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431.
AnnAGNPS 模型应用于辽河源头小流域的主要参数确定方法 总被引:3,自引:0,他引:3
农业非点源污染已成为辽河源头区水体污染的治理重点,农业非点源污染模型AnnAGNPS(Annualized Agricultural Non-point Source Pollution Model)模拟农业非点源污染是可行的,但模拟精度取决于模型参数.本文以辽河源头区典型小流域为例,根据集水区的划分与流域非点源污染的空间分布密切相关,以不同的临界汇水区面积CSA(the critical source area)和最小初始沟道长度MSCL(the minimum source channel length)划分出不同数量的集水区进行多次模型模拟,当多种污染源负荷均趋于稳定时确定集水区单元划分数量;针对我国土壤普查数据的土壤质地体系与建立AnnAGNPS模型的土壤质地体系不同,假设土壤累积粒径成对数正态分布,利用插值进行土壤粒径的转换,采用EPIC(Erosion-Productivity Impact Calculator)模型计算土壤可蚀性因子;经多次模拟实验与野外实测数据分析,上述确定参数方法是可行的. 相似文献
432.
超低排放路线下燃煤烟气可凝结颗粒物在WFGD、WESP中的转化特性 总被引:8,自引:6,他引:8
固定污染源可凝结颗粒物在监测时常被忽视,为了减少可凝结颗粒物排放,本文研究了其在烟气净化设施中的转化规律.结果表明,湿法脱硫装置、湿式电除尘装置对可凝结颗粒物的去除有协同作用,烟气中可凝结颗粒物质量浓度均高于可过滤颗粒物,但总颗粒物(可凝结颗粒物和可过滤颗粒物之和)排放量达到超低排放要求.在湿法脱硫进出口处可凝结颗粒物中有机物的质量浓度均超过了无机物的质量浓度,但在湿式电除尘出口处趋近相等.根据可凝结颗粒物无机部分水溶性离子成分及浓度的测试结果,推测可凝结颗粒物捕集过程中会有PM0.3进入,可凝结颗粒物形成过程中会产生酸雾,并且在湿法脱硫、湿式电除尘作用下,酸性加强.本研究发现SO2-4是可凝结颗粒物无机部分主要的特征水溶性离子. 相似文献
433.
434.
活性炭纤维(ACF)经硝酸处理后采用浸渍法制备了CeO2-CoO/ACF复合催化剂,测试了其在以氨气为还原剂的低温SCR过程中的催化活性,同时研究了金属氧化物浸渍顺序及负载量、催化剂煅烧温度、空速比(SV)、NH3/NO(摩尔比)、O2含量等因素对NO转化效率的影响。研究发现,负载量为10%的CeO2-CoO/ACF复合催化剂经煅烧后在120~240℃时具有很高的催化活性,并且在NO初始浓度为1 000 mg/m3、空速比(SV)为6 000 h-1、NH3/NO为1.05、O2体积分数在3.0%时具有较高的NO转化效率。 相似文献
435.
目前,水质监测的范围非常广泛,通常包括易受污染水体和未受污染水体的监测。一般在水质监测过程中,首先需要确定的是科学合理的检测方法,然后对影响该检测方法精度的因素进行综合分析并进行有效监测,当今水质监测中氨氮浓度是评价水质好坏的重要指标之一。基于此,文章综合分析了水体中氨氮浓度检测的基本原理并重点探讨了水体监测中影响氨氮测定的主要因素。 相似文献
436.
Power fluctuation and fault-related complication are the two major issues for doubly fed induction generator (DFIG)-based wind energy conversion system (WECS). The occurrence of fault leads to the rotor over current, stator over current, and DC-link overvoltage as well. These uncertainties may damage the rotor circuit, converter circuit and force the disconnection of wind system from the grid. To get rid of these issues, a supercapacitor energy storage element along with a passive series dynamic resistor (SDR) is suggested in this paper. Supercapacitor energy storage system (SCESS) is located across the DC-link, which able to handle the power fluctuation and the SDR is placed in rotor circuit, which will reduce the overcurrent possibility. Simulation is carried for a DFIG-based WECS for three phase to ground fault and two phase to ground fault. During symmetrical fault as well as asymmetrical fault, various operational disorders appeared such as rotor overcurrent, stator overcurrent and DC-Link overvoltage are found to be within their permissible limits. The results reveal the effectiveness of the proposed strategy over the conventional vector control scheme and SCESS as well. 相似文献
437.
