复合固化剂固化淤泥的耐久性和稳定性研究
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摘要
为解决水泥对含有机质和重金属污染物的淤泥固化效果不佳的问题,提出采用水泥、生石灰、高铁酸钾和高分子吸水树脂作为复合固化剂对淤泥进行固化处理的方法。通过干湿循环试验和渗出液试验,从固化淤泥平均累计相对质量损失率、无侧限抗压强度和固化淤泥渗出液中重金属离子浓度等指标的变化,探究了复合固化剂对固化淤泥耐久性和稳定性的影响。试验结果表明:增加水泥掺量在一定程度上能提高固化淤泥的强度、改善固化淤泥的耐久性和固化淤泥中重金属的稳定性,但仅掺入水泥难以达到理想的固化效果;而掺入复合固化剂的固化淤泥,在干湿循环作用下能保证整体的完整性,其平均累计相对质量损失率仅为3.89%,无侧限抗压强度相比28d养护的试样提高了4.1%;在渗流作用下,掺入复合固化剂的固化淤泥末次渗出液中未检出Pb离子,而Cu、Zn离子的浓度仅为初次渗出液中的15.24%和2.25%,表明复合固化剂克服了因化淤泥体系酸碱度变化的影响,通过包裹作用和络合作用稳定了淤泥中的重金属离子,有效地降低了固化淤泥渗出液中Cu、Zn、Pb离子的浓度。
In order to solve the problem that cement has poor solidification effect on sludge containing organic matters and heavy metal pollutants,this paper uses cement,quick lime,potassium ferrate and super absorbent resin as composite stabilizer to solidify sludge.The paper conducts the wetting-drying cycle test and the exudative fluid test to investigate the effect of composite stabilizer on durability and stability of solidified sludge by measuring the average cumulative relative mass loss rate and the unconfined compressive strength of solidified sludge,and heavy metal ion concentration in the solidified sludge exudate.The experimental results show that increasing the cement content can improve the strength of solidified sludge,the durability of solidified sludge and the stability of heavy metals in solidified sludge,but it is difficult to achieve the desired solidify effect only by adding cement.After wet and dry cycles,the average cumulative mass loss rate of sludge mixed with composite stabilizer is 3.89%,and unconfined compressive strength of the solidified sludge increases 4.1%in comparison to the 28-day cured sample.Besides,after multiple exudation,lead ions in the final exudative fluid of sludge treated bycomposite stabilizer fail to check out,while the concentrations of copper and zinc ions are only 15.24%and 2.25%in comparison to the initial exudative fluid.It is indicated that the composite stabilizer overcomes the influence of the pH change of the solidified sludge system;the heavy metal ions in the sludge are stabilized by the encapsulation and complexation,and the concentration of Cu,Zn and Pb ions in the solidified sludge exudate is effectively reduced.
In order to solve the problem that cement has poor solidification effect on sludge containing organic matters and heavy metal pollutants,this paper uses cement,quick lime,potassium ferrate and super absorbent resin as composite stabilizer to solidify sludge.The paper conducts the wetting-drying cycle test and the exudative fluid test to investigate the effect of composite stabilizer on durability and stability of solidified sludge by measuring the average cumulative relative mass loss rate and the unconfined compressive strength of solidified sludge,and heavy metal ion concentration in the solidified sludge exudate.The experimental results show that increasing the cement content can improve the strength of solidified sludge,the durability of solidified sludge and the stability of heavy metals in solidified sludge,but it is difficult to achieve the desired solidify effect only by adding cement.After wet and dry cycles,the average cumulative mass loss rate of sludge mixed with composite stabilizer is 3.89%,and unconfined compressive strength of the solidified sludge increases 4.1%in comparison to the 28-day cured sample.Besides,after multiple exudation,lead ions in the final exudative fluid of sludge treated bycomposite stabilizer fail to check out,while the concentrations of copper and zinc ions are only 15.24%and 2.25%in comparison to the initial exudative fluid.It is indicated that the composite stabilizer overcomes the influence of the pH change of the solidified sludge system;the heavy metal ions in the sludge are stabilized by the encapsulation and complexation,and the concentration of Cu,Zn and Pb ions in the solidified sludge exudate is effectively reduced.
