群感效应与信号分子在污泥颗粒化过程中的作用研究进展

好氧颗粒污泥具有良好的沉降性能和较好的污水处理效果等优点.本文综述好氧颗粒污泥的形成过程,重点分析在污泥颗粒化过程中群感效应和细胞信号分子的作用.研究发现,群感效应和细胞信号分子在污泥颗粒化过程中发挥着重要作用,群感效应可以加快污泥胞外聚合物合成和提高微生物表面附着能力,信号分子可以促进微生物分泌胞外聚合物并影响生物膜的形成.举例说明信号分子中的c-di-GMP作为第二信使在污泥颗粒化过程中的重要作用,c-di-GMP可以将细菌从单细胞游走型转变为多细胞黏附型——生物膜状态.投加钙离子会促进能够分泌c-diGMP的菌群生长从而加快好氧颗粒污泥的形成,投加锰离子会减少好氧颗粒污泥中c-di-GMP的含量导致好氧颗粒污泥解体.最后进行前景展望,认为从群感效应和信号分子的角度去解析好氧颗粒污泥形成机理,可为确立好氧颗粒污泥形成机制奠定理论基础,对其进一步的工程化应用具有现实意义.     

不同碳源驯化除磷污泥的除磷效果及菌群结构分析

采用SBR反应器,分别以乙酸钠、甘油、丙酸钠为单一碳源,在严格厌氧/缺氧条件下驯化培养反硝化除磷污泥,考察不同碳源对反硝化除磷效果的影响,并采用高通量测序技术研究了不同碳源除磷污泥的菌群结构,分析其中除磷菌所占比例. 结果表明,以乙酸钠、甘油、丙酸钠为碳源的各系统出水中,ρ(TP)平均值分别为0.79、0.98、0.29 mg/L,TP去除率分别为82.5%、79.2%、93.4%. 取自污水厂的种泥微生物多样性最高;其次为以甘油驯化的污泥和以乙酸钠与丙酸钠培养的污泥,二者表现出相似的多样性与菌群结构. 各反应器中的污泥在“纲”与“目”分类级别上分别均以β-Proteobacteria与Rhodocyclales占主导. 稳定期乙酸钠、甘油、丙酸钠为碳源的系统中的除磷菌所占比例分别为9.5%、8.0%、41.5%,以丙酸钠为碳源的系统中除磷菌所占比例最高. 对于厌氧/缺氧系统,与以乙酸钠、甘油相比,丙酸钠为碳源时系统的除磷效果更好,并且有利于除磷菌的富集.      

新型高效H2-SCR尖晶石型NiFe2O4催化还原NO

采用柠檬酸配位溶胶-凝胶法制备尖晶石型复合金属氧化物NiFe2O4,以H2为还原剂,在固定床反应器中考察了该催化剂催化还原NO的性能,并借助X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、比表面积测定(BET)、程序升温还原(TPR)和程序升温脱附(TPD)等方法对样品的晶体结构、形貌等特性进行了表征.结果表明.在空速4500 h-1,H2/NO浓度比为1,温度为400℃下,H2催化还原NO的效率可达97.8%,高H2/NO浓度比对NO转化率提升不大,高空速对其催化活性无明显影响.所制备的NiFe2O4催化剂具有典型的尖晶石结构,颗粒不规则,粒径大约为30—150 nm,并且具有良好的双官能团氧化还原性质.     

基于改进贝叶斯网络的加油站火灾爆炸分析

为了找出导致加油站发生火灾爆炸事故的基本事件及其可能性大小,以加油站火灾爆炸故障树为基础建立相应的贝叶斯网络风险模型。在FTA向BN转化算法的基础上对条件概率做出了修正。利用GeNIe软件计算加油站火灾爆炸事故基事件的后验概率,同时进行灵敏度和影响力分析。最后通过实例分析,找出了导致某加油站发生火灾爆炸事故危险性最大的因素集为:加油站接打手机、机械碰撞、给塑料容器加油、加油冒油、油枪渗漏等。结果表明,注重基事件的多态性和事件间逻辑关系合理性的新模型,能推算出更准确的基事件概率分布,同时可以找出导致事故发生的最有可能途径,为加油站事故预防,系统改进提供较为合理性建议。     

