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151.
152.
采用内电解—Fenton氧化—絮凝沉淀的化学集成技术预处理焦化废水,优化了各工段的运行参数。实验结果表明:在钢铁铁屑与活性炭的体积比为1∶1的条件下,内电解工段的优化参数为进水pH 2.6~3.1、HRT=1.0 h;Fenton氧化工段的优化参数为Fe2+加入量200 mg/L、H2O2加入量1 000 mg/L、进水pH 3.0左右、反应时间1.0 h;絮凝沉淀工段的设定参数为进水pH 9.5~10.0、聚丙烯酰胺加入量1 mg/L、静置沉降0.5 h。在上述工艺条件下,该集成技术对废水的总COD去除率大于55%,处理后的废水BOD5/COD大于0.28,不添加稀释新水即可进入后续生化处理系统。该工艺占地面积小、系统结构简单、易于工业化,废水预处理成本为4~5元/t。 相似文献
153.
Mercury concentrations are usually significant in historic Hg mining districts all over the world, so the atmospheric environment is potentially affected. In Asturias, northern Spain, past mining operations have left a legacy of ruins and Hg-rich wastes, soils and sediments in abandoned sites. Total Hg concentrations in the ambient air of these abandoned mine sites have been investigated to evaluate the impact of the Hg emissions. This paper presents the synthesis of current knowledge about atmospheric Hg contents in the area of the abandoned Hg mining and smelting works at ‘La Peña–El Terronal’ and La Soterraña, located in Mieres and Pola de Lena districts, respectively, both within the Caudal River basin. It was found that average atmospheric Hg concentrations are higher than the background level in the area (0.1 μg Nm?3), reaching up to 203.7 μg Nm?3 at 0.2 m above the ground level, close to the old smelting chimney at El Terronal mine site. Data suggest that past Hg mining activities have big influences on the increased Hg concentrations around abandoned sites and that atmospheric transfer is a major pathway for Hg cycling in these environments. 相似文献
154.
Lu LT Chang IC Hsiao TY Yu YH Ma HW 《Environmental science and pollution research international》2007,14(1):49-59
Background Since the 1970s, at least 200 hectares (ha) of farmland has been polluted by the heavy metal cadmium (Cd).Consequently, the
Cd pollution has led to contaminate the rice production and caused acute social panic. According to the recent investigation
results performed by the Taiwan Environmental Protection Administration (TEPA), it is indicated that most of the Cd pollution
incidents in Taiwan resulted from the wastewater discharge of stearate Cd factories. To prevent the Cd pollution incidents
from spreading, the TEPA has either forced these factories to close down or assisted them in improving their production processes
since the 1980s. Unfortunately, accidental incidents of Cd pollution still emerge in an endless stream, despite the strict
governmental controls placed on these questionable factories. Whether this pollution has resulted from undetected or hidden
pollution sources stemming from two decades ago or comes from some new source, will be an outstanding issue. Therefore, this
study attempts to identify the pollution sources of Cd in soil in Taiwan as well as to find the solution to the above-mentioned,
outstanding issue by way of a methodology termed Material Flow Analysis (MFA).
Method logy. The MFA has proved to be a useful tool on providing quantitative information of the flow of substances through an economic
to an environmental system. Based upon the supply-and-demand theory of MFA, researchers have successfully conducted an overview
of the use of materials in many industries, the construction industry being one of these. Therefore, this study tries to establish
a set of analytical processes by way of MFA for identifying the pollution source of Cd in soil in Taiwan. In addition, the
spirit of Life Cycle Analysis (LCA) technique was also employed to identify the materials, and products should be ignored
as a crucial pollution source in this study.
Results and Discussion According to the MFA methodology applied in this study and on the basis of related studies performed by Taiwanese governmental
authorities, we arrive at the following analysis results: (1) the total amount of Cd from the economic perspective of material
and product flow was approximately 441.2 tons; (2) the wastewater directly discharged into irrigation water can be concluded
to be the major pollution route of Cd in farmland soil in Taiwan; (3) material plastic stabilizer (cadmium oxide, CdO), Zn-Pd
compounds and Cu compounds should be the crucial pollution sources to contaminate environment through the route of wastewater
in Cd flow analysis; (4) the crucial pollution sources to contaminate environment through the route of wastewater in Cd flow
analysis were five factories, Coin, Jili, Taiwan Dye, Guangzheng and Mingguan, and they were all categorized as stearate Cd
industries; (5) the typical source of the Cd pollution in soil in Changhua County through the pollution route of wastewater
should be the metal surfacing process industries.
