lb [4.5 kg]) was 0.0018 mrem (0.018 μSv); this is far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem (1000 μSv). Soil‐to‐nut CRs for most radionuclides were within the range of default values in the literature for common fruits and vegetables.     

Degradation and sorption of imidacloprid in dissimilar surface and subsurface soils

Degradation and sorption/desorption are important processes affecting the leaching of pesticides through soil. This research characterized the degradation and sorption of imidacloprid (1-[(6-chloro-3-pyridinyl)-methyl]-N-nitro-2-imidazolidinimine) in Drummer (silty clay loam) and Exeter (sandy loam) surface soils and their corresponding subsurface soils using sequential extraction methods over 400 days. By the end of the incubation, approximately 55% of imidacloprid applied at a rate of 1.0 mg kg^?1 degraded in the Exeter sandy loam surface and subsurface soils, compared to 40% of applied imidacloprid within 300 days in Drummer surface and subsurface soils. At the 0.1 mg kg^?1 application rate, dissipation was slower for all four soils. Water-extractable imidacloprid in Exeter surface soil decreased from 98% of applied at day 1 to > 70% of the imidacloprid remaining after 400 d, as compared to 55% in the Drummer surface soil at day 1 and 12% at day 400. These data suggest that imidacloprid was bioavailable to degrading soil microorganisms and sorption/desorption was not the limiting factor for biodegradation. In subsurface soils > 40% of ¹⁴C-benzoic acid was mineralized over 21 days, demonstrating an active microbial community. In contrast, cumulative ¹⁴CO₂ was less than 1.5% of applied ¹⁴C-imidacloprid in all soils over 400 d. Qualitative differences in the microbial communities appear to limit the degradation of imidacloprid in the subsurface soils.     

Biochemical interaction of six op delayed neurotoxicants with several neurotargets

Abstract

Five organophosphorous insecticides: Leptophos, EPN, Cyano‐fenphos, trichloronate and salithion proved to cause irreversible ataxia not only to chicken but also to mice and sheep. TOCP was included as a reference. Cyanofenphos blocked the catecholamine B‐receptor binding activity with ³H‐norepinephrine at a level similar to that of the specific inhibitor propranolol in the mouse heart preparation. In the lamb heart preparation, the B‐receptor was more sensitive to Leptophos, salithion and TOCP than to propranolol. The six compounds and their oxons were screened for their in‐vitro inhibition to monamine oxidase (MAO), acetyl cholinesterase (AChE) and neurotoxic esterase (NTE) in the brain of either mouse, lamb or chicken. It is believed that their AChE inhibition stands for their acute toxicity, while NTE inhibition is responsible for their paralytic ataxia.