为了研究低DO下负荷对污泥膨胀的影响,采用SBR反应器,在DO〈0.5 mg.L-1,pH 7.2~8.0,温度（23±0.5）℃,MLSS 3000~3500 mg.L-1,负荷分别为0.22、0.44、0.66 g COD.（g MLSS）-1.d-1的条件下,研究不同负荷下的SVI变化趋势、污泥膨胀...为了研究低DO下负荷对污泥膨胀的影响,采用SBR反应器,在DO〈0.5 mg.L-1,pH 7.2~8.0,温度（23±0.5）℃,MLSS 3000~3500 mg.L-1,负荷分别为0.22、0.44、0.66 g COD.（g MLSS）-1.d-1的条件下,研究不同负荷下的SVI变化趋势、污泥膨胀类型、引发原因、耗氧速率、脱氮除磷效果与同步硝化反硝化率。结果显示,低DO下（〈0.5 mg.L-1）,负荷0.22 g COD.（g MLSS）-1.d-1时未发生污泥膨胀,随着负荷升高,污泥沉降性恶化加快。并且不同负荷引发的污泥膨胀类型不同,在负荷0.66 g COD.（g MLSS）-1.d-1时发生黏性膨胀,而负荷0.44 g COD.（g MLSS）-1.d-1时发生丝状菌微膨胀。黏性膨胀时出水氨氮及磷去除效果变差,但丝状菌膨胀时出水水质并没有受到影响,且比吸磷速率更快,出水SS更低。未发生污泥膨胀时同步硝化反硝化率最大,丝状菌膨胀时次之,黏性膨胀时最小。SOUR过高时,很可能伴随着污泥沉降性变差和出水水质恶化。展开更多
The expansive clays are extremely sensitive to the slight moisture alteration,exhibiting sequentially volume change.Uneven settlement of the buildings and infrastructures underlying expansive soil is a critical challe...The expansive clays are extremely sensitive to the slight moisture alteration,exhibiting sequentially volume change.Uneven settlement of the buildings and infrastructures underlying expansive soil is a critical challenge that geotechnical engineers have to deal with.Therefore,the objective of this study is to assess the alteration in the compressibility behavior of expansive clay respecting partial replacement of cement by zeolite in cemented samples.For this purpose,7 and 28 d cured samples treated with 6%,8%,10%,and 12%cement addition and 0,10%,30%,50%,70%,and 90%cement replacement by zeolite were investigated through Atterberg limit and a series of one-dimensional consolidation tests to evaluate the consistency limits and compressibility alteration.The liquid limits of the soil samples indicated a decremental trend as the cement content rose.Afterward,the increase of zeolite replacement up to 30%in each specific cement content diminished liquid limit to its lowest value.Further increment of zeolite replacement increased the liquid limit of the soil-binder mixtures.The lowest plasticity index was also achieved at the 30%zeolite replacement percentage;hence,the lowest swelling potential would be resulted,concerning an indirect classification.The results of the consolidation experimentations disclosed that zeolite replacement had adverse influence on consolidation parameters of cemented samples such as compression index,swell index,coefficient of compressibility,coefficient of volume compressibility,and coefficient of consolidation after 7 d of curing whereas after 28 d of curing,the 30%zeolite-replaced samples represented the best consolidation parameters.Eventually,it can be stated that the addition of cement alongside the partial substitution of cement by zeolite can be a beneficial strategy for the geo-environmental targets of this study.展开更多
To analyze the water swelling characteristics of black cotton soil(BCS),X-ray fluorescence and X-ray diffraction characterizations were performed to investigate the chemical compositions and types of clay minerals in ...To analyze the water swelling characteristics of black cotton soil(BCS),X-ray fluorescence and X-ray diffraction characterizations were performed to investigate the chemical compositions and types of clay minerals in BCS.A montmorillonite crystal lattice was established to simulate the hydration of interlayer cations by applying the SPC/E potential energy model,universal force field,algorithm of charge balance,and periodic boundary.Results indicated that the main clay mineral found in the BCS was montmorillonite(32.6%)with small amounts of interstratified illite-montmorillonite(10.9%),illite(2.3%),and kaolinite(1.5%).The high expansive potential of BCS comes from the strong adsorption property of montmorillonite with a high content of magnesium and sodium ions to water molecules.The exchangeable cations of Na^(+)in BCS were only 3.73%,but they enhanced the adsorption capacity of clay to water molecules and accelerated the hydration of Mg^(2+)(47.1%)and Ca^(2+)(4.78%).The free swell index can be used as a classification index of the swelling potential of BCS.展开更多
