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饮用水除氟技术及其机理 总被引:2,自引:0,他引:2
综述了近年来国内外饮用水除氟技术,如沉淀法、吸附法、离子交换法、电凝聚法、电渗析法、反渗透法等,同时讨论了各种除氟方法的机理及研究进展. 相似文献
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采用小试规模的流化床反应器处理氟质量浓度为500~1 400 mg/L的模拟高浓度含氟废水。以氟化钙颗粒为晶种,以氯化钙溶液为沉淀剂(流量25 L/h),考察了流化床连续运行过程中沉淀除氟的效率和稳定性。实验结果表明:氟化钙的沉淀反应在30.7 s内即可完成;在废水流量为11~23 L/h、反应pH为7.0~9.0、上升流速为0.005 9~0.013 0 m/s、钙与氟的摩尔比为0.85~1.00的条件下,出水清液中氟质量浓度低于10 mg/L,达到《污水综合排放标准》(GB 8978—1996)要求。连续运行过程中,流化床沉淀除氟高效稳定,操作条件范围较宽。流化床出水中细颗粒沉淀物的存在会导致氟浓度显著升高,应采取有效措施减少其产生或溢出,以保证沉淀除氟效率。 相似文献
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淮北电厂灰场排水氟含量11.3~16.1mg/L,略有超标。为解决氟超标问题,对所用原煤、除尘器排水及除灰系统沿程氟含量作了测试调查,并用调整文丘里除尘器喷淋水压和燃用煤种比例以及向灰水中添加药剂等办法寻求可能的治理途径。 相似文献
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《化工环保》2018,(6)
采用CaCl_2和纳米SiO_2-聚硅酸铝铁复合混凝剂对含氟废水进行两步除氟。实验结果表明:ρ(F-)为420.0 mg/L、pH为8.5的含氟废水经CaCl_2处理后ρ(F-)降至26.5 mg/L;在二级除氟pH为11.5、复合混凝剂加入量(复合混凝剂与废水体积比)为0.50%的最佳条件下处理60 min后废水中ρ(F-)降至5.7 mg/L,而采用聚合氯化铝(PAC)进行二级除氟时,ρ(F-)可降至8.7 mg/L,表明复合混凝剂比PAC的除氟效果更佳。复合混凝剂中自由离子和单体羟基配合物形态Al和Fe的含量相对较高,分别占76.5%和92.5%,而低聚合度的多核羟基配合物及高聚物形态Al和Fe的含量相对较低。 相似文献
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采用CaCl2和纳米SiO2-聚硅酸铝铁复合混凝剂对含氟废水进行两步除氟。实验结果表明:ρ( F–)为 420.0 mg/L、pH为8.5的含氟废水经CaCl2处理后ρ( F–)降至26.5 mg/L;在二级除氟pH为11.5、复合混凝剂加入量(复合混凝剂与废水体积比)为0.50%的最佳条件下处理60 min后废水中ρ( F–)降至5.7 mg/L,而采用聚合氯化铝(PAC)进行二级除氟时,ρ( F–)可降至8.7 mg/L,表明复合混凝剂比PAC的除氟效果更佳。复合混凝剂中自由离子和单体羟基配合物形态Al和Fe的含量相对较高,分别占76.5%和92.5%,而低聚合度的多核羟基配合物及高聚物形态Al和Fe的含量相对较低。 相似文献
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Concentrations and total quantity of cadmium (Cd), cupper (Cu),lead (Pb) and zink (Zn) were determined in biomass and soil compartments in a replicated tree species experiment with 27-yr-old stands growing on former farmland in N.E. Sweden. Sequentialextractions of soil samples were performed in order to estimate the exchangeable and an organically bound fraction of each element. The tree species included were Picea abies (L.)H. Karst., Pinus sylvestris L., Pinus contorta Dougl., Larix sibirica Ledeb., and Betula pendula Roth.Tree species influenced the rate of removal of Cu, Pb and Zn incase of stemwood harvesting, and of Cd, Cu and Zn in the case ofwhole-tree harvesting. B. pendula and P. abies had higher quantities and average concentrations of Zn in the biomass. For all species, >50% of the Zn in the stems was found in the bark. P. abies and L. sibirica had higher quantities of Cu in the biomass than the other species.P. abies and P. contorta had high quantities of Cd inthe biomass in relation to the other species. Branches and stembark contained high concentrations of Cd and Pb in relation to foliage and stemwood. Dead branches had especially high concentrations of Pb. The high accumulation rate of Zn in thebiomass of B. pendula was related to a low exchangeable amount of Zn in the A horizon. In the superficial centimeters ofthe A horizon, a depletion similar to that found for Zn was detected for Cu, whereas for Cd and Pb, no correlations were found between quantities of elements in the trees and element pools in the soil. 相似文献
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Bioassessment of silvicultural impacts in streams and wetlands of the Eastern United States 总被引:1,自引:0,他引:1
John J. Hutchens Jr. Darold P. Batzer Elizabeth Reese 《Water, Air, & Soil Pollution: Focus》2004,4(1):37-53
Bioassessment is a useful tool to determine the impact of logging practices on the biological integrity of streams and wetlands. Measuring biota directly has an intuitive appeal for impact assessment, and biota can be superior indicators to physical or chemical characteristics because they can reflect cumulative impacts over time. Logging can affect stream and wetland biota by increasing sedimentation rates, altering hydrologic, thermal, and chemical regimes, and changing the base of food webs. Biotic impacts of logging on streams compared to wetlands probably differ, and in this paper we review some of those differences. In streams, invertebrates, fishes, amphibians, algae, and macrophytes have been used as indicators of logging impacts. In wetlands, bioassessment is just beginning to be used, and plants and birds are the most promising indicator taxa. Various best management practices (BMPs) have been developed to reduce the impacts of logging on stream and wetland biota, and we review quantitative studies that have evaluated the efficacy of some of these techniques in streams and wetlands in the eastern United States. Remarkably few studies that address the overall efficacy of BMPs in limiting biotic changes in streams and wetlands after BMP implementation have been published in scientific journals, although some work exists in reports or is unpublished. We review these works, and compile conclusions about BMP efficacy for biota from this body of research. 相似文献