ABSTRACTNitrogen (N) application is the main agricultural management that increases nitrous oxide (N2O) concentration in the atmosphere. Freezing conditions are common phenomenon in the northern China that significantly affect soil N2O emissions through alterations in nutrients availability and microbial population. To develop a comprehensive understanding of how N fertilizer managements affect soil N2O emissions during the freezing process, a lab incubation was conducted in three typical cultivated soils (black soil, fluvo-aquic soil, or loess soil) by adding different N fertilizer sources, including ammonium chloride, sodium nitrate, or urea at different N levels (0, 80, 200, or 500 mg N/kg) at the start of freezing. The N2O emissions in the fluvo-aquic soil were significantly higher than in other soils. The application of nitrate in the fluvo-aquic soil promoted N2O emissions by five- and seven-fold higher compared to ammonium chloride and urea, whereas N2O emissions in black soil were enhanced by application of ammonium chloride. Data indicate that denitrification is the major pathway for N2O production in the fluvo-aquic soil during the freezing process, while ammonia oxidation responses accounts for elevated N2O production in black soil. No significant influence of N fertilizer levels on N2O emissions were found during soil freezing. These results suggest that agricultural practices that focus on mitigation of N2O emissions need to avoid selection of nitrate as N fertilizer source in fluvo-aquic soil prior to the freezing season. Future studies need to focus on how the expression of enzymes and/or shifts in microbial communities respond to different N fertilizers during freezing conditions. 相似文献
438.
Madhavaraj Lavanya Ho-Dong Lim Kong-Min Kim Dae-Hyuk Kim Balasubramani Ravindran Gui Hwan Han 《Frontiers of Environmental Science & Engineering》2020,14(3):53
439.
Xiaofeng Liao Shuangyan Zhu Delai Zhong Jingping Zhu Li Liao 《Waste management (New York, N.Y.)》2014,34(11):2278-2284
In order to investigate the effect of raw leachate on anaerobic digestion of food waste, co-digestions of food waste with raw leachate were carried out. A series of single-phase batch mesophilic (35 ± 1 °C) anaerobic digestions were performed at a food waste concentration of 41.8 g VS/L. The results showed that inhibition of biogas production by volatile fatty acids (VFA) occurred without raw leachate addition. A certain amount of raw leachate in the reactors effectively relieved acidic inhibition caused by VFA accumulation, and the system maintained stable with methane yield of 369–466 mL/g VS. Total ammonia nitrogen introduced into the digestion systems with initial 2000–3000 mgNH4–N/L not only replenished nitrogen for bacterial growth, but also formed a buffer system with VFA to maintain a delicate biochemical balance between the acidogenic and methanogenic microorganisms. UV spectroscopy and fluorescence excitation–emission matrix spectroscopy data showed that food waste was completely degraded.We concluded that using raw leachate for supplement water addition and pH modifier on anaerobic digestion of food waste was effective. An appropriate fraction of leachate could stimulate methanogenic activity and enhance biogas production. 相似文献
440.
空气和煤气吹脱法处理高氨氮废水的对比研究 总被引:1,自引:0,他引:1
研究了在实验室使用空气吹脱法去除高浓度氨氮废水的条件,通过正交实验得出其影响因素大小顺序为:废水pH>气液比r>废水温度tw>表面活性剂浓度c,最佳吹脱条件为pH=11.0,r=550,c=10mg/L,tw=75℃,最高氨氮去除效率达到71.4%。在某焦化厂以终冷塔后焦炉煤气为解吸介质,现场试验影响因素大小顺序为:o废水pH>废水温度tw>气液比r>煤气温度tg>表面活性剂浓度c,最佳吹脱条件为pH=11.5,tw=90℃,r=650,tg=55℃,c=20mg/L。为煤气吹脱解吸回收氨工艺的应用提出了建议。 相似文献