Effect of solid–liquid separation enhanced by low-temperature hydrolysis in methanogenic phase on two-phase anaerobic sludge digestion system

  • Y. Wei
  • J. Liu
  • X. ZhouEmail author
  • J. Wu
  • X. Qian
Original Paper


In this study, a mesophilic two-phase anaerobic digestion system was used to treat waste activated sludge at the temperature of 35 ± 1 °C. The internal structure of the anaerobic sequencing batch reactor (methanogenic phase) has been improved by providing a solid–liquid separation plate, and a continuous-flow stirred tank reactor was employed as the acidogenic phase. The results of the study indicate that solid–liquid separation can be achieved in the methanogenic phase, and the low-temperature hydrolysis pretreatment can enhance solid–liquid separation capability. The separation of solids retention time and hydraulic retention time was also achieved in methanogenic phase, and the solids retention time was extended, which effectively improved the anaerobic digestion performance of the system. The organic concentration and total solids concentration in the methanogenic reactor were significantly different in height. The bottom of the reactor formed an area of high solids and low organic precipitation, while the upper part of the reactor formed a clear water area. The suspended solids concentration in the reactor clear water area was maintained at 359 ± 84 to 533 ± 93 mg/L, and the better solid–liquid separation effect was obtained inside the methanogenic phase. The maximum biogas yield was 258 ± 3 mL/g with the maximum volatile solids degradation rates of 59.43% in the system in Stage 3. Considering the efficiency of anaerobic digestion and the operating costs, the operating condition of Stage 4 (the designed hydraulic retention time was 10.67 d, the feed sludge was thermally pretreated, and its volume was 3 L) in this test is the optimal.


Anaerobic sequencing batch reactor Low-temperature hydrolysis Solid–liquid separation Two-phase anaerobic digestion Waste activated sludge 



The authors gratefully acknowledge the support of this work by The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, China.


