Improving supercritical water gasification of sludge by oil palm empty fruit bunch addition: Promotion of syngas production and heavy metal stabilization

doi:10.1016/j.cjche.2019.08.004

摘要/Abstract

摘要： The co-gasification of sewage sludge and palm oil empty fruit bunch (EFB) in supercritical water (SCW) was conducted at 400℃ with a pressure of over 25 MPa. This study aimed to investigate the influence of EFB addition on the syngas production and its composition. The heavy metal distribution and the leaching potential of the solid residue were also assessed. The results showed that syngas yield significantly increased with the addition of EFB into the feedstock. The cold gas efficiency (CGE) and carbon efficiency (CE) of co-gasification were higher than those of individual gasification. The actual syngas production from co-gasification of sludge and EFB was 45% higher than the theoretical total volume. The results indicated that the addition of EFB to sludge had the synergetic promotion effect on syngas production from sludge and EFB in supercritical water. This enhancement might be due to the dissolution of alkali metals from EFB and the adjustment of organic ratio. In addition, higher percentage of heavy metals were deposited and stabilized in the solid residue after SCWG. The leaching concentration of heavy metals from the solid residues was decreased to a level below the standard limit which enables it to be safely disposed of in landfill. In conclusion, the EFB addition has been proved to promote syngas production, as well as, stabilize the heavy metal in solid residues during co-SCWG.

关键词: Co-gasification, Supercritical water, Sludge, Empty fruit bunch, Syngas, Heavy metal

Abstract: The co-gasification of sewage sludge and palm oil empty fruit bunch (EFB) in supercritical water (SCW) was conducted at 400℃ with a pressure of over 25 MPa. This study aimed to investigate the influence of EFB addition on the syngas production and its composition. The heavy metal distribution and the leaching potential of the solid residue were also assessed. The results showed that syngas yield significantly increased with the addition of EFB into the feedstock. The cold gas efficiency (CGE) and carbon efficiency (CE) of co-gasification were higher than those of individual gasification. The actual syngas production from co-gasification of sludge and EFB was 45% higher than the theoretical total volume. The results indicated that the addition of EFB to sludge had the synergetic promotion effect on syngas production from sludge and EFB in supercritical water. This enhancement might be due to the dissolution of alkali metals from EFB and the adjustment of organic ratio. In addition, higher percentage of heavy metals were deposited and stabilized in the solid residue after SCWG. The leaching concentration of heavy metals from the solid residues was decreased to a level below the standard limit which enables it to be safely disposed of in landfill. In conclusion, the EFB addition has been proved to promote syngas production, as well as, stabilize the heavy metal in solid residues during co-SCWG.

Key words: Co-gasification, Supercritical water, Sludge, Empty fruit bunch, Syngas, Heavy metal

Zhouchao Weng, Ekkachai Kanchanatip, Dwi Hantoko, Mi Yan, Hongcai Su, Sicheng Zhang, Guobin Wang. Improving supercritical water gasification of sludge by oil palm empty fruit bunch addition: Promotion of syngas production and heavy metal stabilization[J]. 中国化学工程学报, 2020, 28(1): 293-298.

