电-Fenton法处理页岩气压裂返排液

页岩气开发压裂返排液处理是近年的研究热点,本文采用电-Fenton氧化技术对压裂返排液絮凝出水进行深度处理研究,主要考察了H2O2投加量、pH值、电压和反应时间对COD去除效果的影响。通过正交实验和单因素影响实验,确定电-Fenton氧化处理絮凝出水的适宜条件为:H2O2投加量为40 mL·L~(-1)、pH=3、电压6 V和反应时间60 min。在此条件下,出水COD为71.3 mg·L~(-1),COD去除率达到62.5%。实验结果表明化学絮凝—电-Fenton氧化是页岩气压裂返排液达标外排的一种适宜处理工艺。     

高铁酸钾的超声辅助化学合成及其对餐厨垃圾渗滤液的处理效果

采用超声辅助化学合成法制备K2Fe O4,用X-射线衍射、红外光谱和扫描电镜等对其进行表征。研究了K2Fe O4对餐厨垃圾渗滤液中COD和氨氮的处理效果。结果表明,本法制备的K2Fe O4具有四方结构,空间群为D2h(Pnma),其产率达到68.2%,纯度高达98.3%。扫描电镜表明,制备的K2Fe O4由规则的条状颗粒组成,颗粒之间存在一定团聚。对餐厨渗滤液处理实验表明,在COD初始浓度为140.6 g/L的餐厨垃圾渗滤液中投加0.12 mol/L K2Fe O4,调节p H为8.7,经处理24 min后COD去除率达到80.4%,氨氮的去除率达到75.9%。     

混凝-吸附联用预处理页岩气压裂返排液

为降低液相中有机污染负荷,采用烧杯实验和气相色谱-质谱联用技术研究和分析了混凝-吸附法联用预处理页岩气压裂返排液的可行性。结果表明:精制硅藻土(硅藻土J)投加有利于污染物的去除,联用顺序和吸附反应时间可以影响处理效果;先投加硅藻土J 8 mg·L~(-1),反应30 min后再投加PAC 2 000 mg·L~(-1),COD和浊度去除率分别达到57%和87%;混凝-吸附联用能去除水中22种有机污染物,大部分烷烃类、醇类、邻苯二甲酸二丁酯和卤代烃得到很好的去除。PAC和硅藻土J联用比传统混凝/吸附可以更高效地降低溶液有机负荷物,可以作为一种页岩气压裂返排液预处理的方法。     

膜蒸馏处理页岩气井压裂返排液

页岩气压裂返排液的有效处理是页岩气开发急需解决的关键环保问题之一。针对新页HF-1井页岩气压裂返排液经预氧化结合湿式氧化(PO-WAO)工艺处理的出水COD不达标、含盐量高等技术难题,采用膜蒸馏处理技术对工艺的出水进行深度处理。通过膜蒸馏单因素和正交实验表明料液温度和冷凝温度对膜蒸馏处理效果影响较大,在料液温度、冷凝液温度、真空度、运行时间分别为80℃、8℃、0.090 MPa和60 min的最佳工艺条件下,膜通量可达1.750 L·(m2·h)-1,出水COD浓度为95.8 mg·L~(-1),出水水质可满足《污水综合排放标准》(GB 8978-1996)中一级排放的要求。膜蒸馏出水中电导率为63μS·cm-1,氯化钠的质量浓度为1.168 0 mg·L~(-1),可有效降低处理后的压裂废液对周围土壤的盐碱化伤害。     

油田压裂返排液的电化学处理

为探究电絮凝和电化学氧化法处理油田压裂返排液的机理,采用响应面法拟合了反应过程,考察了电化学反应动力学、活性物质以及电极板的形貌和成分的变化。结果表明,电絮凝和电化学氧化法的响应面模型相关性显著,精确度和可信度均在合理范围内,在最优实验条件下其对应的COD去除率分别可达88.2%和100.0%;压裂返排液经电絮凝和电化学氧化处理后去除COD的动力学分别适用于零级和一级动力学模型,反应速率常数分别为4.49 mg·(L·min)^-1和0.005 4 min^-1;电絮凝和电化学氧化处理压裂返排液起主要作用的活性物质分别是OH·和O₂·^-;电絮凝反应后,阳极和阴极表面分别附有碳酸钙和絮体有机物,电化学氧化反应后,阳极和阴极表面分别覆盖着致密的有机污染物和钙镁碳酸盐。     

美国页岩气压裂返排液处理技术进展及前景展望

页岩气作为一种非常规天然气资源,正在改变着国际能源市场格局。美国的页岩气储量大,工业开发起步早、时间长,在开发技术方面领先优势显著。由于页岩气储藏的特殊性,在开发过程中会产生大量高盐度、组成复杂的压裂返排液和产出水,处理难度大、污染严重。返排液和产出水的处理通常需经过三级处理流程,依次去除水中悬浮物、压裂液残余成份、浮油和钙镁等二价离子,最后完成脱盐达标排放或回用。目前,我国页岩气产业刚刚起步,学习借鉴美国已成熟并且市场化的技术和设备,对实现我国页岩气开发跨越式发展具有重要的指导意义和借鉴价值。     

