沼气发酵微生物低温驯化研究

[目的]研究6℃低温处理对沼气低温发酵微生物菌群产气特性及菌群数量变化的影响。[方法]利用生化培养箱控制温度条件,采用批量发酵、排水集气知MPN计数法,了解6℃条件沼气发酵器中的主要微生物菌群的数量。[结果]结果表明：通过6℃低温驯化,沼气发酵微生物菌群能维持日平均产气量为23．6ml／2500ml发酵液;发酵细菌数量为3×10^8个／ml,纤维素分解菌为9×10^4个／ml;硫酸盐还原菌数量为1．9×10^5个/ml,其种群数量与常温条件相近;产甲烷菌数量为4×10^5个／ml,比常温条件低2个数量级。[结论]发酵体系中,低温主要影响产甲烷菌群。     

More evidence that anaerobic oxidation of methane is prevalent in soils: Is it time to upgrade our biogeochemical models?

Estimating future fluxes of CH₄ between land and atmosphere requires well-conceived process-based biogeochemical models. Current models do not represent the anaerobic oxidation of methane (AOM) in land surface soils, in spite of increasing evidence that this process is widespread. Our objective was to determine whether AOM, or potential AOM, commonly occurs in 20 hydromorphic soils spanning a wide range of chemical properties. Bulk soil samples were collected under shallow water near the shoreline of 15 recently drained fish ponds in southern Bohemia (Czech Republic), as well as from below the water table at 3 peatland locations in northeast Scotland and 2 acid sulfate soils on the southern coast of Finland. Each soil slurry was incubated under both oxic and anoxic conditions, with or without the addition of alternative electron acceptors (SO₄²⁻ and NO₃⁻) or H₂PO₄⁻. Here, “oxic” and “anoxic” conditions refer to anoxic soil respectively incubated in a headspace containing air or argon. Using the isotope dilution method, we determined the gross production and oxidation rates of CH₄ after 2 days incubation under oxic headspace conditions, and after 2, 21 and 60 days incubation under anoxic conditions. Large differences in net CH₄ fluxes were observed between soil types and between incubation conditions. AOM was detected in each of the 20 bulk soil samples, which spanned >6 pH units and 2 orders of magnitude in organic C content. Significant positive relationships were found between AOM and gross CH₄ production rates under anoxic conditions, resulting in AOM rates that were sometimes higher than CH₄ oxidation rates under oxic headspace conditions. There was no relationship between net and gross CH₄ production rates, such that 2 soil types could display similar low net rates, yet conceal very large differences in gross rates. The effects of alternative electron acceptors on AOM were idiosyncratic and resulted in no net trend. We did find, however, a negative effect of SO₄²⁻ and H₂PO₄⁻ on gross CH₄ production rates under anoxic and oxic conditions respectively. Under oxic headspace conditions, CH₄ oxidation was related to soil organic C content. Taken collectively, our results suggest that AOM, or potential AOM, is prevalent over a wide range of soil types, that AOM may contribute substantially to CH₄ oxidation in soils, and that AOM in soils should be integrated to current process-based CH₄ cycling models.     

不同生物预处理方式对污泥厌氧消化过程性能的影响

利用微生物处理技术对经聚丙烯酰胺脱水后的污泥进行不同方式微生物预处理,研究进料总固体(TS)质量分数为3%、发酵温度为35℃时厌氧消化过程中累积产气量与产甲烷含量、p H值、氨氮和化学需氧量(TCOD)等参数的变化趋势,探索真菌宛氏拟青霉不同预处理方式对脱水污泥厌氧消化过程特性的影响。试验结果表明:微生物预处理脱水污泥厌氧消化技术具有较好的可行性。直接添加宛氏拟青霉和添加宛氏拟青霉预处理2 d的污泥进行厌氧消化反应能够有效提高产气量和产甲烷量,加快水解速率,促进污泥中有机物的有效降解,使产甲烷过程顺利进行。直接添加宛氏拟青霉处理的产甲烷效果最优,其净累积产气量和产甲烷量较纯污泥分别提高85.79%和42.76%,且1 kg污泥可产甲烷12.69 L,较纯污泥提高42.74%。     

