基于三层网络的SBR法深度脱氮智能控制系统的中试研究

以一座处理量为60m3·d-1的SBR法中试系统为研究对象,将三层网络智能控制技术引入SBR工艺中,并对该智能控制系统的深度脱氮效果和稳定性进行了中试研究.在SBR法硝化反硝化过程中,pH、DO、ORP曲线上会出现反映生物脱氮进程的特征点,以pH、DO、ORP为控制参数建立的智能控制策略可以准确判断反应的终点,避免了过度曝气,在保证深度脱氮的前提下节省了能耗.经过10个月的稳定运行,即使在温度较低的情况下,该SBR法智能控制中试系统出水的各项指标完全能够达到国家污水排放一级标准,并且达到了深度脱氮的效果,出水COD低于50 mg·L-1,总氮低于5 mg·L-1.     

Effects of salinity on multiplication and transmission of an intertidal trematode parasite

Salinity levels vary spatially in coastal areas, depending on proximity to freshwater sources, and may also be slowly decreasing as a result of anthropogenic climatic changes. The impact of salinity on host–parasite interactions is potentially a key regulator of transmission processes in intertidal areas, where trematodes are extremely common parasites of invertebrates and vertebrates. We investigated experimentally the effects of long-term exposure to decreased salinity levels on output of infective stages (cercariae) and their transmission success in the trematode Philophthalmus sp. This parasite uses the snail Zeacumantus subcarinatus as intermediate host, in which it asexually produces cercariae. After leaving the snail, cercariae encyst externally on hard substrates to await accidental ingestion by shorebirds, which serve as definitive hosts. We found that at reduced salinities (25 or 30 psu), the cercarial output of the parasite was lower, the time taken by cercariae to encyst was longer, fewer cercariae successfully encysted and encysted parasites had lower long-term survival than at normal seawater salinity (35 psu). The strong effect of salinity on the replication and transmission of this parasite suggests that there may be sources and sinks of transmission to birds along coastal areas, depending on local salinity conditions. Also, unless it evolves to adapt to changing conditions, the predicted reduction in salinity as a consequence of climate change may have negative impact on the parasite’s abundance.     

Advanced nitrogen removal using pilot-scale SBR with intelligent control system built on three layer network

Since eutrophication has become increasingly severe in China, nitrogen and phosphorous have been the concern of wastewater treatment, especially nitrogen removal. The stabilization of the intelligent control system and nitrogen removal efficiency were investigated in a pilot-scale aerobic-anoxic sequencing batch reactor (SBR) with a treatment capacity of 60 m³/d. Characteristic points on the profiles of dissolved oxygen (DO), pH, and oxidation reduction potential (ORP) could exactly reflect the process of nitrification and denitrification. Using the intelligent control system not only could save energy, but also could achieve advanced nitrogen removal. Applying the control strategy water quality of the effluent could stably meet the national first discharge standard during experiment of 10 months. Even at low temperature (t = 13°C), chemical oxygen demand (COD) and total nitrogen (TN) in the effluent were under 50 and 5 mg/L, respectively.     

变频控制DO下SBR硝化反应控制参数及节能的中试研究

根据微生物好氧反应的需氧量调节曝气量在当今能源紧缺的形势下具有十分重要的意义.为了研究曝气量大小对SBR实时控制参数pH、DO的影响,采用变频器调节曝气量以控制系统不同的DO浓度,以60 m3中试SBR反应器处理北京市北小河污水处理厂城市污水,考察了硝化过程中pH值、DO与有机物去除及硝化过程的相关性,并引入了新的控制参数--变频频率f.试验结果表明,控制溶解氧浓度较低时,pH值不能作为硝化结束的控制参数,但可根据变频频率f的特征点判断硝化反应的结束;控制溶解氧为3.0 mg/L和4.0 mg/L时,DO、pH值、变频频率f都可作为硝化结束的控制参数,同时,变频控制可有效降低单位时间内风机的能耗.     

A review of atmospheric mercury emissions,pollution and control in China

Mercury, as a global pollutant, has significant impacts on the environment and human health. The current state of atmospheric mercury emissions, pollution and control in China is comprehensively reviewed in this paper. With about 500-800 t of anthropogenic mercury emissions, China contributes 25%-40% to the global mercury emissions. The dominant mercury emission sources in China are coal combustion, non-ferrous metal smelting, cement production and iron and steel production. The mercury emissions from natural sources in China are equivalent to the anthropogenic mercury emissions. The atmospheric mercury concentration in China is about 2-10 times the background level of North Hemisphere. The mercury deposition fluxes in remote areas in China are usually in the range of 10-50μg·m^-2·yr^-1. To reduce mercury emissions, legislations have been enacted for power plants, non-ferrous metal smelters and waste incinerators. Currently mercury contented in the flue gas is mainly removed through existing air pollution control devices for sulfur dioxide, nitrogen oxides, and particles. Dedicated mercury control technologies are required in the future to further mitigate the mercury emissions in China.     