磁分离-精细过滤-超滤-碟管式反渗透耦合工艺高效回用页岩气压裂返排液

页岩气压裂返排液高效处理回用是页岩气开发中亟待解决的关键问题之一。本研究在某页岩气开采平台上,构建了“磁分离-精细过滤-超滤(UF)-碟管式反渗透(DTRO)”返排液处理工艺装备,进行现场实验研究并分析污染物去除效能和机理。在优化运行条件下,磁分离-精细过滤对浊度去除率达95.5%,精细过滤出水可内部回用于复配水力压裂液;DTRO工艺对TDS、DOC、总荧光强度去除率分别达99.9%、98.7%和96.3%,出水满足《污水综合排放标准》(GB 8978-1996)和《农田灌溉水质标准》(GB 5084-2021),有望通过外排和灌溉等方式进行外部回用。此外,装备运行直接处理成本约34.90元·m^-3。相较其他技术,本工艺兼具高效性与经济性。因此,该工艺装备具有实现返排液高效回用的巨大应用潜力。     

Fenton试剂氧化处理火炸药污染土壤淋洗液

采用Fenton试剂对火炸药污染土壤淋洗液进行氧化处理,研究了Fe SO4·7H2O投加量、H2O2投加量、初始pH、反应时间及温度对处理效果的影响,采用发光细菌发评价处理前后水样的急性毒性变化。结果表明,Fenton试剂氧化可有效去除火炸药污染土壤淋洗液的COD,当Fe SO4·7H2O投加量为8.0 g/L,H2O2投加量为64 m L/L,初始pH为3,反应时间120 min及反应温度30℃时,污染土壤淋洗液的COD由4 553.9 mg/L降至800.1 mg/L,COD去除率82.4%,COD的降解符合二级动力学模型。经Fenton氧化处理后,水样的急性毒性降低94.7%,B/C由0.007升至0.22,可生化性得到明显改善。     

基于MOF模板的纳米立方块α-Fe_2O_3水热合成及光催化降解活性测试研究

在无表面活性剂条件下,以普鲁士蓝结构的Fe4(Fe(CN)6)3为前驱体,通过水热法合成了纳米立方块结构的α-Fe2O3,并利用X射线衍射、透射电子显微镜、扫描电子显微镜对产物的形貌进行了表征。同时对其光催化降解活性进行了研究,结果表明,立方体纳米α-Fe2O3可以作为一种新型的光催化剂用于环境有机物的光催化降解。     

Fe/TiO2光催化降解水溶液中的4-氯苯酚

以TiO2-P25及FeC2O4为前驱物制备了Fe3 掺杂TiO2光催化剂--Fe/TiO2.X射线衍射结果表明,500 ℃煅烧温度下的Fe/TiO2主要是锐态矿晶型,当掺Fe3 量为0.5%(质量分数,下同)时,Fe3 以取代掺杂形式进入TiO2晶格,而当掺Fe3 量达5.0%时,则出现α-Fe2O3的特征衍射峰;900 ℃煅烧温度下的Fe/TiO2则均为金红石晶型,掺Fe3 量达2.0%～5.0%时,出现Fe2TiO5的特征衍射峰.4-氯苯酚的光催化实验结果表明,煅烧温度及Fe3 掺杂量对Fe/TiO2的光催化活性有显著影响,以煅烧温度500 ℃及掺Fe3 量0.5%的Fe/TiO2为光催化剂,反应80 min,4-氯苯酚的降解率达100%,总有机碳去除率约95%.     

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.     

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.     

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.     

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.     

Evaluation of trichloroethene recovery processes in heterogeneous aquifer cells flushed with biodegradable surfactants

The ability of two biodegradable surfactants, polyoxyethylene (20) sorbitan monooleate (Tween 80) and sodium dihexyl sulfosuccinate (Aerosol MA), to recover a representative dense non-aqueous-phase liquid (DNAPL), trichloroethene (TCE), from heterogeneous porous media was evaluated through a combination of batch and aquifer cell experiments. An aqueous solution containing 3.3% Aerosol MA, 8% 2-propanol and 6 g/l CaCl(2) yielded a weight solubilization ratio (WSR) of 1.21 g TCE/g surfactant, with a corresponding liquid-liquid interfacial tension (IFT) of 0.19 dyn/cm. Flushing of aquifer cells containing a TCE-DNAPL source zone with approximately two pore volumes of the AMA formulation resulted in substantial (>30%) mobilization of TCE-DNAPL. However, a TCE mass recovery of 81% was achieved when the aqueous-phase flow rate was sufficient to displace the mobile TCE-DNAPL toward the effluent well. Aqueous solutions of Tween 80 exhibited a greater capacity to solubilize TCE (WSR=1.74 g TCE/g surfactant) and exerted markedly less reduction in IFT (10.4 dyn/cm). These data contradict an accepted empirical correlation used to estimate IFT values from solubilization capacity, and indicate a unique capacity of T80 to form concentrated TCE emulsions. Flushing of aquifer cells with less than 2.5 pore volumes of a 4% T80 solution achieved TCE mass recoveries ranging from 66 to 85%, with only slight TCE-DNAPL mobilization (<5%) occurring when the total trapping number exceeded 2 x 10(-5). These findings demonstrate the ability of Tween 80 and Aerosol MA solutions to efficiently recover TCE from a heterogeneous DNAPL source zone, and the utility of the total trapping number as a design parameter for a priori prediction of DNAPL mobilization and bank angle formation when flushing with low-IFT solutions. Given their potential to stimulate microbial reductive dechlorination at low concentrations, these surfactants are well-suited for remedial action plans that couple aggressive mass removal followed by enhanced bioremediation to treat chlorinated solvent source zones.     

