固化重金属铜镉污染底泥渗透特性试验研究
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摘要
采用固化剂对含复合重金属铜镉污染底泥进行固化处理,对其渗透特性进行了研究。结果表明:在渗透液pH相同的条件下,重金属渗出量随着养护龄期的增加而减少;在相同的养护龄期条件下,Cu~(2+)在酸性条件下的渗出量大于在中性条件下的渗出量;Cd~(2+)在C—S—H凝胶固化中与HCO_3~-作用生成难溶于酸的Cd(HCO_3)_2化合物,使其渗出量较少。研究了不同污染物掺量对渗透系数k与污染物渗出总量的影响,得到Cu~(2+)掺量的质量分数小于等于0.75%,Cd~(2+)掺量的质量分数小于等于0.225%时,试样渗透系数k与污染物渗出总量同污染物掺量呈正相关;Cu~(2+)掺量的质量分数大于0.75%,Cd~(2+)掺量的质量分数大于0.225%时,其渗透系数k随着污染物掺量的增加反而减小。并通过扫描电镜分析了不同的污染物浓度对试样微观结构的影响,随着重金属浓度的提高,结构表面形成蜂窝状的重金属水化产物。
The curing agent was used to solidify the sludge contaminated by heavy metal Cu~(2+) and Cd~(2+),and its permeability property was studied. The testing results show that the amount of heavy metal in exudation fluid decreases with the increase of curing time under penetrant with the same pH value. The exudation of Cu~(2+) in acidic conditions is greater than that of neutral conditions under the same curing age. Based on the process of C—S—H gelation, Cd(HCO_3)_2 which is difficultly dissolved in acidic fluid is produced by Cd~(2+) and HCO_3~-. which leads to the few exudation amount of Cd~(2+). The effects of different amounts of heavy metals on the permeability coefficient k and the total exudation quantity of contaminants were investigated, which illustrates that the k and the total exudation concentration are positively related to the increased amount of pollutants when the mass fraction of Cu~(2+) is equal or less than 0.75% and the mass fraction of Cd~(2+) is equal or less than 0.225%. However, the k decreases with the increase of pollutant content when the mass fraction of Cu~(2+) is more than 0.75% and the mass fraction of Cd~(2+) is more than 0.225%. Besides, a scanning electron microscopy was used to analyze the effect of different pollutant concentration on the microstructure of the sample. With the increase of heavy metal concentration, on the structure surface form honeycomb heavy metal hydration products.
The curing agent was used to solidify the sludge contaminated by heavy metal Cu~(2+) and Cd~(2+),and its permeability property was studied. The testing results show that the amount of heavy metal in exudation fluid decreases with the increase of curing time under penetrant with the same pH value. The exudation of Cu~(2+) in acidic conditions is greater than that of neutral conditions under the same curing age. Based on the process of C—S—H gelation, Cd(HCO_3)_2 which is difficultly dissolved in acidic fluid is produced by Cd~(2+) and HCO_3~-. which leads to the few exudation amount of Cd~(2+). The effects of different amounts of heavy metals on the permeability coefficient k and the total exudation quantity of contaminants were investigated, which illustrates that the k and the total exudation concentration are positively related to the increased amount of pollutants when the mass fraction of Cu~(2+) is equal or less than 0.75% and the mass fraction of Cd~(2+) is equal or less than 0.225%. However, the k decreases with the increase of pollutant content when the mass fraction of Cu~(2+) is more than 0.75% and the mass fraction of Cd~(2+) is more than 0.225%. Besides, a scanning electron microscopy was used to analyze the effect of different pollutant concentration on the microstructure of the sample. With the increase of heavy metal concentration, on the structure surface form honeycomb heavy metal hydration products.
引文
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[2]高宜涛.重金属对水泥固化污染土工程性质影响的试验研究[D].太原:太原理工大学,2016.
[3]MALLIOU O,KATSIOTI M,GEORGIADIS A,et al.Properties of stabilized/solidified admixtures of cement and sewage sludge[J].Cement and Concrete Composites,2007,29(1):55-61.
[4]王志新,孙家瑛.城市污水污泥固结体重金属浸出毒性及路用性能研究[J].环境污染治理技术与设备,2005,6(12):86-89.
[5]WANG F,WANG H L,AL-TABBAA A.Leachability and heavy metal speciation of 17-year old stabilised/solidified contaminated site soils[J].Journal of Hazardous Materials,2014,278:144-151.
[6]张亚灿,赵仲辉,胡孝彭,等.固化淤泥渗透性的微观分析[J].科学技术与工程,2015,15(7):243-247.
[7]蒋宁俊,杜延军,刘松玉,等.酸雨入渗对水泥固化铅污染土淋滤特性的影响研究[J].岩土工程学报,2013,35(4):739-744.
[8]刘兆鹏,杜延军,蒋宁俊,等.基于半动态淋滤试验的水泥固化铅污染黏土溶出特性研究[J].岩土工程学报,2013,35(12):2212-2218.
[9]查甫生,郝爱玲,许龙,等.水泥固化重金属污染土的淋滤特性试验研究[J].工业建筑,2014,44(1):65-70.
[10]雄厚金,林天健,李宁.岩土工程化学[M].北京:科学出版社,2009.
[11]CUISINIER O,LE BORGNE T,DENEELE D,et al.Quantification of the effects of nitrates,phosphates and chlorides on soil stabilization with lime and cement[J].Engineering Geology,2011,117(3/4):229-235.
[12]KUMPIENE J,LAGERKVIST A,MAURICE C.Stabilization of As,Cr,Cu,Pb and Zn in soil using amendments——A review[J].Waste Management,2007,28(1):215-225.
[13]QIAO X C,POON C S,CHEESEMAN C R.Investigation into the stabilization/solidification performance of Portland cement through cement clinker phases[J].Journal of Hazardous Materials,2007,139(2):238-243.
[14]国家环境保护总局.GB 5085.3-2007危险废物鉴别标准浸出毒性鉴别[S].北京:中国环境出版社,2007.
[15]BENSTED J,BARNES P.Structure and performance of cements[M].2nd ed.London,U K:Taylor&Francis,2008.