Enhancing the efficiency of nitrogen removing bacterial population to a wide range of C:N ratio (1.5:1 to 14:1) for simultaneous C & N removal

• Simultaneous C & N removal in Methammox occurs at wide C:N ratio. • Biological Nitrogen Removal at wide C:N ratio of 1.5:1 to 14:1 is not reported. • Ammonia removal shifted from mixotrophy to heterotrophy at high C:N ratio. • Acetogenic population compensated for ammonia oxidizers at high C:N ratio. • Methanogens increase the plasticity of nitrogen removers at high C:N ratio. High C:N ratio in the wastewater limits biological nitrogen removal (BNR), especially in anammox based technologies. The present study attempts to improve the COD tolerance of the BNR process by associating methanogens with nitrogen removing bacterial (NRB) populations. The new microbial system coined as ‘Methammox’, was investigated for simultaneous removal of COD (C) and ammonia (N) at C:N ratio 1.5:1 to 14:1. The ammonia removal rate (11.5 mg N/g VSS/d) and the COD removal rates (70.6 mg O/g VSS/d) of Methammox was close to that of the NRB (11.1 mg N/g VSS/d) and the methanogenic populations (77.9 mg O/g VSS/d), respectively. The activities established that these two populations existed simultaneously and independently in ‘Methammox’. Further studies in biofilm reactor fetched a balanced COD and ammonia removal (55%–60%) at a low C:N ratio (≤2:1) and high C:N ratio (≥9:1). The population abundance of methanogens was reasonably constant, but the nitrogen removal shifted from mixotrophy to heterotrophy as the C:N ratio shifted from low (C:N≤2:1) to high (C:N≥9:1). The reduced autotrophic NRB (ammonia- and nitrite-oxidizing bacteria and Anammox) population at a high C:N ratio was compensated by the fermentative group that could carry out denitrification heterotrophically. The functional plasticity of the Methammox system to adjust to a broad C:N ratio opens new frontiers in biological nitrogen removal of high COD containing wastewaters.     

玉米芯和稻草秸秆强化潜流人工湿地对低C/N污水的处理效果

人工湿地在处理低C/N污水时存在碳源缺乏而严重限制反硝化进行的问题.为了补充反硝化需要的碳源,选择了玉米芯和稻草秸秆作为外加碳源引入湿地系统,对比两种碳源对湿地脱氮的强化效果.结果表明,通过11 d的纯水浸提释放实验发现,碳素累积释放量：稻草秸秆［（145.17±9.44） mg·g^-1］>玉米芯［（57.41±5.04） mg·g^-1］;氮素累积释放量：稻草秸秆［（2.31±0.09） mg·g^-1］>玉米芯［（0.66±0.08） mg·g^-1］.在观测的时间内,玉米芯和稻草秸秆累积释放碳氮比平均值分别为94.78和63.64.相比于稻草秸秆,玉米芯更适合作为外加碳源.在为期58 d的潜流人工湿地实验中,发现除了第8~12 d,添加玉米芯和稻草秸秆人工湿地出水中ρ（COD）超过50 mg·L^-1外,其它时间都低于50 mg·L^-1.在观测期间,添加玉米芯人工湿地的NO₃^--N去除率为93%~99%,具有良好的反硝化性能.而添加稻草秸秆人工湿地在运行后期NO₃^--N去除率最低只有76.8%,反硝化速率明显下降.对照组NO₃^--N去除率只有76.2%~77.7%,出现了明显碳源不足的现象.碳源不足还造成了NO₂^--N的蓄积.添加稻草秸秆和对照组人工湿地中NO₂^--N的出水质量浓度分别是玉米芯人工湿地的2.5~6倍和6~26倍.与添加稻草秸秆比,添加玉米芯可以使人工湿地中NO₂^--N出水质量浓度得到更显著地降低（P<0.05）.玉米芯、稻草秸秆和对照组人工湿地TN去除率分别为83.75%~93.49%、76.59%~78.85%和67.85%~72.56%,三者之间存在显著性差异（P<0.01）.最后,通过对玉米芯进行了稀碱加热预处理,使玉米芯的碳素累积释放量提高到（93.73±17.49） mg·g^-1,累积释放的碳氮比提高至175.8,进一步提高了玉米芯的释碳性能,表现为更合适的外加碳源.     