猪粪厌氧发酵联产氢气和甲烷的能源转换效率研究

[目的]探讨猪粪厌氧发酵先产氢气后产甲烷的能源转换效率,以期提高传统厌氧发酵的能源转换效率。[方法]将发酵料液的p H调节至4.5~5.5,首先进行厌氧发酵产氢气,产氢结束后将产氢发酵液的p H调节至6.5~7.5进行厌氧发酵产甲烷。[结果]猪粪厌氧发酵联产氢气和甲烷的产能效率为44.06%,明显高于猪粪单独厌氧发酵产氢的产能效率(14.43%)以及猪粪单独厌氧发酵产甲烷的产能效率(32.80%)。[结论]厌氧发酵联产氢气和甲烷能有效提升传统厌氧发酵产能效率。     

微量金属元素对中低温厌氧消化工艺的影响

[目的]探究微量金属元素对中低温厌氧消化工艺的影响。[方法]通过向序批式反应体系内投放微量金属元素(Fe、Co、Ni),研究不同温度条件下,厌氧消化效率的差异。[结果]35℃条件下,厌氧发酵对底物消耗更为迅速,产气效率更高,而20℃条件下,则更有利于刺激嗜冷产甲烷菌群的活性,各处理的p H多维持在6.5~7.0,更适宜厌氧发酵反应的进行。其产生的沼气,甲烷含量也相对更高,其中WP20处理平均甲烷含量可达52%。而投放微量金属元素,对不同菌种的刺激效果存在一定差异,在20℃条件下,微量元素对W菌种厌氧发酵产气效率影响最为显著;35℃条件下,微量元素对G1菌种影响较为明显,G1P35累计产气量达7 129 m L。[结论]该研究可为深入探讨低温条件下沼气生物强化菌群的微生物特性、环境因子互作、菌群时空分布和种群动力学提供技术支撑。     

微氧条件下颗粒污泥的特性及影响因素研究

微氧颗粒污泥是近几年发现的在微氧条件下形成的固定化颗粒,具有良好的沉降性能和较高的抗冲击负荷的能力。微氧技术结合了好氧和厌氧技术的优点,许多难降解物质可以在好氧菌与厌氧菌共同参与下被彻底降解。该文主要分析了微氧颗粒污泥的工作特性、形成过程以及影响污泥颗粒化的各种因素。     

不同结构填埋场的环境污染分析

介绍了中国城市生活垃圾填埋处理状况、渗滤液和填埋气的特性及污染性 分析了厌氧填埋、好氧填埋、准好氧填埋等3种不同结构填埋场内垃圾降解反应的特点及对环境的危害性 探讨了适合中国国情的垃圾填埋处理技术,建议采用准好氧填埋处理,同时再辅以渗滤液回灌和微生物加速降解的组合工艺处理技术。     

有机废水生物处理及综合利用技术的研究进展

比较了几种不同的有机废水生物处理技术的优缺点,并进行了相关讨论。     

土壤剖面胶体中铁氧化物及其厌氧还原特征研究

采用自由沉降法分离提取玄武岩赤红壤不同剖面深度的土壤胶体,分析其基本特征,并通过厌氧培养试验测试不同剖面土壤胶体中铁氧化物的厌氧还原特征。化学分析结果表明,土壤胶体中铁的游离度表现出A层>B1层>AB层的趋势,铁的活化度则随剖面深度的增加而降低,XRD、FTIR的表征结果显示,玄武岩赤红壤胶体中铁氧化物主要是结晶较差的赤铁矿和针铁矿。培养试验结果表明,不同剖面深度的土壤胶体厌氧培养过程中,Fe(Ⅱ)浓度均表现出不断增大的趋势,A层土壤胶体铁氧化物易被还原且累积量较高,可达(0.104±0.003)mg/g土。Fe(Ⅱ)的最大累积量随着土壤胶体中无定形铁的含量和铁的活化度的增加而增加,其速率常数与土壤有机质含量有一定的正相关关系。