AB-ASBR工艺处理高浓度有机物废水的优化运行

以人工模拟废水,采用高径比(H/D)为1.9吸附-生物降解厌氧序批式反应器(AB-ASBR)对A反应器进水期、再生期,B反应器反应期的搅拌频率以及絮凝剂聚丙烯酰胺(PAM)的投加量等参数进行了优化。进水浓度从7 000mg/L提高到10 000 mg/L时反应器运行稳定,厌氧条件下出水浓度低于100 mg/L,达到国家污水排放二级标准(GB 8978-2002)。优化后运行参数为:A反应器吸附期搅拌频率为20 s/(2 min)、B反应器反应期搅拌频率为7 min/h、A反应器闲置期搅拌频为4 min/h、絮凝剂投加量为15 mg/L。     

间歇曝气比在短程硝化中对硝化活性的影响

采用序批式间歇反应器(SBR)处理生活污水,温度控制在(25.0±0.5)℃,研究好氧曝气与缺氧搅拌时间比(间歇曝气比)分别为30min∶30min(A模式)和40min∶20min(B模式)对亚硝酸盐氮积累、污泥性能参数、反应速率(比氨氮氧化速率、比硝酸盐氮产生速率、比亚硝酸盐氮产生速率)、氨氧化菌(AOB)和亚硝酸盐氧化菌(NOB)活性的影响。A模式下运行64个周期时,出水亚硝酸盐氮质量浓度为19.04mg/L,亚硝酸盐氮积累率高达99.21%;B模式下运行75个周期时,出水亚硝酸盐氮质量浓度为19.42mg/L,亚硝酸盐氮积累率高达95.47%;研究表明缺氧时间所占比例越大越有利于短程硝化的实现。在实现短程硝化过程中,A模式在38个周期之后AOB活性超过NOB活性;B模式在34个周期之后AOB活性超过NOB活性。     

钱江隧道盾构废弃泥浆的混凝分离

为了实现钱江隧道盾构废弃泥浆的无害化处理,对盾构废弃的砂土泥浆和粘土泥浆分别进行混凝分离的实验条件研究,结果表明:对于砂土泥浆,密度为1.20 g/cm3有利于实现高效的泥水分离;PAM作为絮凝剂的分离效果最好;混凝分离的最优化分离条件为:投药量为150 mg/L,pH为8左右,水力条件为以300 r/min搅拌1 min,再以80 r/min搅拌20 min。对于粘土泥浆,密度为1.10 g/cm3有利于实现高效的泥水分离;PAM作为絮凝剂的分离效果最好;混凝分离的最优化分离条件为:投药量为150 mg/L,pH为6左右,水力条件为以300 r/min搅拌1 min,再以80 r/min搅拌20 min。该实验为废弃泥浆的进一步处理奠定了基础。     

硝基苯酚类的快速吸附与降解

以对硝基苯酚(PNP)和邻硝基苯酚(ONP)为主要研究对象,采用粉末活性炭和Fenton试剂快速吸附与降解PNP和ONP溶液,使其浓度降至生活饮用水准许浓度(分别为0.02 mg/L和0.06 mg/L)以下,并比较2种物质的处理效果,为硝基苯酚的水体污染治理和废水处理中的深度降解提供依据。结果表明,用粉末活性炭吸附浓度为1 mg/L和4 mg/L的PNP溶液60 min后,浓度低于0.02 mg/L,长时间跟踪监测,污染物浓度仍控制在0.02 mg/L以下,在pH<6时,粉末活性炭吸附PNP的效果较好;用Fenton试剂处理浓度为10 mg/L的PNP溶液70 min后,可完全降解PNP。粉末活性炭吸附12 mg/L的ONP溶液时,效率高于吸附PNP;Fenton试剂处理浓度为12 mg/L的ONP时,与PNP的处理效果相当。     