Conclusions This study proved that MFA can be a good tool for identifying Cd flow as well as for recognizing the crux of the problem
concerning incidents of Cd pollution. This study led to the conclusion that the causal relationship between farmland pollution
caused by Cd and stearate Cd factories in Taiwan seemed quite close by way of MFA methodology. In addition, this study also
found that the wastewater discharged from a single metal surfacing process factory will not cause remarkable farmland pollution.
However, the wastewater simultaneously discharged from a group of pollution factories can result in a significant pollution
incident.
Recommendations and Outlook This case study is only a small contribution to the understanding of the toxic material flow related to Cd in the environment.
This study recommends that Taiwanese governmental authorities should not deal with problems on an ad hoc basis, but should
instead deal with Cd pollution problems overall employing control measures. Finally, the more accurate information or data
we can collect, the more reliable results we can identify. Therefore, the quality and quantity of related data used in this
MFA model should be closely scrutinized in order to ensure the most correct and comprehensive investigation on the toxic material
flow. 相似文献
155.
为探索焦化废水深度处理新途径,采用了焦粒、活性炭负载Mn(NO3)2和Zn(NO3)2化合物粒子电极为第3极的三维电极反应器对二级生化处理后的焦化废水进行深度处理。考察了焦化废水中有机物去除的影响因素及处理效果,并探讨了有机物的降解动力学。结果表明,以焦粒为载体的粒子电极三维电极系统在pH为6.5,电导率为4 580μS/cm,电流密度为16 mA/cm2,投加量大于25 g/L时,降解20 min,COD去除率超过35%以上。焦化废水的降解的动力学研究表明,焦化废水降解符合表观一级反应动力学规律。该研究可为三维电极反应器在焦化废水深度处理工程应用中提供参数依据。 相似文献
156.
焦化废水处理过程外排污泥中重金属形态特征及其潜在环境风险 总被引:1,自引:0,他引:1
焦化废水处理过程所排放污泥中重金属的含量及化学形态是否构成环境风险将直接影响污泥处置方法的选择,为此,实验采用BCR顺序提取法分析了焦化废水处理站外排污泥中重金属(Cd、Hg、Pb、Cr、As、Ni、Zn、Cu和Mn)的形态特征,并采用地累积指数(Igeo)和潜在生态危害指数(RI)评价了重金属对土壤的潜在环境风险。研究结果表明:除Ni主要以可氧化态存在外,焦化废水外排污泥中其他几种重金属元素主要存在于残渣态,重金属元素的含量低于《城镇污水处理厂污染物排放标准(GB18918—2002)》中的控制限值;与城市污泥相比,焦化废水外排污泥具有低Pb、Cr、Zn、Cu含量,而高Cd、Hg、Mn含量的特点;基于Igeo和RI的评价结果,Cd和Hg是外排污泥中具有一定环境风险的元素,需要考虑其下游去向。焦化废水处理外排污泥中主要存在残渣态重金属成分,不表现为很高的环境风险,其处置应重点考虑其中有机污染物特别是POPs。 相似文献
157.
废弃油基钻井液热化学破乳-离心分离实验 总被引:5,自引:1,他引:4
废弃油基钻井液是一种含油量较高的油包水稳定体系,具有回收利用价值。采用热化学破乳-离心分离的方法,考察了破乳剂加量、破乳温度、离心机转速、破乳时间、离心时间和破乳剂浓度对废弃油基钻井液分离的影响。通过实验确定了破乳效果最好的破乳剂为巴斯夫L62,并对热化学破乳-离心分离废弃油基钻井液的影响因素进行了优化实验研究。实验结果表明,在破乳剂加量300 mg/L、离心机转速8 000 r/min、破乳温度80℃、破乳时间3 h、离心时间25 min和破乳剂质量浓度0.25%的条件下,热化学破乳-离心法处理废弃油基钻井液的脱水率达75%、脱油率达72.73%。热化学破乳-离心分离方法回收废弃油基钻井液中的油具有潜在的应用价值。 相似文献
158.
对我国当前焦化废水深度处理技术的研究应用情况以及回用现状进行了介绍,分析了焦化废水回用中存在的问题,并提出了改进方案。 相似文献
159.
160.
钢结构厂房在工业企业中应用广泛,但由于其耐火能力差,近年来发生了多起钢结构厂房在火灾中倒塌导致多人伤亡的事故。从钢结构建筑防火设计和防火管理的角度出发,分析了影响钢结构厂房抗火灾能力的主要因素,发现变更使用条件是导致钢结构建筑消防能力不足的重要原因。建议钢结构建筑管理方改变管理模式,实施主动地火灾风险管理,并不断提升专业水平以满足特性火灾风险管理的需求。另外,将企业风险管理方法引入火灾风险管理中,提出实施火灾风险管理的流程,并就管理操作中的重点内容进行分析,希望对钢结构火灾风险管理的系统分析和具体实施提供帮助。 相似文献