马旭光, 江滔, 唐琼, 常佳丽, 罗涛, 梅自力. 油菜秸秆和鸡粪比例及含固率对其发酵产甲烷特性的影响[J]. 农业工程学报, 2018, 34(12): 236-244. DOI: 10.11975/j.issn.1002-6819.2018.12.029
    引用本文: 马旭光, 江滔, 唐琼, 常佳丽, 罗涛, 梅自力. 油菜秸秆和鸡粪比例及含固率对其发酵产甲烷特性的影响[J]. 农业工程学报, 2018, 34(12): 236-244. DOI: 10.11975/j.issn.1002-6819.2018.12.029
    Ma Xuguang, Jiang Tao, Tang Qiong, Chang Jiali, Luo Tao, Mei Zili. Effect of total solid content on biogas production from rape stalk and chicken manure with different mixing ratios[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2018, 34(12): 236-244. DOI: 10.11975/j.issn.1002-6819.2018.12.029
    Citation: Ma Xuguang, Jiang Tao, Tang Qiong, Chang Jiali, Luo Tao, Mei Zili. Effect of total solid content on biogas production from rape stalk and chicken manure with different mixing ratios[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2018, 34(12): 236-244. DOI: 10.11975/j.issn.1002-6819.2018.12.029

    油菜秸秆和鸡粪比例及含固率对其发酵产甲烷特性的影响

    Effect of total solid content on biogas production from rape stalk and chicken manure with different mixing ratios

    • 摘要: 基于低含固率粪秸厌氧发酵工艺存在的缺点和多原料共发酵的优势,以碳素和氮素含量互补的油菜秸秆和鸡粪为原料,采用批次中温((37±1) ℃)发酵工艺,研究了不同含固率和挥发性物质质量混合比对2种原料产甲烷效率的影响,并分析了产甲烷过程稳定性及动力学特性,以期为粪秸高效产甲烷提供优化工艺参数。结果表明,当油菜秸秆和鸡粪的混合比为90∶10、85∶15和80∶20时,物料产甲烷效率均具有显著的协同效应,其中混合比为90∶10的物料产甲烷效率最高(288.7 mL/g),分别比纯鸡粪和纯油菜秸秆高16.1%和30.4%;当TS≥15%时,不同混合比粪秸的物料甲烷产率和容积甲烷产率较TS≤10%时均显著降低;在TS=10%条件下,二者混合比例为90∶10的物料甲烷产率和容积甲烷产率均较高,分别为224.4 mL/g和0.50 mL/(mL·d);挥发性脂肪酸的大量积累和高浓度铵态氮分别是破坏高C/N和低C/N物料产甲烷稳定性的原因,VFA/TA和氨氮浓度是评价不同C/N物料产甲烷过程稳定性的重要指标。根据动力学特性结果,建议在粪秸高含固率连续产甲烷启动阶段,适宜的固体滞留时间设为14 d。上述结果为油菜秸秆和鸡粪混合发酵高效产甲烷及其发酵过程稳定性的控制具有指导意义。

       

      Abstract: Abstract: China has the largest cultivated area of oilseed rape in the word and only the seeds are harvested for human assumption and animal feed, resulting in the production of an estimated 30 Mt every year of stalk materials. Due to the lack if an effective utilization, most of rape stalk (RS) is burned in the open air or left in the field, which could produce carbon dioxide and solid particles, resulting in the serious environmental and safety problems. Anaerobic digestion plays an important role in transforming crop residues into green energy (bio-methane). There are some advantages of RS as feedstock for anaerobic digestion, such as concentrated geographical distribution, facilitating harvest and transport, the low sulphur content and the high cellulose content. Despite these advantages, RS has the low methane yield because of its high carbon content and imbalance C/N ratio for microbes during anaerobic digestion. Chicken manure (CM) is a well-studied co-substrate due to its high buffering capacity and high nitrogen content. Secondly, RS is hardly compatible with traditional wet anaerobic digestion technology (total solid (TS) <10%) in view of its high TS. Solid state anaerobic digestion (TS≥10%) has been claimed to be a number of advantages over wet anaerobic digestion including the minimal biogas slurry generation, the high volumetric methane production and the positive energy balance. There is no literature so far on the evaluation of methane production and anaerobic digestion stability of RS and CM with low C/N ratio with various mix ratios from wet anaerobic digestion to solid state anaerobic digestion systems. In order to obtain the optimal digestion parameters and high methane yield from RS and CM, methane production rate from co-digestion of RS and CM with balance nutrient was investigated at different total solid content (TS) in batch experiments under the temperature of (37±1) ℃ condition, then anaerobic digestion stability and kinetic characteristics of co-digestion of RS and CM were evaluated in this paper. Results showed that the significant synergistic effects were found when the two mixtures at RS:CM ratios of 90:10, 85:15 and 80:20 (based on volatile solid content), and the highest specific methane production rate (SMPR) of 288.7 mL/g was obtained at RS:CM ratio of 90:10, which was 16.1% and 30.4% higher than that of pure CM and RS, respectively. SMPR of substrates were decreased with the increase of TS and the volumetric methane production rate (VMPR) of substrates in TS of 10% and 15%, which were significant higher than those in TS of 5% and 20%. The higher SMPR of 224.4 mL/g and the higher VMPR of 0.50 mL/(mL·d) was achieved in TS=10% at RS:CM ratio of 90:10. The excessive accumulation of volatile fatty acids (VFAs) and the high concentration ammonia nitrogen could disrupt separately the digestion stability of substrates with high C/N ratio or low C/N ratio. VFA/TA and ammonia nitrogen content were the two important evaluation indicators for the digestion stability of substrates with different C/N ratios. Based on the dynamic results, the optimal solid retention time (SRT) was 14 d with TS=10% and RS:CM ratio 90:10 at the start-up stage of continuous anaerobic digestion in the full scale operation. The above results of this study provide useful information to improve the efficiency and stability of co-digestion of RS and CM under different anaerobic digestion conditions.

       

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