中晚期垃圾渗滤液的处理研究

垃圾渗滤液的处理一直是近几年污水处理领域的热点和难点问题.采用"吹脱-SBR-混凝沉淀-氯化"处理工艺对中晚期垃圾渗滤液进行实验研究,确定了各工艺的最佳运行参数,并对SBR的强化进行了新的探索.结果表明,该工艺可使垃圾渗滤液的COD值从1360 mg/L下降到93.6 mg/L,BOD5值从320 mg/L降低到28mg/L,NH3-N的值从1098.6 mg/L下降到16.1 mg/L,出水色度接近无色,处理效果良好.     

矿化垃圾床＋SBR工艺处理渗滤液的论证及研究

通过论证，选择了矿化垃圾床 SBR工艺进行渗滤液处理的研究。当两类渗滤液水质CODcr分别为22．648和13．236g／L，NH3-N分别为850和642mg／L时，采用矿化垃圾床 SBR工艺处理垃圾渗滤液取得了良好的效果。试验结果表明，处理后渗滤液CODcr降到小于300mg／L，NH3-N降到小于20mg／L的水平，达到了渗滤液的二级排放标准。     

两级UASB与好氧组合工艺处理城市生活垃圾渗滤液的启动研究

采用两级UASB与好氧组合工艺处理早期城市生活垃圾渗滤液。系统出水按不同比例回流到一级UASB中进行反硝化，同时进行产甲烷反应，有机物在二级UASB中被进一步降解，好氧池完成剩余有机物的去除和氨氮的硝化。启动阶段通过对原渗滤液不同比例的稀释，分5次逐步提高进水浓度，启动结束时完成了对原渗滤液的高效处理。在进水COD浓度从3000mg／L提高到15000mg／L，氨氮浓度从250mg／L提高到1400mg／L时，最终COD去除率稳定在92％左右，氨氮去除率可达99％以上，一级UASB中反硝化率接近100％，回流比为300％时系统总氮去除率为70％～80％。     

支撑气膜法脱除／回收垃圾渗滤液中氨氮

利用由微孔疏水性聚丙烯中空纤维制成的工业级膜组件对垃圾渗滤液中氨氮进行支撑气膜法脱除研究，考察了泡沫分离．石灰絮凝等预处理技术对垃圾渗滤液表面张力及COD值的处理效果，在此基础上研究了物料因素和操作因素对膜传质性能的影响，并对该工艺的长期操作稳定性进行了研究。实验结果表明该预处理技术不仅可显著提高垃圾渗滤液的表面张力，还可大大降低其色度和COD值。当进料流量为100L／h、进料氨氮浓度为1000～3000mg／L、硫酸吸收液流量为200L／h、硫酸浓度为6％～10％、温度为20～30℃时，支撑气膜过程（两级膜组件串联）可有效脱除垃圾渗滤液中99％以上的氨氮，同时得到含10％～15％硫酸铵的水溶液作为副产品。工业级支撑气膜组件在连续运行的2个月内保持了良好的传质稳定性。     

吹脱法去除垃圾渗滤液中的氨氮研究

对吹脱法去除垃圾渗滤液中的氨氮进行了研究，控制吹脱效率高低的关键因素是温度、气液比和pH值。在水温大于25℃，气液比控制在3500左右，渗滤液pH值控制在10．5左右，对于氨氮浓度高达2000～4000mg／L的垃圾渗滤液，去除率可达到90％以上。     

混凝沉淀-SBR-活性炭过滤处理垃圾渗滤液

采用沉淀-SBR-活性炭过滤复合工艺对城市垃圾渗滤液进行处理，确定混凝、SBR和活性炭过滤的最隹参数。结果表明，当进水COD为2500mg／L、氨氮在900mg／L的条件下，经该系统处理后，出水COD均在300mg／L以下，氨氮在20mg／L以下，COD去除率达90％以上，氨氮去除率达98％以上，达到较好的去除有机物和去氨效果。     