  1. American Public Health Association (APHA) (2005) Standard methods for the examination of water and wastewater, 21st edn. APHA, Washington, DCGoogle Scholar
  2. Appels L, Baeyens J, Degrève J, Dewil R (2008) Principles and potential of the anaerobic digestion of waste-activated sludge. Prog Energy Combust Sci 34(6):755–781CrossRefGoogle Scholar
  3. Appels L, Degrève J, Van der Bruggen B, Van Impe J, Dewil R (2010) Influence of low temperature thermal pre-treatment on sludge solubilisation, heavy metal release and anaerobic digestion. Bioresour Technol 101(15):5743–5748CrossRefGoogle Scholar
  4. Ariunbaatar J, Panico A, Esposito G, Pirozzi F, Lens PNL (2014) Pretreatment methods to enhance anaerobic digestion of organic solid waste. Appl Energy 123:143–156CrossRefGoogle Scholar
  5. Carrère H, Dumas C, Battimelli A, Batstone DJ, Delgenès JP, Steyer JP, Ferrer I (2010) Pretreatment methods to improve sludge anaerobic degradability: a review. J Hazard Mater 183(1–3):1–15CrossRefGoogle Scholar
  6. Chen X, Xiang X, Dai R, Wang Y, Ma P (2017) Effect of low temperature of thermal pretreatment on anaerobic digestion of textile dyeing sludge. Bioresour Technol 243:426–432CrossRefGoogle Scholar
  7. Daija L, Selberg A, Rikmann E, Zekker I, Tenno T, Tenno T (2016) The influence of lower temperature, influent fluctuations and long retention time on the performance of an upflow mode laboratory-scale septic tank. Desalin Water Treat 57(40):18679–18687CrossRefGoogle Scholar
  8. Donoso-Bravo A, Perez-Elvira S, Fdz-Polanco F (2015) Simplified mechanistic model for the two-stage anaerobic degradation of sewage sludge. Environ Technol 36(10):1334–1346CrossRefGoogle Scholar
  9. Duan N, Dong B, Wu B, Dai X (2012) High-solid anaerobic digestion of sewage sludge under mesophilic conditions: feasibility study. Bioresour Technol 104:150–156CrossRefGoogle Scholar
  10. Ferrer I, Ponsá S, Vázquez F, Font X (2008) Increasing biogas production by thermal (70 °C) sludge pre-treatment prior to thermophilic anaerobic digestion. Biochem Eng J 42(2):186–192CrossRefGoogle Scholar
  11. He C, Giannis A, Wang J (2013) Conversion of sewage sludge to clean solid fuel using hydrothermal carbonization: hydrochar fuel characteristics and combustion behavior. Appl Energy 111:257–266CrossRefGoogle Scholar
  12. Hidalgo D, Gómez M, Martín-Marroquín JM, Aguado A, Sastre E (2015) Two-phase anaerobic co-digestion of used vegetable oils’ wastes and pig manure. Int J Environ Sci Technol 12(5):1727–1736CrossRefGoogle Scholar
  13. Izumi K, Okishio Y, Nagao N, Niwa C, Yamamoto S, Toda T (2010) Effects of particle size on anaerobic digestion of food waste. Int Biodeterior Biodegrad 64(7):601–608CrossRefGoogle Scholar
  14. Karthikeyan OP, Visvanathan C (2013) Bio-energy recovery from high-solid organic substrates by dry anaerobic bio-conversion processes: a review. Rev Environ Sci Biotechnol 12(3):257–284CrossRefGoogle Scholar
  15. Kim D, Youn Y (2011) Characteristics of sludge hydrolysis by ultrasound and thermal pretreatment at low temperature. Korean J Chem Eng 28(9):1876–1881CrossRefGoogle Scholar
  16. Kim D, Lee K, Park KY (2015) Enhancement of biogas production from anaerobic digestion of waste activated sludge by hydrothermal pre-treatment. Int Biodeterior Biodegrad 101:42–46CrossRefGoogle Scholar
  17. Klein K, Kivi A, Dulova N, Zekker I, Mölder E, Tenno T, Trapido M, Tenno T (2017) A pilot study of three-stage biological–chemical treatment of landfill leachate applying continuous ferric sludge reuse in Fenton-like process. Clean Techn Environ Policy 19(2):541–551CrossRefGoogle Scholar
  18. Koch K, Wichern M, Lübken M, Horn H (2009) Mono fermentation of grass silage by means of loop reactors. Bioresour Technol 100(23):5934–5940CrossRefGoogle Scholar
  19. Li C, Wang X, Zhang G, Yu G, Lin J, Wang Y (2017) Hydrothermal and alkaline hydrothermal pretreatments plus anaerobic digestion of sewage sludge for dewatering and biogas production: bench-scale research and pilot-scale verification. Water Res 117:49–57CrossRefGoogle Scholar