参考文献

[1] A. Pathak, M.G. Dastidar, T.R. Sreekrishnan, Bioleaching of heavy metals from sewage sludge:A review, J. Environ. Manag. 90(2009) 2343-2353.
[2] Q. Zhang, J. Hu, D.J. Lee, Y. Chang, Y.J. Lee, Sludge treatment:Current research trends, Bioresour. Technol. 243(2017) 1159-1172.
[3] E. Gasafi, M.Y. Reinecke, A. Kruse, L. Schebek, Economic analysis of sewage sludge gasification in supercritical water for hydrogen production, Biomass Bioenergy 32(2008) 1085-1096.
[4] W.G. James, H.R. Dennis, The first commercial supercritical water oxidation sludge processing plant, Waste Manag. 22(2002) 453-459.
[5] A. Amrullah, Y. Matsumura, Supercritical water gasification of sewage sludge in continuous reactor, Bioresour. Technol. 249(2018) 276-283.
[6] Y. Chen, L. Guo, H. Jin, J. Yin, Y. Lu, X. Zhang, An experimental investigation of sewage sludge gasification in near and super-critical water using a batch reactor, Int. J. Hydrog. Energy 38(2013) 12912-12920.
[7] S.N. Reddy, S. Nanda, A.K. Dalai, J.A. Kozinski, Supercritical water gasification of biomass for hydrogen production, Int. J. Hydrog. Energy 39(2014) 6912-6926.
[8] M. Gong, W. Zhu, Z.R. Xu, H.W. Zhang, H.P. Yang, Influence of sludge properties on the direct gasification of dewatered sewage sludge in supercritical water, Renew. Energy 66(2014) 605-611.
[9] Z.R. Xu, W. Zhu, M. Li, Influence of moisture content on the direct gasification of dewatered sludge via supercritical water, Int. J. Hydrog. Energy 37(2012) 6527-6535.
[10] Y.B. Zhai, C. Wang, H.M. Chen, C.T. Li, G.M. Zeng, D.X. Pang, P. Lu, Digested sewage sludge gasification in supercritical water, Waste Manag. Res. 31(2013) 393-400.
[11] E. Afif, P. Azadi, R. Farnood, Catalytic hydrothermal gasification of activated sludge, Appl. Catal. B Environ. 105(2011) 136-143.
[12] G. Akgül, A. Kruse, Influence of salts on the subcritical water-gas shift reaction, J. Supercrit. Fluids 66(2012) 207-214.
[13] M. Gong, W. Zhu, H.W. Zhang, Q. Ma, Y. Su, Y.J. Fan, Influence of NaOH and Ni catalysts on hydrogen production from the supercritical water gasification of dewatered sewage sludge, Int. J. Hydrog. Energy 39(2014) 19947-19954.
[14] S.H. Chang, An overview of empty fruit bunch from oil palm as feedstock for bio-oil production, Biomass Bioenergy 62(2014) 174-181.
[15] S. Novianti, A. Nurdiawati, I.N. Zaini, P. Prawisudha, H. Sumida, K. Yoshikawa, Lowpotassium fuel production from empty fruit bunches by hydrothermal treatment processing and water leaching, Energy Procedia 75(2015) 584-589.
[16] K.Y. Chiang, K.L. Chien, C.H. Lu, Characterization and comparison of biomass produced from various sources:Suggestions for selection of pretreatment technologies in biomass-to-energy, Appl. Energy 100(2012) 164-171.
[17] M. Gong, W. Zhu, Y. Fan, H. Zhang, Y. Su, Influence of the reactant carbon-hydrogenoxygen composition on the key products of the direct gasification of dewatered sewage sludge in supercritical water, Bioresour. Technol. 208(2016) 81-86.
[18] D. Bo, F.S. Zhang, L. Zhao, Influence of supercritical water treatment on heavy metals in medical waste incinerator fly ash, J. Hazard. Mater. 170(2009) 66-71.
[19] Y. Yakubu, J. Zhou, D. Ping, Z. Shu, Y. Chen, Effects of pH dynamics on solidification/stabilization of municipal solid waste incineration fly ash, J. Environ. Manag. 207(2018) 243-248.
[20] W. Shi, C. Liu, Y. Shu, C. Feng, Z. Lei, Z. Zhang, Synergistic effect of rice husk addition on hydrothermal treatment of sewage sludge:Fate and environmental risk of heavy metals, Bioresour. Technol. 149(2013) 496-502.
[21] Q. Yan, L. Guo, Y. Lu, Thermodynamic analysis of hydrogen production from biomass gasification in supercritical water, Energy Convers. Manag. 47(2006) 1515-1528.
[22] J. Yanik, S. Ebale, A. Kruse, M. Saglam, M. Yuksel, Biomass gasification in supercritical water:Part 1. Effect of the nature of biomass, Fuel 86(2007) 2410-2415.
[23] Y. Lu, L. Guo, X. Zhang, Q. Yan, Thermodynamic modeling and analysis of biomass gasification for hydrogen production in supercritical water, Chem. Eng. J. 131(2007) 233-244.
[24] W.J. Gong, B.B. Li, Q.Y. Wang, Z.H. Huang, L. Zhao, Supercritical water gasification of landfill leachate for hydrogen production in the presence and absence of alkali catalyst, Waste Manag. 73(2018) 439-446.
[25] A. Sınag, A. Kruse, V. Schwarzkopf, Key compounds of the hydropyrolysis of glucose in supercritical water in the presence of K₂CO₃, Ind. Eng. Chem. Res. 42(2003) 3516-3521.
[26] Y. Lu, S. Li, L. Guo, X. Zhang, Hydrogen production by biomass gasification in supercritical water over Ni/γAl₂O₃ and Ni/CeO₂-γAl₂O₃ catalysts, Int. J. Hydrog. Energy 35(2010) 7161-7168.
[27] C.R. Correa, A. Kruse, Supercritical water gasification of biomass for hydrogen production review, J. Supercrit. Fluids 133(2018) 573-590.
[28] L. Li, Z.R. Xu, C. Zhang, J. Bao, X. Dai, Quantitative evaluation of heavy metals in solid residues from sub- and super-critical water gasification of sewage sludge, Bioresour. Technol. 121(2012) 169-175.
[29] W.S. Shi, C.G. Liu, D.H. Ding, Z.F. Lei, Y.N. Yang, C.P. Feng, Z.Y. Zhang, Immobilization of heavy metals in sewage sludge by using subcritical water technology, Bioresour. Technol. 137(2013) 18-24.
[30] B.I.E. Eswed, O.M. Aldagag, F.I. Khalili, Efficiency and mechanism of stabilization/solidification of Pb(II), Cd(II), Cu(II), Th(IV) and U(VI) in metakaolin based geopolymers, Appl. Clay Sci. 140(2017) 148-156.
[31] J. Li, J. Chen, S. Chen, Supercritical water treatment of heavy metal and arsenic metalloid-bioaccumulating-biomass, Ecotoxicol. Environ. Saf. 157(2018) 102-110.
[32] W.D.C. Udayanga, A. Veksha, A. Giannis, G. Lisak, W.C. Chang, T.T. Lim, Fate and distribution of heavy metals during thermal processing of sewage sludge, Fuel 226(2018) 721-744.
[33] X.P. Zhang, C. Zhang, X. Li, S.H. Yu, P. Tan, Q.Y. Fang, G. Chen, A two-step process for sewage sludge treatment:Hydrothermal treatment of sludge and catalytic hydrothermal gasification of its derived liquid, Fuel Process. Technol. 180(2018) 67-74.
[34] H.J. Huang, X.Z. Yuan, The migration and transformation behaviors of heavy metals during the hydrothermal treatment of sewage sludge, Bioresour. Technol. 200(2016) 991-998.
[35] S. Platzer, M. Kar, R. Leyma, S. Chib, A. Roller, F. Jirsa, R. Krachler, D.R.M. Farlance, W. Kandioller, B.K. Keppler, Task-specific thioglycolate ionic liquids for heavy metal extraction:Synthesis, extraction efficacies and recycling properties, J. Hazard. Mater. 324B (2017) 241-249.