文摘为了研究低DO下负荷对污泥膨胀的影响,采用SBR反应器,在DO〈0.5 mg.L-1,pH 7.2~8.0,温度（23±0.5）℃,MLSS 3000~3500 mg.L-1,负荷分别为0.22、0.44、0.66 g COD.（g MLSS）-1.d-1的条件下,研究不同负荷下的SVI变化趋势、污泥膨胀类型、引发原因、耗氧速率、脱氮除磷效果与同步硝化反硝化率。结果显示,低DO下（〈0.5 mg.L-1）,负荷0.22 g COD.（g MLSS）-1.d-1时未发生污泥膨胀,随着负荷升高,污泥沉降性恶化加快。并且不同负荷引发的污泥膨胀类型不同,在负荷0.66 g COD.（g MLSS）-1.d-1时发生黏性膨胀,而负荷0.44 g COD.（g MLSS）-1.d-1时发生丝状菌微膨胀。黏性膨胀时出水氨氮及磷去除效果变差,但丝状菌膨胀时出水水质并没有受到影响,且比吸磷速率更快,出水SS更低。未发生污泥膨胀时同步硝化反硝化率最大,丝状菌膨胀时次之,黏性膨胀时最小。SOUR过高时,很可能伴随着污泥沉降性变差和出水水质恶化。
文摘The expansive clays are extremely sensitive to the slight moisture alteration,exhibiting sequentially volume change.Uneven settlement of the buildings and infrastructures underlying expansive soil is a critical challenge that geotechnical engineers have to deal with.Therefore,the objective of this study is to assess the alteration in the compressibility behavior of expansive clay respecting partial replacement of cement by zeolite in cemented samples.For this purpose,7 and 28 d cured samples treated with 6%,8%,10%,and 12%cement addition and 0,10%,30%,50%,70%,and 90%cement replacement by zeolite were investigated through Atterberg limit and a series of one-dimensional consolidation tests to evaluate the consistency limits and compressibility alteration.The liquid limits of the soil samples indicated a decremental trend as the cement content rose.Afterward,the increase of zeolite replacement up to 30%in each specific cement content diminished liquid limit to its lowest value.Further increment of zeolite replacement increased the liquid limit of the soil-binder mixtures.The lowest plasticity index was also achieved at the 30%zeolite replacement percentage;hence,the lowest swelling potential would be resulted,concerning an indirect classification.The results of the consolidation experimentations disclosed that zeolite replacement had adverse influence on consolidation parameters of cemented samples such as compression index,swell index,coefficient of compressibility,coefficient of volume compressibility,and coefficient of consolidation after 7 d of curing whereas after 28 d of curing,the 30%zeolite-replaced samples represented the best consolidation parameters.Eventually,it can be stated that the addition of cement alongside the partial substitution of cement by zeolite can be a beneficial strategy for the geo-environmental targets of this study.
基金The National Natural Science Foundation of China(No.51778139)Jiangsu Planned Projects for Postdoctoral Research Funds(No.2020Z422).
文摘To analyze the water swelling characteristics of black cotton soil(BCS),X-ray fluorescence and X-ray diffraction characterizations were performed to investigate the chemical compositions and types of clay minerals in BCS.A montmorillonite crystal lattice was established to simulate the hydration of interlayer cations by applying the SPC/E potential energy model,universal force field,algorithm of charge balance,and periodic boundary.Results indicated that the main clay mineral found in the BCS was montmorillonite(32.6%)with small amounts of interstratified illite-montmorillonite(10.9%),illite(2.3%),and kaolinite(1.5%).The high expansive potential of BCS comes from the strong adsorption property of montmorillonite with a high content of magnesium and sodium ions to water molecules.The exchangeable cations of Na^(+)in BCS were only 3.73%,but they enhanced the adsorption capacity of clay to water molecules and accelerated the hydration of Mg^(2+)(47.1%)and Ca^(2+)(4.78%).The free swell index can be used as a classification index of the swelling potential of BCS.