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.     

Phytoextraction of lead-contaminated soil using vetivergrass (<Emphasis Type="Italic">Vetiveria zizanioides</Emphasis> L.), cogongrass (<Emphasis Type="Italic">Imperata cylindrica</Emphasis> L.) and carabaograss (<Emphasis Type="Italic">Paspalum conjugatum</Emphasis> L.)

Background, Aims and Scope The global problem concerning contamination of the environment as a consequence of human activities is increasing. Most of the environmental contaminants are chemical by-products and heavy metals such as lead (Pb). Lead released into the environment makes its way into the air, soil and water. Lead contributes to a variety of health effects such as decline in mental, cognitive and physical health of the individual. An alternative way of reducing Pb concentration from the soil is through phytoremediation. Phytoremediation is an alternative method that uses plants to clean up a contaminated area. The objectives of this study were: (1) to determine the survival rate and vegetative characteristics of three grass species such as vetivergrass, cogongrass and carabaograss grown in soils with different Pb levels; and (2) to determine and compare the ability of the three grass species as potential phytoremediators in terms of Pb accumulation by plants. Methods The three test plants: vetivergrass (Vetiveria zizanioides L.); cogongrass (Imperata cylindrica L.); and carabaograss (Paspalum conjugatum L.) were grown in individual plastic bags containing soils with 75 mg kg⁻¹ (37.5 kg ha⁻¹) and 150 mg kg⁻¹ (75 kg ha⁻¹) of Pb, respectively. The Pb contents of the test plants and the soil were analyzed before and after experimental treatments using an atomic absorption spectrophotometer. This study was laid out following a 3 × 2 factorial experiment in a completely randomized design. Results On the vegetative characteristics of the test plants, vetivergrass registered the highest whole plant dry matter weight (33.85–39.39 Mg ha⁻¹). Carabaograss had the lowest herbage mass production of 4.12 Mg ha⁻¹ and 5.72 Mg ha⁻¹ from soils added with 75 and 150 mg Pb kg⁻¹, respectively. Vetivergrass also had the highest percent plant survival which meant it best tolerated the Pb contamination in soils. Vetivergrass registered the highest rate of Pb absorption (10.16 ± 2.81 mg kg⁻¹). This was followed by cogongrass (2.34 ± 0.52 mg kg⁻¹) and carabaograss with a mean Pb level of 0.49 ± 0.56 mg kg⁻¹. Levels of Pb among the three grasses (shoots + roots) did not vary significantly with the amount of Pb added (75 and 150 mg kg⁻¹) to the soil. Discussion Vetivergrass yielded the highest biomass; it also has the greatest amount of Pb absorbed (roots + shoots). This can be attributed to the highly extensive root system of vetivergrass with the presence of an enormous amount of root hairs. Extensive root system denotes more contact to nutrients in soils, therefore more likelihood of nutrient absorption and Pb uptake. The efficiency of plants as phytoremediators could be correlated with the plants’ total biomass. This implies that the higher the biomass, the greater the Pb uptake. Plants characteristically exhibit remarkable capacity to absorb what they need and exclude what they do not need. Some plants utilize exclusion mechanisms, where there is a reduced uptake by the roots or a restricted transport of the metals from root to shoots. Combination of high metal accumulation and high biomass production results in the most metal removal from the soil. Conclusions The present study indicated that vetivergrass possessed many beneficial characteristics to uptake Pb from contaminated soil. It was the most tolerant and could grow in soil contaminated with high Pb concentration. Cogongrass and carabaograss are also potential phytoremediators since they can absorb small amount of Pb in soils, although cogongrass is more tolerant to Pb-contaminated soil compared with carabaograss. The important implication of our findings is that vetivergrass can be used for phytoextraction on sites contaminated with high levels of heavy metals; particularly Pb. Recommendations and Perspectives High levels of Pb in localized areas are still a concern especially in urban areas with high levels of traffic, near Pb smelters, battery plants, or industrial facilities that burn fuel ending up in water and soils. The grasses used in the study, and particularly vetivergrass, can be used to phytoremediate urban soil with various contaminations by planting these grasses in lawns and public parks. ESS-Submission Editor: Dr. Willie Peijnenburg (wjgm.peijnenburg@rivm.nl)