改性粉煤灰对活性艳兰染料吸附性能的研究

采用添加熟石灰并升温活化的方法对粉煤灰进行改性,研究了粉煤灰改性的适宜条件及其对活性艳兰染料的吸附脱色规律。试验结果表明,活性艳兰染料溶液浓度60mg/L,改性粉煤灰用量40g/L,pH范围5~10,搅拌吸附时间30min,脱色率可达98%以上。改性粉煤灰对活性艳兰染料的脱色吸附符合Freundlich方程。随着吸附温度的升高,改性粉煤灰的吸附能力下降。     

纳米TiO_2对甲酚红的吸附及光催化降解研究

采用纳米TiO2对甲酚红模拟废水进行吸附及光催化降解研究,考察了甲酚红初始浓度、pH、吸附剂用量、搅拌时间等因素对甲酚红去除率的影响。结果表明,当甲酚红初始质量浓度为18mg/L,pH为6.0,纳米TiO2投加量为1.4g/L时,搅拌30min后的甲酚红去除率达66.47%;在搅拌过程中增加高压汞灯照射,甲酚红去除率可提高至77.83%。纳米TiO2可用于处理甲酚红模拟废水,深度处理后的废水可达标排放。     

高氨氮对厌氧生物法处理城市垃圾渗沥液的影响

研究了高浓度氨氮对厌氧膜生物法处理城市垃圾渗沥液的影响。结果表明,COD去除率、沼气产量、沼气产率、辅酶F420和最大比产甲烷活性均随氨氮浓度的增加而减小;当氨氮浓度<3600mg/L时,不会对厌氧膜生物反应器的运行产生明显的影响;氨氮对厌氧污泥产甲烷活性的50%抑制浓度为4350mg/L;高浓度氨氮会造成系统VFA浓度增加;当氨氮浓度由4800mg/L降低到2000mg/L后,受重度抑制的厌氧微生物的活性可以在20d里恢复到未受抑制时的活性水平。     

化学沉降沸石吸附法处理高浓度电镀含锌废水的研究

含锌废水对人体健康和环境具有严重的危害性。处理高浓度的含锌废水时需先进行化学沉降,然后再进行深度处理。试验结果证明,对于含289 mg/L Zn2+的电镀废水,用质量分数为10%的氢氧化钠处理,其投加量为3.7 mL/100 mL,处理后的Zn2+的浓度为6.6 mg/L。再用沸石进行吸附,沸石用量为0.25 g/L,搅拌(110 r/min)50 min,处理后,废水的锌离子去除率最高可达88.8%,剩余Zn2+浓度为0.47 mg/L,远低于《国家污水综合排放标准》(GB 8978-2002)的一级标准。     

壳聚糖混凝处理丁腈橡胶废水的实验研究

利用壳聚糖作混凝剂处理丁腈橡胶废水。对投加量、pH、搅拌速率和沉降时间四因素进行L₉(3⁴)正交实验，确定壳聚糖混凝处理丁腈橡胶废水的最佳实验条件。结果表明，壳聚糖投加量为100 mg/L， pH为6，搅拌速率为200 r/min，沉降时间为5 min，COD去除率达96.7%，出水COD降为276 mg/L，达到国家三级排放标准。     

磷酸铵镁结晶技术处理模拟氨氮废水

从工程应用角度出发,考察了不同氨氮起始浓度、反应温度、搅拌速率及搅拌时间对磷酸铵镁化学结晶技术沉氨效果的影响。研究结果表明,当氨氮起始浓度超过200 mg/L时,氨氮去除率达到90%以上。不同温度条件下,氨氮去除率超过80%。随着温度升高,氨氮去除率明显上升,最高可达90%以上。搅拌是晶粒生长的一个重要影响因素;搅拌速率对晶粒生长作用复杂,当搅拌速率低于150 r/min时,加速了晶粒生长,达2.25 nm;提高搅拌速率,晶粒大小降至1.54nm。而搅拌时间对晶粒生长起着非常明显的促进作用;随着搅拌时间的延长,晶粒出现明显的增长,从5 min的0.47 nm长至120 min的1.71 nm。     

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.     

