浅析氨氮在线自动监测仪的应用情况与存在问题

氨氮在线自动监测仪已经在我国水质自动监测系统中得到广泛应用。目前,氨氮在线自动监测仪生产厂家众多,各有特色。生产厂家技术日趋成熟、相关标准逐步出台、仪器性能基本达标。但在实际应用过程中,根据各地的实际情况,在仪器的使用和维护方面还有很多问题需要进一步认识和改进。文章从多个方面对几种典型的氨氮在线自动监测仪进行了分析和比较,并提出了相关建议。     

Effects of nonionic surfactant Triton X-100 on the laccase-catalyzed conversion of bisphenol A

The laccase-catalyzed conversion of bisphenol A (BPA) in aqueous solutions was studied in the absence and presence of nonionic surfactant Triton X-100. It was found that the addition of Triton X-100 into the reaction system increased the conversion of BPA, especially near the critical micelle concentration of Triton X-100. Also it was found that the stability of laccase was greatly improved in the presence of TritonX-100. Studies on the endogenous fluorescence emission of laccase indicated that there existed an interaction between Triton X-100 and laccase, which was beneficial to folding and stabilizating of laccase. The binding of Triton X-100 to the laccase surface also mitigated the inactivation e ect caused by the free radicals and polymerization products. Under otherwise identical conditions, a lower dosage of laccase was needed for the higher conversion of BPA in the presence of Triton X-100.     

ASM3在城市污水处理厂工艺调整中的应用

现今城市污水处理厂氨氮处理能力不强,工艺改进实验需要大量资金投入,为了解决这一问题．结合国际水质协会（IWA）开发推荐的活性污泥模型（ASM3）数学模型来寻找一个最佳的解决方案,以便对污水处理厂工艺优化分析及模拟优化改造。     

Microbial fuel cell with three-dimensional electrodes for domestic wastewater treatment and electricity generation北大核心CSCD

A single chamber microbial fuel cell (MFC) with three-dimensional electrodes packed bed carbon felts was developed to treat domestic wastewater while simultaneously generating electricity. The influence of batch and continuous operation mode on treatment effectiveness and electricity production of the MFC was investigated to provide a reference for the application of the MFC. The MFC with a total working volume of 1 440 mL was operated in the fed-batch mode for 5 d repeatedly three times, and then shifted to the continuous mode. During the testing of the continuous mode, wastewater was continuously pumped into the anode compartment at a flow rate of approximately 0.2 mL/min, resulting in a hydraulic retention time of 5 d. During the batch test, the MFC obtained 91.1% chemical oxygen demand (COD) and 98.2% NH4 +-N removal, which accorded with the first criteria specified in the discharge standard of pollutants for municipal wastewater treatment plants in China (GB18918-2002). A maximum power density of 27.88 mW/m3 was achieved at a 51 Ω external resistor. During the continuous test, the COD removal efficiencies ranged from 83.2% to 97.4%. The concentration of NH4 +-N gradually decreased within 5 d and was then maintained below 9.45 mg/L, thus an enhanced removal performance of NH4 +-N was acquired. However, a low removal efficiency of total nitrogen was observed owing to the accumulation of NO3 --N in the effluent since day 11. Additionally, the MFC continually generated electricity with a maximum power density of 582.5 mW/m3 and average output voltage of 0.087 7 V during the stable period in the continuous operation mode. Moreover, 16S rRNA gene high-throughput sequencing showed that Thauera sp., Saprospiraceae-UN sp., and OPB56-UN sp. were identified as dominant populations. The results suggested that the organic matter associated with power generation was constantly utilized by the microorganisms in the reactor, which caused an excellent electricity generation performance during the continuous test. Therefore, the continuous operation mode could improve the low output voltage phenomenon in the MFC. Thauera sp., as a type of nitrate-reducing bacteria, was enriched in the autotrophic denitrifying microbial communities; therefore, bio-enrichment with denitrifying bacteria such as Thauera sp. could decrease the concentration of NO3 --N in the effluent during the continuous operation mode, which is expected to be an innovation for improvement of wastewater treatment. © 2018 Science Press. All rights reserved.     