  20. Liao X, Li H, Cheng Y, Chen N, Li C, Yang Y (2014) Process performance of high-solids batch anaerobic digestion of sewage sludge. Environ Technol 35(21–24):2652–2659CrossRefGoogle Scholar
  21. Liao X, Li H, Zhang Y, Liu C, Chen Q (2016) Accelerated high-solids anaerobic digestion of sewage sludge using low-temperature thermal pretreatment. Int Biodeterior Biodegrad 106:141–149CrossRefGoogle Scholar
  22. Liu Y, Li X, Kang X (2015) Effect of volume ratio on anaerobic co-digestion of thermal hydrolysis of food waste with activated sludge. Int Biodeterior Biodegrad 102:154–158CrossRefGoogle Scholar
  23. Luo G, Xie L, Zhou Q (2009) Enhanced treatment efficiency of an anaerobic sequencing batch reactor (ASBR) for cassava stillage with high solids content. J Biosci Bioeng 107(6):641–645CrossRefGoogle Scholar
  24. Ma J, Duong TH, Smits M, Verstraete W, Carballa M (2011) Enhanced biomethanation of kitchen waste by different pre-treatments. Bioresour Technol 102(2):592–599CrossRefGoogle Scholar
  25. Mandel A, Zekker I, Jaagura M, Tenno T (2019) Enhancement of anoxic phosphorus uptake of denitrifying phosphorus removal process by biomass adaption. Int J Environ Sci Technol. CrossRefGoogle Scholar
  26. Neumann P, González Z, Vidal G (2017) Sequential ultrasound and low-temperature thermal pretreatment: process optimization and influence on sewage sludge solubilization, enzyme activity and anaerobic digestion. Bioresour Technol 234:178–187CrossRefGoogle Scholar
  27. Nghiem LD, Nguyen TT, Manassa P, Fitzgerald SK, Dawson M, Vierboom S (2014) Co-digestion of sewage sludge and crude glycerol for on-demand biogas production. Int Biodeterior Biodegrad 95:160–166CrossRefGoogle Scholar
  28. Passos F, García J, Ferrer I (2013) Impact of low temperature pretreatment on the anaerobic digestion of microalgal biomass. Bioresour Technol 138:79–86CrossRefGoogle Scholar
  29. Priyadarshini R, Vaishnavi L, Murugan D, Sivarajan M, Sivasamy A, Saravanan P, Balasubramanian N, Rai CL (2015) Kinetic studies on anaerobic co-digestion of ultrasonic disintegrated feed and biomass and its effect substantiated by microcalorimetry. Int J Environ Sci Technol 12(9):3029–3038CrossRefGoogle Scholar
  30. Rafique R, Poulsen TG, Nizami A, Asam Z, Murphy JD, Kiely G (2010) Effect of thermal, chemical and thermo-chemical pre-treatments to enhance methane production. Energy 35(12):4556–4561CrossRefGoogle Scholar
  31. Ratanatamskul C, Onnum G, Yamamoto K (2014) A prototype single-stage anaerobic digester for co-digestion of food waste and sewage sludge from high-rise building for on-site biogas production. Int Biodeterior Biodegrad 95:176–180CrossRefGoogle Scholar
  32. Rikmann E, Zekker I, Tenno T, Saluste A, Tenno T (2018) Inoculum-free start-up of biofilm- and sludge-based deammonification systems in pilot scale. Int J Environ Sci Technol 15(1):133–148CrossRefGoogle Scholar
  33. Tenno T, Rikmann E, Zekker I, Tenno T, Daija L, Mashirin A (2016) Modelling equilibrium distribution of carbonaceous ions and molecules in a heterogeneous system of CaCO3–water–gas. Proc Eston Acad Sci 65(1):68–77CrossRefGoogle Scholar
  34. Tenno T, Uiga K, Mashirin A, Zekker I, Rikmann E (2017) Modeling closed equilibrium systems of H2O–dissolved CO2–solid CaCO3. J Phys Chem A 121(16):3094–3100CrossRefGoogle Scholar
  35. Wang Z, Wang W, Zhang X, Zhang G (2009) Digestion of thermally hydrolyzed sewage sludge by anaerobic sequencing batch reactor. J Hazard Mater 162(2–3):799–803CrossRefGoogle Scholar
  36. Zekker I, Kivirüüt A, Rikmann E, Mandel A, Jaagura M, Tenno T, Artemchuk O, Rubin SD, Tenno T (2019) Enhanced efficiency of nitritating–anammox sequencing batch reactor achieved at low decrease rates of oxidation–reduction potential. Environ Eng Sci 36(3):350–360CrossRefGoogle Scholar

Copyright information

© Islamic Azad University (IAU) 2019

Authors and Affiliations

  1. 1.School of Environment and EnergySouth China University of TechnologyGuangzhouPeople’s Republic of China
  2. 2.Shenzhen Water Investment Co., Ltd.ShenzhenPeople’s Republic of China
  3. 3.The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry ClustersMinistry of EducationGuangzhouPeople’s Republic of China

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