A History of Dry Cleaners and Sources of Solvent Releases from Dry Cleaning Equipment

Approximately 25, 000-35, 000 dry cleaning facilities currently operate in the U.S. The release of perchloroethylene and other solvents from these establishments represents a major source of soil and groundwater contamination. The manner in which dry cleaning solvents escape from dry cleaning plants is, for all practical purposes, identical for chlorinated and petroleum hydrocarbon solvents and is related to one of the following events: the catastrophic failure of a component of the dry cleaning system, the improper installation, operation or maintenance of the dry cleaning equipment or a combination of all of these causes. Acceptable customs, codes and regulations can also dictate what is authorized for operation of a dry cleaning facility in a particular community, geographic area during a particular time frame. Environmental litigation dealing with the origin of a solvent release from dry cleaners tends to focus on the design and manufacture of dry cleaning industry machines such as washers, washer extractors, tumblers, solvent filters, water separators, stills and spotting boards. A thorough analysis of the daily operations of dry cleaners often reveals that poor maintenance, failure to follow the manufacturer's instructions and the actions of the operator are the most likely causes of soil and groundwater pollution. In order to forensically evaluate the most probable origins of a solvent release and to examine issues regarding liability, a thorough understanding of the history of dry cleaning and a detailed analysis of the operation and maintenance of the dry cleaning equipment are necessary. The discovery of solvent plumes in the vicinity of dry cleaning plants may suggest that the solvent source is the dry cleaning plant; however, the presence of these plumes does not necessarily indicate that the dry cleaning equipment was defectively designed or manufactured. A thorough review of the type of equipment used over the life of the dry cleaning plant and verifiable solvent mileage records frequently indicates that operators of the plant have disposed of solvent and contaminated solids into the municipal sewer or on ground surfaces.     

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.     

Malathion-induced sublethal toxicity on the intestine of cricket frog (Fejervarya limnocharis)

The effect of malathion [diethyl(dimethoxythiophosphorylthio)succinate] at sublethal concentration (0.006 ppm) on intestinal parameters of cricket frog (Fejervarya limnocharis) was studied for 24 hrs to 240 hrs of exposure and remarkable histopathological alterations were observed. The study on intestinal parameters revealed acute pathological conditions in the intestinal wall. The toxic effect became evident as the cytoplasm of the cells disintegrated and the cells became empty and vacuolated. The cell membranes were also ruptured. Degenerative changes of the absorptive surface (villi) of the intestine in the different periods of exposure were pronounced. Severe atrophic nature (necrotic mucosa) of the intestine began from 48 hrs onwards to 96 hrs of exposure.     

Radionuclides in deer and elk from Los Alamos national laboratory and the doses to humans from the ingestion of muscle and bone

Abstract

This paper summarizes radionuclide concentrations (³H, ⁹⁰Sr, ¹³⁷Cs, ²³⁸Pu, ^239,240Pu, ²⁴¹Am, and ^totU) in muscle and bone tissue of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) collected from Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer (n = 11) and elk (n = 22) collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p<0.10) than in similar tissues from deer (n = 3) and elk (n = 7) collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% on LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDEs (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (50 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.22 mrem y^‐1 (2.2 μSv y^‐1), deer bone = 3.8 mrem y^‐1 (38 μSv y^‐1), elk muscle = 0.12 mrem y^‐1 (1.2 μSv y^‐1), and elk bone = 1.7 mrem y^‐1 (17 μSv y^‐1). All CEDEs were far below the International Commission on Radiological Protection guideline of 100 mrem y^‐1 (1000 μSv y^‐1), and the highest muscle plus bone net CEDE corresponded to a RECF of 2E‐06, which is far below the Environmental Protection Agency upper level guideline of 1E‐04.     

Nitrogen leaching and acidification during 19 years of NH₄NO₃ additions to a coniferous-forested catchment at Gårdsjön, Sweden (NITREX)

The role of nitrogen (N) in acidification of soil and water has become relatively more important as the deposition of sulphur has decreased. Starting in 1991, we have conducted a whole-catchment experiment with N addition at Gårdsjön, Sweden, to investigate the risk of N saturation. We have added 41 kg N ha⁻¹ yr⁻¹ as NH₄NO₃ to the ambient 9 kg N ha⁻¹ yr⁻¹ in fortnightly doses by means of sprinkling system. The fraction of input N lost to runoff has increased from 0% to 10%. Increased concentrations of NO₃ in runoff partially offset the decreasing concentrations of SO₄ and slowed ecosystem recovery from acid deposition. From 1990-2002, about 5% of the total N input went to runoff, 44% to biomass, and the remaining 51% to soil. The soil N pool increased by 5%. N deposition enhanced carbon (C) sequestration at a mean C/N ratio of 42-59 g g⁻¹.     

