丁酸型发酵生物制氢反应器的运行特性研究

采用连续流搅拌槽式反应器(CSTR),利用厌氧活性污泥以糖蜜废水为底物发酵产氢,探讨了丁酸型发酵生物制氢反应器稳定运行的工程控制参数,并运用变性梯度凝胶电泳技术(denaturinggradientgelelectrophoresis,DGGE)对微生物菌群结构稳定性进行了分析.研究表明,在污泥接种量(SS)为15g·L-1、温度为(35±1)℃、容积负荷为40kg·m-3·d-1、水力停留时间(HRT)为4h条件下,可以获得CSTR丁酸型发酵的最大产氢速率2 37m3·(m3·d)-1.此时系统的pH、氧化还原电位(ORP)分别在5 2～5 5、-480～-500mV之间.液相末端发酵产物中乙酸和丁酸、乙醇、丙酸、戊酸的含量分别占挥发酸总含量的70%,20%,7%,6%.气相中的氢气含量在30%～40%之间.根据PCR DGGE指纹图谱显示此时期丁酸型发酵优势菌群在反应器内结构保持稳定.     

密切值法和污染损失率法在水环境质量评价中的应用与比较

简要论述了近几年应用较多的密切值评价法和污染损失率法的应用原理与评价过程,并以兰州黄河水质断面监测结果为实例计算,排序评价结果显示与指数评价结果具有良好的一致性,最后分析指出两种评价方法的计算特点及应用价值。     

基于EFA的旅游景区生态承载力及可持续发展

生态足迹分析(EFA)是一种测量人类对自然利用程度、量化生态承载力的新方法。为测度旅游景区的建设强度对其开发区域生态承载力的影响,本文提出基于生态足迹的“生态占用率”及划分“生态占用适宜度”的“生态占用黄金分割法”,并以湖北中华山森林公园为实例,定量分析该项目对景区生态承载力的影响及游客规模限量;为旅游业的可持续发展提供了新思路。     

厦门海域春夏季微型浮游动物对浮游植物的摄食压力初探

应用稀释法对厦门海域浮游植物生长率(k)和微型浮游动物的摄食率(g)进行了估算。结果显示：5月,西海域18测站k、g分别为2．41、0．78d^-1;南部海域27测站分别为2．43、1．32d^-1。8月18测站k、g分别为3．00、2．90d^-1;27测站分别为1．94、0．91d^-1。说明厦门海域作为典型的亚热带港湾,具有高的k、g值。分粒级研究结果显示：8月,18测站微型浮游动物对微型浮游植物(Micro)具摄食偏好;而27测站微型浮游动物对Micro和Nano级的摄食率相近。应用流式细胞技术研究18测站微微型真核浮游植物的k、g,结果表明：春季,生长率和摄食率分别为2．00、1．02d^-1;夏季分别为1．52、0．96d^-1。     

Assessment of mammal reproduction for hunting sustainability through community‐based sampling of species in the wild

Wildlife subsistence hunting is a major source of protein for tropical rural populations and a prominent conservation issue. The intrinsic rate of natural increase. (r_max) of populations is a key reproductive parameter in the most used assessments of hunting sustainability. However, researchers face severe difficulties in obtaining reproductive data in the wild, so these assessments often rely on classic reproductive rates calculated mostly from studies of captive animals conducted 30 years ago. The result is a flaw in almost 50% of studies, which hampers management decision making. We conducted a 15‐year study in the Amazon in which we used reproductive data from the genitalia of 950 hunted female mammals. Genitalia were collected by local hunters. We examined tissue from these samples to estimate birthrates for wild populations of the 10 most hunted mammals. We compared our estimates with classic measures and considered the utility of the use of r_max in sustainability assessments. For woolly monkey (Lagothrix poeppigii) and tapir (Tapirus terrestris), wild birthrates were similar to those from captive populations, whereas birthrates for other ungulates and lowland‐paca (Cuniculus paca) were significantly lower than previous estimates. Conversely, for capuchin monkeys (Sapajus macrocephalus), agoutis (Dasyprocta sp.), and coatis (Nasua nasua), our calculated reproductive rates greatly exceeded often‐used values. Researchers could keep applying classic measures compatible with our estimates, but for other species previous estimates of r_max may not be appropriate. We suggest that data from local studies be used to set hunting quotas. Our maximum rates of population growth in the wild correlated with body weight, which suggests that our method is consistent and reliable. Integration of this method into community‐based wildlife management and the training of local hunters to record pregnancies in hunted animals could efficiently generate useful information of life histories of wild species and thus improve management of natural resources.     

