利用废铁屑和粉煤灰的电化学原理处理印染废水的方法研究

提出一种改进的铁屑法处理印染废水 ,对其机理进行探讨 ,并确定工艺条件为 p H4.0 ,处理时间 3 0 min,铁屑和粉煤灰的投加率分别为 5 %和 6%时 ,CODcr可降至 40 0 mg/L以下 ,去除率达 77%以上 ,脱色率 95 %以上 ,是一种高效可行的印染废水预处理方法  

粉煤灰测定若干消化方法的比较研究

采用多种消化法对粉煤灰标样进行消化处理,通过较系统的实验分析对比,寻求到了最佳消化体系,取得了较满意的结果.实验中采用直接火焰原子吸收法对其中微量铜、锌、铬元素含量进行测定;采用导数-原子捕集-火焰原子吸收法对其中痕量铅、镉进行测定.  

粉煤灰吸附处理炼油污水中石油类物质的应用研究

以炼油污水气浮后用于冲灰为目的，对粉煤灰吸附炼油污水中的石油类物质进行了初步研究，主要研究了水灰比、与油水的混合时间、静置沉淀时间等因素对粉煤灰吸附石油类效率的影响。研究表明，水灰比对粉煤灰吸附石油类效率的影响最显著。通过正交试验法，找出了粉煤灰处理炼油污水的最优工艺参数组合，为指导现场工作提供了理论依据。同时对粉煤灰吸附处理炼油污水中石油类的性能进行了研究，证实在常温状态下粉煤灰对石油类的吸附等温线符合Freundlich方程。  

垃圾焚烧飞灰中二噁英类的研究概况

随着垃圾焚烧技术的推广应用,焚烧产生的污染越来越受关注,本文介绍了二噁英的检测方法、垃圾焚烧飞灰中二噁英的分布、影响因素及飞灰的处置和综合利用技术研究概况。  

Effects of leachant temperature and pH on leachability of metals from fly ash. A case study: Can thermal power plant, province of Canakkale, Turkey

Lignite powered electric generation plants result in increasing environmental problems associated with gaseous emissions and the disposal of ash residues. Especially, low quality coals with high ash content cause enormous quantities of both gaseous and solid fly ash emissions. The main problem is related to the disposal of fly ash, which, in many cases, contains heavy metals. It is known that toxic trace metals may leach when fly ash is in contact with water. In this study, fly ash samples obtained from the thermal power plant in the town of Can in Turkey were investigated for leachability of metals under different acidic and temperature conditions. The experimental results show that a decrease in pH of the leachant favors the extraction of metal ions from fly ash. A significant increase in the extraction of arsenic, cadmium, chromium, zinc, lead, mercury, and selenium ions from the ash is attributed to the instability of the mineral phases. These heavy metals concentrations increase with respect to increasing acidic conditions and temperature. Peak concentrations, in general, were found at around 30°C.  

Bioaccumulation and translocation of metals in the natural vegetation growing on fly ash lagoons: a field study from Santaldih thermal power plant, West Bengal, India

A field study was conducted in the fly ash lagoons of Santandih Thermal Power Plant located in West Bengal (India) to find out total, EDTA and DTPA extractable metals in fly ash and their bioaccumulation in root and shoot portion of the naturally growing vegetation. Fly ash sample has alkaline pH and low conductivity. The concentration of total Cu, Zn, Pb and Ni were found higher than weathered fly ash and natural soil, where as Co, Cd and Cr were found traces. Five dominant vegetation namely, Typha latifolia, Fimbristylis dichotoma, Amaranthus defluxes, Saccharum spontaenum and Cynodon dactylon were collected in the winter months (November–December). Bioaccumulation of metals in root and shoot portions were found varied significantly among the species, but all concentration were found within toxic limits. Correlation between total, DTPA and EDTA extractable metals viz. root and shoot metals concentration were studied. Translocation factor (TF) for Cu, Zn and Ni were found less than unity, indicates that these metals are immobilized in the root part of the plants. Metals like Mn have TF greater than unity. The study infers that natural vegetation removed Mn by phytoextraction mechanisms (TF > 1), while other metals like Zn, Cu, Pb and Ni were removed by rhizofiltration mechanisms (TF < 1). The field study revealed that T. latifolia and S. spontaenum plants could be used for bioremediation of fly ash lagoon.  

