Effects of non-mixed seeding on methane production characteristics of the batch dry anaerobic digestion of pig manure
LI Danni1,, ZHANG Keqiang1, KONG Dewang2, LIANG Junfeng1, DU Lianzhu1,, 1.Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China 2.Hangzhou Energy Environmental Engineering Ltd., Hangzhou 310020, China
Abstract:In order to alleviate the accumulation of organic acids and enhance the methane production, a small batch experiment was performed in a self-made vertical plexiglass reactor under mesophilic temperature of 37 °C and total solids (TS) of 20%. Pig manure was used as major substrate with different seeding ways including full mixed seeding digestion and inoculum, non-mixed seeding digestion, full mixed digestion maize straw and inoculum, and non-mixed seeding digestion of mixed pig manure and maize straw. The results showed that the mass concentration of total volatile fatty acids (TVFAs) were 15.2 mg·g?1 and 3.6 mg·g?1 with the seeding ways of mixed seeding digestion of the full mixed seeding digestion of pig manure and full mixed raw materials of pig manure and maize straw respectively, which were 6.3 times and 5.0 times higher than that of the corresponding non-mixed seeding raw materials. In the non-mixed seeding system, the TVFAs mass concentration rapidly decreased on day 21. Particularly, the TVFAs mass concentration of the pig manure and straw mixed raw material was lower than 1.50 mg·g?1 on day 30. In addition, the methane yield of non-mixed seeding digestion of the mixed raw materials of pig manure and maize straw reached a highest value of 148.2 mL·g?1, along with a highest methane content of 75.1%. The fitting results of the modified-Gompertz model showed that the fermentation lag time of non-mixed seeding digestion of the mixed raw materials of pig manure and maize straw and non-mixed seeding digestion of pig manure were 10.6 days and 12.4 days respectively, which were 5.9 days and 6.1 days shorter than that of corresponding mixed seeding raw materials. Moreover, the cumulative methane yields reached 6.2 and 4.8 mL·(g·d)?1, respectively, which was increased by 1.7 times and 4.9 times. These results demonstrated that the non-mixed seeding could effectively alleviate the organic acid inhibition and increase methane yield during the dry anaerobic digestion of pig manure. Key words:agro-byproduct/ non-mixed seeding/ dry anaerobic digestion/ acid inhibition/ pig manure/ methane production.
图1发酵装置结构 Figure1.Structural diagram of digestion equipment
图2TVFAs、乙酸、正丁酸、丙酸和异丁酸的质量浓度变化 Figure2.Variations of concentrations of TVFAs, acetic acids, butyrate acids, propionic acids and isobutyrate acids during the experiment
BROWN D, SHI J, LI Y. Comparison of solid-state to liquid anaerobic digestion of lignocellulosic feedstocks for biogas production[J]. Bioresource Technology, 2012, 124(11): 379-386.
[4]
FAGBOHUNGBE M O, DODD I C, HERBERT B M J, et al. High solid anaerobic digestion: Operational challenges and possibilities[J]. Environmental Technology and Innovation, 2015, 4: 268-284. doi: 10.1016/j.eti.2015.09.003
KIM D H, OH S E. Continuous high-solids anaerobic co-digestion of organic solid wastes under mesophilic conditions[J]. Waste Management, 2011, 31(9): 1943-1948.
[11]
ZHANG W Q, LANG Q Q, WU S B. Anaerobic digestion characteristics of pig manures depending on various growth stages and initial substrate concentrations in a scaled pig farm in Southern China[J]. Bioresource Technology, 2014, 156: 63-69. doi: 10.1016/j.biortech.2014.01.013
[12]
LI D W, ZHOU T, CHEN L. Using porphyritic andesite as a new additive for improving hydrolysis and acidogenesis of solid organic wastes[J]. Bioresource Technology, 2009, 100(23): 5594-5599. doi: 10.1016/j.biortech.2009.06.005
[13]
WANG Y, ZHANG Y, WANG J, et al. Effects of volatile fatty acid concentrations on methane yield and methanogenic bacteria[J]. Biomass Bioenergy, 2009, 33(5): 848-853. doi: 10.1016/j.biombioe.2009.01.007
[14]
YU J, ZHAO Y, ZHANG H, et al. Hydrolysis and acidification of agricultural waste in a non-airtight system: Effect of solid content, temperature, and mixing mode[J]. Waste Management, 2016, 59: 487-497.
[15]
WANG Z J, XU F Q, LI Y B. Effects of total ammonia nitrogen concentration on solid-state anaerobic digestion of corn stover[J]. Bioresource Technology, 2013, 144: 281-287. doi: 10.1016/j.biortech.2013.06.106
CAI Y, WANG J, ZHAO Y, et al. A new perspective of using sequential extraction: To predict the deficiency of trace elements during anaerobic digestion[J]. Water Research, 2018, 140: 335-343. doi: 10.1016/j.watres.2018.04.047
CHEN Y, CHENG J J, CREAMER K S. Inhibition of anaerobic digestion process: A review[J]. Bioresource Technology, 2008, 99(10): 4044-4064. doi: 10.1016/j.biortech.2007.01.057
[26]
HANSEN K, ANGELIDAKI I, AHRING B. Anaerobic digestion of swine manure: Inhibition by ammonia[J]. Water Research, 1998, 32(1): 5-12. doi: 10.1016/S0043-1354(97)00201-7
1.Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China 2.Hangzhou Energy Environmental Engineering Ltd., Hangzhou 310020, China Received Date: 2020-03-23 Accepted Date: 2020-08-03 Available Online: 2021-01-13 Keywords:agro-byproduct/ non-mixed seeding/ dry anaerobic digestion/ acid inhibition/ pig manure/ methane production Abstract:In order to alleviate the accumulation of organic acids and enhance the methane production, a small batch experiment was performed in a self-made vertical plexiglass reactor under mesophilic temperature of 37 °C and total solids (TS) of 20%. Pig manure was used as major substrate with different seeding ways including full mixed seeding digestion and inoculum, non-mixed seeding digestion, full mixed digestion maize straw and inoculum, and non-mixed seeding digestion of mixed pig manure and maize straw. The results showed that the mass concentration of total volatile fatty acids (TVFAs) were 15.2 mg·g?1 and 3.6 mg·g?1 with the seeding ways of mixed seeding digestion of the full mixed seeding digestion of pig manure and full mixed raw materials of pig manure and maize straw respectively, which were 6.3 times and 5.0 times higher than that of the corresponding non-mixed seeding raw materials. In the non-mixed seeding system, the TVFAs mass concentration rapidly decreased on day 21. Particularly, the TVFAs mass concentration of the pig manure and straw mixed raw material was lower than 1.50 mg·g?1 on day 30. In addition, the methane yield of non-mixed seeding digestion of the mixed raw materials of pig manure and maize straw reached a highest value of 148.2 mL·g?1, along with a highest methane content of 75.1%. The fitting results of the modified-Gompertz model showed that the fermentation lag time of non-mixed seeding digestion of the mixed raw materials of pig manure and maize straw and non-mixed seeding digestion of pig manure were 10.6 days and 12.4 days respectively, which were 5.9 days and 6.1 days shorter than that of corresponding mixed seeding raw materials. Moreover, the cumulative methane yields reached 6.2 and 4.8 mL·(g·d)?1, respectively, which was increased by 1.7 times and 4.9 times. These results demonstrated that the non-mixed seeding could effectively alleviate the organic acid inhibition and increase methane yield during the dry anaerobic digestion of pig manure.