δ15N-stable isotope analysis of NHx: An overview on analytical measurements,source sampling and its source apportionment

• Challenges in sampling of NH₃ sources for d¹⁵N analysis are highlighted. • Uncertainties in the isotope-based source apportionment of NH₃ and NH₄⁺ are outlined. • Characterizing dynamic isotopic fractionation may reduce uncertainties of NH_x science. Agricultural sources and non-agricultural emissions contribute to gaseous ammonia (NH₃) that plays a vital role in severe haze formation. Qualitative and quantitative contributions of these sources to ambient PM_2.5 (particulate matter with an aerodynamic equivalent diameter below 2.5 µm) concentrations remains uncertain. Stable nitrogen isotopic composition (δ¹⁵N) of NH₃ and NH₄⁺ (δ¹⁵N(NH₃) and δ¹⁵N(NH₄⁺), respectively) can yield valuable information about its sources and associated processes. This review provides an overview of the recent progress in analytical techniques for δ¹⁵N(NH₃) and δ¹⁵N(NH₄⁺) measurement, sampling of atmospheric NH₃ and NH₄⁺ in the ambient air and their sources signature (e.g., agricultural vs. fossil fuel), and isotope-based source apportionment of NH₃ in urban atmosphere. This study highlights that collecting sample that are fully representative of emission sources remains a challenge in fingerprinting δ¹⁵N(NH₃) values of NH₃ emission sources. Furthermore, isotopic fractionation during NH₃ gas-to-particle conversion under varying ambient field conditions (e.g., relative humidity, particle pH, temperature) remains unclear, which indicates more field and laboratory studies to validate theoretically predicted isotopic fractionation are required. Thus, this study concludes that lack of refined δ¹⁵N(NH₃) fingerprints and full understanding of isotopic fractionation during aerosol formation in a laboratory and field conditions is a limitation for isotope-based source apportionment of NH₃. More experimental work (in chamber studies) and theoretical estimations in combinations of field verification are necessary in characterizing isotopic fractionation under various environmental and atmospheric neutralization conditions, which would help to better interpret isotopic data and our understanding on NH_x (NH₃ + NH₄⁺) dynamics in the atmosphere.     

高温条件下EGSB处理酒精废水的流态及基质产沼气转化

通过流态实验,分析了EGSB反应器在高温条件下处理酒精废水的流态特征,考察了EGSB产沼气转化和基质降解能力。结果表明,EGSB的死区容积仅为4.47%,CSTR的串联数N为2.42,离散数D为0.286,反应器流态趋近于完全混合式。反应器运行第3~66天和第202~275天2个时间段标准状态下的沼气转化率分别为0.213 m3/kg COD和0.315 m3/kg COD,均低于理论沼气转化率。生物降解动力学分析表明,EGSB在高温条件下对基质的降解能力较强。     

High solids co-digestion of food and landscape waste and the potential for ammonia toxicity

A pilot-scale study was completed to determine the feasibility of high-solids anaerobic digestion (HSAD) of a mixture of food and landscape wastes at a university in central Pennsylvania (USA). HSAD was stable at low loadings (2 g COD/L-day), but developed inhibitory ammonia concentrations at high loadings (15 g COD/L-day). At low loadings, methane yields were 232 L CH₄/kg COD fed and 229 L CH₄/kg VS fed, and at high loadings yields were 211 L CH₄/kg COD fed and 272 L CH₄/kg VS fed. Based on characterization and biodegradability studies, food waste appears to be a good candidate for HSAD at low organic loading rates; however, the development of ammonia inhibition at high loading rates suggests that the C:N ratio is too low for use as a single substrate. The relatively low biodegradability of landscape waste as reported herein made it an unsuitable substrate to increase the C:N ratio. Codigestion of food waste with a substrate high in bioavailable carbon is recommended to increase the C:N ratio sufficiently to allow HSAD at loading rates of 15 g COD/L-day.     

