| 微藻藻渣生物质厌氧发酵制氢气和甲烷技术研究 |
| 杨智满
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| 导师 | 郭荣波
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| 2010-09
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| 学位授予单位 | 中国科学院研究生院
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| 学位授予地点 | 北京
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| 学位专业 | 环境工程
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| 关键词 | Key Words: Lipid-extracted Microalgal Biomass Residues
Hydrogen Production
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| 其他摘要 | 当前，微藻生物柴油受到学术界和工业界的广泛关注。随着微藻生物柴油工业的发展，必须认真考虑提油后藻类生物质残渣（简称藻渣）的处理问题。因藻渣富含蛋白质和碳水化合物，因此可利用厌氧发酵的办法将藻渣转化成为氢气和甲烷等能源产品。本研究的目的是系统研究藻渣厌氧发酵制氢气和甲烷燃气的可行性、影响因素以及具体的工艺技术路线，从而开发出藻渣有效利用的合理技术。本研究首先进行了原始藻渣厌氧发酵产氢的初步研究。结果表明，利用藻渣作为底物厌氧发酵制氢具有一定的可行性。研究发现，与酸碱、氯仿等接种物预处理方式相比，厌氧消化污泥热处理是富集产氢菌群的最有效的方法。同时发现，发酵产氢过程受初始 pH 值影响明显。在初始 pH、接种物浓度和底物浓度分别是 pH6.0~6.5、2.35 g-VSS(挥发性悬浮状固体)/L 和 36 g-VS(挥发性固体)/L 的条件下，藻渣最大产氢速率是 2.82 mL H2/h，氢气产量可达到 30.03 mL H2/g-VS。为了进一步提高藻渣厌氧发酵的氢气产量，本文对藻渣预处理方法进行了比较研究，并且考察了预处理对藻渣溶解率和产氢的影响。预处理方法包括碱处理、热处理和热碱处理。结果表明热碱处理显著提高了藻渣的溶解率和氢气产量。热碱处理（100°C）它不但使藻渣的溶解率达到 80%，也使氢气产量提高了三倍。因此热碱处理（100°C）是提高藻渣溶解率和氢气产量的最好方法。然而，在藻渣热碱处理过程（100°C）中, NaOH 剂量、处理时间和藻渣浓度均影响氢气产生过程。在 NaOH 剂量为 8 g/L，处理时间为 2.5 h 和藻渣浓度为 6.7%的最佳的预处理条件下, 藻渣的氢气产量和氢气产生速率分别提高了 1.6 倍和 5 倍。同时重复批次发酵实验证明重复批次发酵不但提高了氢气产量和氢气产生速率，而且缩短了产氢发酵时间。氢气产量和氢气产生速率从启动时的 47~48 mL H2/g-VS 和4.69~4.84 mL H2/h 分别提高到 66 mL H2/g-VS 和 38~40 mL H2/h。另外，藻渣发酵产氢过程中添加乙酸盐和丁酸盐所引起的产氢抑制效应表明，添加乙酸盐只影响氢气产生速率和产氢延迟时间，而不影响氢气产量。然而，添加丁酸盐引起的产氢抑制效应明显强于添加乙酸盐，添加高浓度的丁酸盐严重抑制了氢气产生。为了实现藻渣生物质的充分利用和转化，本文在藻渣厌氧发酵制氢研究的基础上，开展了藻渣两相厌氧发酵联产氢气和甲烷的研究。结果表明，在第一相产氢阶段，氢气产量是 45.54 mL H2/g-VS；在第二相产甲烷阶段，甲烷产量是 393.6mL CH4/g-VS。与单相厌氧发酵产甲烷工艺相比，两相发酵工艺的甲烷产量提高了 22%。结果证明，热碱处理后的藻渣两相发酵联产氢气和甲烷具有较好的技术上可行性。; Nowadays, the potential of microalgal biodiesel as a source of biofuels is subject to intense research. With the development of microalgal biodiesel industries, the disposal of large amounts of lipid-extracted microalgal biomass residues (LMBRs) could be serious considered. Since LMBRs are rich in carbohydrate and protein, one approach is to convert LMBRs into biogas. The aim of this work was to systematically investigate the feasibility of biogas production from LMBRs.Firstly, hydrogen production from untreated LMBRs was studied and it was found hydrogen production was dependent on types of inocua and initial pH. The optimum initial pH, inoculum concentration and LMBRs concentration for hydrogen production were respectively pH 6.0-6.5, 2.35 g-VSS/L of inoculum, and 36 g-VS/L of LMBRs using the heat-treated anaerobic digested sludge as inoculum. The maximum hydrogen production rate of 2.82 mL H2/h and hydrogen yield of 30.03 mL H2/g-VS were obtained under optimal conditions.Different methods were used to pretreat LMBRs to improve their solubilization and anaerobic hydrogen production abilities. The pretreatment methods studied included thermal (100°C and 121°C), alkaline and thermo-alkaline pretreatments (combinations of alkaline and thermal pretreatments). The results showed that thermo-alkaline pretreatments resulted in remarkable improvements on LMBR solubilization, which led to an increase in hydrogen yield. The highest hydrogen yield of 45.54 mL H2/g-VS was achieved from LMBRs pretreated by the thermo-alkaline pretreatment at 100°C, which was approximately three-fold higher than the yield from untreated LMBRs. The results proved that thermo-alkaline pretreatment at 100°C is an effective method to improve LMBR solubilization and increase the hydrogen production from LMBRs.In order to obtain the high hydrogen yield from LMBRs, the effects of dosage of NaOH, pretreatment time and solid content in thermo-alkaline pretreatment process on hydrogen production from LMBRs were investigated. The results revealed that the optimal pretreatment conditions were attained with 6.7% LMBRs soaked with 8 g/L NaOH at 100°C for 2.5h, which resulted in 160% and 500% improvement in hydrogen yield and hydrogen production rate. It was also found that repeated batch cultivation can not only improve hydrogen yield and hydrogen production rate, but also reduce the lag-phase time of hydrogen fermentation. The hydrogen yield and hydrogen production rate increased respectively from 47 mL H2/g-VS (volatile solid) and 4.69 mL H2/h at start-up to 66 mL H2/g-VS and 39.7 mL H2/h after five repeated transfers in repeated batch cultivation.The inhibitory effects of acetate and butyrate addition on hydrogen production during LMBR fermentation by mixed culture were also investigated. The experimental results showed that increasing the added acetate concentration had a negative effect on the hydrogen production rate and lag-phase time rather than on the hydrogen yield. The inhibitory effect of butyrate addition on hydrogen production was higher than that of acetate addition. High level of butyrate had a significant inhibitory influence on substrate degradation and hydrogen production.A two-stage process to produce hydrogen and methane from LMBRs was investigated. The hydrogen yield of 46 mL H2/g-VS was produced in the first stage. The methane production was 393.62 mL CH4/g-VS in the second stage, which was 22% higher than that in the one-stage process. This work demonstrated the feasibility of using a renewable resource (LMBRs) as the feedstock to produce hydrogen and menthane. |
| 作者部门 | 生物制氢与沼气团队 |
| 学科领域 | 生物制氢与沼气
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| 公开日期 | 2011-08-29
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| 学位类型 | 博士
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| 语种 | 中文
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| 文献类型 | 学位论文
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| 条目标识符 | http://ir.qibebt.ac.cn/handle/337004/326
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| 专题 | 工业生物燃气研究组
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推荐引用方式
GB/T 7714 |
杨智满. 微藻藻渣生物质厌氧发酵制氢气和甲烷技术研究[D]. 北京. 中国科学院研究生院,2010.
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