影响上海的一次沙尘过程WRF-Dust数值模拟

利用完全耦合大气化学模式WRF-Dust(Weather Research and Forecasting-Dust)对2011年5月1~4日影响上海地区的一次典型沙尘天气过程进行了数值模拟研究,并与观测资料进行了对比分析.结果表明:WRF-Dust模式成功模拟了此次沙尘过程的形成、发展和演变的整体特征及其影响时间及范围;较好地模拟了沙尘到达上海的时间(模式和观测均在1日11:00前后)和直接影响的结束时间(2日02:00前后),而且模式沙尘浓度与观测资料较为一致;但局部地区和部分时段的气象条件和沙尘模拟还存在一定的偏差,未能准确模拟过程后期沙尘回流对长三角沿海地区的影响.分析了导致模拟偏差的原因,并探讨了提高模式沙尘模拟能力的可能途径.     

曝气生物滤池流态特性研究

为了解流体在反应器中的流动特征并为进一步提高反应器处理效率而改善水力条件,通过以KCl为示踪剂的脉冲示踪电导法对上向流曝气生物滤池在不同填料层高度和操作条件下的水力学特性进行摸拟研究.结果表明,平均停留时间主要受填料高度和水流速度影响,受气速影响较小.曝气生物滤池的流态随填料层高度的增加趋于相对稳定且接近推流;但滤床底部和顶部的流态却受水流速度和气流速度的影响较大且偏离推流.最后,建立了在曝气和不曝气两种操作条件下平均停留时间、流态与填料层高度、水流速度、气流速度的数学模型,这可用来预测反应器的流态变化特征,以改善曝气生物滤池的水力条件.     

Influence of arsanilic acid,Cu2+, PO43− and their interaction on anaerobic digestion of pig manure

The methanogenesis was severely inhibited with 0.46 mM ASA addition.PO₄³⁻ didn’t attenuate the methanogenesis inhibition in the existence of ASA.ASA was transformed to As(III), As(V), MMA and DMA in anaerobic digestion.Cu²⁺ mitigated the methanogenesis inhibition via impeding the degradation of ASA.Arsanilic acid (ASA), copper ion (Cu²⁺) and phosphate (PO₄³⁻) are widely used as feed additives for pigs. Most of these three supplemented feed additives were excreted in feces and urine. Anaerobic digestion is often used for the management of pig manure. However, the interaction of ASA with Cu²⁺ or PO₄³⁻ on anaerobic digestion is still not clear. In this study, the influence of ASA, Cu²⁺, PO₄³⁻ and their interaction on anaerobic digestion of pig manure and the possible mechanisms were investigated. The initial concentrations of ASA, Cu²⁺ and PO₄³⁻ were 0.46 mM, 2 mM and 2 mM in the anaerobic digester, respectively. The methanogenesis was severely inhibited in the assays with only ASA addition, only Cu²⁺ addition and ASA+ PO₄³⁻ addition with the inhibition index of 97.8%, 46.6% and 82.6%, respectively, but the methanogenesis inhibition in the assay with ASA+ Cu²⁺ addition was mitigated with the inhibition index of 39.4%. PO₄³⁻ had no obvious impacts on the degradation of ASA. However, Cu²⁺ addition inhibited the degradation of ASA, mitigating the methanogenesis inhibition. The existence of ASA would inhibit methanogenesis and generate more toxic inorganic arsenic compounds during anaerobic digestion, implying the limitation of anaerobic digestion for ASA- contaminated animal manure. However, the co-existence of ASA and Cu²⁺ could mitigate the inhibition. These results could provide useful information for the management of anaerobic digestion of pig manure containing ASA with Cu²⁺.     

