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Mesophilic Anaerobic Co-Digestion of Vegetable Wastes and Swine Manure
anaerobic co-digestion,swine manure,vegetable wastes,methane,wastewater treatment,
|Publication Year :||2016|
|Abstract:||本研究以豬糞與葉菜廢棄物進行中溫(37±1℃)厭氧共消化的實驗，探討生產甲烷氣的最佳操作條件及混合比例。研究分成兩部分的實驗，實驗一為豬糞消化後之沼液與葉菜廢棄物的共消化試驗，探討豬糞在不同水力停留時間(HRT分別為12天、10天及8天)的初次消化後，觀察其出流液(沼液)在補充適當碳源的條件下進行二次厭氧消化是否可以有效提升其產氣效率。初次消化進流豬糞的總固形物(Total solids, TS)調製在5%，二次消化的葉菜廢棄物TS則調製在4%，共消化試驗的混合碳氮比(C/N)皆調配為30:1。實驗二為豬糞與葉菜廢棄物的共消化，探討在HRT 5天的高有機負荷時，不同豬糞(SM)與葉菜廢棄物(VW)混合比例(SM:VW分別為1:0、4:1、3:1、2:1及1:1)的產氣效率以及葉菜廢棄物可添加的上限，實驗二所有進流基質包含豬糞及葉菜廢棄物的TS皆控制在5%的濃度。
實驗一的實驗結果顯示在進流中混入30%之葉菜廢棄物(即HRT 12天)時，可明顯相對提升有機物之去除率(COD 增加5.5%，TS 7.81%，VS 15.77%)及氣體產率(GPR增加0.26 L/L/day，MPR 0.12 L CH4/L/day)。實驗二結果顯示在HRT 5天，純以豬糞為進流基質 (SM:VW為1:0) 時有最好的產氣效率，GPR、MPR及甲烷比例分別為1.70 L/L/day、 1.06 L CH4/L/day及61.90%，COD、TS、VS的去除率則為16.27%、14.40%及12.14%。若添加葉菜廢棄物進行共消化，則以豬糞和葉菜廢棄物混合比4:1為最佳，GPR、MPR及甲烷比例分別為1.49 L/L/day、 0.77 L CH4/L/day及51.33%，COD、TS、VS的去除率則為16.95%、13.27%及11.73%。而本實驗進流之葉菜廢棄物佔比的極限為33%，即豬糞和葉菜混合比2:1，此時之甲烷產率仍有0.54 L CH4/L/day，COD去除率則為13.85%；超過此混合比時，會造成反應槽的抑制現象，不過在加入鹼(Sodium bicarbonate)調整進流及反應槽pH值後，可提高葉菜佔比最大至50%。綜合以上結果以及與其他共消化的研究比較，本研究在進流高濃度的固形物以及較高的有機負荷下，可成功地進行共消化，並達到極佳的產氣效果。
In this study, the experiment of mesophilic (37±1℃) anaerobic co-digestion of swine manure (SM) and vegetable wastes (VW) was conducted to investigate the optimal operational condition and mixing ratio. The whole study includes two experiments. The first experiment was the co-digestion of digestate (the effluent of the primary digestion of swine manure) and vegetable wastes. This experiment was to evaluate if the gas production of digestate in the secondary digestion could be improved effectively after the supplement of proper carbon source under different hydraulic retention times (HRT) of 8, 10 and 12 days. The influent of the primary digestion was 5% TS swine manure, while the vegetable wastes used in the secondary digestion was controlled at 4% TS. Also, the carbon to nitrogen ratio (C/N) of feed mixture of co-digestion was prepared and controlled at around 30:1. The second experiment was the co-digestion of swine manure and vegetable wastes. This experiment was to evaluate the gas production and the limit of adding vegetable wastes at different mixing ratios of 1:0, 4:1, 3:1, 2:1 and 1:1 (SM:VW) under a relative high organic loading rate of 5-day HRT. The influent substrates including both swine manure and vegetable wastes were prepared at around 5% TS before mixing and feeding.
The results of the first experiment showed that in test of adding 30% of vegetable wastes to the primary digestate as feeding mixture (12-day HRT) could improve the COD, TS and VS removal efficiencies of 5.5%, 7.81% and 15.77%, respectively, and also improve the gas production rate (GPR) and methane production rate (MPR) of 0.26 L/L/day and 0.12 L CH4/L/day, respectively. The results of the second experiment showed, at 5-day HRT, the test of using 100% swine manure (SM:VW is 1:0) had the best gas production performance with GPR, MPR and methane content of 1.70 L/L/day, 1.06 L CH4/L/day and 61.90%, respectively, and the COD, TS and VS removal efficiencies of 16.27%, 14.40% and 12.14%, respectively. In respect of adding vegetable wastes for co-digestion, the test of 4:1 (SM:VW) mixing ratio had the best gas production performance with GPR, MPR and methane content of 1.49 L/L/day, 0.77 L CH4/L/day and 51.33%, respectively, and the COD, TS and VS removal efficiencies of 16.95%, 13.27% and 11.73%, respectively.
The results also showed to maintain the system working, the highest proportion of the vegetable wastes could be added was 33%, i.e. SM:VW of 2:1. The MPR of 0.54 L CH4/L/day and TS removal efficiency of 10.87% was observed during this testing period. Beyond this adding ratio of vegetable waste, imbalance of reactor would be occurred due to inhibition. To suppress the inhibition effect, addition of alkali (Sodium bicarbonate) to adjust the pH value of influent and reactor, the proportion of vegetable wastes could then lift up to 50%. In conclusion, the anaerobic co-digestion of swine manure and vegetable wastes with high solids concentration influent and organic loading rate was successfully proved, and a high gas production could be achieved in this study.
|Appears in Collections:||生物機電工程學系|
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