Advanced nitrogen removal using pilot-scale SBR with intelligent control system built on three layer network

Since eutrophication has become increasingly severe in China, nitrogen and phosphorous have been the concern of wastewater treatment, especially nitrogen removal. The stabilization of the intelligent control system and nitrogen removal efficiency were investigated in a pilot-scale aerobic-anoxic sequencing batch reactor (SBR) with a treatment capacity of 60 m³/d. Characteristic points on the profiles of dissolved oxygen (DO), pH, and oxidation reduction potential (ORP) could exactly reflect the process of nitrification and denitrification. Using the intelligent control system not only could save energy, but also could achieve advanced nitrogen removal. Applying the control strategy water quality of the effluent could stably meet the national first discharge standard during experiment of 10 months. Even at low temperature (t = 13°C), chemical oxygen demand (COD) and total nitrogen (TN) in the effluent were under 50 and 5 mg/L, respectively. Translated from Acta Scientise Circumstantiae, 2006, 26(5): 745–750 [译自: 环境科学学报]     

植物铜素毒害及其抗性机制研究进展

Cu是植物生命活动必需的微量矿质元素，广泛参与各种生命活动；但过量Cu胁迫将诱导植物细胞产生大量活性氧，引起膜脂过氧化，膜透性增大，细胞内容物大量外渗，甚至发生细胞死亡。Cu^2 扩散到细胞核内会诱发DNA之间、蛋白质之间以及DNA和蛋白质之间发生分子内和分子间交联，DNA链的断裂、重排和脱嘌呤作用等前诱变损伤以及DNA期外合成、DNA甲基化异常等遗传毒害。植物细胞在长期进化过程中形成了各种抗Cu素毒害机制，如细胞壁的固着作用、质膜的限制作用、有机小分子(有机酸、植物螯合肽、金属硫蛋白)螯合作用等。文章综述了有关研究的最新进展。     

Measurement of tropospheric HO2 radical using fluorescence assay by gas expansion with low interferences

An instrument to detect atmospheric HO₂ radicals using fluorescence assay by gas expansion (FAGE) technique has been developed. HO₂ is measured by reaction with NO to form OH and subsequent detection of OH by laser-induced fluorescence at low pressure. The system performance has been improved by optimizing the expansion distance and pressure, the influence factors of HO₂ conversion efficiency are also studied. The interferences of RO₂ radicals were investigated by determining the conversion efficiency of RO₂ to OH during the measurement of HO₂. The dependence of the conversion of HO₂ on NO concentration was investigated, and low HO₂ conversion efficiency was selected to realize the ambient HO₂ measurement, where the conversion efficiency of RO₂ derived by propane, ethene, isoprene and methanol to OH has been reduced to less than 6% in the atmosphere. Furthermore, no significant interferences from PM_2.5 and NO were found in the ambient HO₂ measurement. The detection limits for HO₂ (S/N = 2) are estimated to 4.8 × 10⁵ cm^?3 and 1.1 × 10⁶ cm^?3 (${\rho }_{\mathrm{H}{\mathrm{O}}_2}$= 20%) under night and noon conditions, with 60 sec signal integration time. The instrument was successfully deployed during STORM-2018 field campaign at Shenzhen graduate school of Peking University. The concentration of atmospheric HOx radical and the good correlation of OH with j(O¹D) was obtained here. The diurnal variation of HOx concentration shows that the OH maximum concentration of those days is about 5.3 × 10⁶ cm^?3 appearing around 12:00, while the HO₂ maximum concentration is about 4.2 × 10⁸ cm^?3 appearing around 13:30.     

A hydroxyl radical detection system using gas expansion and fast gating laser-induced fluorescence techniques

An OH radical measurement instrument based on Fluorescence Assay by Gas Expansion(FAGE)has been developed in our laboratory.Ambient air is introduced into a low-pressure fluorescence cell through a pinhole aperture and irradiated by a dye laser at a high repetition rate of 8.5 k Hz.The OH radical is both excited and detected at 308 nm using A-X(0,0)band.To satisfy the high efficiency needs of fluorescence collection and detection,a 4-lens optical system and a self-designed gated photomultiplier(PMT)is used,and gating is actualized by switching the voltage applied on the PMT dynodes.A micro channel photomultiplier(MCP)is also prepared for fluorescence detection.Then the weak signal is accumulated by a photon counter in a specific timing.The OH radical excitation spectrum range in the wavelength of 307.82–308.2 nm is detected and the excited line for OH detection is determined to be Q_1(2)line.The calibration of the FAGE system is researched by using simultaneous photolysis of H_2O and O_2.The minimum detection limit of the instrument using gated PMT is determined to be 9.4×10~5molecules/cm~3,and the sensitivity is 9.5×10~(-7)cps/(OH·cm~(-3)),with a signal-to-noise ratio of 2 and an integration time of 60 sec,while OH detection limit and the detection sensitivity using MCP is calculated to be 1.6×10~5molecules/cm~3and 2.3×10~(-6)cps/(OH·cm~(-3)).The laboratory OH radical measurement is carried out and results show that the proposed system can be used for atmospheric OH radical measurement.     

配电设备的风险评估与状态检修决策方法

针对当前配电设备采用的定期检修方式未将可靠性与经济性综合考虑的问题，提出1种基于风险评估结果确定配电设备状态检修决策的方法。首先，根据配电设备健康状态评估结果计算配电设备实时健康指数，利用指数模型对配电设备的实时故障率进行计算；然后，采用最小路法计算配网中所有设备的平均实时故障率，并结合停电时用户损失严重度、配电设备损失严重度和环境损失严重度确定配电设备故障后果严重度；最后，利用风险偏好型效用函数量化计算配电设备的经济运行风险水平，计算各配电设备的相对风险值，并以相对风险值为指标确定各配电设备的状态检修策略。结合算例对所提的方法进行验证，结果表明该方法合理有效。