基于内弹道仿真的火药点火器燃喉比优化与试验验证

目的 减小火药点火器不同药剂批次下的散差,提高其工作可靠性。方法 分析火药点火器不同批次药剂性能与内弹道数据,发现在恒定燃喉比下,药剂性能波动会显著影响其工作可靠性,因此应根据不同批次组合下的药剂性能选取合理的燃喉比。首先,通过标准试验测试火药点火器内装药剂的关键性能参数。然后,通过建立火药点火器内弹道的仿真模型,计算基线燃喉比附近的内弹道参数,输入到基于历史点火冲量数据建立的正态容许限法模型。最后,在预设燃喉比范围内进行发火试验,并利用正态容许限法计算出不同燃喉比对应的点火可靠度。结果 共模拟了8种水平的燃喉比试验,计算出对应的可靠度为0.177 242~0.999 999。根据模型计算出的可靠度及火工品相关标准的要求,确定合理的燃喉比,并增加样本,进一步验证其可靠度。此外,在选定燃喉比附近进行的裕度试验,试验数据均符合预期。结论 通过内弹道仿真建模,结合可靠性试验数据分析,为火药点火器优选了燃喉比,工作可靠度达到了0. 999 908,比改进前的可靠度0.999有了显著提升。     

不锈钢与船体钢在海水中的电偶腐蚀行为研究

目的 研究不锈钢与船体钢在天然海水中的电偶腐蚀行为,为不锈钢的应用提供数据支撑。方法 利用电化学设备研究不锈钢与船体钢在天然海水中的自腐蚀和电偶腐蚀行为,并结合质量损失和腐蚀形貌研究阴阳极面积比对电偶腐蚀敏感性的影响。结果 2种金属的自腐蚀电位相差600 mV,电偶腐蚀倾向严重。当二者发生电偶腐蚀时,不锈钢作阴极,船体钢作阳极。随着不锈钢与船体钢阴阳极面积比的减小,船体钢的腐蚀速率和平均腐蚀深度减小,不锈钢的腐蚀形貌则不受面积比的影响。结论 在实际工程中,可通过增加阳极材料面积的方法来降低电偶腐蚀效应的影响。     

附着生物对富营养化水体氮磷的去除效果

以太湖梅梁湾“863示范工程”水草恢复区原位湖水以及该区渔网围隔上的附着生物为材料，通过室内静态培养试验，研究了附着生物对富营养化湖水的氮、磷去除效果。结果表明，附着生物对水体中的氮有显著的去除效果，半个月内，附着生物对水体中总氮的累积去除率可达60%，在有附着生物的水体中总氮浓度从5 mg/L左右下降到2 mg/L左右；附着生物对水柱中氮的累积去除率和水柱中氮的浓度、附着生物的生物量以及附着生物作用时间密切相关。从培养过程中水体磷的浓度变化来说，培养初期，水体中磷的浓度比较高，附着生物对其有一定的去除作用；培养后期，水柱中磷的浓度比较低，附着生物不但不去除水中的磷，而且还向水柱中释放磷，这可能与附着生物向水体分泌碱性磷酸酶密切相关。     

RELATIONSHIP BETWEEN THE VARIATION OF LUNISOLAR TIDAL FORCE AND EARTHQUAKES IN TAI WAN

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Intrageneric differences in the four stereoisomers of stenusine in the rove beetle genus, Stenus (Coleoptera, Staphylinidae)

Most species of the rove beetle genus Stenus employ the spreading alkaloid stenusine as an escape mechanism on water surfaces. In the case of danger, they emit stenusine from their pygidial glands, and it propels them over the water very quickly. Stenusine is a chiral molecule with four stereoisomers: (2′R,3R)-, (2′S,3R)-, (2′S,3S)-, and (2′R,3S)-stenusine. The percentile ratio of these four isomers is only known for the most common species of the genus: Stenus comma. With the intention of determining the stereoisomer ratios of five additional species from the two subgenera, Stenus and Hypostenus, we used GC/mass spectrometry measurements with a chiral phase. The results showed that the ratio differs among the genus. These findings can be a basis for chemotaxonomy. It is also possible that the biological function of stenusine, e.g., as antibiotic or fungicide, varies with changing stereoisomer composition.