Impact of Fly Ash from Coal-Fired Power Stations in Delhi, with Particular Reference to Metal Contamination

Indraprastha Power Station (IPP Stn) and Rajghat Power House (RPH), owned by Delhi Electric Supply Undertaking, are both coal-fired power stations located on Ring Road in New Delhi. Ash content of the coal used ranges between 38–47%. The ash is collected in electrostatic precipitators which have an efficiency of 99.3% (IPP station), and 99.7% (RPH). There are instances of major dust pollution around the power stations from fly ash dispersal. The main method of disposal of fly ash from the power stations is by mixing with water, the resultant slurry is pumped through pipes to ash disposal ponds. The supernatant from these ponds is discharged into River Yamuna. Field studies have revealed large quantities of fly ash being deposited into the river. Local populations of Eichhornia crassipes have reduced dramatically between 1987–1995, with a marked reduction in the year 1994–1995. Field studies, conducted in January, 1995 have investigated the impact of fly ash dispersal in the Delhi region with particular reference to metal contamination. Elemental concentrations for a range of elements are determined by ICP-AES in fly ash and top soils along four transects from the power stations up to a distance of 8 km. The effects of fly ash leachates from the ash settling ponds on the river are determined by analyzing river overbank soils and vegetation for their elemental contents. It is concluded that fly ash dispersal from the stacks are a source of alkali, alkaline-earth and to some extent heavy metals in soils in the vicinity of the power stations, and enrichment of elements in river overbank soils are a result of discharge of fly ash leachates from ash disposal ponds. However, the impact from both these sources of metal contamination is not large enough to give cause for concern. Marked reduction in populations of Eichhornia crassipes downstream of the river where it receives leachates from the ash disposal ponds are attributed to turbidity of the ash pond leachates and metal toxicity. Elemental enrichment in the floodplain soils, as a result of fly ash particle deposition during monsoons, may enhance the horticultural value of these soils as is shown by a healthy cultivated crop of Brassica juncea.  

Prediction of Fly-Ash Dispersion in the Southern Black Sea: A Preliminary Modelling Study

The distribution of fly ash that is discharged in the form of slurry from a power plant situated on the southern coast of the Black Sea was simulated with a transport model that used the velocity fields produced by isopycnic modelling. It is shown that a significant amount of ash is deposited in the vicinity of the discharge location. The ash remaining in the water column settles in a manner dependent on the direction and intensity of the local current regime. Generally, summer and spring are found to be seasons when the circulation is weak and the ash dispersion is confined to the shore. The model results are conditional upon obtaining observational data for validation.  

Bioavailability of Metals in Fly Ash and Their Bioaccumulation in Naturally Occurring Vegetation: A Pilot Scale Study

A pilot scale study was conducted to find out the different forms of metals if fly ash (FA) and bioaccumulation of these metals in the naturally growing vegetation on FA dumps. The total, acid extractable, bioavailable and water soluble fraction of metals of Fe, Cu, Mn, Zn, Ni, Co and Pb, and their bioaccumulation coefficients (BAC) on naturally growing vegetation were determined. FA samples had a neutral pH, low electrical conductivity, low organic C and trace amounts of N and P. The relative abundance of total metals in FA were found in the order Fe ≤ ≤ Zn ≤ Ni ≤ Co ≤ Cu. The concentration of bioavailable (DTPA) metals depend on the type and nature of coal used in thermal power stations. In the water the extract solution, only Fe and Zn were found above detection limits. After one year only four species of naturally occurring herbaceous vegetation were found growing and Cynodon dactylon (grass) covered almost entire surface of the FA. Iron accumulated to the greatest extent in vegetation followed by Mn, Zn, Cu, Pb, Ni and Co. The sequence of BAC for different metals were Fe (202) ≤ Mn (90) ≤ Zn (63) ≤ Pb (49) ≤ Ni (41) ≤ Cu (24). The experimental study revealed that Cynodon grass could be used for remediation of fly ash without any amendments, as this grass species act as metal excluder type.  

Scatterscore: A Reconnaissance Method To Evaluate Changes In Water Quality

Water quality data collected in periodic monitoring programs are often difficult to evaluate, especially if the number of parameters is large, the sampling schedule varies, and values are of different orders of magnitude. The Scatterscore Water Quality Evaluation was developed to yield a quantitative score, based on all measured variables in periodic water quality reports, indicating positive, negative or random change. This new methodology calculates a reconnaissance score based on the differences between up-gradient (control) versus down-gradient (treatment) water quality data sets. All parameters measured over a period of time at two or more sampling points are compared. The relationship between the ranges of measured values and the ratio of the medians for each parameter produces a data point that falls into one of four sections on a scattergram. The number and average values of positive, negative and random change points is used to calculate a Scatterscore that indicates the magnitude and direction of overall change in water quality. The Scatterscore Water Quality Evaluation, a reconnaissance method to track general changes, has been applied to 20 sites at which coal utilization by-products (CUB) were used to control acid mine drainage (AMD).