Similar articles

Abstract: Due to large-scale dredging operations, a large amount of sludge is inevitably produced. Large areas of land are occupied when the dredged sludge is discarded in the disposal site as waste material. The sludge dewatering with aeration-vacuum (SDAV) method is suit for treating the sludge with high water content and high clay content in the disposal site. The water in the sludge can be discharged out. The volume of the sludge can be reduced quickly, and the recycling of the land can be accelerated by this method. Most importantly, this technique is an efficient way to deal with clogging problems when pumping water from high water content, high clay content dredged sludge. vacuum degree range tests, the aeration rate range tests, and the influencing factors of sludge dewatering behavior tests were conducted with a self-developed SDAV model test device. Sludge samples were taken from the South-to-North Water Diversion East Line Project in Huai’an White-Horse Lake disposal site, Jiangsu Province, China. The optimal range of vacuum degree and aeration rate were obtained through the test results, and the mechanisms for how the two factors work and how they affect the sludge dewatering behavior were analyzed. The suitable vacuum degree range in SDAV is below 50 kPa, and the suitable aeration rate is about 1.0 m³/h. The low-vacuum degree contributes to reduce the adsorption effect of micro-channels on soil particles in filter material and to maintain the arch structures. Aeration has the effects of expansion, disturbance, changing Reynolds number, and dynamic sieve separating. The pump quantity of water per meter of filter tube (Δm) has different change rules as the vacuum degree changes under different aeration rates. The reason is that the formed arch structures’ conformation and permeability differ greatly under different combined-conditions of vacuum degree and aeration rate. The optimal combined-condition for dewatering the sludge is 35 kPa with 1.0 m³/h.

[1]Bhattacharyya, R., Fullen, M., Davies, A.K., Booth, C.A., 2009. Utilizing palm-leaf geotextile mats to conserve loamy sand soil in the United Kingdom. Agriculture, Ecosystems and Environment, 130(1-2):50-58.

[2]Cargill, K.W., 1984. Prediction of consolidation of very soft soil. Journal of Geotechnical Engineering, ASCE, 110(6):775-795.

[3]Chen, L., Yi, H., Xu, Q., Zhuang, Y., 2006. The study of the structure stability simulated tests in soil-geotextile filtration system. Journal of Hydroelectric Engineering, 25(4):117-121 (in Chinese).

[4]Chen, L., Xu, Q., Yi, H., Zhuang, Y., 2007. Simulating test study on the seepage stability of the soil-geotextile filtration under cyclic flow. Journal of Hydroelectric Engineering, 26(4):115-119 (in Chinese).

[5]Chen, R.H., Ho, C.C., Hsu, C.Y., 2008. The effect of fine soil content on the filtration characteristics of geotextile under cyclic flows. Geosynthetics International, 15(2):95-106.

[6]Craven, W., Townsend, T.G., Vogel, K., Laux, S., 1999. Field investigation of landfill leachate collection system clogging. Practice Periodical of Hazardous, Toxic, and Radioactive Waste Management, ASCE, 3(1):2-9.

[7]de Mendonca, M.B., Ehrlich, M., 2006. Column test studies of ochre biofilm formation in geotextile filters. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 132(10):1284-1292.

[8]Deng, D., 2007. Comparison of remolded shear strength with intrinsic strength line for dredged deposits. China Ocean Engineering, 21(2):363-369.

[9]Deng, D., Hong, Z., Zhu, W., Liu, C., Ding, J., Hong, P., 2007. High Water-content Dredged Sludge’s Ventilating Vacuum Dewatering Technique in Yard. China Patent, No. 200710132092.9 (in Chinese).

[10]Deng, D., Hong, Z., Liu, C., Ding, J., Hong, P., 2009. Large-scale model tests on dewater of dredged clay by use of ventilating vacuum method. Chinese Journal of Geotechnical Engineering, 31(2):250-253 (in Chinese).

[11]Fannin, R.J., Pishe, R., 2001. Testing and Specifications for Geotextile Filters in Cyclic Flow Applications. Proceedings of the Geosynthetics Conference, Portland, Oregon, USA, p.423-435.

[12]Faure, Y.H., Baudoin, A., Pierson, P., Plé, O., 2006. A contribution for predicting geotextile clogging during filtration of suspended solids. Geotextiles and Geomembranes, 24(1):11-20.

[13]Gao, Y., Zhou, Y., Deng, D., Hong, Z., Tao, H., Chai, Y., 2009. Compound Filter Structure and Its Binding Method for Aeration and Clogging-proof. China Patent, No. 200910028430.3 (in Chinese).

[14]Guo, H., 1986. Design and Calculation of Vacuum System. Metallurgy Industry Press, Beijing, China, p.7-9 (in Chinese).

[15]Hong, Z., Liu, S., Shen, S., Negami, T., 2006. Comparison in undrained shear strength between undisturbed and remolded Ariake clays. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 132(2):272-275.

[16]Koerner, G.R., Koerner, R.M., 1992. Leachate flow rate behavior through geotextile and soil filters and possible remediation methods. Geotextiles & Geomembranes, 11(4-6):401-430.

[17]Liu, C., 2008. Experimental Study on Dewatering Behavior of Baimahu Dredged Clays with Ventilating Vacuum Method. MS Thesis, Hohai University, Nanjing, China (in Chinese).

[18]Liu, C., Zhou, Y., Ji, F., 2008. Experimental Study on High Moisture Content Dredged Sludge Dewatering Technique. China’s Scientific and Technological Papers Online. Available from: http://www.paper.edu.cn/index.php/default/releasepaper/content/21206 [Accessed on Aug. 19, 2010] (in Chinese).

[19]McIsaac, R., Rowe, R.K., 2006. Effect of filter-separators on the clogging of leachate collection systems. Canadian Geotechnical Journal, 43(7):674-693.

[20]Narejo, D.B., Koerner, R.M., 1992. A dynamic filtration test for geotextile filters. Geotextiles & Geomembranes, 11(4-6):395-400.

[21]Palmeira, E.M., Fannin, R.J., Vaid, Y.P., 1996. A study on the behaviour of soil-geotextile systems in filtration tests. Canadian Geotechnical Journal, 33(6):899-912.

[22]Reddi, L.N., 1997. Particle transport in soils: review of significant processes in infrastructure systems. Journal of Infrastructure Systems, ASCE, 3(2):78-86.

[23]Rowe, R.K., Gnanendran, C.T., Landva, A.O., Valsangkar, A.J., 1996. Calculated and observed behaviors of a reinforced embankment over soft compressible soil. Canadian Geotechnical Journal, 33(2):324-338.

[24]Wakeman, R.J., 2007. Separation technologies for sludge dewatering. Journal of Hazardous Materials, 144(3):614-619.

[25]Xie, K., Wen, J., Xia, J., 2005. Solution to 1-D consolidation of non-homogeneous soft clay. Journal of Zhejiang University-SCIENCE, 6A(Suppl. I):29-34.

[26]Xie, K., Qi, T., Dong, Y., 2006. Nonlinear analytical solution for one-dimensional consolidation of soft soil under cyclic loading. Journal of Zhejiang University-SCIENCE A, 7(8):1358-1364.

[27]Zhuang, Y., Xie, K., Li, X., 2005. Nonlinear analysis of consolidation with variable compressibility and permeability. Journal of Zhejiang University-SCIENCE, 6A(3):181-187.