Kum Bentonit Karışımında Sızıntı Suyunun Hidrolik İletkenliğe Etkisi

Abstract

Bu çalışmada düzenli atık depolama sahaları altında geçirimsiz tabaka olarak da kullanılan kum-bentonit karışımlarının sızıntı suyu karşısındaki geçirimsizlik davranışı incelenmiştir. Bu amaçla kum-bentonit karışımı içerisinden sızıntı suyunun geçirildiği esnek duvarlı hidrolik iletkenlik deneyine tabi tutulmuştur. Literatürde genel olarak musluk suyu ya da yapay kirleticiler ile gerçekleştirilen hidrolik iletkenlik deneyleri, bu çalışmada orijinal sızıntı suyu ile gerçekleştirilmiştir. Sızıntı suyu olarak da Ege Bölgesinden seçilen bir katı atık depolama sahasından elde edilen sızıntı suları kullanılmıştır. Kum-bentonit karışımının oranı kuru ağırlıkça %10 bentonit içerecek şekilde hazırlanmıştır. Deney esnasında sızıntı suyunun giriş ve çıkış sıvılarının bazı kimyasal analizleri de gerçekleştirilmiştir. Ölçülen hidrolik iletkenlik değerlerinin sınır koşullara yakın olmak kaydı ile, kriterleri sağladığı belirlenmiştir. Bununla beraber, musluk suyu sonuçlarına göre artış görüldüğü de dikkati çekmiştir. Ortam pH’ı tüm deneylerde bazik olarak ölçülmüştür. Sızıntı suyuna ait giriş sıvısının elektriksel iletkenliğinin, tüm örneklerin çıkış sıvılarının elektriksel iletkenliğine oranı 1’in altında kalmıştır. Bu durum deneyin sonlandırıldığı anda katyon değişimlerinin sonlanmadığını işaret etmektedir. Son olarak da giriş ve çıkış sıvılarındaki bazı alkali ve toprak alkali metali iyonlarındaki değişimler ölçülmüş, karışımdaki kilin sızıntı suyu maruziyeti altında mineral yapısındaki değişimler belirlenmiş ve hidrolik iletkenliğe etkisi de tartışılarak sunulmuştur.

Keywords

• Geçirimsiz Tabaka
• Kum Kil Karışımları
• Sızıntı Suyu
• Hidrolik İletkenlik

The Effect of Leachate on the Hydraulic Conductivity of a Sand Bentonite Mixture

Abstract

The permeability behavior of sand-bentonite mixtures which are used as liner, was investigated by using original leachate. In this regard, the flexible wall hydraulic conductivity tests were performed. In literature, the conventional test procedures generally comprise the permeability values of the liners by using tap water, this study suggested determining the hydraulic conductivities under the effect of leachate. Thus, leachate samples were taken from a municipal solid waste site located in the Aegean region. The selected proportion is 10% bentonite as the dry weight for a sand-bentonite mixture. Some chemical analyses were also done for the inlet and outlet leachate samples. It is found that the mixture ensures the hydraulic conductivity criteria for landfill liners while it approaches the critical value. Also, it should be noted that the hydraulic conductivity with leachate was found to be more than that of with tap water. The pH of the environment for each test was found to be basic. The electrical conductivity values for each test were found to be under 1. This situation implies that the cation exchange process was not completed. Finally, some alkaline and alkaline earth metals were measured in both inlet and outlet fluids, changes in the mineral structure of the clay in the mixture under leachate exposure were determined and their effect on the hydraulic conductivity was discussed.

Keywords

• Landfill Liner
• Sand-Bentonite Mixtures
• Leachate
• Hydraulic Conductivity

References

1. Kraus, J.F., Benson, C.F., Erickson, A.E., Chamberlain, E.J. 1997. Freeze Thaw Cycling and Hydraulic Conductivity of Bentonitic Barriers. Journal of Geotechnical and Geoenvironmental Engineering, 123 (3), 229-238.
2. Tay, Y.Y., Stewart, D.I., Cousens, T.W. 2001. Shrinkage And Dessication Cracking in Bentonite-Sand Landfill Liners. Engineering Geology, 20 (1-4), 263-274.
3. Cho, W-J., Lee, J.O. and Kang, C-H. 2002. Hydraulic Conductivity of Compacted Soil-Bentonite Mixture for A Liner Material in Landfill Facilities. Korean Society of Environmental Engineers, 7 (3), 121-127.
4. Komine, H. 2004. Simplified Evaluation On Hydraulic Conductivities Of Sand–Bentonite Mixture Backfill. Applied Clay Science, 26 (1-4), 13-19.
5. Meer, S.R., Benson, C.H. 2007. Hydraulic Conductivity of Geosynthetic Clay Liners Exhumed from Landfill Final Covers. Journal of Geotechnical and Geoenvironmental Engineering, 133 (5), 550-563.
6. Akgün, H. 2010. Geotechnical Characterization and Performance Assessment of Bentonite / Sand Mixtures for Underground Waste Repository Sealing. Applied Clay Science, 49 (4), 394-399.
7. Ören, A.H., Kaya, A., Kayalar, A.Ş. 2011. Hydraulic Conductivity of Zeolite Bentonite Mixtures in Comparison to Sand Bentonite Mixtures. Canadian Geotechnical Journal, 48 (9), 1343-1353.
8. Akcanca, F., Aytekin, M. 2014. Impact of Wetting-Drying Cycles on The Hydraulic Conductivity of Liners Made of Lime-Stabilized Sand-Bentonite Mixtures for Sanitary Landfills. Environmental Earth Sciences, 72 (1), 59-66.