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Starch granules were modified with trisodium trimetaphosphate (TSTP) and characterized by P31-NMR, FTIR and DSC. Seventy-micron films were prepared from modified starch and polycaprolactone blends by solvent casting technique. Three different types of films—PCL (100% polycaprolactone), MOD-ST/PCL (50% modified starch and 50% polycaprolactone blend) and NONMOD-ST/PCL (50% nonmodified starch and 50% polycaprolactone blends)—were prepared, and their thermal, mechanical, and morphologic properties were investigated to show the increased performance of PCL with the addition of starch and also the effect of modification. It was observed that with the addition of starch the Young's modulus of polycaprolactone was increased and became less ductile, whereas tensile strength and elongation at break values decreased. Biodegradation of these films was inspected under different aerobic environments with the presence of Pseudomonas putida, activated sludge, and compost. It was observed that whereas P. putida had almost no effect on degradation during 90 days, with the presence of activated sludge, considerable deformation of films was observed even in the first 7 days of degradation. In a compost environment, degradation was even faster, and all polymer films were broken into pieces within first 7 days of degradation and no film remained after 15 days. 相似文献
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Peter H. Doering Barbara K. Sullivan Heeseon Jeon 《Journal of Polymers and the Environment》1994,2(4):271-275
We examined the metabolic response of an estuarine benthic community to additions of three materials being considered for use in manufacture of biodegradable substitutes for plastics. Diver-collected cores containing benthos were dosed with 59 g/m2 of three test materials, cornstarch, a bacterial polyester (PHBV), and ethylene vinyl alcohol (EVOH), or left undisturbed as controls. Fluxes of dissolved nutrients (ammonia, nitrate + nitrite, phosphate, silica) and dissolved inorganic carbon (DIC) were similar in control cores and cores dosed with EVOH during a 1-month test period at 20°C. Fluxes in cores dosed with starch and PHBV differed significantly from controls but not from each other. After 2 weeks of incubation, production of DIC was higher in cores containing starch and PHBV, while efflux of ammonia, nitrate, and nitrite was reduced. After 4 weeks of incubation, production of DIC was similar among all treatments and controls, while efflux of ammonia was high in the starch- and PHBV-containing cores compared to controls and cores with EVOH. Fluxes of silica and phosphate were similar in all cores during the experiment. These results indicate that both starch and PHBV are carbon-rich substrates readily metabolized by the benthic community but that their presence significantly alters normal nutrient exchange patterns. This response is expected because of the high carbon-to-nitrogen ratio of starch and PHBV and indicates that impacts of these two materials would be similar. However, the high biological oxygen demand of such materials and resulting disturbance of normal nutrient regeneration patterns of the benthos (delayed ammonia efflux and potential stimulation of denitrification) must be considered in developing strategies for their disposal.Paper presented at the Biodegradable Materials and Packaging Conference, September 22–23, 1993, Natick, Massachusetts. 相似文献
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The solubility and potential mobility of heavy metals (Cd, Cu,Hg, Pb and Zn) in two urban soils were studied by sequential andleaching extractions (rainwater). Compared to rural (arable) soils on similar parent material, the urban soils were highlycontaminated with Hg and Pb and to a lesser extent also with Cd,Cu and Zn. Metal concentrations in rainwater leachates were related to sequential extractions and metal levels reported fromStockholm groundwater. Cadmium and Zn in the soils were mainly recovered in easily extractable fractions, whereas Cu and Pb were complex bound. Concentrations of Pb in the residual fractionwere between two- and eightfold those in arable soils, indicatingthat the sequential extraction scheme did not reflect the solidphases affected by anthropogenic inputs. Cadmium and Zn conc. inthe rainwater leachates were within the range detected in Stockholm groundwater, while Cu and Pb conc. were higher, whichsuggests that Cu and Pb released from the surface soil were immobilised in deeper soil layers. In a soil highly contaminatedwith Hg, the Hg conc. in the leachate was above the median concentration, but still 50 times lower than the max concentration found in groundwater, indicating the possibilityof other sources. In conclusion, it proved difficult to quantitatively predict the mobility of metals in soils by sequential extractions. 相似文献