Effects of eggshell addition on calcium-deficient acid soils contaminated with heavy metals

The eggshell was used to remediate the contaminated soil by heavy metals. The eggshell addition decreased the available state of the heavy metals. The available calcium in the soil increased due to eggshell addition. The efficiency was investigated in different moisture conditions. In this study, effects of water conditions (flooded, wet, or dry) and eggshell dosages (0, 0.1, 1.0, and 10.0 g/kg soil, respectively) on pH variation, content of unavailable state of heavy metals, form of heavy metals, and available nutritious element calcium (Ca) in acid soils contaminated with heavy metals were investigated, respectively. The soil samples were continuously cultivated indoors and analyzed by toxicity characteristic leaching procedure and community bureau of reference (BCR) sequential extraction procedure. The results showed that the addition of eggshell could effectively improve the pH of acid soil and increase it to neutral level. Moreover, the contents of unavailable state of heavy metals Cu, Zn, and Cd increased significantly. Furthermore, when the soil was cultivated under the flooded condition with 1.0 g/kg eggshell, the unavailable state of Cu, Zn, and Cd increased the most, and these heavy metals were transformed into residual state. On the other hand, the amount of available state of Ca increased to 432.19 from 73.34 mg/kg with the addition of 1.0 g/kg eggshell, which indicated that the addition of eggshell dramatically improved the available state of Ca. Therefore, eggshell could ameliorate the soil environment as it led to the decrease of available heavy metals and improvement of fertilization effectively. In a word, this study indicates that the addition of eggshell would be a new potential method for remediation of acid field soils contaminated with heavy metals.     

粤港澳大湾区生态环境监测发展现状与展望

"十四五"期间,粤港澳大湾区将会迎来新一轮大开发、大建设、大发展,绿色发展与山水林田湖草一体化保护将面临更大的机遇与挑战。生态环境监测作为生态环境保护的重要基础,亟需强化支撑、引领、服务作用。文章对粤港澳大湾区生态环境监测发展现状进行了梳理,从环境质量状况、生态环境管理、环境监测网络等方面将粤港澳大湾区与东京、纽约、旧金山三大世界级湾区进行系统比较,对标查找差距与不足,并对面临的机遇与挑战进行了深入剖析。在此基础上,针对生态环境监测区域布局、现代感知网络、智慧应用与"美丽湾区"综合评价、联合监测与信息发布、产学研用一体化等方面,提出了粤港澳大湾区当前及今后一个时期生态环境监测发展的相关建议。     

太湖地区典型轮作与休耕方式对稻田水稻季N2O和CH4排放量的影响

轮作休耕是实现"藏粮于地、藏粮于技"的重要途径之一,目前在太湖稻田区域主要推广紫云英(Astragalus sinicus L.)-水稻(Oryza sativa L.)、油菜(Brassica napus L.)-水稻和休耕-水稻典型轮作与休耕方式。在太湖地区典型稻田水稻生长季设置了6个处理:(1)紫云英-水稻轮作,不施N肥处理,MRN0;(2)紫云英-水稻轮作,当地常规施肥量(300 kg·hm^-2,以纯氮计,下同),MRN300;(3)油菜-水稻轮作,不施N肥处理,RRN0;(4)油菜-水稻轮作,当地常规施肥量(300 kg·hm^-2),RRN300;(5)休耕-水稻轮作,不施N肥处理,FRN0;(6)休耕-水稻轮作,当地常规施肥量(300 kg·hm^-2),FRN300。通过田间试验,研究了不同轮作与休耕方式对水稻产量、氮肥利用率及稻田温室气体CH₄和N₂O排放的影响,从而为综合评价轮作休耕方式提供科学依据。田间试验结果显示,与不施氮肥处理相比,在不同轮作休耕方式下施氮300 kg·hm^-2,可增加53.7%—60.0%的水稻产量,以MRN300处理水稻产量最高,与RRN300和FRN300处理相比,水稻产量分别提高了1.6%和6.0%。在不施氮水平下,MRN0、RRN0和FRN0各轮作处理间N₂O排放通量和累积排放量均值差异不显著(P>0.05)。而在施氮300 kg·hm^-2下,紫云英-水稻轮作可降低N₂O排放通量和累积排放量,与RRN300和FRN300处理相比,N₂O排放通量分别降低了36.0%(P<0.05)和2.1%(P>0.05)。在同一施氮水平下,紫云英-水稻轮作CH₄排放通量和累积排放量最小,与RRN300和FRN300处理相比,MRN300处理CH₄排放通量分别降低了1.1%和6.7%,CH₄和N₂O的全球增温潜势(GWP)分别降低了3.3%和6.5%,单位水稻产量温室气体排放强度(GHGI)分别降低了4.6%和11.6%。综上,紫云英-水稻轮作对提高水稻产量,降低温室气体排放效果最好。