9. Varank, G., Demir, A., Adar, E., Bilgili, M.S., Top, S., Güvenç, Y.S., Özçoban, M.Ş. 2017. Investigation of Liner Systems in Transport of Organic And Inorganic Contaminants In Sanitary Landfill: A Case Study. Celan – Soil, Air, Water, 45 (1), 1-8.
10. Kleppe, J.H., Olson, R.E. 1985. Desiccation Cracking of Soil Barriers. ASTM, Special Technical Publication, 874, 263-275.
11. Hong, C.S., Shackelford, C.D. 2017. Long-Term Column Testing of Zeolite-Amended Backfills. I: Testing Methodology and Chemical Compatibility. J. Geotech. Geoenvironmental Eng., 143 (9), 04017050.
12. Bradshaw, S.L., Benson, C.H. 2013. Effect of Municipal Solid Waste Leachate on Hydraulic Conductivity And Exchange Complex Of Geosynthetic Clay Liners. J. Geotech. Geoenviron., 140 (4), 1-17.
13. Benson, C.H., Chen, J.N., Edil, T.B., Likos, W.J. 2018. Hydraulic Conductivity of Compacted Soil Liners Permeated with Coal Combustion Product Leachates. J. Geotech. Geoenvironmental Eng., 144 (4), 1–15.
14. Adhikari, B., Dahal, K. R., Khanal, S.N. 2014. A Review of Factors Affecting the Composition of Municipal Solid Waste Landfill Leachate. International Journal of Engineering Science and Innovative Technology, 3 (5), 272–281.
15. Luo, H., Zeng, Y., Cheng, Y., He, D., Pan, X. 2020. Recent Advances in Municipal Landfill Leachate: A Review Focusing on Its Characteristics, Treatment and Toxicity Assessment. Science of the Total Environment, 703, 135468.
16. Bao, C., Jiaxing, G., Huixin, Z. 2016. Alteration of Compacted GMZ Bentonite by Infiltration of Alkaline Solution. Clay Minerals, 51 (2), 237–247.
17. Xiang, G., Ye, W., Lv, L. 2019. Swelling Characteristics of Bentonite After Long-Term Dissolution in Alkaline Solution. Clay Minerals, 54 (4), 409–416. Margat, J., Gun V.D.J. 2013. "Groundwater Around The World", CRC Press/Balkema.
18. Abdellah, D., Gueddouda, M.K., Goual, I., Souli, H., Ghembaza, M.S. 2020. Effect of Landfill Leachate on the Hydromechanical Behavior of Bentonite-Geomaterials Mixture. Construction and Building Materials, 234, 117356.
19. Tang, Q., Gu, F., Zhang, Y., Zhang, Y., Mo, J. 2018. Impact of Biological Clogging on The Barrier Performance of Landfill Liners. Journal ofEnvironmental Management, 222, 44–53.
20. Chen, J., Qian, H., Yang, M., Qin, J., Qu, W. 2021. Effects Of Bacterial Activity on The Saturated Hydraulic Conductivity of Remolded Loess. Engineering Geology, 287, 106101.
21. Özçoban, M. Ş., Acarer, S., Tüfekci, N. 2022. Effect Of Solid Waste Landfill Leachate Contaminants on Hydraulic Conductivity of Landfill Liners. Water Science and Technology, 85 (5), 1581–1599.
22. Freeze, R.A., Cherry, J.A. 1979. Groundwater, Prentice-Hall, Inc., Englewoods Cliffs, N.J. ISBN: 0-13-365312-9, pp 624.
23. ASTM D 5084. 2016. Standard Test Method for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using A Flexible Wall Permeameter. The American Society for Testing and Materials, West Conshohocken, United States.
24. Uddin, M.K. 2017. A Review On The Adsorption of Heavy Metals By Clay Minerals, With Special Focus on The Past Decade. Chemical Engineering Journal, 308, 438–462.
25. Abollino, O., Aceto, M., Malandrino, M., Sarzanini, C., Mentasti, E. 2003. Adsorption of Heavy Metals on Na-monmorillonite. Effect of pH and Organic Substances. Water Research, 37 (7), 1619–1627.
26. Ören, A.H., Durukan, S., Kayalar, A.Ş. 2014. Influence of Compaction Water Content on The Hydraulic Conductivity of Sand–Bentonite And Zeolite–Bentonite Mixtures. Clay Minerals, 49(1), 109–121.
27. Shackelford, C.D., Benson, C.H., Katsumi, T., Edil, T.B., Lin, L. 2000. Evaluating The Hydraulic Conductivity of Gcls Permeated With Non-Standard Liquids. Geotextiles and Geomembranes, 18 (2–4), 133–161.
28. Yilmaz, G., Yetimoglu, T., Arasan, S. 2008. Hydraulic Conductivity of Compacted Clay Liners Permeated with Inorganic Salt Solutions. Waste Management and Research, 26 (5), 464–473.
29. Emmanuel, E., Anggraini, V., Asadi, A., Raghunandan, M.E. 2020. Interaction of Landfill Leachate with Olivine-Treated Marine Clay: Suitability For Bottom Liner Application. Environmental Technology and Innovation, 17, 100574.
30. Zhou, X., Liu, D., Bu, H., Deng, L., Liu, H., Yuan, P. 2018. XRD-based quantitative analysis of clay minerals using reference intensity ratios , mineral intensity factors , Rietveld , and full pattern summation methods : A critical review. Solid Earth Sci. 3, 16–29.