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P. J. Murray D. J. Hatch E. R. Dixon S. Granger C. OPrey R. J. Stevens R. J. Laughlin S. C. Jarvis 《Water, Air, & Soil Pollution: Focus》2004,4(6):45-52
Much work has been done on gaseous emissions and leaching of nitrogenous compounds from whole soil profiles and also from soil surface measurements which are assumed to be mainly due to topsoil activity. In soils with an impervious clay subsoil, the boundary between the topsoil and subsoil may provide an interface for microbial activity, including N transformations. In this study, we investigated movement and transformations of two reactive N species (nitrate and urea) at the subsoil interface using a series of replicate, intact soil blocks, under two contrasting watering regimes. We measured fluxes in both liquid and gaseous phases and demonstrated that nitrate reaching the subsoil interface does not necessarily leach into water systems, but may denitrify immediately and could, therefore, add to atmospheric pollution through N2O production. On the other hand, ammonium reaching the subsoil interface either directly, or after mineralization, appears to be more mobile than expected and has the potential to pollute watercourses. 相似文献
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利用工业碱木质素分别经KOH及H3PO4活化制备两种木质素活性炭(KAC和PAC),并用于模拟硝基苯废水的处理。采用SEM和IR等手段对木质素活性炭进行了表征。考察了木质素活性炭加入量、废水pH、吸附时间等因素对硝基苯吸附量的影响。表征结果显示,KAC具有丰富的孔结构,PAC表面含有多种功能基团。实验结果表明: 在吸附温度298 K、初始硝基苯质量浓度250 mg/L、木质素活性炭加入量1.0 g/L、废水pH 3、吸附时间24 h的条件下,KAC及PAC对硝基苯的吸附量分别为237.8 mg/g和211.9 mg/g,去除率分别达到91%和84%; KAC及PAC对硝基苯的吸附过程符合拟二级动力学方程,吸附等温线满足Langmuir等温吸附方程;当解吸剂的V(乙醇)∶V(去离子水)=9时,在PAC和KAC上吸附的硝基苯的解吸率分别达到99%和93%;木质素活性炭重复使用5次后,KAC和PAC对硝基苯的吸附量分别为115.4 mg/g和130.7 mg/g。 相似文献
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Cecilia Akselsson Olle Westling Harald Sverdrup Johan Holmqvist Gunnar Thelin Eva Uggla Gunnar Malm 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):201-210
The effects of harvesting on the long-term mass balances of calcium (Ca), magnesium (Mg) and potassium (K) were evaluated
on a regional level in Sweden. A new high-resolution weathering database was used together with estimates of total deposition,
losses through harvest and leaching. Estimates were made for pine and spruce separately and for two harvesting intensity scenarios:
stem harvesting and whole-tree harvesting. The mass balance calculations showed net losses of Ca and Mg in almost the whole
country for both scenarios. The losses were smaller for pine than for spruce. The K balances were mainly positive for pine
but negative for spruce. Leaching was a main factor in the mass balances, especially for Ca and Mg. Whole-tree harvesting
in spruce forests led to substantially higher net losses of K and Ca than stem harvesting, according to the calculations.
In the whole-tree harvesting scenario in spruce forests the estimated yearly net losses of Ca, Mg and K corresponded to at
least 5%, 8% and 3% of the pools of exchangeable base cations, respectively, at 25% of the analysed sites. If losses of this
magnitude continue the depletion of the pools of Ca, Mg and K may lead to very low base saturation of the soils, possibly
accompanied by negative effects on soil fertility, runoff water quality, tree vitality and tree growth within a forest rotation
in parts of Sweden. Avoiding whole-tree harvesting can improve the situation substantially for K, but the losses of Ca and
Mg will still be significant. 相似文献
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采用电动力修复技术处理Pb、Cd复合污染土壤,考察了柠檬酸和乙二胺四乙酸二钠(EDTA)作为电解液对棕壤(ZR)和红壤(HR)两种我国典型壤质中Pb、Cd去除效果的影响。实验结果表明:在电压梯度为2 V/cm,修复时间为4 d的条件下,ZR的最佳电解液为EDTA,Pb、Cd平均去除率为13.2%和17.8%,HR的最佳电解液为柠檬酸,Pb、Cd的平均去除率为20.0%和33.8%;延长修复时间至10 d能显著提高HR中Pb、Cd的去除率,电解液为柠檬酸时Cd平均去除率达91.1%,电解液为EDTA时Pb平均去除率达63.2%,修复后土壤中Cd和Pb含量均低于建筑用地土壤污染风险筛选值。综合考虑能耗及修复效果,EDTA是高效且经济的修复电解液。 相似文献