基质类型和粒径对垂直潜流人工湿地堵塞效应的研究
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摘要
为了探讨基质类型和基质粒径对潜流人工湿地堵塞的作用,选取了两种具有不同内部结构的基质,并将其按照不同粒径类别,填充入垂直潜流湿地实验模拟系统中。系统运行过程中,定期对各个系统填充基质的孔隙度和渗透系数进行监测。结果表明,基质的初始孔隙度由填充基质间孔隙和基质内部孔隙决定,粒径越大,基质间孔隙越大,内部多孔结构的基质孔隙度要高于相同粒径的内部非多孔结构的基质。基质的初始渗透系数主要取决于基质间的孔隙,受基质内部的微孔隙影响很小。湿地系统稳定运行下,基质孔隙度随着运行时间而减小,二者的线性拟合结果较好(R~2为0.69~0.97),内部多孔结构基质的孔隙度减小速率高于相同粒径的内部非多孔结构基质。基质的渗透系数随着时间的变化取决于基质粒径,与基质内部是否为多孔结构无关。基质粒径大于5 mm的人工湿地模拟系统,基质渗透系数随着时间先增大,在第25天附近达到峰值,然后急剧减小;基质粒径小于5 mm的人工湿地模拟系统,渗透系数缓慢减小。
In order to investigate the effect of matrix type and particle size on the clogging of subsurface flow constructed wetlands, two types of substrates with different internal structures were selected and filled into vertical-flow constructed wetland experimental systems according to different particle size categories. The porosities and osmotic coefficients of the filled substrates were monitored during the operation of the system to characterize the clogging process of the wetland experimental systems. The results showed that the initial porosity of the matrix was determined by both interstitial and internal pores of the matrix. The larger the particle size was, the larger the intergranular pores would be, and the porosities of substrates with internal porous structure were higher than that of the substrates with internal non-porous structure. The initial osmotic coefficients of the matrix depended mainly on the interstitial pores, rather than internal micro pores of the matrix. Under the stable operation of the wetland system, porosities of the matrix decreased with the running time with good linear fitting results with R2 being 0.69-0.97. With the same particle size, porosity reduction rate of the matrix with internal porous structure was higher than that of the matrix with internal non-porous structure. Variation of the osmotic coefficients of the substrates depended on the particle size of the matrix, regardless of whether the interior of the matrix was porous. When the particle size was larger than 5 mm, the osmotic coefficients increased first and reached to peak on the 25 days, and then decreased sharply. Under the condition that the particle size was less than 5 mm, the infiltration rates decreased slowly.
In order to investigate the effect of matrix type and particle size on the clogging of subsurface flow constructed wetlands, two types of substrates with different internal structures were selected and filled into vertical-flow constructed wetland experimental systems according to different particle size categories. The porosities and osmotic coefficients of the filled substrates were monitored during the operation of the system to characterize the clogging process of the wetland experimental systems. The results showed that the initial porosity of the matrix was determined by both interstitial and internal pores of the matrix. The larger the particle size was, the larger the intergranular pores would be, and the porosities of substrates with internal porous structure were higher than that of the substrates with internal non-porous structure. The initial osmotic coefficients of the matrix depended mainly on the interstitial pores, rather than internal micro pores of the matrix. Under the stable operation of the wetland system, porosities of the matrix decreased with the running time with good linear fitting results with R2 being 0.69-0.97. With the same particle size, porosity reduction rate of the matrix with internal porous structure was higher than that of the matrix with internal non-porous structure. Variation of the osmotic coefficients of the substrates depended on the particle size of the matrix, regardless of whether the interior of the matrix was porous. When the particle size was larger than 5 mm, the osmotic coefficients increased first and reached to peak on the 25 days, and then decreased sharply. Under the condition that the particle size was less than 5 mm, the infiltration rates decreased slowly.
引文
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[10]南京水利科学研究院.土工试验方法标准GB/T50123-1999[S].北京:中国标准出版社,1999.
[11]Langergraber G,Haberl R,Laber J,et al.Evaluation of substrate clogging process in vertical flow constructed wetlands[J].Water Science and Technology,2003,48:25-34.
[2]曹笑笑,吕宪国,张仲胜,等.人工湿地设计研究进展[J].湿地科学,2013,11(1):121-128.
[3]Mitsch W J,Jorgensen S E.生态工程与生态系统重建[M].台北:六合出版社,2004.
[4]Nivala J,Knowles P,Dotro G,et al.Clogging in subsurface-flow treatment wetlands:Measurement,modeling and management[J].Water Research,2012,46:1625-1640.
[5]Knowles P,Dotro G,Nivala J,et al.Clogging in subsurface-flow treatment wetlands:Occurrence and contributing factors[J].Ecological Engineering,2011,37:99-112.
[6]宋志鑫,丁彦礼,解庆林,等.潜流人工湿地流场分布与基质堵塞关系研究进展[J].湿地科学,2014,12(5):677-682.
[7]Hua G F,Zhu W,Zhao L F,et al.Clogging pattern in verticalflow constructed wetlands:Insight from a laboratory study[J].Journal of Hazardous Materials,2010,180:668-674.
[8]Suliman F,French H K,Haugen L E,et al.Change in flow and transport patterns in horizontal subsurface flow constructed wetlands as a result of biological growth[J].Ecological Engineering,2006,27:124-133.
[9]Zhao L,Zhu W,Tong W.Clogging processes caused by biofilm growth and organic particle accumulation in lab-scale vertical flow constructed wetlands[J].Journal of Environmental Sciences,2009,21:750-757.
[10]南京水利科学研究院.土工试验方法标准GB/T50123-1999[S].北京:中国标准出版社,1999.
[11]Langergraber G,Haberl R,Laber J,et al.Evaluation of substrate clogging process in vertical flow constructed wetlands[J].Water Science and Technology,2003,48:25-34.
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