沿海滩涂垦殖对土壤氮总转化速率的影响分析

滩涂湿地在吸收、转化和滞留氮、磷等营养元素方面具有重要功能。选取江苏东部沿海典型滩涂区,分别对垦殖时间为0、3、6、17、30、60 a的沿海滩涂进行采样,对相应的土壤氮总转化速率指标进行实验测定。结果表明,滩涂垦殖后,表征氮素活化过程的指标,如总矿化率、总硝化率、净矿化率和净硝化率等有所增加,而有利于氮固持的铵态氮同化率指标无显著变化,硝态氮同化率指标变慢;围垦期限超过30 a后,各氮总转化速率指标渐趋稳定。相关性分析表明,净矿化率、总矿化率、铵态氮同化率、净硝化率、总硝化率与围垦年限呈显著正相关(p<0.01),相关性系数分别为0.966、0.929、0.819、0.800、0.798;硝态氮同化率与围垦年限呈显著负相关(p<0.01),相关性系数为-0.685;除铵态氮外,全氮、硝态氮、pH值、有机碳均与各氮总转化速率指标呈显著相关关系(p<0.01)。滩涂垦殖后土壤理化性质指标的改变带来土壤氮总转化速率的变化,一定程度上破坏了土壤氮生态系统平衡。     

ABR-MBR工艺处理生活污水实现短程硝化

采用ABR-MBR耦合工艺对MBR反应器中实现短程硝化的运行控制条件进行了研究,并为后续研究系统的反硝化除磷性能打下基础.ABR-MBR耦合工艺在不同条件下的运行研究结果表明,在ABR反应器的水力停留时间(hydraulic retention time,HRT)6 h,污泥回流比100%,硝化液回流比300%,温度30℃±2℃的条件下,通过控制好氧区溶解氧浓度(DO从0.5~1.0 mg·L~(-1)降为0.3~0.7 mg·L~(-1))以及改变MBR反应器有效容积以控制其HRT,最终在MBR反应器HRT从3 h逐步延长至5 h时短程硝化遭到破坏,亚硝酸盐积累率(nitrite accumulation rate,NAR)从60%急剧下降至15%.短程硝化影响因素的分析表明:pH值、游离氨(free ammonia,FA)和游离亚硝酸(free nitrous acid,FNA)对本试验实现短程硝化无显著影响,维持低DO浓度(0.3~0.7 mg·L~(-1))并逐步缩短HRT是本试验实现短程硝化的关键控制因素,温度和污泥停留时间(sludge retention time,SRT)可作为辅助因素与之共同调控.短程硝化期间,系统获得了高效且稳定的COD和NH_4~+-N去除效果,平均出水浓度分别低于50 mg·L~(-1)和2 mg·L~(-1),去除率均在90%以上,TN平均去除率高达72%.     

Degradation of monofluorophenols in water irradiated with gaseous plasma

Decomposition of aqueous monofluorophenols (MFPs) was investigated by contact glow discharge electrolysis (CGDE). During CGDE, both MFPs and the corresponding total organic carbon (TOC) in water were consumed smoothly, suggesting that carbon atoms of benzene nucleus could be eventually mineralized to inorganic carbon (IC). And all the fluorine atoms in the MFPs were equally converted to fluoride ions. Based on the primary intermediates from each starting materials, it showed that aromatic hydroxylation preferentially occurred at the para-or ortho-position to the phenolic OH group of each MFPs. The disappearance of both MFPs and TOC followed the first-order rate law. The apparent rate constants for the decay of MFPs were independent from the pK_a values of MFPs.     

美人蕉生态护坡对径流污染净化作用的初步研究

2010-04-10月,研究了合肥市南淝河美人蕉生态护坡对河道的水质改善作用。试验用水取自南淝河,TSS、TN、NH4+-N、TP和COD的平均浓度分别是94.1,5.42,2.98,0.202和55.5 mg/L,河水经流生态护坡后,相应的平均去除率分别为:76.4%,45.6%,57.5%,40.1%和29.0%。另外,考察了植物对土壤微生物(细菌、真菌、放线菌)数量的影响,美人蕉护坡微生物的数量显著多于无植物坡岸(p<0.01),微生物总数分别为:3.17×107和0.830×107cfu/g。由此,植物护坡兼具净化和生态景观效应。     

UASB系统低 pH运行时对产氢性能的分析

采用升流式厌氧污泥床(UASB)作为反应装置,以红糖水为发酵底物,污水处理厂剩余污泥为反应的启动污泥,加入活性炭固定污泥成颗粒状,形成稳定的乙醇型发酵后,对生物制氢系统在低pH运行时的产氢性能进行了研究.结果表明,在进水COD浓度为4 000 mg·L-1、温度为(35±1)℃、水力停留时间(HRT)为8 h的条件下,投加NaHCO3将出水pH由稳定期的3.72分别提高至3.80、3.85、3.94、4.04,稳定时的产氢速率由5.5 L·d-1提高到约7.0、8.0、9.5、6.0 L·d-1,较稳定期分别提高了27.27%、45.45%、72.73%、9.09%.pH为3.94时,产气速率也达到最大值15.83 L·d-1,是稳定期产气量的1.75倍,产氢效率为58.05%,产气产氢效果最佳,突破了发酵法制氢pH的下限值4.0.