引文
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[23]Chen H,Wang A.Adsorption characteristics of Cu(II)from aqueous solution onto poly(acrylamide)/attapulgite composite[J].Journal of Hazardous Materials,2009,165(1/2/3):223-230.
[2]Maherzi W.Dredged marine sediments geotechnical characterisation for their reuse in road construction[J].Engineering Journal,2014,18(4):27-37.
[3]Tribout C,Husson B,Nzihou A.Use of treated dredged sediments as road base materials:Environmental assessment[J].Waste&Biomass Valorization,2011,2(3):337-346.
[4]Banoune B,Melbouci B,Rosquo3t F,et al.Treatment of river sediments by hydraulic binders for valorization in road construction[J].Bulletin of Engineering Geology&the Environment,2016,75(4):1-13.
[5]Alpaslan B,Yukselen M A.Remediation of lead contaminated soils by stabilization/solidification[J].Water Air&Soil Pollution,2002,133(1/2/3/4):253-263.
[6]范昭平,朱伟,张春雷.有机质含量对淤泥固化效果影响的试验研究[J].岩土力学,2005,26(8):1327-1330.
[7]Yin C Y,Mahmud H B,Shaaban M G.Stabilization/solidification of lead-contaminated soil using cement and rice husk ash[J].Journal of Hazardous Materials,2006,137(3):1758-1764.
[8]陈蕾,刘松玉,杜延军,等.水泥固化重金属铅污染土的强度特性研究[J].岩土工程学报,2010,32(12):1898-1903.
[9]Li J S,Xue Q,Wang P,et al.Effect of drying-wetting cycles on leaching behavior of cement solidified lead-contaminated soil[J].Chemosphere,2014,117(1):10-13.
[10]王东星,徐卫亚.大掺量粉煤灰淤泥固化土的强度与耐久性研究[J].岩土力学,2012,33(12):3659-3664.
[11]朱伟,林城,李磊,等.以膨润土为辅助添加剂固化/稳定化污泥的试验研究[J].环境科学,2007,28(5):1020-1025.
[12]李磊,朱伟,林城,等.干湿循环条件下固化污泥的物理稳定性研究[J].岩土力学,2009,30(10):3001-3004.
[13]郭印,徐日庆,邵允铖.淤泥质土的固化机理研究[J].浙江大学学报(工学版),2008,42(6):1071-1075.
[14]Goodarzi A R,Zandi M H.Assessing geo-mechanical and leaching behavior of cement-silica-fume-stabilized heavy metal-contaminated clayey soil[J].Environmental Earth Sciences,2016,75(10):1-17.
[15]南京水利科学研究院.土工试验规程:SL237-1999[S].北京:中国水利水电出版社,1999.
[16]Sharma V K.Potassium ferrate(VI):An environmentally friendly oxidant[J].Advances in Environmental Research,2002,6(2):143-156.
[17]Flory P J.Principles of Polymer Chemistry[M].New York:Cornell University Press,1953.
[18]American Society for Testing and Materials.Standard Test Method for Wetting and Drying Test of Solid Wastes:ASTMD4843-1988[S].Philadephta:ASTM Press,1988.
[19]孔祥明,张珍林.高吸水性树脂对高强混凝土自收缩的减缩机理[J].硅酸盐学报,2014,42(2):150-155.
[20]何振立.污染及有益元素的土壤化学平衡[M].北京:中国环境科学出版社,1998.
[21]Olmo I F,Chacon E,Irabien A.Influence of lead,zinc,iron(III)and chromium(III)oxides on the setting time and strength development of Portland cement[J].Cement&Concrete Research,2001,31(8):1213-1219.
[22]蓝俊康,王焰新.利用复合水泥固化Pb2+的机理探讨[J].硅酸盐通报,2005,24(4):10-15.
[23]Chen H,Wang A.Adsorption characteristics of Cu(II)from aqueous solution onto poly(acrylamide)/attapulgite composite[J].Journal of Hazardous Materials,2009,165(1/2/3):223-230.
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