Experimental On The Effect Of Combined Addition Of Iron Powder And Biochar Powder On Anaerobic Digestion With Stalk

In recent years,the research of additives promoting anaerobic digestion performance had become one of the hot spots.Carbon based materials can affect the biological activities of microorganisms,and nano metal ions could improve the digestion performance and promote the interspecific electron transfer.Due to the waxy structure on the surface of corn stalks,it would cause slow anaerobic digestion and decomposition of the stalks,low biogas production efficiency,and low degradation rate.In order to further strengthen anaerobic digestion.In this study,nano zero-valent iron(NZVI)powder and biochar(BC)powder as additives at a medium temperature of 35?,corn stalk was used as the substrate for anaerobic digestion.The individual effects of BC,NZVI and combined effect of them on the digestion performance was explored.On this basis,the combined addition amount of and the best addition ratio of NZVI and BC on the promotion of anaerobic digestion of stalk are obtained.The results are as follows:1.Under the premise of fixed the separate addition amount of NZVI powder and BC powder,and taking the cumulative methane production as the optimization target,the combined addition of NZVI powder and BC powder can further improve the biogas production and methane production by anaerobic digestion of corn stalk compared with the addition of individual addition.The effects of BC powder,NZVI powder and their combined addition on methane production by anaerobic digestion of corn stalk were studied.The results showed that the combined addition of NZVI powder and BC powder could further improve methane production.The cumulative methane production of 5%(C)+5%(Fe)?5%(Fe)?5%(C)and control run were 186.87 mL/g VS,171.66 mL/g VS,144.25 mL/g VS and 129.55 mL/g VS,respectively,The combined addition of NZVI powder and BC powder has the highest cumulative methane production was increased by 45.96%compared with the control run.The average methane content of runs with addition of 5%(C)+5%(Fe),5%(Fe),5%(C)and blank group was 52.71%,52.28%,47.53%and 49.67%.Compared with the control run,the combined addition of NZVI powder and BC powder could increase average methane content by 4.87%,and the combined addition of NZVI powder and BC powder can reduce the TS content of stalk and improve the TS removal rate of stalk by 26.99%,and can further reduce the carbon dioxide content.2.Under the premise that the NZVI powder to BC powder ratio of 1:1,and taking the cumulative methane production as the optimization target,the optimal adding amount is 9%.The experiment of anaerobic digestion of stalk with the combined addition of NZVI powder and BC powder was carried out,the results showed that:under laboratory conditions,the addition of 9%had the best promotion effect on the anaerobic digestion of stalk,the cumulative methane production and cumulative biogas production was 167.88 mL/g VS and 347.79 mL/g VS,which was 26.99%and 16.81%higher than that of the control run.The additive amount of NZVI powder and BC powder in the range of 12%can improve the methane conversion rate,after 28 days of anaerobic digestion,the total methane content of each digester is 44.39%,48.14%,47.95%,48.27%,47.06%,and 44.27%respectively.Compared with the control run,the addition of 9%can increase the methane conversion rate by 8.74%;The 9%addition amount of the test group has a better VS removal rate,which is increased by 2 0.41%compared with the blank control run.3.Under the premise that the combined addition dosage of 9%,and taking the cumulative methane production as the optimization target,the optimal ratio of NZVI powder and BC powder is obtained as 1:2.The experiment of anaerobic digestion of stalk with the combined ratio of NZVI powder and BC powder was carried out,the results showed that:under laboratory conditions,the all of experimental run with 9%of additive was beneficial to anaerobic digestion of stalk,the highest cumulative biogas production and methane production were obtained with NZVI powder to BC powder ratio of 1:2,which were 357.83 mL/g VS and 179.96 mL/g VS,respectively,compared with the 262.81mL/g VS and 123.51mL/g VS of the control run,which increased by 36.16%and 38.36%,respectively.After 28 days of anaerobic digestion,the average methane content of each run was 47.01%,50.01%,50.08%,50.29%,49.27%and 47.11%,respectively.Compared with the control run,the average methane content was increased by 7.01%with NZVI powder to BC powder ratio of 1:2.