Leaching of seven pesticides currently used in cotton crop in Mato Grosso State—Brazil

This study aimed to evaluate the leaching of pesticides and the applicability of the Attenuation Factor (AF) Model to predict their leaching. The leaching of carbofuran, carbendazim, diuron, metolachlor, α and β endosulfan and chlorpyrifos was studied in an Oxisol using a field experiment lysimeter located in Dom Aquino – Mato Grosso. The samples of percolated water were collected by rain event and analyzed. Chemical and physical soil attributes were determined before pesticide application to the plots. The results showed that carbofuran was the pesticide that presented a higher leaching rate in the studied soil, so was the one representing the highest contamination potential. From the total carbofuran applied in the soil surface, around 6 % leached below 50 cm. The other pesticides showed lower mobility in the studied soil. The calculated values to AF were 7.06E-12 (carbendazim), 5.08E-03 (carbofuran), 3.12E-17 (diuron), 6.66E-345 (α-endosulfan), 1.47E-162 (β-endosulfan), 1.50E-06 (metolachlor), 3.51E-155 (chlorpyrifos). AF Model was useful to classify the pesticides' potential for contamination; however, that model underestimated pesticide leaching.     

Endosulfan in China 2—emissions and residues

Background, aim, and scope  Endosulfan is one of the organochlorine pesticides (OCPs) and also a candidate to be included in a group of new persistent organic pollutants (UNEP 2007). The first national endosulfan usage inventories in China with 1/4° longitude by 1/6° latitude resolution has been reported in an accompanying paper. In the second part of the paper, we compiled the gridded historical emissions and soil residues of endosulfan in China from the usage inventories. Based on the residue/emission data, gridded concentrations of endosulfan in Chinese soil and air have been calculated. These inventories will provide valuable data for the further study of endosulfan. Methods  Emission and residue of endosulfan were calculated from endosulfan usage by using a simplified gridded pesticide emission and residue model—SGPERM, which is an integrated modeling system combining mathematical model, database management system, and geographic information system. By using the emission and residue inventories, annual air and soil concentrations of endosulfan in each cell were determined. Results and discussion  Historical gridded emission and residue inventories of α- and β-endosulfan in agricultural soil in China with 1/4° longitude by 1/6° latitude resolution have been created. Total emissions were around 10,800 t, with α-endosulfan at 7,400 t and β-endosulfan at 3,400 t from 1994 to 2004. The highest residues were 140 t for α-endosulfan and 390 t for β-endosulfan, and the lowest residues were 0.7 t for α-endosulfan and 170 t for β-endosulfan in 2004 in Chinese agricultural soil where endosulfan was applied. Based on the emission and residue inventories, concentrations of α- and β-endosulfan in Chinese air and agricultural surface soil were also calculated for each grid cell. We have estimated annual averaged air concentrations and the annual minimum and maximum soil concentrations across China. The real concentrations will be different from season to season. Although our model does not consider the transport of the insecticide in the atmosphere, which could be very important in some areas during some special time, the estimated concentrations of endosulfan in Chinese air and soil derived from the endosulfan emission and residue inventories are in general consistent with the published monitoring data. Conclusions  To our knowledge, this work is the first inventory of this kind for endosulfan published on a national scale. Concentrations of the chemical in Chinese air and agricultural surface soil were calculated for each grid cell. Results show that the estimated concentrations of endosulfan in Chinese air and soil agree reasonably well with the monitoring data in general. Recommendations and perspectives  The gridded endosulfan emission/residue inventories and also the air and soil concentration inventories created in this study will be updated upon availability of new information, including usage and monitoring data. The establishment of these inventories for the OCP is important for both scientific communities and policy makers.