臭氧预氧化-BAF工艺深度处理垃圾渗滤液

以广东省江门市垃圾填埋场垃圾渗滤液为研究对象，对经SBR生化处理和聚合硫酸铁混凝后的垃圾渗滤液，采用臭氧-BAF(曝气生物滤池)工艺进行深度处理。该工艺优点在于：臭氧高级氧化技术使大分子有机污染物降解成二氧化碳和水，或者小分子有机污染物，有利于后继BAF的生化处理，且臭氧处理过后废水的色度明显降低，是废水处理的有效方法之一。而后采用曝气生物滤池对垃圾渗滤液进行进一步处理，对COD进一步去除。结果表明，当臭氧的加入量为150 mg/L，BAF停留时间＞4 h，出水COD低于85 mg/L，稳定达到国家GB 16889-1997《生活垃圾填埋污染控制标准》一级排放标准，臭氧氧化法处理每吨垃圾渗滤液的费用为4.8元。     

垃圾填埋场渗滤液物化深度处理研究

通过Fenton法和结合聚合硫酸铁的混凝作用，实现垃圾渗滤液氧化塘出水COD的深度处理；并利用水泥水化产物的凝胶物质，强化COD去除率。30％H2O2投加量为0．75mL／L、七水硫酸亚铁投加量为1．5g／L、n（H2O2）：n（Fe^2＋）=1．2：1（摩尔比）时，Fenton法对渗滤液COD的去除率可达52％；水灰比为2：1、搅拌24h的水泥水化物将Fenton法的出水pH值从4调至10，该工艺流程总的COD去除率为73．6％，较普通的Ca（OH）2调节法提高9．3％，出水COD可以从进水的1200mg／L降至315mg／L。     

新型MBR工艺对垃圾渗滤液TN去除的研究

实验采用A^2／O^3-UF组成的MBR工艺，进水采用广州兴丰垃圾填埋场的垃圾渗滤液。在进水COD为3590～32600mg／L、NH3-N为720～2300mg／L的条件下，NH3^-N容积负荷为0．21kg／（d·m^3）时，该工艺对于NH3^-N仍有85％的去除率；而NO3^-N的去除率受到碳源的影响，由于渗滤液C／N偏低，因此需人为投加碳源，以保证反硝化能彻底进行。在碳源充足的条件下，出水NO3^-N亦可控制在5mg／L左右。结果证明，MBR工艺对于TN有良好的去除效果。     

日光/H2O2/草酸铁体系对垃圾渗滤液深度处理的试验研究

以草酸铁络合物／H2O2作光氧化剂，利用日光对垃圾渗滤生化出水进行了光氧化降解试验。结果表明，在溶液的初始体系pH=3．0，H2O2投加量为460mg／L，Fe^3＋质量浓度为20mg／L条件下，反应60min后，CODCr去除率可达80％以上；溶液初始体系的pH、H2O2和Fe^3＋的投加量及废水的水质对光解过程有显著影响，而且在太阳光照射下，CODCr去除率比紫外光照射下高。研究表明，在一定试验条件下，用日光／H2O2／草酸铁体系对城市垃圾渗滤液处理效果较好，可作为垃圾渗滤液的深度处理。     

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.     

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.     

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.     

Detection and occurrence of pentachlorophenol residues in chicken liver and fat

Abstract

A method for the detection of pentachlorophenol (PCP) residues in chicken liver and fat is presented. A detection limit of 0.002 mg/kg was achieved. Recoveries from liver and fat were in the range 82–88% and 95–97%, respectively.

Low level residues of PCP were found in all 1072 liver and 723 fat samples. These levels were <0.010 mg/kg in 92.7% of the fat and 75.6% of the livers. Only 0.75% of the liver samples had PCP levels>0.1 mg/kg. None of the more toxic impurities of PCP were detected in the chicken tissues.     

The efficiency of tobacco Bel-W3 and native species for ozone biomonitoring in subtropical climate, as revealed by histo-cytochemical techniques

We aimed to verify whether hydrogen peroxide (H₂O₂) accumulation and cell death are detected early in three bioindicators of ozone (O₃), Nicotiana tabacum ‘Bel-W3’, Ipomoea nil ‘Scarlet O’Hara’ and Psidium guajava ‘Paluma’, and whether environmental factors also affect those microscopic markers. The three species were exposed to chronic levels of O₃ in a subtropical area and a histo-cytochemical technique that combines 3,3′-diaminobenzidine (DAB) with Evans blue staining was used in the assessments. The three species accumulated H₂O₂, but a positive correlation with O₃ concentration was only observed in N. tabacum. A positive correlation between O₃ and cellular death was also observed in N. tabacum. In I. nil and P. guajava, environmental factors were responsible for symptoms at the microscopic level, especially in P. guajava. We conclude that the most appropriate and least appropriate bioindicator plant for O₃ monitoring in the subtropics are N. tabacum ‘Bel-W3’ and P. guajava ‘Paluma’, respectively.     

