响应面法优化超声-微波协同萃取蓝藻中叶绿素a工艺研究

为了探索蓝藻叶绿素a的最佳萃取工艺参数,在单因素试验基础上,选取乙醇体积分数、萃取时间以及液固体积质量比为自变量,叶绿素a萃取得率为响应值,采用中心组合设计的方法,研究各自变量及其交互作用对响应值叶绿素a萃取率的影响。利用响应面分析方法,模拟得到了2次多项式回归方程的预测模型,并确定叶绿素a萃取工艺的最佳参数:乙醇体积分数86%、时间133 s、液固体积质量比16∶1(mL∶g),在开启超声波、微波功率250 w、萃取两次的条件下,叶绿素a萃取率达到(2.686±0.013)mg/g。     

南水北调中线总干渠藻类的生态调度

南水北调中线总干渠无在线调蓄水库,对藻类生态调度过程中出现的问题开展生态调度实现策略和实施方式研究。主要实现策略包括:划定自身的调蓄区,隔离生态调度对下游的影响;采用高效的渠池运行方式,减少生态调度时蓄量的反复调整;综合考虑安全、快速、平稳等需求,设定生态调度实施进程和方式。具体实施方式包括:将总干渠划分为流速调控区、调蓄区和正常运行区,分别实施等体积、控制蓄量和闸前常水位方式运行;将生态调度过程划分为充水阶段和泄水阶段,基于流速调控目标值、持续时长和水位降幅约束条件,确定各阶段时长和各分区的闸门群调控方案等。基于2018年3月输水工况,采用明渠一维非恒定流模型,仿真总干渠上游15个渠池的藻类生态调度过程。结果表明,生态调度可在3.5 d内完成,各渠池的平均流速由0.48 m/s增至0.93 m/s,持续时间超过2 h。在整个生态调度过程中,水位变化平稳,水位变幅符合安全阈值要求,下游渠道的正常运行未受生态调度明显影响。     

Carbon,nitrogen and phosphorus recovery from liquid swine wastes: a review

Due to the pollution characteristics of the wastewater generated in piggeries, these waste streams have to be treated before discharging into the environment. These wastes have a high content of organic matter, nitrogen and phosphorus that can be converted or recovered into valuable products. The valuation of swine waste by anaerobic digestion has already been assessed, but no systematic review on the technologies used for recovering nutrients from this waste has been reported to date. Therefore, the present work has the goal of presenting the most studied technologies to different scales of recovery of carbon (i.e. organic matter), nitrogen and phosphorus from swine waste. The main characteristics and parameters of the processes involved in these technologies (mainly air stripping, membrane, enhance biological phosphorus removal and struvite formation) are also highlighted, pointing out its advantages and disadvantages and posing some final feasibility considerations on the subject addressed. Experiments reported in the literature proved that technologies used for nutrient recovery from swine waste are mostly applied to the effluents previously treated by anaerobic digestion as a primary treatment, and greater effort is required for the future implementation of these technologies in large scale. © 2020 Society of Chemical Industry     

深度学习在藻类分类识别中的应用

为了解决藻类分类识别中人工选取特征困难的问题,提出了一种基于深度学习的藻类分类识别方法。首先,对训练和测试样本集数据进行处理,得到所需数据的格式;其次,研究各种深度学习模型,理解卷积层、全连接层等的作用,基于Caffe设计深度学习网络模型;最后,根据设计的深度学习网络模型,比较各个模型的性能,得到最好的模型。实验结果表明,使用该方法做藻类分类,优于张松等基于视觉词包模型训练SVM分类器的方法,得到比较理想的效果。     

Biofilm early stage development in two nutrient‐rich streams with different urban impacts

The aim of this study was to describe the colonization of the biofilm during its early stages under different concentrations of nutrients and organic matter, specifically in urban streams influenced by agriculture and urbanization. We hypothesized that in a stream with higher concentrations of nutrients and organic matter, the initial biomass growth would be faster, and the changes in the structure of the community would be greater. Sterile glass substrates were placed in 2 urban streams that differed in nutrient and organic matter concentrations; samples were collected during their first week of colonization to measure total biomass, bacterial biomass, chlorophyll a, activity of the electron transfer system, and the community composition. Results show that biofilm development in both streams began within a few hours and differed under different conditions of nutrients; in the stream with a better water quality, the colonization dynamics consisted of 2 increments of bacterial biomass linked with an increase of algal biomass. In the urban stream with higher nutrient and organic matter concentrations, biofilm development was slower and consisted of a simultaneous increase of bacteria and algae, consistent with a lower electron transfer system activity. Therefore, the dynamics of the colonization process in addition to those characteristics of the fully developed biofilm could have potential applications in water monitoring of urban streams.     

渭河流域水生态系统群落结构特征及其健康评价

以渭河流域为对象,基于77个点位的水生态采样和调查结果,分析了该流域干支流着生藻类、大型底栖动物和鱼类3种生物类群群落结构特征,采用生物完整性指数评价了渭河流域鱼类、大型底栖动物和着生藻类的完整性,并对3种生物类群进行评价分析与比较。结果表明:基于3种生物类群的水生态系统健康评价结果存在一定差异,主要是由于3种生物类群对环境变化的响应各有不同,其中大型底栖动物的评价结果最好,其次为着生藻类,鱼类健康评价结果最差。综合来看,渭河流域水生态系统健康状况较差,受人类活动影响明显,大体表现为从上游到下游健康状况越来越差的趋势。对于渭河流域,影响鱼类、大型底栖动物和着生藻类的环境因子各有不同。通过系统全面地调查分析渭河流域不同生物类群的群落结构,可为流域水生态系统恢复提供科学依据。