| 摘要: |
| 【目的】研究NaOH及其与超声联合预处理对小麦秸秆与猪粪混合厌氧发酵特性的影响。【方法】采用0%，3%，6% NaOH单独（分别命名为CK，3%，6%处理）或其联合250 W超声波15 min （分别命名为CK+，3%+，6%+处理）预处理小麦秸秆，用扫描电镜观察小麦秸秆表层结构的变化，之后将预处理的小麦秸秆与猪粪按照2∶1，1∶1，1∶2比例（质量比）进行混合发酵，测定小麦秸秆与猪粪不同配比下混合厌氧发酵过程中产气量、pH、碱度和挥发性脂肪酸（volatile fatty acids，VFA）的变化。【结果】经NaOH单独预处理或其与超声波联合预处理后，小麦秸秆表面结构均受到了明显破坏。从发酵开始，各处理的日产气量均在第3天左右达到第1次峰值，在第8天左右下降到最低值；随着水解酸化的进行，各处理的日产气量又出现第2次高峰，但出现高峰时间差异较大。在NaOH单独预处理组或其与超声波联合处理组中，当小麦秸秆与猪粪按照2∶1，1∶1比例混合时，随NaOH含量的增加，累积产气量均呈增大趋势；当小麦秸秆与猪粪按照1∶2比例混合时，NaOH单独预处理组中CK组累积产气量最大，而联合预处理组中3%+处理累积产气量最大。预处理小麦秸秆与猪粪混合厌氧发酵效果依赖于两者混合比例。在整个发酵过程中，当小麦秸秆与猪粪配比分别为2∶1，1∶1和1∶2时，NaOH单独预处理的pH分别为5.6~7.7，5.6~7.6，5.7~7.7，NaOH与超声波联合预处理的pH分别为5.7~7.9，5.6~7.6，5.7~7.7，可见NaOH单独预处理及其与超声波联合预处理的pH并无明显差异。当小麦秸秆与猪粪按照2∶1比例混合时，碱度增加速率最快，并在整个发酵期内总体较高，其次是1∶1配比组，1∶2配比组最低。在发酵过程前期VFA质量浓度变动幅度较大，发酵后期VFA质量浓度变动幅度较小。总体上各预处理小麦秸秆与猪粪配比为1∶1时的VFA质量浓度与1∶2配比组接近，但是高于2∶1配比组。超声单独预处理可提升产气效果，但相比NaOH单独处理，超声与NaOH联合预处理并不具有增强产气效果的协同作用。【结论】经6% NaOH预处理后小麦秸秆与猪粪按照2∶1比例混合后，可获得良好的产气效果。 |
| 关键词: 沼气 小麦秸秆 混合预处理 猪粪 厌氧发酵 |
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| 基金项目:西北农林科技大学青年英才培育计划资助项目；国家自然科学基金项目（51508467）；中国博士后科学基金项目（2016T90950,2015M582708）；陕西省科技厅自然科学基金项目（2016JQ4007） |
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| Anaerobic co-digestion characteristics of pig manure and pretreated wheat straw with ultrasonic and NaOH |
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ZHAO Nan,XUE Shengrong,YANG Gaihe,et al
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| Abstract: |
| 【Objective】The effects of NaOH pretreatment and its combination with ultrasound on anaerobic co-digestion performance of wheat straw and pig manure were studied.【Method】Pretreatments with 0%,3%,and 6% NaOH (CK,3% and 6%) and its combination with 15 min 250 W ultrasonic pretreatment (CK+,3%+ and 6%+) were conducted for wheat straw before the fermentation with pig manure at mass ratios of 2∶1,1∶1 and 1∶2 was carried out.The changes in anaerobic fermentation characteristics including biogas production,pH,alkaline and volatile fatty acids (VFA) were determined.【Result】The surface structure of wheat straw was obviously damaged by NaOH pretreatment alone or combined with ultrasonic pretreatment.At the beginning of fermentation,daily biogas productions of all treatments reached the first peak around day 3,and dropped to the lowest value around day 8.With hydrolytic acidification,daily biogas productions showed the second peak at different times.In the NaOH pretreatment or ultrasound combined with NaOH pretreatment groups,when wheat straw was mixed with pig manure at ratios of 2∶1 and 1∶1,the cumulative gas production increased with the increase of NaOH content.When wheat straw was mixed with pig manure at the ratio of 1∶2,CK group had the largest cumulative gas production in NaOH pretreatment alone groups,while 3%+ treatment had the largest cumulative gas production in the combined pretreatment groups.The anaerobic fermentation efficiency of pretreated wheat straw and pig manure depended on mixture ratio.When the ratios of wheat straw to pig dung were 2∶1,1∶1 and 1∶2,the pH values of NaOH pretreatment alone were 5.6-7.7,5.6-7.6,and 5.7-7.7,and those of NaOH pretreatment combined with ultrasound pretreatment were 5.7-7.9,5.6-7.6,and 5.7-7.7.There was no significant difference in pH values.When the wheat straw to pig manure ratio was 2∶1,the alkaline increase rate was the fastest and remained high during the whole fermentation period,followed by 1∶1 groups and 1∶2 groups.In the early stage of fermentation,VFA mass concentration fluctuated greatly,while it changed slightly in the later stage.Overall,VFA of pretreated wheat straw with pig manure at the ratio of 1∶1 was close to that of the 1∶2 groups,both were higher than that of the 2∶1 groups.Ultrasonic treatment alone can improve gas production effect,and ultrasonic treatment combined with NaOH did not show synergistic effect on gas production.【Conclusion】The wheat straw after pretreatment with 6% NaOH mixed with pig manure at the ratio of 2∶1 could achieve good anaerobic co digestion performance. |
| Key words: methane wheat straw pretreatment pig manure anaerobic digestion |