Climate and land-use changes affecting river sediment and brown trout in alpine countries—a review

Background, aim, and scope

Catch decline of freshwater fish has been recorded in several countries. Among the possible causes, habitat change is discussed. This article focuses on potentially increased levels of fine sediments going to rivers and their effects on gravel-spawning brown trout. Indications of increased erosion rates are evident from land-use change in agriculture, changes in forest management practices, and from climate change. The latter induces an increase in air and river water temperatures, reduction in permafrost, changes in snow dynamics and an increase in heavy rain events. As a result, an increase in river sediment is likely. Suspended sediment may affect fish health and behaviour directly. Furthermore, sediment loads may clog gravel beds impeding fish such as brown trout from spawning and reducing recruitment rates. To assess the potential impact on fine sediments, knowledge of brown trout reproductive needs and the effects of sediment on brown trout health were evaluated.

Approach

We critically reviewed the literature and included results from ongoing studies to answer the following questions, focusing on recent decades and rivers in alpine countries.

Have climate change and land-use change increased erosion and sediment loads in rivers?

Do we have indications of an increase in riverbed clogging?

Are there indications of direct or indirect effects on brown trout from increased suspended sediment concentrations in rivers or from an increase in riverbed clogging?

Results

Rising air temperatures have led to more intensive precipitation in winter months, earlier snow melt in spring, and rising snow lines and hence to increased erosion. Intensification of land use has supported erosion in lowland and pre-alpine areas in the second half of the twentieth century. In the Alps, however, reforestation of abandoned land at high altitudes might reduce the erosion risk while intensification on the lower, more easily accessible slopes increases erosion risk. Data from laboratory experiments show that suspended sediments affect the health and behaviour of fish when available in high amounts. Point measurements in large rivers indicate no common lethal threat and suspended sediment is rarely measured continuously in small rivers. However, effects on fish can be expected under environmentally relevant conditions. River bed clogging impairs the reproductive performance of gravel-spawning fish.

Discussion

Overall, higher erosion and increased levels of fine sediment going into rivers are expected in future. Additionally, sediment loads in rivers are suspected to have considerably impaired gravel bed structure and brown trout spawning is impeded. Timing of discharge is put forward and is now more likely to affect brown trout spawning than in previous decades.

Conclusions

Reports on riverbed clogging from changes in erosion and fine sediment deposition patterns, caused by climate change and land-use change are rare. This review identifies both a risk of increases in climate erosive forces and fine sediment loads in rivers of alpine countries. Increased river discharge and sediment loads in winter and early spring could be especially harmful for brown trout reproduction and development of young life stages. Recently published studies indicate a decline in trout reproduction from riverbed clogging in many rivers in lowlands and alpine regions. However, the multitude of factors in natural complex ecosystems makes it difficult to address a single causative factor.

Recommendations and perspectives

Further investigations into the consequences of climate change and land-use change on river systems are needed. Small rivers, of high importance for the recruitment of gravel-spawning fish, are often neglected. Studies on river bed clogging are rare and the few existing studies are not comparable. Thus, there is a strong need for the development of methods to assess sediment input and river bed clogging. As well, studies on the effects to fish from suspended sediments and consequences of gravel beds clogging under natural conditions are urgently needed.     

Rapid assays for environmental and biological monitoring

Abstract

Rapid, inexpensive, sensitive, and selective enzyme‐linked immunosorbent assays (ELISAs) now are utilized in environmental science. In this laboratory, many ELISAs have been developed for pesticides and other toxic substances and also for their metabolites. Compounds for which ELISAs have recently been devised include insecticides (organophosphates, carbaryl, pyrethroids, and fenoxycarb), herbicides (s‐triazines, arylureas, triclopyr, and bromacil), fungicides (myclobutanil), TCDD, and metabolites of naphthalene and toluene. New rapid assays have been developed for mercury.