运行方式对潜流人工湿地氧分布及脱氮的影响

为了探究运行方式对水平潜流人工湿地脱氮效率的影响,分别采用了连续运行和不同落干时间的间歇运行方式处理生活污水。通过对比分析各方式下湿地床体溶解氧的空间分布来揭示脱氮效果差异。结果表明,间歇运行方式对湿地床体中上层有较明显复氧作用,落干时间的延长可以增强复氧效果;间歇运行方式下湿地的硝化和反硝化能力均要强于连续运行方式,其中硝化反应强度随着湿地氧环境的改善而提高,总氮的去除率与硝化反应强度呈正相关关系,但是间歇运行不同落干时间下反硝化能力没有显著差异,硝化反应强度是水平潜流人工湿地脱氮的限制因素。

搅拌桨组合的构型对螺旋霉素发酵合成的影响

通过对三种不同构型的搅拌桨在70m3发酵罐螺旋霉素发酵过程的应用设计研究,发现不同的搅拌构型对螺旋霉素发酵的影响作用不同。混合式搅拌桨传质能力强、混合效果好、搅拌剪切温和,有利于螺旋霉素产生菌的生长和产物的合成,螺旋霉素平均放罐效价较径向流组合搅拌桨提高了11.1%。

人工湿地强化复氧技术研究现状及设计构想

指出了改善人工湿地复氧能力以提高湿地处理能力的研究包括选用利于复氧的植物和填料、跌水曝气、进水端机械曝气、间歇式运行等,采取这些措施时,必须结合湿地规模、场地条件、卫生条件要求等实际情况。提出了一种基于间歇式运行的改良小型人工湿地设计构想,为该类型人工湿地强化复氧提供了设计思路。

Scavenging reactive oxygen species is a potential strategy to protect Larimichthys crocea against environmental hypoxia by mitigating oxidative stress

The large yellow croaker(Larimichthys crocea),which is an economically important mariculture fish in China,is often exposed to environmental hypoxia.Reactive oxygen species(ROS)homeostasis is essential for the maintenance of normal physiological conditions in an organism.Direct evidence that environmental hypoxia leads to ROS overproduction is scarce in marine fish.Furthermore,the sources of ROS overproduction in marine fish under hypoxic stress are poorly known.In this study,we investigated the effects of hypoxia on redox homeostasis in L.crocea and the impact of impaired redox homeostasis on fish.We first confirmed that hypoxia drove ROS production mainly via the mitochondrial electron transport chain and NADPH oxidase complex pathways in L.crocea and its cell line(large yellow croaker fry(LYCF)cells).We subsequently detected a marked increase in the antioxidant systems of the fish.However,imbalance between the pro-oxidation and antioxidation systems ultimately led to excessive ROS and oxidative stress.Cell viability showed a remarkable decrease while oxidative indicators,such as malondialdehyde,proteincarbonylation,and8-hydroxy-2 deoxyguanosine,showed a significant increase after hypoxia,accompanied by tissue damage.Nacetylcysteine(NAC)reduced ROS levels,alleviated oxidative damage,and improved cell viability in vitro.Appropriate uptake of ROS scavengers(e.g.,NAC and elamipretide Szeto-Schiller-31)and inhibitors(e.g.,apocynin,diphenylene iodonium,and 5-hydroxydecanoate)may be effective at overcoming hypoxic toxicity.Our findings highlight previously unstudied strategies of hypoxic toxicity resistance in marine fish.

Modeling of the Dissolved Oxygen in a River with Storage Zone on the Banks

The prediction of water quality in terms of variables like dissolved oxygen (DO), biochemical oxygen demand (BOD), pH value, total dissolved solids (TDS) and salinity etc. is useful for evaluating the use of water for various related purposes. The widely used Streeter and Phelps models for computing biochemical oxygen demand and its impact on dissolved oxygen do not account for the settleable component of BOD and related implications. The model also does not account for the impact of storage zone on the stream’s DO. In the present work an attempt is made to develop a model which simultaneously accounts for the settleable component of BOD and the effect of storage zones onriver’s DO. An application of the model to real field data suggests that the cumulative impact of settleable BOD and presence of storage zone in the river is to shift the critical deficit closer to the point source and magnify its amount.

废水的硝化作用

硝化作用是废水生物脱氮中的关键。本文介绍了硝化作用的生化反应、硝化细菌的类群、硝化反应动力学和影响硝化作用的主要环境因子：溶解氧、ｐＨ、温度和毒物。

某酶制剂厂废水处理系统的工艺调控与运行优化

针对某酶制剂厂废水处理系统存在的问题,采用在线氨氮浓度表征生物处理系统中有机物的降解程度,根据生物反应罐内的在线氨氮浓度设定溶解氧浓度,以此控制供风量,并采用三阶段控制方法。当有机物降解较彻底时,采用同步硝化反硝化工艺;随着有机物降解效果变差,提高溶解氧浓度的设定值;当有机物的降解效果较差时,采用完全好氧工艺。实际运行效果证明,该控制方法抗冲击负荷能力强,与原来的间歇曝气方法相比,对COD和氨氮的去除效果并没有下降,而且还明显改善了对硝酸盐氮和总氮的去除效果,污泥SV值有一定的降低,同时,该控制方法在运行过程中有效节约了14.45%的供风量,降低了运行成本。