含油污泥热解残渣制备渗水砖的重金属和多环芳烃浸出特性

Leaching characteristics of heavy metals and polycyclic aromatic hydrocarbons from permeable bricks prepared by pyrolysis residue of oily sludge

热解残渣作为含油污泥热解的伴生物,存量日益增多,严重威胁生态环境。含油污泥热解残渣的成分与黏土矿物类似,为此,利用热解残渣代替黏土制备渗水砖,探究制备过程中残渣添加量、加水量和挤压应力对渗水砖抗压强度和透水性能的影响以及对渗水砖浸出液中重金属和多环芳烃(PAHs)浓度的影响。分析结果表明,残渣添加量、加水量和挤压应力对渗水砖的抗压强度和透水性能有较大影响,当残渣添加量为15%、加水量为13%(以上均为质量分数)、挤压应力为30MPa时,渗水砖的物理性能最佳。此时,抗压强度为32.20MPa,达到Cc30等级标准;透水系数为1.80×10^(-2)cm/s,高于《透水砖》(JC/T 945—2005)中所规定的1.00×10^(-2)cm/s。重金属和PAHs浸出实验结果表明,渗水砖浸出液中检出的金属包括Cr、Pb、Cu、Ni和Zn,且Cr、Cu和Zn的浓度均低于《地表水环境质量标准》(GB 3838—2002)中所规定的Ⅱ类标准限值和《地下水质量标准》(GB/T 14848—2017)中所规定的Ⅲ类标准限值。残渣添加量、加水量和挤压应力对浸出液中Ni的影响较大,而对Cr的影响较小。渗水砖浸出液中主要检测出萘、苊、二氢苊、芴和菲这5种PAHs,总浓度范围为218.43~408.34μg/L。其中,苊是浸出液中的主要成分,其相对质量分布比例为59.80%~77.55%。本研究可为含油污泥热解残渣的无害化处理和资源化利用提供科学依据。

As a by-product of oil sludge pyrolysis,the stock of pyrolysis residue is increasing,which seriously threatens the ecological environment.Given that the composition of the pyrolysis residue of oily sludge was similar to that of clay minerals,in this study,pyrolysis residue was used to prepare water-permeating bricks instead of clay.The effects of pyrolysis residue addition amount,water amount and extrusion stress on the compressive strength and permeability of the prepared water-permeating bricks were investigated,and the concentration of heavy metals and polycyclic aromatic hydrocarbons(PAHs)in the leaching solution of permeated brick were also studied.The results show that the addition amount of pyrolysis residue,water amount and extrusion stress have significant impact on the compressive strength and permeability of the permeable brick.When the addition amount of pyrolysis residue is 15%,the amount of water is 13%and the extrusion stress is 30MPa,the physical properties of the permeable brick are the best.At this point,the compressive strength is 32.20MPa,reaching the Cc30 standard,and the permeable coefficient is 1.80×10^(-2)cm/s,which is higher than 1.00×10^(-2)cm/s specified in Water Permeable Brick(JC/T 945—2005).The leaching experiment results of heavy metals and PAHs show that the metals detected in the leaching solution of water permeated brick include Cr,Pb,Cu,Ni and Zn.The concentrations of Cr,Cu and Zn are lower than the ClassⅡstandard limits stipulated in the Environmental Quality Standard for Surface Water(GB 3838—2002)and the classⅢstandard limits stipulated in the Quality Standard for Groundwater(GB/T 14848—2017).The amount of residue added,the amount of water added and the extrusion stress have significant impacts on Ni in the leaching solution,but have little influence on Cr.The main PAHs detected in the leachate of permeated brick include naphthalene,acenaphthene,dihydroacenaphthene,fluorene and phenanthrene.The total concentration is in the range of 218.43—408.34μg/L.Acenaphthene is the main component in the leaching solution,and its relative mass distribution ratio is 59.80%—77.55%.This study can provide scientific basis for harmless treatment and resource utilization of oily sludge pyrolysis residue.