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481.
Occurrence of organic contaminants in sewage sludges from eleven wastewater treatment plants, China 总被引:15,自引:0,他引:15
This study presents the occurrence of 43 semi-volatile organic compounds (SVOCs) listed as priority pollutants by both China and the United States Environmental Protection Agency, in sewage sludges collected from eleven wastewater treatment plants (WWTPs) of mainland and Hong Kong, China. Thirty-six SVOCs were detected by gas chromatography coupled with mass spectrometer (GC-MS) and at least 14 in each sample. The most abundant compounds were phthalic acid esters (PAEs) and polycyclic aromatic hydrocarbons (PAHs) with total concentrations ranging from 10 to 114mgkg(-1) dry weight (d.w.) (with a mean of 30mgkg(-1) d.w.) and from 1.4 to 33mgkg(-1)d.w. (with a mean of 16mgkg(-1) d.w.), respectively, followed by chlorobenzenes, nitroaromatics, haloethers and halogenated hydrocarbons which occurred generally at concentrations lower than 10mgkg(-1) d.w. Large variations were observed between the concentrations of individual compounds as well as their total concentrations in sludge samples from different WWTPs. The highest values of sum concentration of 16 PAHs and of 6 PAEs were found in sewage sludge from Beijing. The mean total concentration of each class of SVOCs in sewage sludge from mainland was remarkably higher than that from Hong Kong. The concentrations of di(2-ethylhexyl) phthalate in 91% sludge samples met the limit (100mgkg(-1)d.w.) proposed by the Europe Union for land application, whereas the PAH concentrations of 64% sludge samples exceeded the maximum permissible concentration (6.0mgkg(-1)d.w.). The occurrence of SVOCs in this study are compared with other studies and their sources are discussed. 相似文献
482.
Technical developments have now made it possible to emplace granular zero-valent iron (Fe(0)) in fractured media to create a Fe(0) fracture reactive barrier (Fe(0) FRB) for the treatment of contaminated groundwater. To evaluate this concept, we conducted a laboratory experiment in which trichloroethylene (TCE) contaminated water was flushed through a single uniform fracture created between two sandstone blocks. This fracture was partly filled with what was intended to be a uniform thickness of iron. Partial treatment of TCE by iron demonstrated that the concept of a Fe(0) FRB is practical, but was less than anticipated for an iron layer of uniform thickness. When the experiment was disassembled, evidence of discrete channelised flow was noted and attributed to imperfect placement of the iron. To evaluate the effect of the channel flow, an explicit Channel Model was developed that simplifies this complex flow regime into a conceptualised set of uniform and parallel channels. The mathematical representation of this conceptualisation directly accounts for (i) flow channels and immobile fluid arising from the non-uniform iron placement, (ii) mass transfer from the open fracture to iron and immobile fluid regions, and (iii) degradation in the iron regions. A favourable comparison between laboratory data and the results from the developed mathematical model suggests that the model is capable of representing TCE degradation in fractures with non-uniform iron placement. In order to apply this Channel Model concept to a Fe(0) FRB system, a simplified, or implicit, Lumped Channel Model was developed where the physical and chemical processes in the iron layer and immobile fluid regions are captured by a first-order lumped rate parameter. The performance of this Lumped Channel Model was compared to laboratory data, and benchmarked against the Channel Model. The advantages of the Lumped Channel Model are that the degradation of TCE in the system is represented by a first-order parameter that can be used directly in readily available numerical simulators. 相似文献
483.
484.
浮萍生长及其除磷效率的影响因素的研究 总被引:2,自引:0,他引:2
磷是藻类增殖的限制因子,是引起水体富营养化的关键营养物质.有效除磷,能在很大程度上减轻水体的富营养化.利用浮萍科植物吸收转化污水中的营养物质引起了越来越多研究者的关注,但对浮萍科植物除磷效果的影响因素的研究相对较少.以少根紫萍(Spirodela oligorrhiza)为供试材料,以完全培养液为处理对象,研究了培养液pH、少根紫萍初始放养密度对其生长及除磷效率的影响.结果表明:少根紫萍能够耐受的最低pH在4左右,在pH=5~9能正常生长,在pH=6~8具有较高的TP去除率,最高去除率可达84.1%;少根紫萍的相对增长率随其初始放养密度的增加而降低,但其鲜重增长量、平均增长速率、TP去除率及平均TP去除速率均随着初始放养密度的增加而增加. 相似文献
485.
486.
在白银露天矿污染气象站五年的污染气象观测基础上,分析了采场粉尘浓度与污染源强度和气象因素之间的相关性,提出了粉尘污染预报的模式和方法,其准确率达到66.9%。并以粉尘污染预报模式为依据。提出了污染源控制管理模式。试验表明利用本模式对污染源实施控制管理具有实用意义和价值。 相似文献
487.
活性碳纤维在环境保护的应用 总被引:6,自引:0,他引:6
蔡体凯 《城市环境与城市生态》1992,5(3):44-47
活性碳纤维与普通活性碳相比,具有微孔多、孔径分布窄、比表面积大、吸附和脱附速度快,可制成纱、布、毡等形式,是吸附性、机械性能较好的新型吸附材料.可以广泛用于溶剂回收、脱臭装置、废水、废气处理、防毒面具等.活性碳纤维装置重量轻、占地少,回收溶剂质量高、操作简易,很有发展前途. 相似文献
488.
489.
Performance of Trickle-Bed Air Biofilter: A Comparative Study of a Hydrophilic and a Hydrophobic Voc
Two lab-scale trickle-bed air biofilters were operated for investigating the difference in performance between a hydrophilic
and a hydrophobic volatile organic compound (VOC). Methyl isobutyl ketone (MIBK) and styrene were selected as a model hydrophilic
and hydrophobic VOCs, respectively. Effects of loading rates, biofilter re-acclimation, removal profile along biofilter depth,
nitrogen consumption, and CO2 production were compared under three operating conditions, namely, backwashing and two non-use periods (starvation and stagnant).
Consistent over 99% removal efficiency up to loading rates of 3.26 kg COD/m3-day was obtained for the MIBK biofilter at 0.76 min empty bed retention time (EBRT) and 1.5 L/d nutrient flow. A similar
performance for the styrene biofilter was obtained for loading rates up to 1.9kg COD/m3-day at 2.02 min EBRT and 2.4 L/d nutrient flow. The MIBK biofilter required only an initial acclimation period of 16 days
while styrene biofilter required 46 days. Non-use periods can be used as another means of biomass control for both biofilters
when the employed loading rate did not exceed 1.27 and 2.17 kg COD/m3-day for styrene and MIBK biofilters, respectively. The re-acclimation of both biofilter was delayed with increase of loading
rate. MIBK biofilter re-acclimated in 90 min, while styrene biofilter re-acclimated in more than 600 min. Under similar loading
rates, MIBK biofilter utilized less biofilter depth than styrene biofilter. Nitrogen consumption behaviors were apparently
different between the two biofilters. Styrene biofilter had higher CO2 production than MIBK biofilter and its CO2 production was closely related to the theoretical complete chemical oxidation. 相似文献
490.
通过对溜矿井卸矿点产尘及其特点的研究 ,提出了一种独特的防尘思维模式 ,并有针对地设计出一种自净式喷雾装置 ,适用效果良好。 相似文献