长期保藏对厌氧氨氧化污泥脱氮性能的影响

主要目的是开发经济有效的ANAMMOX污泥保藏技术。把厌氧氨氧化污泥在30℃、自然环境、5℃和-20℃下分别保藏15、30、45、150和365 d。结果表明,保藏后的厌氧氨氧化污泥对底物的转化比都不是典型的ANAMMOX反应计量比。通过物料衡算,保藏后的污泥都具有不同程度的硝化能力。冷冻(-20℃)保藏不但运行费用高,而且使污泥的厌氧氨氧化活性丧失。厌氧氨氧化污泥在5℃保藏后的剩余活性高于同期30℃保藏的污泥。但短期(≤45 d)内,厌氧氨氧化污泥在自然环境(春、秋和冬季)中避光缺氧保藏是较经济有效的方法。     

中国高速铁路运营的减碳及经济环境互馈影响研究

二氧化碳等温室气体排放备受世界关注,新形势下低碳发展成为中国发展路径的新选择,而高速铁路是长距离运输低碳化的具体体现。基于运营阶段的行车碳排放换算,综合考虑多种交通工具的实际运载能力、标准运行速度等指标,分析中国高速铁路行车运营的减碳效果及经济环境互馈影响。研究发现:(1)以单位运输能耗量及该能源的碳排放系数计算,中国高速铁路行车与其余交通运输方式相比具有显著减碳效果,其百公里人均碳排放量约为航空运输的1/5和高速公路运输的1/3,且随着中国能源结构的逐步优化,减碳效果将会愈发凸显。(2)结合中国旅客周转量比例进行折算,自2008年至2015年高速铁路运输累计减碳2 610万t,从空间上看,省域差距明显,高速铁路运输繁忙的京沪线及京广线沿线地区,成为2015年高速铁路行车运营减碳效果的高值区,亦由此呈现出带状聚邻的正空间自相关性。(3)高速铁路运营产生经济环境的良性互馈影响,一方面环境优化具有潜在经济效益,2008—2015年的减碳效果相当于降低碳交易成本逾10亿元,其绿色设计及应用也益于区域经济发展;另一方面高速铁路运营经济收益具有潜在环境补偿能力,2008—2015年累计对区域节能环保支出贡献逾30亿元,其中高值区以中国中部地区为主,空间分布呈斜T字型结构,其成因与地区节能环保支出占比、出行结构等因素相关。基于上述分析并结合中国发展的客观实际,提出合理增强高速铁路运输效能、继续优化能源供给结构等优化对策,以期从出行视角为中国低碳发展提供交通领域的理论支撑。     

Design and analysis of artificial bee-colony-based MPPT algorithm for DFIG-based wind energy conversion systems

In this article, the proposed maximum power point tracking (MPPT) method is designed by taking rotor speed as an optimization problem, which is solved by artificial bee colony (ABC) algorithm to generate the maximum power output. The main advantage of this algorithm is that its optimal solution is independent of the initial positions and requirement of lesser number of control parameters, which leads to simple and robust MPPT algorithm than other algorithm. Furthermore, the hill climb search and particle swarm optimization-based MPPT algorithm are also discussed and the results obtained by these are compared to verify the effectiveness of proposed algorithm. Simulations for MPPT control along with doubly fed induction-generator-based wind energy conversion system is carried out in MATLAB/Simulink environment. Three statistical methods are used to evaluate the accuracy of each MPPT algorithm. All results are analyzed and compared under randomly selected wind as well as real wind speed configuration. Comparison of both numerical and simulation results under two different varying wind speed conditions strongly suggest that the proposed ABC-based MPPT algorithm is superior than other two MPPT algorithms.