氨化水饱和预处理麦秸厌氧消化产气性能的研究

试验以氨水为预处理试剂,研究在水饱和状态下,氨水添加量及负荷率对麦秸厌氧消化产气性能的影响。对氨化预处理前后麦秸的主要组分进行测定,采用傅立叶变换红外光谱(FTIR)对氨化水饱和预处理秸秆及秸秆中木素、纤维素和半纤维素的结构变化进行研究。结果表明,在3种负荷率下,氨化水饱和预处理后麦秸单位质量VS产气量分别提高了14%~23%,26%~36%和31%~45%。4%氨化预处理后的麦秸在65 g/L负荷率下获得最大377 mL/g的生物气产量。组分分析表明,氨化水饱和预处理可有效脱除39%~42%的半纤维素及11%~20%的纤维素,对木素含量影响较小。结构分析表明,氨化水饱和预处理可脱除细胞壁中的蜡质成分,使木素中部分官能团、纤维素中的氢键和糖苷键、半纤维素的部分氢键和糖单元之间的连接键发生断裂;从而使纤维素从木素的包裹中释放出来并发生溶胀,破坏其晶体结构;使半纤维素亲水性增强且更易于降解。这些秸秆内部结构的变化是提高麦秸厌氧消化产气性能的根本原因。     

大气细颗粒物组分分析及研究

大气细颗粒物（PM2.5）的危害与其化学组分密切相关。本文详细介绍了PM2.5的主要组分,包括水溶性无机盐离子、元素碳和有机碳、痕量元素以及地壳元素等。PM2.5的组分受不同因素影响会有所变化。本文总结了季节、地域和特殊污染过程三个主要影响因素,并且比较了几个不同城市的PM2.5组分,对PM2.5的组分研究具有一定意义。     

原子荧光法和电感耦合等离子体质谱法测定地表水中砷、锑对比分析

分别用原子荧光法(AFS)和电感耦合等离子体质谱法(ICP-MS)测定水中砷和锑。AFS法和ICPMS法均线性良好,相关系数范围为0.9995~1.0000,用国家标准物质验证两种方法的可靠性与准确度。结果表明,测定值均在标准值允许范围内,两种方法准确度高、精密度好、灵敏度高,具有很强的可比性等。两种方都可以有效的监测地表水中的砷和锑。ICP-MS法可以同时进行多元素分析,但是相对成本较高。     

Enhancing Biogas Production from Anaerobically Digested Wheat Straw Through Ammonia Pretreatment

Aqueous ammonia was used to pretreat wheat straw to improve biodegradability and provide nitrogen source for enhancing biogas production. Three doses of ammonia （2%, 4%, and 6%, dry matter） and three moisture contents （30%, 60%, and 80%, dry matter） were applied to pretreat wheat straw for 7 days. The pretreated wheat straws were anaerobically digested at three loading rates （50, 65, and 80 g·L^-1） to produce biogas. The results indi-cated that the wheat straw pretreated with 80%moisture content and 4%ammonia achieved the highest methane yield of 199.7 ml·g^-1 （based on per unit volatile solids loaded）, with shorter digestion time （T80） of 25 days at the loading rate of 65 g·L^-1 compared to untreated one. The main chemical compositions of wheat straw were also ana-lyzed. The cellulose and hemicellulose contents were decomposed by 2%-20%and 26%-42%, respectively, while the lignin content was hardly removed, cold-water and hot-water extracts were increased by 4%-44%, and 12%-52%, respectively, for the ammonia-pretreated wheat straws at different moisture contents. The appropriate C/N ratio and decomposition of original chemical compositions into relatively readily biodegradable substances will improve the biodegradability and biogas yield.